WebGL 2: generate appropriate error for different dimensions of images attached to fbo.

This change fixed the bug in framebuffer-object-attachment.html

BUG=295792
TEST=conformance2/renderbuffers/framebuffer-object-attachment.html

Review URL: https://codereview.chromium.org/1549393002

Cr-Commit-Position: refs/heads/master@{#367053}

third_party/WebKit/Source/modules/webgl/WebGLFramebuffer.cpp

@@ -46,6 +46,7 @@ private:
 
     GLsizei width() const override;
     GLsizei height() const override;
+    GLsizei depth() const override;
     GLenum format() const override;
     GLenum type() const override;
     bool isCubeComplete() const override;
@@ -85,6 +86,11 @@ GLsizei WebGLRenderbufferAttachment::height() const
     return m_renderbuffer->height();
 }
 
+GLsizei WebGLRenderbufferAttachment::depth() const
+{
+    return 1;
+}
+
 GLenum WebGLRenderbufferAttachment::format() const
 {
     GLenum format = m_renderbuffer->internalFormat();
@@ -160,6 +166,7 @@ private:
 
     GLsizei width() const override;
     GLsizei height() const override;
+    GLsizei depth() const override;
     GLenum format() const override;
     GLenum type() const override;
     bool isCubeComplete() const override;
@@ -205,6 +212,11 @@ GLsizei WebGLTextureAttachment::height() const
     return m_texture->getHeight(m_target, m_level);
 }
 
+GLsizei WebGLTextureAttachment::depth() const
+{
+    return m_texture->getDepth(m_target, m_level);
+}
+
 GLenum WebGLTextureAttachment::format() const
 {
     return m_texture->getInternalFormat(m_target, m_level);
@@ -539,7 +551,7 @@ GLenum WebGLFramebuffer::colorBufferFormat() const
 GLenum WebGLFramebuffer::checkStatus(const char** reason) const
 {
     unsigned count = 0;
-    GLsizei width = 0, height = 0;
+    GLsizei width = 0, height = 0, depth = 0;
     WebGLAttachment* depthAttachment = nullptr;
     WebGLAttachment* stencilAttachment = nullptr;
     WebGLAttachment* depthStencilAttachment = nullptr;
@@ -567,17 +579,20 @@ GLenum WebGLFramebuffer::checkStatus(const char** reason) const
             depthStencilAttachment = attachment;
             break;
         }
-        if (!isWebGL2OrHigher) {
+        // Note: In GLES 3, images for a framebuffer need not to have the same dimensions to be framebuffer complete.
+        // However, in Direct3D 11, on top of which OpenGL ES 3 behavior is emulated in Windows, all render targets
+        // must have the same size in all dimensions. In order to have consistent WebGL 2 behaviors across platforms,
+        // we generate FRAMEBUFFER_INCOMPLETE_DIMENSIONS in this situation.
         if (!count) {
             width = attachment->width();
             height = attachment->height();
+            depth = attachment->depth();
         } else {
-                if (width != attachment->width() || height != attachment->height()) {
+            if (width != attachment->width() || height != attachment->height() || depth != attachment->depth()) {
                 *reason = "attachments do not have the same dimensions";
                 return GL_FRAMEBUFFER_INCOMPLETE_DIMENSIONS;
             }
         }
-        }
         ++count;
     }
     if (!count) {

third_party/WebKit/Source/modules/webgl/WebGLFramebuffer.h

@@ -43,6 +43,7 @@ public:
 
         virtual GLsizei width() const = 0;
         virtual GLsizei height() const = 0;
+        virtual GLsizei depth() const = 0;
         virtual GLenum format() const = 0;
         // For texture attachment, type() returns the type of the attached texture.
         // For renderbuffer attachment, the type of the renderbuffer may vary with GL implementation.