Add glCopyCompressedTextureCHROMIUM

gpu/GLES2/extensions/CHROMIUM/CHROMIUM_compressed_copy_texture.txt

+Name
+
+    CHROMIUM_copy_compressed_texture
+
+Name Strings
+
+    GL_CHROMIUM_copy_compressed_texture
+
+Version
+
+    Last Modifed Date: May 28, 2015
+
+Dependencies
+
+    OpenGL ES 2.0 is required.
+
+    GL_AMD_compressed_ATC_texture, GL_ATI_texture_compression_atitc,
+    GL_EXT_texture_compression_dxt1, GL_ANGLE_texture_compression_dxt5,
+    GL_EXT_texture_compression_s3tc and GL_OES_compressed_ETC1_RGB8_texture
+    affects the definition of this extension.
+
+Overview
+
+    This extension provides functionality for copying compressed textures. It
+    adds a new function glCompressedCopyTextureCHROMIUM that works similarily
+    to glCopyTextureCHROMIUM, but for compressed textures.
+
+    Which compressed texture formats that this extension supports depends on
+    the supported texture compression formats of the host GPU.
+
+Issues
+
+    glCompressedCopyTextureCHROMIUM will first try to copy into a compressed
+    texture of the same format as the source texture. If unsucessful, the
+    destination texture format will be changed to GL_RGBA and the texture will
+    be stored uncompressed.
+
+New Procedures and Functions
+
+    The command
+
+        void glCompressedCopyTextureCHROMIUM (GLenum target, GLenum source_id,
+                                              GLenum dest_id,
+                                              GLint internal_format,
+                                              GLsizei source_size)

[piman, 2015/06/09 00:24:19]

nit: can we remove internal_format and source_size? They provide no value since
they have to match the source texture anyway.

[christiank, 2015/06/11 07:31:56]

Done.

+
+    Copies the contents of a compressed texture referred to by <source_id> to
+    <dest_id> texture.
+
+    Texture level 0 is copied from the source image to level 0 of the
+    destination texture.
+
+    The internal format of the source and destination texture must be
+    compressed, and they must match. The <internal_format> must be one of the
+    following symbolic constants: GL_ATC_RGB_AMD,
+    GL_ATC_RGBA_INTERPOLATED_ALPHA_AMD, GL_COMPRESSED_RGB_S3TC_DXT1_EXT,
+    GL_COMPRESSED_RGBA_S3TC_DXT5_EXT, GL_ETC1_RGB8_OES
+
+    <target> uses the same parameters as TexImage2D.
+
+    INVALID_OPERATION is generated if <internal_format> is not one of the valid
+    formats described above.
+
+    INVALID_OPERATION is generated if internal format of source and destination
+    texture doesn't match.
+
+    INVALID_VALUE is generated if <source_id> or <dest_id> are not valid texture
+    objects.
+
+    INVALID_VALUE is generated if textures corresponding to <dest_id> have not
+    been bound as GL_TEXTURE_2D object.
+
+    INVALID_VALUE is generated if level 0 of the source texture is not defined.
+
+Errors
+
+    None.
+
+New Tokens
+
+    None.
+
+New State
+
+    None.
+
+Revision History
+
+    28/5/2015    Documented the extension.