Update ANGLE_texture_compression_dxt

git-svn-id: https://angleproject.googlecode.com/svn/branches/dx11proto@1822 736b8ea6-26fd-11df-bfd4-992fa37f6226

extensions/ANGLE_texture_compression_dxt.txt

@@ -4,6 +4,7 @@ Name
 
 Name Strings
 
+    GL_ANGLE_texture_compression_dxt1
     GL_ANGLE_texture_compression_dxt3
     GL_ANGLE_texture_compression_dxt5
 
@@ -23,27 +24,36 @@ Status
 
 Version
 
-    Last Modified Date: Aug 2, 2011
+    Last Modified Date: Sept 22, 2012
+    Author Revision: 2
 
 Number
 
-    OpenGL ES Extension #..
+    OpenGL ES Extension #111
 
 Dependencies
 
-    Requires OpenGL ES 2.0.
+    Requires OpenGL ES 1.0.
 
     The extension is written against the OpenGL ES 2.0 specification.
 
 Overview
 
     These extensions are exactly the same as EXT_texture_compression_dxt1
-    except they expose the formats COMPRESSED_RGBA_S3TC_DXT3_ANGLE and
-    COMPRESSED_RGBA_S3TC_DXT5_ANGLE respectively.
+    except they additionally expose the COMPRESSED_RGBA_S3TC_DXT3_ANGLE and
+    COMPRESSED_RGBA_S3TC_DXT5_ANGLE formats and have a size restrictions
+    such that the size must be a multiple of four (except for mip levels
+    where the dimensions are either 2 or 1).
 
     See EXT_texture_compression_dxt1 for the full list of changes. Also
     see EXT_texture_compression_s3tc for a description of the formats.
 
+IP Status
+
+    A license to the S3TC Intellectual Property may be necessary for 
+    implementation of this extension.  You should consult with your 
+    Attorney to determine the need for a license.
+
 New Procedures and Functions
 
     None.
@@ -57,17 +67,97 @@ New Tokens
     Accepted by the <internalformat> parameter of CompressedTexImage2D
     and the <format> parameter of CompressedTexSubImage2D:
 
+    COMPRESSED_RGB_S3TC_DXT1_ANGLE                    0x83F0
+    COMPRESSED_RGBA_S3TC_DXT1_ANGLE                   0x83F1
     COMPRESSED_RGBA_S3TC_DXT3_ANGLE                   0x83F2
     COMPRESSED_RGBA_S3TC_DXT5_ANGLE                   0x83F3
 
+Additions to Chapter 3 of the OpenGL ES 2.0 Specification (Rasterization)
+
+    Add the following to Section 3.7.3 (Compressed Texture Images)
+    (at the end of the description of the CompressedTexImage2D command):
+
+    Compressed Internal Format        Base Internal Format
+    ==========================        ====================
+    COMPRESSED_RGB_S3TC_DXT1_ANGLE    RGB
+    COMPRESSED_RGBA_S3TC_DXT1_ANGLE   RGBA
+    COMPRESSED_RGBA_S3TC_DXT3_ANGLE   RGBA
+    COMPRESSED_RGBA_S3TC_DXT5_ANGLE   RGBA
+
+    Table 3.x: Specific Compressed Internal Formats
+
+    If <internalformat> is one of the S3TC formats listed in Table 3.x,
+    the compressed texture is stored in the appropriate S3TC compressed
+    texture format (see Appendix). The GL and the S3TC texture compression
+    algorithm support only 2D images without borders.
+
+    CompressedTexImage2D will produce the INVALID_OPERATION error when
+    <internalformat> is one of the values from Table 3.x under the following
+    conditions: 
+
+      * <border> is non-zero.
+      * <width> is not one, two, or a multiple of four.
+      * <height> is not one, two, or a multiple of four.
+
+    Add the following to Section 3.7.3 (Compressed Texture Images)
+    (at the end of the description of the CompressedTexSubImage2D command):
+
+    If the internal format of the texture image being modified is listed
+    in Table 3.x, the texture is stored in the appropriate S3TC compressed
+    texture format (see Appendix). Since DXT/S3TC images are easily edited
+    along 4x4 texel boundaries, the limitations of CompressedTexSubImage2D
+    are relaxed. CompressedTexSubImage2D will result in an INVALID_OPERATION
+    error only if one of the following conditions occurs:
+
+      * <width> is not a multiple of four or equal to TEXTURE_WIDTH.
+      * <height> is not a multipls of four or equal to TEXTURE_HEIGHT.
+      * <xoffset> or <yoffset> is not a multiple of four.
+      * <format> does not match the internal format of the texture image
+        being modified.
+
+    The following restrictions at the end of section 3.7.3 do not apply
+    to S3TC DXT texture formats, since subimage modification is straightforward
+    as long as the subimage is properly aligned.
+
 Errors
 
-    None.
+    INVALID_OPERATION is generated by CompressedTexImage2D if <internalformat>
+    is one of the compressed internal formats from Table 3.x and any of the 
+    following apply:
+      - <border> is not equal to zero.
+      - <width> is not one, two, or a multiple of four. 
+      - <height> is not one, two, or a multiple of four. 
+
+    INVALID_OPERATION is generated by TexImage2D and CopyTexImage2D if
+    <internalformat> is one of the compressed internal formats from
+    Table 3.x.
+
+    INVALID_OPERATION is generated by TexSubImage2D and CopyTexSubImage2D
+    if the internal format of the texture currently bound to <target> is
+    one of the compressed internal formats from Table 3.x.
+
+    INVALID_OPERATION is generated by CompressedTexSubImage2D if <format>
+    is one of the compressed interal formats from Table 3.x and any of the
+    following apply:
+      - <width> is not a multiple of four or equal to TEXTURE_WIDTH;
+      - <height> is not a multiple of four or equal to TEXTURE_HEIGHT;
+      - <xoffset> or <yoffset> is not a multiple of four;
+      - <format> does not match the internal format of the texture image
+      being modified.
 
 New State
 
     None.
 
+Appendix: 
+
+    The format for the S3TC Compressed Texture Images Formats is documented
+    in the appendix of EXT_texture_compression_s3tc.
+
 Revision History
 
+    Revision 1, 2010/08/06 - gman
+      - Initial revision
+    Revision 2, 2012/09/22 - dgkoch
+      - Added DXT1 formats and documented multiple of 4 restriction.