dom/canvas/WebGLFramebuffer.cpp

   1 /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "WebGLFramebuffer.h"
   7
   8 // You know it's going to be fun when these two show up:
   9 #include <algorithm>
  10 #include <iterator>
  11
  12 #include "GLBlitHelper.h"
  13 #include "GLContext.h"
  14 #include "GLScreenBuffer.h"
  15 #include "MozFramebuffer.h"
  16 #include "mozilla/dom/WebGLRenderingContextBinding.h"
  17 #include "mozilla/IntegerRange.h"
  18 #include "nsPrintfCString.h"
  19 #include "WebGLContext.h"
  20 #include "WebGLContextUtils.h"
  21 #include "WebGLExtensions.h"
  22 #include "WebGLFormats.h"
  23 #include "WebGLRenderbuffer.h"
  24 #include "WebGLTexture.h"
  25
  26 namespace mozilla {
  27
  28 static bool ShouldDeferAttachment(const WebGLContext* const webgl,
  29                                   const GLenum attachPoint) {
  30   if (webgl->IsWebGL2()) return false;
  31
  32   switch (attachPoint) {
  33     case LOCAL_GL_DEPTH_ATTACHMENT:
  34     case LOCAL_GL_STENCIL_ATTACHMENT:
  35     case LOCAL_GL_DEPTH_STENCIL_ATTACHMENT:
  36       return true;
  37     default:
  38       return false;
  39   }
  40 }
  41
  42 WebGLFBAttachPoint::WebGLFBAttachPoint() = default;
  43 WebGLFBAttachPoint::WebGLFBAttachPoint(WebGLFBAttachPoint&) = default;
  44
  45 WebGLFBAttachPoint::WebGLFBAttachPoint(const WebGLContext* const webgl,
  46                                        const GLenum attachmentPoint)
  47     : mAttachmentPoint(attachmentPoint),
  48       mDeferAttachment(ShouldDeferAttachment(webgl, mAttachmentPoint)) {}
  49
  50 WebGLFBAttachPoint::~WebGLFBAttachPoint() {
  51   MOZ_ASSERT(!mRenderbufferPtr);
  52   MOZ_ASSERT(!mTexturePtr);
  53 }
  54
  55 void WebGLFBAttachPoint::Clear() { Set(nullptr, {}); }
  56
  57 void WebGLFBAttachPoint::Set(gl::GLContext* const gl,
  58                              const webgl::FbAttachInfo& toAttach) {
  59   mRenderbufferPtr = toAttach.rb;
  60   mTexturePtr = toAttach.tex;
  61   mTexImageLayer = AssertedCast<uint32_t>(toAttach.zLayer);
  62   mTexImageZLayerCount = AssertedCast<uint8_t>(toAttach.zLayerCount);
  63   mTexImageLevel = AssertedCast<uint8_t>(toAttach.mipLevel);
  64   mIsMultiview = toAttach.isMultiview;
  65
  66   if (gl && !mDeferAttachment) {
  67     DoAttachment(gl);
  68   }
  69 }
  70
  71 const webgl::ImageInfo* WebGLFBAttachPoint::GetImageInfo() const {
  72   if (mTexturePtr) {
  73     const auto target = Texture()->Target();
  74     uint8_t face = 0;
  75     if (target == LOCAL_GL_TEXTURE_CUBE_MAP) {
  76       face = Layer() % 6;
  77     }
  78     return &mTexturePtr->ImageInfoAtFace(face, mTexImageLevel);
  79   }
  80   if (mRenderbufferPtr) return &mRenderbufferPtr->ImageInfo();
  81   return nullptr;
  82 }
  83
  84 bool WebGLFBAttachPoint::IsComplete(WebGLContext* webgl,
  85                                     nsCString* const out_info) const {
  86   MOZ_ASSERT(HasAttachment());
  87
  88   const auto fnWriteErrorInfo = [&](const char* const text) {
  89     WebGLContext::EnumName(mAttachmentPoint, out_info);
  90     out_info->AppendLiteral(": ");
  91     out_info->AppendASCII(text);
  92   };
  93
  94   const auto& imageInfo = *GetImageInfo();
  95   if (!imageInfo.mWidth || !imageInfo.mHeight) {
  96     fnWriteErrorInfo("Attachment has no width or height.");
  97     return false;
  98   }
  99   MOZ_ASSERT(imageInfo.IsDefined());
 100
 101   const auto& tex = Texture();
 102   if (tex) {
 103     // ES 3.0 spec, pg 213 has giant blocks of text that bake down to requiring
 104     // that attached *non-immutable* tex images are within the valid mip-levels
 105     // of the texture. We still need to check immutable textures though, because
 106     // checking completeness is also when we zero invalidated/no-data tex
 107     // images.
 108     const auto attachedMipLevel = MipLevel();
 109
 110     const bool withinValidMipLevels = [&]() {
 111       const bool ensureInit = false;
 112       const auto texCompleteness = tex->CalcCompletenessInfo(ensureInit);
 113       if (!texCompleteness) return false;  // OOM
 114
 115       if (tex->Immutable()) {
 116         // Immutable textures can attach a level that's not valid for sampling.
 117         // It still has to exist though!
 118         return attachedMipLevel < tex->ImmutableLevelCount();
 119       }
 120
 121       // Base level must be complete.
 122       if (!texCompleteness->levels) return false;
 123
 124       const auto baseLevel = tex->Es3_level_base();
 125       if (attachedMipLevel == baseLevel) return true;
 126
 127       // If not base level, must be mip-complete and within mips.
 128       if (!texCompleteness->mipmapComplete) return false;
 129       const auto maxLevel = baseLevel + texCompleteness->levels - 1;
 130       return baseLevel <= attachedMipLevel && attachedMipLevel <= maxLevel;
 131     }();
 132     if (!withinValidMipLevels) {
 133       fnWriteErrorInfo("Attached mip level is invalid for texture.");
 134       return false;
 135     }
 136
 137     const auto& levelInfo = tex->ImageInfoAtFace(0, attachedMipLevel);
 138     const auto faceDepth = levelInfo.mDepth * tex->FaceCount();
 139     const bool withinValidZLayers = Layer() + ZLayerCount() - 1 < faceDepth;
 140     if (!withinValidZLayers) {
 141       fnWriteErrorInfo("Attached z layer is invalid for texture.");
 142       return false;
 143     }
 144   }
 145
 146   const auto& formatUsage = imageInfo.mFormat;
 147   if (!formatUsage->IsRenderable()) {
 148     const auto info = nsPrintfCString(
 149         "Attachment has an effective format of %s,"
 150         " which is not renderable.",
 151         formatUsage->format->name);
 152     fnWriteErrorInfo(info.BeginReading());
 153     return false;
 154   }
 155   if (!formatUsage->IsExplicitlyRenderable()) {
 156     webgl->WarnIfImplicit(formatUsage->GetExtensionID());
 157   }
 158
 159   const auto format = formatUsage->format;
 160
 161   bool hasRequiredBits;
 162
 163   switch (mAttachmentPoint) {
 164     case LOCAL_GL_DEPTH_ATTACHMENT:
 165       hasRequiredBits = format->d;
 166       break;
 167
 168     case LOCAL_GL_STENCIL_ATTACHMENT:
 169       hasRequiredBits = format->s;
 170       break;
 171
 172     case LOCAL_GL_DEPTH_STENCIL_ATTACHMENT:
 173       MOZ_ASSERT(!webgl->IsWebGL2());
 174       hasRequiredBits = (format->d && format->s);
 175       break;
 176
 177     default:
 178       MOZ_ASSERT(mAttachmentPoint >= LOCAL_GL_COLOR_ATTACHMENT0);
 179       hasRequiredBits = format->IsColorFormat();
 180       break;
 181   }
 182
 183   if (!hasRequiredBits) {
 184     fnWriteErrorInfo(
 185         "Attachment's format is missing required color/depth/stencil"
 186         " bits.");
 187     return false;
 188   }
 189
 190   if (!webgl->IsWebGL2()) {
 191     bool hasSurplusPlanes = false;
 192
 193     switch (mAttachmentPoint) {
 194       case LOCAL_GL_DEPTH_ATTACHMENT:
 195         hasSurplusPlanes = format->s;
 196         break;
 197
 198       case LOCAL_GL_STENCIL_ATTACHMENT:
 199         hasSurplusPlanes = format->d;
 200         break;
 201     }
 202
 203     if (hasSurplusPlanes) {
 204       fnWriteErrorInfo(
 205           "Attachment has depth or stencil bits when it shouldn't.");
 206       return false;
 207     }
 208   }
 209
 210   return true;
 211 }
 212
 213 void WebGLFBAttachPoint::DoAttachment(gl::GLContext* const gl) const {
 214   if (Renderbuffer()) {
 215     Renderbuffer()->DoFramebufferRenderbuffer(mAttachmentPoint);
 216     return;
 217   }
 218
 219   if (!Texture()) {
 220     MOZ_ASSERT(mAttachmentPoint != LOCAL_GL_DEPTH_STENCIL_ATTACHMENT);
 221     // WebGL 2 doesn't have a real attachment for this, and WebGL 1 is defered
 222     // and only DoAttachment if HasAttachment.
 223
 224     gl->fFramebufferRenderbuffer(LOCAL_GL_FRAMEBUFFER, mAttachmentPoint,
 225                                  LOCAL_GL_RENDERBUFFER, 0);
 226     return;
 227   }
 228
 229   const auto& texName = Texture()->mGLName;
 230
 231   switch (Texture()->Target().get()) {
 232     case LOCAL_GL_TEXTURE_2D:
 233     case LOCAL_GL_TEXTURE_CUBE_MAP: {
 234       TexImageTarget imageTarget = LOCAL_GL_TEXTURE_2D;
 235       if (Texture()->Target() == LOCAL_GL_TEXTURE_CUBE_MAP) {
 236         imageTarget = LOCAL_GL_TEXTURE_CUBE_MAP_POSITIVE_X + Layer();
 237       }
 238
 239       if (mAttachmentPoint == LOCAL_GL_DEPTH_STENCIL_ATTACHMENT) {
 240         gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER,
 241                                   LOCAL_GL_DEPTH_ATTACHMENT, imageTarget.get(),
 242                                   texName, MipLevel());
 243         gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER,
 244                                   LOCAL_GL_STENCIL_ATTACHMENT,
 245                                   imageTarget.get(), texName, MipLevel());
 246       } else {
 247         gl->fFramebufferTexture2D(LOCAL_GL_FRAMEBUFFER, mAttachmentPoint,
 248                                   imageTarget.get(), texName, MipLevel());
 249       }
 250       break;
 251     }
 252
 253     case LOCAL_GL_TEXTURE_2D_ARRAY:
 254     case LOCAL_GL_TEXTURE_3D:
 255       if (ZLayerCount() != 1) {
 256         gl->fFramebufferTextureMultiview(LOCAL_GL_FRAMEBUFFER, mAttachmentPoint,
 257                                          texName, MipLevel(), Layer(),
 258                                          ZLayerCount());
 259       } else {
 260         gl->fFramebufferTextureLayer(LOCAL_GL_FRAMEBUFFER, mAttachmentPoint,
 261                                      texName, MipLevel(), Layer());
 262       }
 263       break;
 264   }
 265 }
 266
 267 Maybe<double> WebGLFBAttachPoint::GetParameter(WebGLContext* webgl,
 268                                                GLenum attachment,
 269                                                GLenum pname) const {
 270   if (!HasAttachment()) {
 271     // Divergent between GLES 3 and 2.
 272
 273     // GLES 2.0.25 p127:
 274     //   "If the value of FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is NONE, then
 275     //   querying any other pname will generate INVALID_ENUM."
 276
 277     // GLES 3.0.4 p240:
 278     //   "If the value of FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE is NONE, no
 279     //   framebuffer is bound to target. In this case querying pname
 280     //   FRAMEBUFFER_ATTACHMENT_OBJECT_NAME will return zero, and all other
 281     //   queries will generate an INVALID_OPERATION error."
 282     switch (pname) {
 283       case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE:
 284         return Some(LOCAL_GL_NONE);
 285
 286       case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_OBJECT_NAME:
 287         if (webgl->IsWebGL2()) return Nothing();
 288
 289         break;
 290
 291       default:
 292         break;
 293     }
 294     nsCString attachmentName;
 295     WebGLContext::EnumName(attachment, &attachmentName);
 296     if (webgl->IsWebGL2()) {
 297       webgl->ErrorInvalidOperation("No attachment at %s.",
 298                                    attachmentName.BeginReading());
 299     } else {
 300       webgl->ErrorInvalidEnum("No attachment at %s.",
 301                               attachmentName.BeginReading());
 302     }
 303     return Nothing();
 304   }
 305
 306   bool isPNameValid = false;
 307   switch (pname) {
 308     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE:
 309       return Some(mTexturePtr ? LOCAL_GL_TEXTURE : LOCAL_GL_RENDERBUFFER);
 310
 311       //////
 312
 313     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LEVEL:
 314       if (mTexturePtr) return Some(AssertedCast<uint32_t>(MipLevel()));
 315       break;
 316
 317     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_CUBE_MAP_FACE:
 318       if (mTexturePtr) {
 319         GLenum face = 0;
 320         if (mTexturePtr->Target() == LOCAL_GL_TEXTURE_CUBE_MAP) {
 321           face = LOCAL_GL_TEXTURE_CUBE_MAP_POSITIVE_X + Layer();
 322         }
 323         return Some(face);
 324       }
 325       break;
 326
 327       //////
 328
 329     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER:
 330       if (webgl->IsWebGL2()) {
 331         return Some(AssertedCast<int32_t>(Layer()));
 332       }
 333       break;
 334
 335     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_BASE_VIEW_INDEX_OVR:
 336       if (webgl->IsExtensionEnabled(WebGLExtensionID::OVR_multiview2)) {
 337         return Some(AssertedCast<int32_t>(Layer()));
 338       }
 339       break;
 340
 341     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_TEXTURE_NUM_VIEWS_OVR:
 342       if (webgl->IsExtensionEnabled(WebGLExtensionID::OVR_multiview2)) {
 343         return Some(AssertedCast<uint32_t>(ZLayerCount()));
 344       }
 345       break;
 346
 347       //////
 348
 349     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE:
 350     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE:
 351     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE:
 352     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE:
 353     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE:
 354     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE:
 355       isPNameValid = webgl->IsWebGL2();
 356       break;
 357
 358     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE:
 359       isPNameValid = (webgl->IsWebGL2() ||
 360                       webgl->IsExtensionEnabled(
 361                           WebGLExtensionID::WEBGL_color_buffer_float) ||
 362                       webgl->IsExtensionEnabled(
 363                           WebGLExtensionID::EXT_color_buffer_half_float));
 364       break;
 365
 366     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING:
 367       isPNameValid = (webgl->IsWebGL2() ||
 368                       webgl->IsExtensionEnabled(WebGLExtensionID::EXT_sRGB));
 369       break;
 370   }
 371
 372   if (!isPNameValid) {
 373     webgl->ErrorInvalidEnum("Invalid pname: 0x%04x", pname);
 374     return Nothing();
 375   }
 376
 377   const auto& imageInfo = *GetImageInfo();
 378   const auto& usage = imageInfo.mFormat;
 379   if (!usage) {
 380     if (pname == LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING)
 381       return Some(LOCAL_GL_LINEAR);
 382
 383     return Nothing();
 384   }
 385
 386   auto format = usage->format;
 387
 388   GLint ret = 0;
 389   switch (pname) {
 390     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_RED_SIZE:
 391       ret = format->r;
 392       break;
 393     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_GREEN_SIZE:
 394       ret = format->g;
 395       break;
 396     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_BLUE_SIZE:
 397       ret = format->b;
 398       break;
 399     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_ALPHA_SIZE:
 400       ret = format->a;
 401       break;
 402     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_DEPTH_SIZE:
 403       ret = format->d;
 404       break;
 405     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_STENCIL_SIZE:
 406       ret = format->s;
 407       break;
 408
 409     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COLOR_ENCODING:
 410       ret = (format->isSRGB ? LOCAL_GL_SRGB : LOCAL_GL_LINEAR);
 411       break;
 412
 413     case LOCAL_GL_FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE:
 414       if (attachment == LOCAL_GL_DEPTH_STENCIL_ATTACHMENT) {
 415         webgl->ErrorInvalidOperation(
 416             "Querying"
 417             " FRAMEBUFFER_ATTACHMENT_COMPONENT_TYPE"
 418             " against DEPTH_STENCIL_ATTACHMENT is an"
 419             " error.");
 420         return Nothing();
 421       }
 422
 423       if (format->unsizedFormat == webgl::UnsizedFormat::DEPTH_STENCIL) {
 424         MOZ_ASSERT(attachment == LOCAL_GL_DEPTH_ATTACHMENT ||
 425                    attachment == LOCAL_GL_STENCIL_ATTACHMENT);
 426
 427         if (attachment == LOCAL_GL_DEPTH_ATTACHMENT) {
 428           switch (format->effectiveFormat) {
 429             case webgl::EffectiveFormat::DEPTH24_STENCIL8:
 430               format =
 431                   webgl::GetFormat(webgl::EffectiveFormat::DEPTH_COMPONENT24);
 432               break;
 433             case webgl::EffectiveFormat::DEPTH32F_STENCIL8:
 434               format =
 435                   webgl::GetFormat(webgl::EffectiveFormat::DEPTH_COMPONENT32F);
 436               break;
 437             default:
 438               MOZ_ASSERT(false, "no matched DS format");
 439               break;
 440           }
 441         } else if (attachment == LOCAL_GL_STENCIL_ATTACHMENT) {
 442           switch (format->effectiveFormat) {
 443             case webgl::EffectiveFormat::DEPTH24_STENCIL8:
 444             case webgl::EffectiveFormat::DEPTH32F_STENCIL8:
 445               format = webgl::GetFormat(webgl::EffectiveFormat::STENCIL_INDEX8);
 446               break;
 447             default:
 448               MOZ_ASSERT(false, "no matched DS format");
 449               break;
 450           }
 451         }
 452       }
 453
 454       switch (format->componentType) {
 455         case webgl::ComponentType::Int:
 456           ret = LOCAL_GL_INT;
 457           break;
 458         case webgl::ComponentType::UInt:
 459           ret = LOCAL_GL_UNSIGNED_INT;
 460           break;
 461         case webgl::ComponentType::NormInt:
 462           ret = LOCAL_GL_SIGNED_NORMALIZED;
 463           break;
 464         case webgl::ComponentType::NormUInt:
 465           ret = LOCAL_GL_UNSIGNED_NORMALIZED;
 466           break;
 467         case webgl::ComponentType::Float:
 468           ret = LOCAL_GL_FLOAT;
 469           break;
 470       }
 471       break;
 472
 473     default:
 474       MOZ_ASSERT(false, "Missing case.");
 475       break;
 476   }
 477
 478   return Some(ret);
 479 }
 480
 481 ////////////////////////////////////////////////////////////////////////////////
 482 ////////////////////////////////////////////////////////////////////////////////
 483 // WebGLFramebuffer
 484
 485 WebGLFramebuffer::WebGLFramebuffer(WebGLContext* webgl, GLuint fbo)
 486     : WebGLContextBoundObject(webgl),
 487       mGLName(fbo),
 488       mDepthAttachment(webgl, LOCAL_GL_DEPTH_ATTACHMENT),
 489       mStencilAttachment(webgl, LOCAL_GL_STENCIL_ATTACHMENT),
 490       mDepthStencilAttachment(webgl, LOCAL_GL_DEPTH_STENCIL_ATTACHMENT) {
 491   mAttachments.push_back(&mDepthAttachment);
 492   mAttachments.push_back(&mStencilAttachment);
 493
 494   if (!webgl->IsWebGL2()) {
 495     // Only WebGL1 has a separate depth+stencil attachment point.
 496     mAttachments.push_back(&mDepthStencilAttachment);
 497   }
 498
 499   size_t i = 0;
 500   for (auto& cur : mColorAttachments) {
 501     new (&cur) WebGLFBAttachPoint(webgl, LOCAL_GL_COLOR_ATTACHMENT0 + i);
 502     i++;
 503
 504     mAttachments.push_back(&cur);
 505   }
 506
 507   mColorDrawBuffers.push_back(&mColorAttachments[0]);
 508   mColorReadBuffer = &mColorAttachments[0];
 509 }
 510
 511 WebGLFramebuffer::WebGLFramebuffer(WebGLContext* webgl,
 512                                    UniquePtr<gl::MozFramebuffer> fbo)
 513     : WebGLContextBoundObject(webgl),
 514       mGLName(fbo->mFB),
 515       mOpaque(std::move(fbo)),
 516       mColorReadBuffer(nullptr) {
 517   // Opaque Framebuffer is guaranteed to be complete at this point.
 518   // Cache the Completeness info.
 519   CompletenessInfo info;
 520   info.width = mOpaque->mSize.width;
 521   info.height = mOpaque->mSize.height;
 522   info.zLayerCount = 1;
 523   info.isMultiview = false;
 524
 525   mCompletenessInfo = Some(std::move(info));
 526 }
 527
 528 WebGLFramebuffer::~WebGLFramebuffer() {
 529   InvalidateCaches();
 530
 531   mDepthAttachment.Clear();
 532   mStencilAttachment.Clear();
 533   mDepthStencilAttachment.Clear();
 534
 535   for (auto& cur : mColorAttachments) {
 536     cur.Clear();
 537   }
 538
 539   if (!mContext) return;
 540   // If opaque, fDeleteFramebuffers is called in the destructor of
 541   // MozFramebuffer.
 542   if (!mOpaque) {
 543     mContext->gl->fDeleteFramebuffers(1, &mGLName);
 544   }
 545 }
 546
 547 ////
 548
 549 Maybe<WebGLFBAttachPoint*> WebGLFramebuffer::GetColorAttachPoint(
 550     GLenum attachPoint) {
 551   if (attachPoint == LOCAL_GL_NONE) return Some<WebGLFBAttachPoint*>(nullptr);
 552
 553   if (attachPoint < LOCAL_GL_COLOR_ATTACHMENT0) return Nothing();
 554
 555   const size_t colorId = attachPoint - LOCAL_GL_COLOR_ATTACHMENT0;
 556
 557   MOZ_ASSERT(mContext->Limits().maxColorDrawBuffers <= webgl::kMaxDrawBuffers);
 558   if (colorId >= mContext->MaxValidDrawBuffers()) return Nothing();
 559
 560   return Some(&mColorAttachments[colorId]);
 561 }
 562
 563 Maybe<WebGLFBAttachPoint*> WebGLFramebuffer::GetAttachPoint(
 564     GLenum attachPoint) {
 565   switch (attachPoint) {
 566     case LOCAL_GL_DEPTH_STENCIL_ATTACHMENT:
 567       return Some(&mDepthStencilAttachment);
 568
 569     case LOCAL_GL_DEPTH_ATTACHMENT:
 570       return Some(&mDepthAttachment);
 571
 572     case LOCAL_GL_STENCIL_ATTACHMENT:
 573       return Some(&mStencilAttachment);
 574
 575     default:
 576       return GetColorAttachPoint(attachPoint);
 577   }
 578 }
 579
 580 void WebGLFramebuffer::DetachTexture(const WebGLTexture* tex) {
 581   for (const auto& attach : mAttachments) {
 582     if (attach->Texture() == tex) {
 583       attach->Clear();
 584     }
 585   }
 586   InvalidateCaches();
 587 }
 588
 589 void WebGLFramebuffer::DetachRenderbuffer(const WebGLRenderbuffer* rb) {
 590   for (const auto& attach : mAttachments) {
 591     if (attach->Renderbuffer() == rb) {
 592       attach->Clear();
 593     }
 594   }
 595   InvalidateCaches();
 596 }
 597
 598 ////////////////////////////////////////////////////////////////////////////////
 599 // Completeness
 600
 601 bool WebGLFramebuffer::HasDuplicateAttachments() const {
 602   std::set<WebGLFBAttachPoint::Ordered> uniqueAttachSet;
 603
 604   for (const auto& attach : mColorAttachments) {
 605     if (!attach.HasAttachment()) continue;
 606
 607     const WebGLFBAttachPoint::Ordered ordered(attach);
 608
 609     const bool didInsert = uniqueAttachSet.insert(ordered).second;
 610     if (!didInsert) return true;
 611   }
 612
 613   return false;
 614 }
 615
 616 bool WebGLFramebuffer::HasDefinedAttachments() const {
 617   bool hasAttachments = false;
 618   for (const auto& attach : mAttachments) {
 619     hasAttachments |= attach->HasAttachment();
 620   }
 621   return hasAttachments;
 622 }
 623
 624 bool WebGLFramebuffer::HasIncompleteAttachments(
 625     nsCString* const out_info) const {
 626   bool hasIncomplete = false;
 627   for (const auto& cur : mAttachments) {
 628     if (!cur->HasAttachment())
 629       continue;  // Not defined, so can't count as incomplete.
 630
 631     hasIncomplete |= !cur->IsComplete(mContext, out_info);
 632   }
 633   return hasIncomplete;
 634 }
 635
 636 bool WebGLFramebuffer::AllImageRectsMatch() const {
 637   MOZ_ASSERT(HasDefinedAttachments());
 638   DebugOnly<nsCString> fbStatusInfo;
 639   MOZ_ASSERT(!HasIncompleteAttachments(&fbStatusInfo));
 640
 641   bool needsInit = true;
 642   uint32_t width = 0;
 643   uint32_t height = 0;
 644
 645   bool hasMismatch = false;
 646   for (const auto& attach : mAttachments) {
 647     const auto& imageInfo = attach->GetImageInfo();
 648     if (!imageInfo) continue;
 649
 650     const auto& curWidth = imageInfo->mWidth;
 651     const auto& curHeight = imageInfo->mHeight;
 652
 653     if (needsInit) {
 654       needsInit = false;
 655       width = curWidth;
 656       height = curHeight;
 657       continue;
 658     }
 659
 660     hasMismatch |= (curWidth != width || curHeight != height);
 661   }
 662   return !hasMismatch;
 663 }
 664
 665 bool WebGLFramebuffer::AllImageSamplesMatch() const {
 666   MOZ_ASSERT(HasDefinedAttachments());
 667   DebugOnly<nsCString> fbStatusInfo;
 668   MOZ_ASSERT(!HasIncompleteAttachments(&fbStatusInfo));
 669
 670   bool needsInit = true;
 671   uint32_t samples = 0;
 672
 673   bool hasMismatch = false;
 674   for (const auto& attach : mAttachments) {
 675     const auto& imageInfo = attach->GetImageInfo();
 676     if (!imageInfo) continue;
 677
 678     const auto& curSamples = imageInfo->mSamples;
 679
 680     if (needsInit) {
 681       needsInit = false;
 682       samples = curSamples;
 683       continue;
 684     }
 685
 686     hasMismatch |= (curSamples != samples);
 687   };
 688   return !hasMismatch;
 689 }
 690
 691 FBStatus WebGLFramebuffer::PrecheckFramebufferStatus(
 692     nsCString* const out_info) const {
 693   MOZ_ASSERT(mContext->mBoundDrawFramebuffer == this ||
 694              mContext->mBoundReadFramebuffer == this);
 695   if (!HasDefinedAttachments())
 696     return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT;  // No
 697                                                                 // attachments
 698
 699   if (HasIncompleteAttachments(out_info))
 700     return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT;
 701
 702   if (!AllImageRectsMatch())
 703     return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS;  // Inconsistent sizes
 704
 705   if (!AllImageSamplesMatch())
 706     return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE;  // Inconsistent samples
 707
 708   if (HasDuplicateAttachments()) return LOCAL_GL_FRAMEBUFFER_UNSUPPORTED;
 709
 710   if (mContext->IsWebGL2()) {
 711     MOZ_ASSERT(!mDepthStencilAttachment.HasAttachment());
 712     if (mDepthAttachment.HasAttachment() &&
 713         mStencilAttachment.HasAttachment()) {
 714       if (!mDepthAttachment.IsEquivalentForFeedback(mStencilAttachment))
 715         return LOCAL_GL_FRAMEBUFFER_UNSUPPORTED;
 716     }
 717   } else {
 718     const auto depthOrStencilCount =
 719         int(mDepthAttachment.HasAttachment()) +
 720         int(mStencilAttachment.HasAttachment()) +
 721         int(mDepthStencilAttachment.HasAttachment());
 722     if (depthOrStencilCount > 1) return LOCAL_GL_FRAMEBUFFER_UNSUPPORTED;
 723   }
 724
 725   {
 726     const WebGLFBAttachPoint* example = nullptr;
 727     for (const auto& x : mAttachments) {
 728       if (!x->HasAttachment()) continue;
 729       if (!example) {
 730         example = x;
 731         continue;
 732       }
 733       if (x->ZLayerCount() != example->ZLayerCount()) {
 734         return LOCAL_GL_FRAMEBUFFER_INCOMPLETE_VIEW_TARGETS_OVR;
 735       }
 736     }
 737   }
 738
 739   return LOCAL_GL_FRAMEBUFFER_COMPLETE;
 740 }
 741
 742 ////////////////////////////////////////
 743 // Validation
 744
 745 bool WebGLFramebuffer::ValidateAndInitAttachments(
 746     const GLenum incompleteFbError) const {
 747   MOZ_ASSERT(mContext->mBoundDrawFramebuffer == this ||
 748              mContext->mBoundReadFramebuffer == this);
 749
 750   const auto fbStatus = CheckFramebufferStatus();
 751   if (fbStatus == LOCAL_GL_FRAMEBUFFER_COMPLETE) return true;
 752
 753   mContext->GenerateError(incompleteFbError, "Framebuffer must be complete.");
 754   return false;
 755 }
 756
 757 bool WebGLFramebuffer::ValidateClearBufferType(
 758     GLenum buffer, uint32_t drawBuffer,
 759     const webgl::AttribBaseType funcType) const {
 760   if (buffer != LOCAL_GL_COLOR) return true;
 761
 762   const auto& attach = mColorAttachments[drawBuffer];
 763   const auto& imageInfo = attach.GetImageInfo();
 764   if (!imageInfo) return true;
 765
 766   if (!count(mColorDrawBuffers.begin(), mColorDrawBuffers.end(), &attach))
 767     return true;  // DRAW_BUFFERi set to NONE.
 768
 769   auto attachType = webgl::AttribBaseType::Float;
 770   switch (imageInfo->mFormat->format->componentType) {
 771     case webgl::ComponentType::Int:
 772       attachType = webgl::AttribBaseType::Int;
 773       break;
 774     case webgl::ComponentType::UInt:
 775       attachType = webgl::AttribBaseType::Uint;
 776       break;
 777     default:
 778       break;
 779   }
 780
 781   if (attachType != funcType) {
 782     mContext->ErrorInvalidOperation(
 783         "This attachment is of type %s, but"
 784         " this function is of type %s.",
 785         ToString(attachType), ToString(funcType));
 786     return false;
 787   }
 788
 789   return true;
 790 }
 791
 792 bool WebGLFramebuffer::ValidateForColorRead(
 793     const webgl::FormatUsageInfo** const out_format, uint32_t* const out_width,
 794     uint32_t* const out_height) const {
 795   if (!mColorReadBuffer) {
 796     mContext->ErrorInvalidOperation("READ_BUFFER must not be NONE.");
 797     return false;
 798   }
 799
 800   if (mColorReadBuffer->ZLayerCount() > 1) {
 801     mContext->GenerateError(LOCAL_GL_INVALID_FRAMEBUFFER_OPERATION,
 802                             "The READ_BUFFER attachment has multiple views.");
 803     return false;
 804   }
 805
 806   const auto& imageInfo = mColorReadBuffer->GetImageInfo();
 807   if (!imageInfo) {
 808     mContext->ErrorInvalidOperation(
 809         "The READ_BUFFER attachment is not defined.");
 810     return false;
 811   }
 812
 813   if (imageInfo->mSamples) {
 814     mContext->ErrorInvalidOperation(
 815         "The READ_BUFFER attachment is multisampled.");
 816     return false;
 817   }
 818
 819   *out_format = imageInfo->mFormat;
 820   *out_width = imageInfo->mWidth;
 821   *out_height = imageInfo->mHeight;
 822   return true;
 823 }
 824
 825 ////////////////////////////////////////////////////////////////////////////////
 826 // Resolution and caching
 827
 828 void WebGLFramebuffer::DoDeferredAttachments() const {
 829   if (mContext->IsWebGL2()) return;
 830
 831   const auto& gl = mContext->gl;
 832   gl->fFramebufferRenderbuffer(LOCAL_GL_FRAMEBUFFER, LOCAL_GL_DEPTH_ATTACHMENT,
 833                                LOCAL_GL_RENDERBUFFER, 0);
 834   gl->fFramebufferRenderbuffer(LOCAL_GL_FRAMEBUFFER,
 835                                LOCAL_GL_STENCIL_ATTACHMENT,
 836                                LOCAL_GL_RENDERBUFFER, 0);
 837
 838   const auto fn = [&](const WebGLFBAttachPoint& attach) {
 839     MOZ_ASSERT(attach.mDeferAttachment);
 840     if (attach.HasAttachment()) {
 841       attach.DoAttachment(gl);
 842     }
 843   };
 844   // Only one of these will have an attachment.
 845   fn(mDepthAttachment);
 846   fn(mStencilAttachment);
 847   fn(mDepthStencilAttachment);
 848 }
 849
 850 void WebGLFramebuffer::ResolveAttachmentData() const {
 851   // GLES 3.0.5 p188:
 852   //   The result of clearing integer color buffers with `Clear` is undefined.
 853
 854   // Two different approaches:
 855   // On WebGL 2, we have glClearBuffer, and *must* use it for integer buffers,
 856   // so let's just use it for all the buffers. One WebGL 1, we might not have
 857   // glClearBuffer,
 858
 859   // WebGL 1 is easier, because we can just call glClear, possibly with
 860   // glDrawBuffers.
 861
 862   const auto& gl = mContext->gl;
 863
 864   const webgl::ScopedPrepForResourceClear scopedPrep(*mContext);
 865
 866   if (mContext->IsWebGL2()) {
 867     const uint32_t uiZeros[4] = {};
 868     const int32_t iZeros[4] = {};
 869     const float fZeros[4] = {};
 870     const float fOne[] = {1.0f};
 871
 872     for (const auto& cur : mAttachments) {
 873       const auto& imageInfo = cur->GetImageInfo();
 874       if (!imageInfo || !imageInfo->mUninitializedSlices)
 875         continue;  // Nothing attached, or already has data.
 876
 877       const auto fnClearBuffer = [&]() {
 878         const auto& format = imageInfo->mFormat->format;
 879         MOZ_ASSERT(format->estimatedBytesPerPixel <= sizeof(uiZeros));
 880         MOZ_ASSERT(format->estimatedBytesPerPixel <= sizeof(iZeros));
 881         MOZ_ASSERT(format->estimatedBytesPerPixel <= sizeof(fZeros));
 882
 883         switch (cur->mAttachmentPoint) {
 884           case LOCAL_GL_DEPTH_ATTACHMENT:
 885             gl->fClearBufferfv(LOCAL_GL_DEPTH, 0, fOne);
 886             break;
 887           case LOCAL_GL_STENCIL_ATTACHMENT:
 888             gl->fClearBufferiv(LOCAL_GL_STENCIL, 0, iZeros);
 889             break;
 890           default:
 891             MOZ_ASSERT(cur->mAttachmentPoint !=
 892                        LOCAL_GL_DEPTH_STENCIL_ATTACHMENT);
 893             const uint32_t drawBuffer =
 894                 cur->mAttachmentPoint - LOCAL_GL_COLOR_ATTACHMENT0;
 895             MOZ_ASSERT(drawBuffer <= 100);
 896             switch (format->componentType) {
 897               case webgl::ComponentType::Int:
 898                 gl->fClearBufferiv(LOCAL_GL_COLOR, drawBuffer, iZeros);
 899                 break;
 900               case webgl::ComponentType::UInt:
 901                 gl->fClearBufferuiv(LOCAL_GL_COLOR, drawBuffer, uiZeros);
 902                 break;
 903               default:
 904                 gl->fClearBufferfv(LOCAL_GL_COLOR, drawBuffer, fZeros);
 905                 break;
 906             }
 907         }
 908       };
 909
 910       if (imageInfo->mDepth > 1) {
 911         const auto& tex = cur->Texture();
 912         const gl::ScopedFramebuffer scopedFB(gl);
 913         const gl::ScopedBindFramebuffer scopedBindFB(gl, scopedFB.FB());
 914         for (const auto z : IntegerRange(imageInfo->mDepth)) {
 915           if ((*imageInfo->mUninitializedSlices)[z]) {
 916             gl->fFramebufferTextureLayer(LOCAL_GL_FRAMEBUFFER,
 917                                          cur->mAttachmentPoint, tex->mGLName,
 918                                          cur->MipLevel(), z);
 919             fnClearBuffer();
 920           }
 921         }
 922       } else {
 923         fnClearBuffer();
 924       }
 925       imageInfo->mUninitializedSlices = Nothing();
 926     }
 927     return;
 928   }
 929
 930   uint32_t clearBits = 0;
 931   std::vector<GLenum> drawBufferForClear;
 932
 933   const auto fnGather = [&](const WebGLFBAttachPoint& attach,
 934                             const uint32_t attachClearBits) {
 935     const auto& imageInfo = attach.GetImageInfo();
 936     if (!imageInfo || !imageInfo->mUninitializedSlices) return false;
 937
 938     clearBits |= attachClearBits;
 939     imageInfo->mUninitializedSlices = Nothing();  // Just mark it now.
 940     return true;
 941   };
 942
 943   //////
 944
 945   for (const auto& cur : mColorAttachments) {
 946     if (fnGather(cur, LOCAL_GL_COLOR_BUFFER_BIT)) {
 947       const uint32_t id = cur.mAttachmentPoint - LOCAL_GL_COLOR_ATTACHMENT0;
 948       MOZ_ASSERT(id <= 100);
 949       drawBufferForClear.resize(id + 1);  // Pads with zeros!
 950       drawBufferForClear[id] = cur.mAttachmentPoint;
 951     }
 952   }
 953
 954   (void)fnGather(mDepthAttachment, LOCAL_GL_DEPTH_BUFFER_BIT);
 955   (void)fnGather(mStencilAttachment, LOCAL_GL_STENCIL_BUFFER_BIT);
 956   (void)fnGather(mDepthStencilAttachment,
 957                  LOCAL_GL_DEPTH_BUFFER_BIT | LOCAL_GL_STENCIL_BUFFER_BIT);
 958
 959   //////
 960
 961   if (!clearBits) return;
 962
 963   if (gl->IsSupported(gl::GLFeature::draw_buffers)) {
 964     gl->fDrawBuffers(drawBufferForClear.size(), drawBufferForClear.data());
 965   }
 966
 967   gl->fClear(clearBits);
 968
 969   RefreshDrawBuffers();
 970 }
 971
 972 WebGLFramebuffer::CompletenessInfo::~CompletenessInfo() {
 973   if (!this->fb) return;
 974   const auto& fb = *this->fb;
 975   const auto& webgl = fb.mContext;
 976   fb.mNumFBStatusInvals++;
 977   if (fb.mNumFBStatusInvals > webgl->mMaxAcceptableFBStatusInvals) {
 978     webgl->GeneratePerfWarning(
 979         "FB was invalidated after being complete %u"
 980         " times. [webgl.perf.max-acceptable-fb-status-invals]",
 981         uint32_t(fb.mNumFBStatusInvals));
 982   }
 983 }
 984
 985 ////////////////////////////////////////////////////////////////////////////////
 986 // Entrypoints
 987
 988 FBStatus WebGLFramebuffer::CheckFramebufferStatus() const {
 989   if (MOZ_UNLIKELY(mOpaque && !mInOpaqueRAF)) {
 990     // Opaque Framebuffers are considered incomplete outside of a RAF.
 991     return LOCAL_GL_FRAMEBUFFER_UNSUPPORTED;
 992   }
 993
 994   if (mCompletenessInfo) return LOCAL_GL_FRAMEBUFFER_COMPLETE;
 995
 996   // Ok, let's try to resolve it!
 997
 998   nsCString statusInfo;
 999   FBStatus ret = PrecheckFramebufferStatus(&statusInfo);
1000   do {
1001     if (ret != LOCAL_GL_FRAMEBUFFER_COMPLETE) break;
1002
1003     // Looks good on our end. Let's ask the driver.
1004     gl::GLContext* const gl = mContext->gl;
1005
1006     const ScopedFBRebinder autoFB(mContext);
1007     gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mGLName);
1008
1009     ////
1010
1011     DoDeferredAttachments();
1012     RefreshDrawBuffers();
1013     RefreshReadBuffer();
1014
1015     ret = gl->fCheckFramebufferStatus(LOCAL_GL_FRAMEBUFFER);
1016
1017     ////
1018
1019     if (ret != LOCAL_GL_FRAMEBUFFER_COMPLETE) {
1020       const nsPrintfCString text("Bad status according to the driver: 0x%04x",
1021                                  ret.get());
1022       statusInfo = text;
1023       break;
1024     }
1025
1026     ResolveAttachmentData();
1027
1028     // Sweet, let's cache that.
1029     auto info = CompletenessInfo{this};
1030     mCompletenessInfo.ResetInvalidators({});
1031     mCompletenessInfo.AddInvalidator(*this);
1032
1033     const auto fnIsFloat32 = [](const webgl::FormatInfo& info) {
1034       if (info.componentType != webgl::ComponentType::Float) return false;
1035       return info.r == 32;
1036     };
1037
1038     for (const auto& cur : mAttachments) {
1039       const auto& tex = cur->Texture();
1040       const auto& rb = cur->Renderbuffer();
1041       if (tex) {
1042         mCompletenessInfo.AddInvalidator(*tex);
1043         info.texAttachments.push_back(cur);
1044       } else if (rb) {
1045         mCompletenessInfo.AddInvalidator(*rb);
1046       } else {
1047         continue;
1048       }
1049       const auto& imageInfo = cur->GetImageInfo();
1050       MOZ_ASSERT(imageInfo);
1051
1052       const auto maybeColorId = cur->ColorAttachmentId();
1053       if (maybeColorId) {
1054         const auto id = *maybeColorId;
1055         info.hasAttachment[id] = true;
1056         info.isAttachmentF32[id] = fnIsFloat32(*imageInfo->mFormat->format);
1057       }
1058
1059       info.width = imageInfo->mWidth;
1060       info.height = imageInfo->mHeight;
1061       info.zLayerCount = cur->ZLayerCount();
1062       info.isMultiview = cur->IsMultiview();
1063     }
1064     MOZ_ASSERT(info.width && info.height);
1065     mCompletenessInfo = Some(std::move(info));
1066     info.fb = nullptr;  // Don't trigger the invalidation warning.
1067     return LOCAL_GL_FRAMEBUFFER_COMPLETE;
1068   } while (false);
1069
1070   MOZ_ASSERT(ret != LOCAL_GL_FRAMEBUFFER_COMPLETE);
1071   mContext->GenerateWarning("Framebuffer not complete. (status: 0x%04x) %s",
1072                             ret.get(), statusInfo.BeginReading());
1073   return ret;
1074 }
1075
1076 ////
1077
1078 void WebGLFramebuffer::RefreshDrawBuffers() const {
1079   const auto& gl = mContext->gl;
1080   if (!gl->IsSupported(gl::GLFeature::draw_buffers)) return;
1081
1082   // Prior to GL4.1, having a no-image FB attachment that's selected by
1083   // DrawBuffers yields a framebuffer status of
1084   // FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER. We could workaround this only on
1085   // affected versions, but it's easier be unconditional.
1086   std::vector<GLenum> driverBuffers(mContext->Limits().maxColorDrawBuffers,
1087                                     LOCAL_GL_NONE);
1088   for (const auto& attach : mColorDrawBuffers) {
1089     if (attach->HasAttachment()) {
1090       const uint32_t index =
1091           attach->mAttachmentPoint - LOCAL_GL_COLOR_ATTACHMENT0;
1092       driverBuffers[index] = attach->mAttachmentPoint;
1093     }
1094   }
1095
1096   gl->fBindFramebuffer(LOCAL_GL_DRAW_FRAMEBUFFER, mGLName);
1097   gl->fDrawBuffers(driverBuffers.size(), driverBuffers.data());
1098 }
1099
1100 void WebGLFramebuffer::RefreshReadBuffer() const {
1101   const auto& gl = mContext->gl;
1102   if (!gl->IsSupported(gl::GLFeature::read_buffer)) return;
1103
1104   // Prior to GL4.1, having a no-image FB attachment that's selected by
1105   // ReadBuffer yields a framebuffer status of
1106   // FRAMEBUFFER_INCOMPLETE_READ_BUFFER. We could workaround this only on
1107   // affected versions, but it's easier be unconditional.
1108   GLenum driverBuffer = LOCAL_GL_NONE;
1109   if (mColorReadBuffer && mColorReadBuffer->HasAttachment()) {
1110     driverBuffer = mColorReadBuffer->mAttachmentPoint;
1111   }
1112
1113   gl->fBindFramebuffer(LOCAL_GL_READ_FRAMEBUFFER, mGLName);
1114   gl->fReadBuffer(driverBuffer);
1115 }
1116
1117 ////
1118
1119 void WebGLFramebuffer::DrawBuffers(const std::vector<GLenum>& buffers) {
1120   if (buffers.size() > mContext->MaxValidDrawBuffers()) {
1121     // "An INVALID_VALUE error is generated if `n` is greater than
1122     // MAX_DRAW_BUFFERS."
1123     mContext->ErrorInvalidValue(
1124         "`buffers` must have a length <="
1125         " MAX_DRAW_BUFFERS.");
1126     return;
1127   }
1128
1129   std::vector<const WebGLFBAttachPoint*> newColorDrawBuffers;
1130   newColorDrawBuffers.reserve(buffers.size());
1131
1132   mDrawBufferEnabled.reset();
1133   for (const auto i : IntegerRange(buffers.size())) {
1134     // "If the GL is bound to a draw framebuffer object, the `i`th buffer listed
1135     // in bufs must be COLOR_ATTACHMENTi or NONE. Specifying a buffer out of
1136     // order, BACK, or COLOR_ATTACHMENTm where `m` is greater than or equal to
1137     // the value of MAX_COLOR_ATTACHMENTS, will generate the error
1138     // INVALID_OPERATION.
1139
1140     // WEBGL_draw_buffers:
1141     // "The value of the MAX_COLOR_ATTACHMENTS_WEBGL parameter must be greater
1142     // than or equal to that of the MAX_DRAW_BUFFERS_WEBGL parameter." This
1143     // means that if buffers.Length() isn't larger than MaxDrawBuffers, it won't
1144     // be larger than MaxColorAttachments.
1145     const auto& cur = buffers[i];
1146     if (cur == LOCAL_GL_COLOR_ATTACHMENT0 + i) {
1147       const auto& attach = mColorAttachments[i];
1148       newColorDrawBuffers.push_back(&attach);
1149       mDrawBufferEnabled[i] = true;
1150     } else if (cur != LOCAL_GL_NONE) {
1151       const bool isColorEnum = (cur >= LOCAL_GL_COLOR_ATTACHMENT0 &&
1152                                 cur < mContext->LastColorAttachmentEnum());
1153       if (cur != LOCAL_GL_BACK && !isColorEnum) {
1154         mContext->ErrorInvalidEnum("Unexpected enum in buffers.");
1155         return;
1156       }
1157
1158       mContext->ErrorInvalidOperation(
1159           "`buffers[i]` must be NONE or"
1160           " COLOR_ATTACHMENTi.");
1161       return;
1162     }
1163   }
1164
1165   ////
1166
1167   mColorDrawBuffers = std::move(newColorDrawBuffers);
1168   RefreshDrawBuffers();  // Calls glDrawBuffers.
1169 }
1170
1171 void WebGLFramebuffer::ReadBuffer(GLenum attachPoint) {
1172   const auto& maybeAttach = GetColorAttachPoint(attachPoint);
1173   if (!maybeAttach) {
1174     const char text[] =
1175         "`mode` must be a COLOR_ATTACHMENTi, for 0 <= i <"
1176         " MAX_DRAW_BUFFERS.";
1177     if (attachPoint == LOCAL_GL_BACK) {
1178       mContext->ErrorInvalidOperation(text);
1179     } else {
1180       mContext->ErrorInvalidEnum(text);
1181     }
1182     return;
1183   }
1184   const auto& attach = maybeAttach.value();  // Might be nullptr.
1185
1186   ////
1187
1188   mColorReadBuffer = attach;
1189   RefreshReadBuffer();  // Calls glReadBuffer.
1190 }
1191
1192 ////
1193
1194 bool WebGLFramebuffer::FramebufferAttach(const GLenum attachEnum,
1195                                          const webgl::FbAttachInfo& toAttach) {
1196   MOZ_ASSERT(mContext->mBoundDrawFramebuffer == this ||
1197              mContext->mBoundReadFramebuffer == this);
1198
1199   if (MOZ_UNLIKELY(mOpaque)) {
1200     // An opaque framebuffer's attachments cannot be inspected or changed.
1201     return false;
1202   }
1203
1204   // `attachment`
1205   const auto maybeAttach = GetAttachPoint(attachEnum);
1206   if (!maybeAttach || !maybeAttach.value()) return false;
1207   const auto& attach = maybeAttach.value();
1208
1209   const auto& gl = mContext->gl;
1210   gl->fBindFramebuffer(LOCAL_GL_FRAMEBUFFER, mGLName);
1211   if (mContext->IsWebGL2() && attachEnum == LOCAL_GL_DEPTH_STENCIL_ATTACHMENT) {
1212     mDepthAttachment.Set(gl, toAttach);
1213     mStencilAttachment.Set(gl, toAttach);
1214   } else {
1215     attach->Set(gl, toAttach);
1216   }
1217   InvalidateCaches();
1218   return true;
1219 }
1220
1221 Maybe<double> WebGLFramebuffer::GetAttachmentParameter(GLenum attachEnum,
1222                                                        GLenum pname) {
1223   const auto maybeAttach = GetAttachPoint(attachEnum);
1224   if (!maybeAttach || attachEnum == LOCAL_GL_NONE) {
1225     mContext->ErrorInvalidEnum(
1226         "Can only query COLOR_ATTACHMENTi,"
1227         " DEPTH_ATTACHMENT, DEPTH_STENCIL_ATTACHMENT, or"
1228         " STENCIL_ATTACHMENT for a framebuffer.");
1229     return Nothing();
1230   }
1231   if (MOZ_UNLIKELY(mOpaque)) {
1232     mContext->ErrorInvalidOperation(
1233         "An opaque framebuffer's attachments cannot be inspected or changed.");
1234     return Nothing();
1235   }
1236   auto attach = maybeAttach.value();
1237
1238   if (mContext->IsWebGL2() && attachEnum == LOCAL_GL_DEPTH_STENCIL_ATTACHMENT) {
1239     if (mDepthAttachment.Renderbuffer() != mStencilAttachment.Renderbuffer() ||
1240         mDepthAttachment.Texture() != mStencilAttachment.Texture()) {
1241       mContext->ErrorInvalidOperation(
1242           "DEPTH_ATTACHMENT and STENCIL_ATTACHMENT"
1243           " have different objects bound.");
1244       return Nothing();
1245     }
1246
1247     attach = &mDepthAttachment;
1248   }
1249
1250   return attach->GetParameter(mContext, attachEnum, pname);
1251 }
1252
1253 ////////////////////
1254
1255 static void GetBackbufferFormats(const WebGLContext* webgl,
1256                                  const webgl::FormatInfo** const out_color,
1257                                  const webgl::FormatInfo** const out_depth,
1258                                  const webgl::FormatInfo** const out_stencil) {
1259   const auto& options = webgl->Options();
1260
1261   const auto effFormat = (options.alpha ? webgl::EffectiveFormat::RGBA8
1262                                         : webgl::EffectiveFormat::RGB8);
1263   *out_color = webgl::GetFormat(effFormat);
1264
1265   *out_depth = nullptr;
1266   *out_stencil = nullptr;
1267   if (options.depth && options.stencil) {
1268     *out_depth = webgl::GetFormat(webgl::EffectiveFormat::DEPTH24_STENCIL8);
1269     *out_stencil = *out_depth;
1270   } else {
1271     if (options.depth) {
1272       *out_depth = webgl::GetFormat(webgl::EffectiveFormat::DEPTH_COMPONENT16);
1273     }
1274     if (options.stencil) {
1275       *out_stencil = webgl::GetFormat(webgl::EffectiveFormat::STENCIL_INDEX8);
1276     }
1277   }
1278 }
1279
1280 /*static*/
1281 void WebGLFramebuffer::BlitFramebuffer(WebGLContext* webgl, GLint _srcX0,
1282                                        GLint _srcY0, GLint _srcX1, GLint _srcY1,
1283                                        GLint _dstX0, GLint _dstY0, GLint _dstX1,
1284                                        GLint _dstY1, GLbitfield mask,
1285                                        GLenum filter) {
1286   auto srcP0 = ivec2{_srcX0, _srcY0};
1287   auto srcP1 = ivec2{_srcX1, _srcY1};
1288   auto dstP0 = ivec2{_dstX0, _dstY0};
1289   auto dstP1 = ivec2{_dstX1, _dstY1};
1290
1291   const GLbitfield depthAndStencilBits =
1292       LOCAL_GL_DEPTH_BUFFER_BIT | LOCAL_GL_STENCIL_BUFFER_BIT;
1293   if (bool(mask & depthAndStencilBits) && filter == LOCAL_GL_LINEAR) {
1294     webgl->ErrorInvalidOperation(
1295         "DEPTH_BUFFER_BIT and STENCIL_BUFFER_BIT can"
1296         " only be used with NEAREST filtering.");
1297     return;
1298   }
1299
1300   const auto& srcFB = webgl->mBoundReadFramebuffer;
1301   const auto& dstFB = webgl->mBoundDrawFramebuffer;
1302
1303   ////
1304   // Collect data
1305
1306   const auto fnGetFormat =
1307       [](const WebGLFBAttachPoint& cur,
1308          bool* const out_hasSamples) -> const webgl::FormatInfo* {
1309     const auto& imageInfo = cur.GetImageInfo();
1310     if (!imageInfo) return nullptr;  // No attachment.
1311     *out_hasSamples = bool(imageInfo->mSamples);
1312     return imageInfo->mFormat->format;
1313   };
1314
1315   bool srcHasSamples = false;
1316   bool srcIsFilterable = true;
1317   const webgl::FormatInfo* srcColorFormat;
1318   const webgl::FormatInfo* srcDepthFormat;
1319   const webgl::FormatInfo* srcStencilFormat;
1320   gfx::IntSize srcSize;
1321
1322   if (srcFB) {
1323     const auto& info = *srcFB->GetCompletenessInfo();
1324     if (info.zLayerCount != 1) {
1325       webgl->GenerateError(
1326           LOCAL_GL_INVALID_FRAMEBUFFER_OPERATION,
1327           "Source framebuffer cannot have more than one multiview layer.");
1328       return;
1329     }
1330     srcColorFormat = nullptr;
1331     if (srcFB->mColorReadBuffer) {
1332       const auto& imageInfo = srcFB->mColorReadBuffer->GetImageInfo();
1333       if (imageInfo) {
1334         srcIsFilterable &= imageInfo->mFormat->isFilterable;
1335       }
1336       srcColorFormat = fnGetFormat(*(srcFB->mColorReadBuffer), &srcHasSamples);
1337     }
1338     srcDepthFormat = fnGetFormat(srcFB->DepthAttachment(), &srcHasSamples);
1339     srcStencilFormat = fnGetFormat(srcFB->StencilAttachment(), &srcHasSamples);
1340     MOZ_ASSERT(!srcFB->DepthStencilAttachment().HasAttachment());
1341     srcSize = {info.width, info.height};
1342   } else {
1343     srcHasSamples = false;  // Always false.
1344
1345     GetBackbufferFormats(webgl, &srcColorFormat, &srcDepthFormat,
1346                          &srcStencilFormat);
1347     const auto& size = webgl->DrawingBufferSize();
1348     srcSize = {size.x, size.y};
1349   }
1350
1351   ////
1352
1353   bool dstHasSamples = false;
1354   const webgl::FormatInfo* dstDepthFormat;
1355   const webgl::FormatInfo* dstStencilFormat;
1356   bool dstHasColor = false;
1357   bool colorFormatsMatch = true;
1358   bool colorTypesMatch = true;
1359   bool colorSrgbMatches = true;
1360   gfx::IntSize dstSize;
1361
1362   const auto fnCheckColorFormat = [&](const webgl::FormatInfo* dstFormat) {
1363     MOZ_ASSERT(dstFormat->r || dstFormat->g || dstFormat->b || dstFormat->a);
1364     dstHasColor = true;
1365     colorFormatsMatch &= (dstFormat == srcColorFormat);
1366     colorTypesMatch &=
1367         srcColorFormat && (dstFormat->baseType == srcColorFormat->baseType);
1368     colorSrgbMatches &=
1369         srcColorFormat && (dstFormat->isSRGB == srcColorFormat->isSRGB);
1370   };
1371
1372   if (dstFB) {
1373     for (const auto& cur : dstFB->mColorDrawBuffers) {
1374       const auto& format = fnGetFormat(*cur, &dstHasSamples);
1375       if (!format) continue;
1376
1377       fnCheckColorFormat(format);
1378     }
1379
1380     dstDepthFormat = fnGetFormat(dstFB->DepthAttachment(), &dstHasSamples);
1381     dstStencilFormat = fnGetFormat(dstFB->StencilAttachment(), &dstHasSamples);
1382     MOZ_ASSERT(!dstFB->DepthStencilAttachment().HasAttachment());
1383
1384     const auto& info = *dstFB->GetCompletenessInfo();
1385     if (info.isMultiview) {
1386       webgl->GenerateError(
1387           LOCAL_GL_INVALID_FRAMEBUFFER_OPERATION,
1388           "Destination framebuffer cannot have multiview attachments.");
1389       return;
1390     }
1391     dstSize = {info.width, info.height};
1392   } else {
1393     dstHasSamples = webgl->Options().antialias;
1394
1395     const webgl::FormatInfo* dstColorFormat;
1396     GetBackbufferFormats(webgl, &dstColorFormat, &dstDepthFormat,
1397                          &dstStencilFormat);
1398
1399     fnCheckColorFormat(dstColorFormat);
1400
1401     const auto& size = webgl->DrawingBufferSize();
1402     dstSize = {size.x, size.y};
1403   }
1404
1405   ////
1406   // Clear unused buffer bits
1407
1408   if (mask & LOCAL_GL_COLOR_BUFFER_BIT && !srcColorFormat && !dstHasColor) {
1409     mask ^= LOCAL_GL_COLOR_BUFFER_BIT;
1410   }
1411
1412   if (mask & LOCAL_GL_DEPTH_BUFFER_BIT && !srcDepthFormat && !dstDepthFormat) {
1413     mask ^= LOCAL_GL_DEPTH_BUFFER_BIT;
1414   }
1415
1416   if (mask & LOCAL_GL_STENCIL_BUFFER_BIT && !srcStencilFormat &&
1417       !dstStencilFormat) {
1418     mask ^= LOCAL_GL_STENCIL_BUFFER_BIT;
1419   }
1420
1421   ////
1422   // Validation
1423
1424   if (dstHasSamples) {
1425     webgl->ErrorInvalidOperation(
1426         "DRAW_FRAMEBUFFER may not have multiple"
1427         " samples.");
1428     return;
1429   }
1430
1431   bool requireFilterable = (filter == LOCAL_GL_LINEAR);
1432   if (srcHasSamples) {
1433     requireFilterable = false;  // It picks one.
1434
1435     if (mask & LOCAL_GL_COLOR_BUFFER_BIT && dstHasColor && !colorFormatsMatch) {
1436       webgl->ErrorInvalidOperation(
1437           "Color buffer formats must match if"
1438           " selected, when reading from a multisampled"
1439           " source.");
1440       return;
1441     }
1442
1443     if (srcP0 != dstP0 || srcP1 != dstP1) {
1444       webgl->ErrorInvalidOperation(
1445           "If the source is multisampled, then the"
1446           " source and dest regions must match exactly.");
1447       return;
1448     }
1449   }
1450
1451   // -
1452
1453   if (mask & LOCAL_GL_COLOR_BUFFER_BIT) {
1454     if (requireFilterable && !srcIsFilterable) {
1455       webgl->ErrorInvalidOperation(
1456           "`filter` is LINEAR and READ_BUFFER"
1457           " contains integer data.");
1458       return;
1459     }
1460
1461     if (!colorTypesMatch) {
1462       webgl->ErrorInvalidOperation(
1463           "Color component types (float/uint/"
1464           "int) must match.");
1465       return;
1466     }
1467   }
1468
1469   /* GLES 3.0.4, p199:
1470    *   Calling BlitFramebuffer will result in an INVALID_OPERATION error if
1471    *   mask includes DEPTH_BUFFER_BIT or STENCIL_BUFFER_BIT, and the source
1472    *   and destination depth and stencil buffer formats do not match.
1473    *
1474    * jgilbert: The wording is such that if only DEPTH_BUFFER_BIT is specified,
1475    * the stencil formats must match. This seems wrong. It could be a spec bug,
1476    * or I could be missing an interaction in one of the earlier paragraphs.
1477    */
1478   if (mask & LOCAL_GL_DEPTH_BUFFER_BIT && dstDepthFormat &&
1479       dstDepthFormat != srcDepthFormat) {
1480     webgl->ErrorInvalidOperation(
1481         "Depth buffer formats must match if selected.");
1482     return;
1483   }
1484
1485   if (mask & LOCAL_GL_STENCIL_BUFFER_BIT && dstStencilFormat &&
1486       dstStencilFormat != srcStencilFormat) {
1487     webgl->ErrorInvalidOperation(
1488         "Stencil buffer formats must match if selected.");
1489     return;
1490   }
1491
1492   ////
1493   // Check for feedback
1494
1495   if (srcFB && dstFB) {
1496     const WebGLFBAttachPoint* feedback = nullptr;
1497
1498     if (mask & LOCAL_GL_COLOR_BUFFER_BIT) {
1499       MOZ_ASSERT(srcFB->mColorReadBuffer->HasAttachment());
1500       for (const auto& cur : dstFB->mColorDrawBuffers) {
1501         if (srcFB->mColorReadBuffer->IsEquivalentForFeedback(*cur)) {
1502           feedback = cur;
1503           break;
1504         }
1505       }
1506     }
1507
1508     if (mask & LOCAL_GL_DEPTH_BUFFER_BIT &&
1509         srcFB->DepthAttachment().IsEquivalentForFeedback(
1510             dstFB->DepthAttachment())) {
1511       feedback = &dstFB->DepthAttachment();
1512     }
1513
1514     if (mask & LOCAL_GL_STENCIL_BUFFER_BIT &&
1515         srcFB->StencilAttachment().IsEquivalentForFeedback(
1516             dstFB->StencilAttachment())) {
1517       feedback = &dstFB->StencilAttachment();
1518     }
1519
1520     if (feedback) {
1521       webgl->ErrorInvalidOperation(
1522           "Feedback detected into DRAW_FRAMEBUFFER's"
1523           " 0x%04x attachment.",
1524           feedback->mAttachmentPoint);
1525       return;
1526     }
1527   } else if (!srcFB && !dstFB) {
1528     webgl->ErrorInvalidOperation("Feedback with default framebuffer.");
1529     return;
1530   }
1531
1532   // -
1533   // Mutually constrain src and dst rects for eldritch blits.
1534
1535   [&] {
1536     using fvec2 = avec2<float>;  // Switch to float, because there's no perfect
1537                                  // solution anyway.
1538
1539     const auto zero2f = fvec2{0, 0};
1540     const auto srcSizef = AsVec(srcSize).StaticCast<fvec2>();
1541     const auto dstSizef = AsVec(dstSize).StaticCast<fvec2>();
1542
1543     const auto srcP0f = srcP0.StaticCast<fvec2>();
1544     const auto srcP1f = srcP1.StaticCast<fvec2>();
1545     const auto dstP0f = dstP0.StaticCast<fvec2>();
1546     const auto dstP1f = dstP1.StaticCast<fvec2>();
1547
1548     const auto srcRectDiff = srcP1f - srcP0f;
1549     const auto dstRectDiff = dstP1f - dstP0f;
1550
1551     // Skip if zero-sized.
1552     if (!srcRectDiff.x || !srcRectDiff.y || !dstRectDiff.x || !dstRectDiff.y) {
1553       srcP0 = srcP1 = dstP0 = dstP1 = {0, 0};
1554       return;
1555     }
1556
1557     // Clamp the rect points
1558     const auto srcQ0 = srcP0f.ClampMinMax(zero2f, srcSizef);
1559     const auto srcQ1 = srcP1f.ClampMinMax(zero2f, srcSizef);
1560
1561     // Normalized to the [0,1] abstact copy rect
1562     const auto srcQ0Norm = (srcQ0 - srcP0f) / srcRectDiff;
1563     const auto srcQ1Norm = (srcQ1 - srcP0f) / srcRectDiff;
1564
1565     // Map into dst
1566     const auto srcQ0InDst = dstP0f + srcQ0Norm * dstRectDiff;
1567     const auto srcQ1InDst = dstP0f + srcQ1Norm * dstRectDiff;
1568
1569     // Clamp the rect points
1570     const auto dstQ0 = srcQ0InDst.ClampMinMax(zero2f, dstSizef);
1571     const auto dstQ1 = srcQ1InDst.ClampMinMax(zero2f, dstSizef);
1572
1573     // Alright, time to go back to src!
1574     // Normalized to the [0,1] abstact copy rect
1575     const auto dstQ0Norm = (dstQ0 - dstP0f) / dstRectDiff;
1576     const auto dstQ1Norm = (dstQ1 - dstP0f) / dstRectDiff;
1577
1578     // Map into src
1579     const auto dstQ0InSrc = srcP0f + dstQ0Norm * srcRectDiff;
1580     const auto dstQ1InSrc = srcP0f + dstQ1Norm * srcRectDiff;
1581
1582     const auto srcQ0Constrained = dstQ0InSrc.ClampMinMax(zero2f, srcSizef);
1583     const auto srcQ1Constrained = dstQ1InSrc.ClampMinMax(zero2f, srcSizef);
1584
1585     // Round, don't floor:
1586     srcP0 = (srcQ0Constrained + 0.5).StaticCast<ivec2>();
1587     srcP1 = (srcQ1Constrained + 0.5).StaticCast<ivec2>();
1588     dstP0 = (dstQ0 + 0.5).StaticCast<ivec2>();
1589     dstP1 = (dstQ1 + 0.5).StaticCast<ivec2>();
1590   }();
1591
1592   bool inBounds = true;
1593   inBounds &= (srcP0 == srcP0.Clamp({0, 0}, AsVec(srcSize)));
1594   inBounds &= (srcP1 == srcP1.Clamp({0, 0}, AsVec(srcSize)));
1595   inBounds &= (dstP0 == dstP0.Clamp({0, 0}, AsVec(dstSize)));
1596   inBounds &= (dstP1 == dstP1.Clamp({0, 0}, AsVec(dstSize)));
1597   if (!inBounds) {
1598     webgl->ErrorImplementationBug(
1599         "Subrects still not within src and dst after constraining.");
1600     return;
1601   }
1602
1603   // -
1604   // Execute as constrained
1605
1606   const auto& gl = webgl->gl;
1607   const ScopedDrawCallWrapper wrapper(*webgl);
1608
1609   gl->fBlitFramebuffer(srcP0.x, srcP0.y, srcP1.x, srcP1.y, dstP0.x, dstP0.y,
1610                        dstP1.x, dstP1.y, mask, filter);
1611
1612   // -
1613
1614   if (mask & LOCAL_GL_COLOR_BUFFER_BIT && !colorSrgbMatches && !gl->IsGLES() &&
1615       gl->Version() < 440) {
1616     // Mostly for Mac.
1617     // Remember, we have to filter in the *linear* format blit.
1618
1619     // src -Blit-> fbB -DrawBlit-> fbC -Blit-> dst
1620
1621     const auto fbB = gl::MozFramebuffer::Create(gl, {1, 1}, 0, false);
1622     const auto fbC = gl::MozFramebuffer::Create(gl, {1, 1}, 0, false);
1623
1624     // -
1625
1626     auto sizeBC = srcSize;
1627     GLenum formatC = LOCAL_GL_RGBA8;
1628     if (srcColorFormat->isSRGB) {
1629       // srgb -> linear
1630     } else {
1631       // linear -> srgb
1632       sizeBC = dstSize;
1633       formatC = LOCAL_GL_SRGB8_ALPHA8;
1634     }
1635
1636     const auto fnSetTex = [&](const gl::MozFramebuffer& fb,
1637                               const GLenum format) {
1638       const gl::ScopedBindTexture bindTex(gl, fb.ColorTex());
1639       gl->fTexStorage2D(LOCAL_GL_TEXTURE_2D, 1, format, sizeBC.width,
1640                         sizeBC.height);
1641     };
1642     fnSetTex(*fbB, srcColorFormat->sizedFormat);
1643     fnSetTex(*fbC, formatC);
1644
1645     // -
1646
1647     {
1648       const gl::ScopedBindFramebuffer bindFb(gl);
1649       gl->fBindFramebuffer(LOCAL_GL_DRAW_FRAMEBUFFER, fbB->mFB);
1650
1651       if (srcColorFormat->isSRGB) {
1652         // srgb -> linear
1653         gl->fBlitFramebuffer(srcP0.x, srcP0.y, srcP1.x, srcP1.y, srcP0.x,
1654                              srcP0.y, srcP1.x, srcP1.y,
1655                              LOCAL_GL_COLOR_BUFFER_BIT, LOCAL_GL_NEAREST);
1656       } else {
1657         // linear -> srgb
1658         gl->fBlitFramebuffer(srcP0.x, srcP0.y, srcP1.x, srcP1.y, dstP0.x,
1659                              dstP0.y, dstP1.x, dstP1.y,
1660                              LOCAL_GL_COLOR_BUFFER_BIT, filter);
1661       }
1662
1663       gl->fBindFramebuffer(LOCAL_GL_DRAW_FRAMEBUFFER, fbC->mFB);
1664       gl->BlitHelper()->DrawBlitTextureToFramebuffer(fbB->ColorTex(), sizeBC,
1665                                                      sizeBC);
1666     }
1667
1668     {
1669       const gl::ScopedBindFramebuffer bindFb(gl);
1670       gl->fBindFramebuffer(LOCAL_GL_READ_FRAMEBUFFER, fbC->mFB);
1671
1672       if (srcColorFormat->isSRGB) {
1673         // srgb -> linear
1674         gl->fBlitFramebuffer(srcP0.x, srcP0.y, srcP1.x, srcP1.y, dstP0.x,
1675                              dstP0.y, dstP1.x, dstP1.y,
1676                              LOCAL_GL_COLOR_BUFFER_BIT, filter);
1677       } else {
1678         // linear -> srgb
1679         gl->fBlitFramebuffer(dstP0.x, dstP0.y, dstP1.x, dstP1.y, dstP0.x,
1680                              dstP0.y, dstP1.x, dstP1.y,
1681                              LOCAL_GL_COLOR_BUFFER_BIT, LOCAL_GL_NEAREST);
1682       }
1683     }
1684   }
1685
1686   // -
1687   // glBlitFramebuffer ignores glColorMask!
1688
1689   if (!webgl->mBoundDrawFramebuffer && webgl->mNeedsFakeNoAlpha) {
1690     const auto dstRectMin = MinExtents(dstP0, dstP1);
1691     const auto dstRectMax = MaxExtents(dstP0, dstP1);
1692     const auto dstRectSize = dstRectMax - dstRectMin;
1693     const WebGLContext::ScissorRect dstRect = {dstRectMin.x, dstRectMin.y,
1694                                                dstRectSize.x, dstRectSize.y};
1695     dstRect.Apply(*gl);
1696
1697     const auto forClear = webgl::ScopedPrepForResourceClear{*webgl};
1698
1699     gl->fClearColor(0, 0, 0, 1);
1700     webgl->DoColorMask(Some(0), 0b1000);  // Only alpha.
1701     gl->fClear(LOCAL_GL_COLOR_BUFFER_BIT);
1702
1703     webgl->mScissorRect.Apply(*gl);
1704   }
1705 }
1706
1707 }  // namespace mozilla