dom/canvas/WebGLExtensionDrawBuffers.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   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 file,
   4  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "WebGLExtensions.h"
   7
   8 #include <algorithm>
   9 #include "GLContext.h"
  10 #include "mozilla/dom/WebGLRenderingContextBinding.h"
  11 #include "WebGLContext.h"
  12 #include "WebGLFramebuffer.h"
  13 #include "WebGLRenderbuffer.h"
  14 #include "WebGLTexture.h"
  15
  16 namespace mozilla {
  17
  18 WebGLExtensionDrawBuffers::WebGLExtensionDrawBuffers(WebGLContext* webgl)
  19     : WebGLExtensionBase(webgl)
  20 {
  21     MOZ_ASSERT(IsSupported(webgl), "Don't construct extension if unsupported.");
  22
  23     GLint maxColorAttachments = 0;
  24     GLint maxDrawBuffers = 0;
  25
  26     webgl->MakeContextCurrent();
  27     gl::GLContext* gl = webgl->GL();
  28
  29     gl->fGetIntegerv(LOCAL_GL_MAX_COLOR_ATTACHMENTS, &maxColorAttachments);
  30     gl->fGetIntegerv(LOCAL_GL_MAX_DRAW_BUFFERS, &maxDrawBuffers);
  31
  32     // WEBGL_draw_buffers specifications don't give a maximal value reachable by MAX_COLOR_ATTACHMENTS.
  33     maxColorAttachments = std::min(maxColorAttachments, GLint(WebGLContext::kMaxColorAttachments));
  34
  35     if (webgl->MinCapabilityMode())
  36         maxColorAttachments = std::min(maxColorAttachments, GLint(kMinColorAttachments));
  37
  38     // WEBGL_draw_buffers specifications request MAX_COLOR_ATTACHMENTS >= MAX_DRAW_BUFFERS.
  39     maxDrawBuffers = std::min(maxDrawBuffers, GLint(maxColorAttachments));
  40
  41     webgl->mGLMaxColorAttachments = maxColorAttachments;
  42     webgl->mGLMaxDrawBuffers = maxDrawBuffers;
  43 }
  44
  45 WebGLExtensionDrawBuffers::~WebGLExtensionDrawBuffers()
  46 {
  47 }
  48
  49 void
  50 WebGLExtensionDrawBuffers::DrawBuffersWEBGL(const dom::Sequence<GLenum>& buffers)
  51 {
  52     if (mIsLost) {
  53         mContext->ErrorInvalidOperation("drawBuffersWEBGL: Extension is lost.");
  54         return;
  55     }
  56
  57     mContext->DrawBuffers(buffers);
  58 }
  59
  60 bool
  61 WebGLExtensionDrawBuffers::IsSupported(const WebGLContext* webgl)
  62 {
  63     gl::GLContext* gl = webgl->GL();
  64
  65     if (!gl->IsSupported(gl::GLFeature::draw_buffers))
  66         return false;
  67
  68     GLint supportedColorAttachments = 0;
  69     GLint supportedDrawBuffers = 0;
  70
  71     webgl->MakeContextCurrent();
  72
  73     gl->fGetIntegerv(LOCAL_GL_MAX_COLOR_ATTACHMENTS, &supportedColorAttachments);
  74     gl->fGetIntegerv(LOCAL_GL_MAX_COLOR_ATTACHMENTS, &supportedDrawBuffers);
  75
  76     // WEBGL_draw_buffers requires at least 4 color attachments.
  77     if (size_t(supportedColorAttachments) < kMinColorAttachments)
  78         return false;
  79
  80     if (size_t(supportedDrawBuffers) < kMinDrawBuffers)
  81         return false;
  82
  83     return true;
  84 }
  85
  86 IMPL_WEBGL_EXTENSION_GOOP(WebGLExtensionDrawBuffers)
  87
  88 } // namespace mozilla