content/canvas/src/WebGLTypes.h

   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
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef WEBGLTYPES_H_
   7 #define WEBGLTYPES_H_
   8
   9 #include "mozilla/TypedEnum.h"
  10
  11 // Most WebIDL typedefs are identical to their OpenGL counterparts.
  12 #include "GLTypes.h"
  13
  14 // Manual reflection of WebIDL typedefs that are different from their
  15 // OpenGL counterparts.
  16 typedef int64_t WebGLsizeiptr;
  17 typedef int64_t WebGLintptr;
  18 typedef bool WebGLboolean;
  19
  20 namespace mozilla {
  21
  22 /*
  23  * WebGLContextFakeBlackStatus and WebGLTextureFakeBlackStatus are enums to
  24  * track what needs to use a dummy 1x1 black texture, which we refer to as a
  25  * 'fake black' texture.
  26  *
  27  * There are generally two things that can cause us to use such 'fake black'
  28  * textures:
  29  *
  30  *   (1) OpenGL ES rules on sampling incomplete textures specify that they
  31  *       must be sampled as RGBA(0, 0, 0, 1) (opaque black). We have to implement these rules
  32  *       ourselves, if only because we do not always run on OpenGL ES, and also
  33  *       because this is dangerously close to the kind of case where we don't
  34  *       want to trust the driver with corner cases of texture memory accesses.
  35  *
  36  *   (2) OpenGL has cases where a renderbuffer, or a texture image, can contain
  37  *       uninitialized image data. See below the comment about WebGLImageDataStatus.
  38  *       WebGL must never have access to uninitialized image data. The WebGL 1 spec,
  39  *       section 4.1 'Resource Restrictions', specifies that in any such case, the
  40  *       uninitialized image data must be exposed to WebGL as if it were filled
  41  *       with zero bytes, which means it's either opaque or transparent black
  42  *       depending on whether the image format has alpha.
  43  *
  44  * Why are there _two_ separate enums there, WebGLContextFakeBlackStatus
  45  * and WebGLTextureFakeBlackStatus? That's because each texture must know the precise
  46  * reason why it needs to be faked (incomplete texture vs. uninitialized image data),
  47  * whereas the WebGL context can only know whether _any_ faking is currently needed at all.
  48  */
  49 MOZ_BEGIN_ENUM_CLASS(WebGLContextFakeBlackStatus, int)
  50   Unknown,
  51   NotNeeded,
  52   Needed
  53 MOZ_END_ENUM_CLASS(WebGLContextFakeBlackStatus)
  54
  55 MOZ_BEGIN_ENUM_CLASS(WebGLTextureFakeBlackStatus, int)
  56   Unknown,
  57   NotNeeded,
  58   IncompleteTexture,
  59   UninitializedImageData
  60 MOZ_END_ENUM_CLASS(WebGLTextureFakeBlackStatus)
  61
  62 /*
  63  * Implementing WebGL (or OpenGL ES 2.0) on top of desktop OpenGL requires
  64  * emulating the vertex attrib 0 array when it's not enabled. Indeed,
  65  * OpenGL ES 2.0 allows drawing without vertex attrib 0 array enabled, but
  66  * desktop OpenGL does not allow that.
  67  */
  68 MOZ_BEGIN_ENUM_CLASS(WebGLVertexAttrib0Status, int)
  69     Default, // default status - no emulation needed
  70     EmulatedUninitializedArray, // need an artificial attrib 0 array, but contents may be left uninitialized
  71     EmulatedInitializedArray // need an artificial attrib 0 array, and contents must be initialized
  72 MOZ_END_ENUM_CLASS(WebGLVertexAttrib0Status)
  73
  74 /*
  75  * Enum to track the status of image data (renderbuffer or texture image) presence
  76  * and initialization.
  77  *
  78  * - NoImageData is the initial state before any image data is allocated.
  79  * - InitializedImageData is the state after image data is allocated and initialized.
  80  * - UninitializedImageData is an intermediate state where data is allocated but not
  81  *   initialized. It is the state that renderbuffers are in after a renderbufferStorage call,
  82  *   and it is the state that texture images are in after a texImage2D call with null data.
  83  */
  84 MOZ_BEGIN_ENUM_CLASS(WebGLImageDataStatus, int)
  85     NoImageData,
  86     UninitializedImageData,
  87     InitializedImageData
  88 MOZ_END_ENUM_CLASS(WebGLImageDataStatus)
  89
  90 /*
  91  * The formats that may participate, either as source or destination formats,
  92  * in WebGL texture conversions. This includes:
  93  *  - all the formats accepted by WebGL.texImage2D, e.g. RGBA4444
  94  *  - additional formats provided by extensions, e.g. RGB32F
  95  *  - additional source formats, depending on browser details, used when uploading
  96  *    textures from DOM elements. See gfxImageSurface::Format().
  97  */
  98 MOZ_BEGIN_ENUM_CLASS(WebGLTexelFormat, int)
  99     // returned by SurfaceFromElementResultToImageSurface to indicate absence of image data
 100     None,
 101     // dummy error code returned by GetWebGLTexelFormat in error cases,
 102     // after assertion failure (so this never happens in debug builds)
 103     BadFormat,
 104     // dummy pseudo-format meaning "use the other format".
 105     // For example, if SrcFormat=Auto and DstFormat=RGB8, then the source
 106     // is implicitly treated as being RGB8 itself.
 107     Auto,
 108     // 1-channel formats
 109     R8,
 110     A8,
 111     D16, // used for WEBGL_depth_texture extension
 112     D32, // used for WEBGL_depth_texture extension
 113     R32F, // used for OES_texture_float extension
 114     A32F, // used for OES_texture_float extension
 115     // 2-channel formats
 116     RA8,
 117     RA32F,
 118     D24S8, // used for WEBGL_depth_texture extension
 119     // 3-channel formats
 120     RGB8,
 121     BGRX8, // used for DOM elements. Source format only.
 122     RGB565,
 123     RGB32F, // used for OES_texture_float extension
 124     // 4-channel formats
 125     RGBA8,
 126     BGRA8, // used for DOM elements
 127     RGBA5551,
 128     RGBA4444,
 129     RGBA32F // used for OES_texture_float extension
 130 MOZ_END_ENUM_CLASS(WebGLTexelFormat)
 131
 132 } // namespace mozilla
 133
 134 #endif