Implement OES_texture_float_linear and OES_texture_half_float_linear extensions in WebGL.

Source/core/html/canvas/WebGLTexture.cpp

Index: Source/core/html/canvas/WebGLTexture.cpp
diff --git a/Source/core/html/canvas/WebGLTexture.cpp b/Source/core/html/canvas/WebGLTexture.cpp
index c8c23bd4be545a9c05708dcf75ca32171cb10ca0..9ad4d55b49cc9a9749297e48e31e6ba5cadf3f64 100644
--- a/Source/core/html/canvas/WebGLTexture.cpp
+++ b/Source/core/html/canvas/WebGLTexture.cpp
@@ -48,6 +48,8 @@ WebGLTexture::WebGLTexture(WebGLRenderingContext* ctx)
     , m_isNPOT(false)
     , m_isComplete(false)
     , m_needToUseBlackTexture(false)
+    , m_isFloatType(false)
+    , m_isHalfFloatType(false)
 {
     setObject(ctx->graphicsContext3D()->createTexture());
 }
@@ -230,10 +232,14 @@ bool WebGLTexture::isNPOT() const
     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;
 }
 
@@ -310,6 +316,20 @@ void WebGLTexture::update()
             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);