Implement OES_texture_float_linear and OES_texture_half_float_linear extensions in WebGL.

Source/core/html/canvas/WebGLTexture.cpp

 /*
  * Copyright (C) 2009 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 30 matching lines @@
 WebGLTexture::WebGLTexture(WebGLRenderingContext* ctx)
     : WebGLSharedObject(ctx)
     , m_target(0)
     , m_minFilter(GraphicsContext3D::NEAREST_MIPMAP_LINEAR)
     , m_magFilter(GraphicsContext3D::LINEAR)
     , m_wrapS(GraphicsContext3D::REPEAT)
     , m_wrapT(GraphicsContext3D::REPEAT)
     , m_isNPOT(false)
     , m_isComplete(false)
     , m_needToUseBlackTexture(false)
+    , m_isFloatType(false)
+    , m_isHalfFloatType(false)
 {
     setObject(ctx->graphicsContext3D()->createTexture());
 }
 
 WebGLTexture::~WebGLTexture()
 {
     deleteObject(0);
 }
 
 void WebGLTexture::setTarget(GC3Denum target, GC3Dint maxLevel)
@@ skipping 162 matching lines @@
     return false;
 }
 
 bool WebGLTexture::isNPOT() const
 {
     if (!object())
         return false;
     return m_isNPOT;
 }
 
-bool WebGLTexture::needToUseBlackTexture() const
+bool WebGLTexture::needToUseBlackTexture(TextureExtensionFlag flag) const
 {
     if (!object())
         return false;
+    if ((m_isFloatType && !(flag & TextureFloatLinearExtensionEnabled)) || (m_isHalfFloatType && !(flag && TextureHalfFloatLinearExtensionEnabled))) {
+        if (m_magFilter != GraphicsContext3D::NEAREST || (m_minFilter != GraphicsContext3D::NEAREST && m_minFilter != GraphicsContext3D::NEAREST_MIPMAP_NEAREST))
+            return true;
+    }

[Ken Russell (switch to Gerrit), 2013/05/15 23:25:10]

Per the comment below, I would write this for clarity as:

  if (m_needToUseBlackTexture)
    return true;
  if ((m_isLevel0FloatType && ... ))
    return true;
  return false;

     return m_needToUseBlackTexture;
 }
 
 void WebGLTexture::deleteObjectImpl(GraphicsContext3D* context3d, Platform3DObject object)
 {
     context3d->deleteTexture(object);
 }
 
 int WebGLTexture::mapTargetToIndex(GC3Denum target) const
 {
@@ skipping 56 matching lines @@
 
 void WebGLTexture::update()
 {
     m_isNPOT = false;
     for (size_t ii = 0; ii < m_info.size(); ++ii) {
         if (isNPOT(m_info[ii][0].width, m_info[ii][0].height)) {
             m_isNPOT = true;
             break;
         }
     }
+    m_isFloatType = false;
+    for (size_t ii = 0; ii < m_info.size(); ++ii) {
+        if (m_info[ii][0].type == GraphicsContext3D::FLOAT) {
+            m_isFloatType = true;
+            break;
+        }
+    }
+    m_isHalfFloatType = false;
+    for (size_t ii = 0; ii < m_info.size(); ++ii) {
+        if (m_info[ii][0].type == GraphicsContext3D::HALF_FLOAT_OES) {
+            m_isHalfFloatType = true;
+            break;
+        }
+    }

[Ken Russell (switch to Gerrit), 2013/05/15 23:25:10]

It isn't necessary to scan all the mip levels. If the texture is complete, then
just look at the format of mip level 0 -- you only want to require showing the
black texture if the texture would otherwise be considered complete. You could
call the new fields m_isLevel0FloatType and m_isLevel0HalfFloatType.

[Jun Jiang, 2013/05/16 02:25:43]

Here only mip level 0 is checked. The "for" loop here is to deal with the case
for TEXTURE_CUBE_MAP in which m_info.size() is 6. For TEXTURE_2D, m_info.size()
is 1.
And as you suggested, we can make it faster by checking m_info[0][0].type only
when texture is complete. 

     m_isComplete = true;
     const LevelInfo& first = m_info[0][0];
     GC3Dint levelCount = computeLevelCount(first.width, first.height);
     if (levelCount < 1)
         m_isComplete = false;
     else {
         for (size_t ii = 0; ii < m_info.size() && m_isComplete; ++ii) {
             const LevelInfo& info0 = m_info[ii][0];
             if (!info0.valid
                 || info0.width != first.width || info0.height != first.height
@@ skipping 34 matching lines @@
         return 0;
     int targetIndex = mapTargetToIndex(target);
     if (targetIndex < 0 || targetIndex >= static_cast<int>(m_info.size()))
         return 0;
     if (level < 0 || level >= static_cast<GC3Dint>(m_info[targetIndex].size()))
         return 0;
     return &(m_info[targetIndex][level]);
 }
 
 }