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kc3-lang/angle/extensions/ANGLE_lossy_etc_decode.txt
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Author :
Minmin Gong
Date : 2015-12-01 15:36:51
Hash : e3939b98
Message : D3D11: Transcode ETC1 to BC1. Adds a new extension to allow transcode ETC formats to suitable BC formats. This commit implements ETC1 to BC1. More formats will be supported soon. BUG=angleproject:1285 Change-Id: Iacbfbc2248dfe1aebf24b92696249a9404e331cd Reviewed-on: https://chromium-review.googlesource.com/316511 Reviewed-by: Corentin Wallez <cwallez@chromium.org> Commit-Queue: Corentin Wallez <cwallez@chromium.org>
- extensions/ANGLE_lossy_etc_decode.txt
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Name ANGLE_lossy_etc_decode Name Strings GL_ANGLE_lossy_etc_decode Contributors Minmin Gong (mgong 'at' microsoft.com) Contacts Minmin Gong (mgong 'at' microsoft.com) Status Draft Version Last Modified Date: Nov 25, 2015 Author Revision: 1 Number TBD Dependencies Requires OpenGL ES 3.0 for ETC2 and EAC formats, or OpenGL ES 2.0 and OES_compressed_ETC1_RGB8_texture for ETC1 format. The extension is written against the OpenGL ES 2.0 specification. Overview Both the OpenGL ES 3.0 specification and OES_compressed_ETC1_RGB8_texture specify that Ericsson Texture Compression (ETC) decoding must not be lossy. The goal of this extension is to allow a lossy decode of compressed textures in the ETC formats in OpenGL ES, for lower memory and bandwidth consumption. This extension uses the same ETC compression format as OpenGL ES 3.0 and OES_compressed_ETC1_RGB8_texture, with the restriction that the texture dimensions must be a multiple of four (except for mip levels where the dimensions are either 2 or 1). And the requirement that ETC decoding must not be lossy is relaxed. See OES_compressed_ETC1_RGB8_texture for a description of the ETC1 format. Also see OpenGL ES 3.0 specification appendix C.2 (ETC Compressed Texture ImageFormats) for a description of ETC2 and EAC formats. IP Status See Ericsson's "IP Statement" New Procedures and Functions None. New Types None. New Tokens Accepted by the <internalformat> parameter of CompressedTexImage2D and the <format> parameter of CompressedTexSubImage2D: ETC1_RGB8_LOSSY_DECODE_ANGLE 0x9690 COMPRESSED_R11_LOSSY_DECODE_EAC_ANGLE 0x9691 COMPRESSED_SIGNED_R11_LOSSY_DECODE_EAC_ANGLE 0x9692 COMPRESSED_RG11_LOSSY_DECODE_EAC_ANGLE 0x9693 COMPRESSED_SIGNED_RG11_LOSSY_DECODE_EAC_ANGLE 0x9694 COMPRESSED_RGB8_LOSSY_DECODE_ETC2_ANGLE 0x9695 COMPRESSED_SRGB8_LOSSY_DECODE_ETC2_ANGLE 0x9696 COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_LOSSY_DECODE_ETC2_ANGLE 0x9697 COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_LOSSY_DECODE_ETC2_ANGLE 0x9698 COMPRESSED_RGBA8_LOSSY_DECODE_ETC2_EAC_ANGLE 0x9699 COMPRESSED_SRGB8_ALPHA8_LOSSY_DECODE_ETC2_EAC_ANGLE 0x969A 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 ========================== ==================== ETC1_RGB8_LOSSY_DECODE_ANGLE RGB COMPRESSED_R11_LOSSY_DECODE_EAC_ANGLE R COMPRESSED_SIGNED_R11_LOSSY_DECODE_EAC_ANGLE R COMPRESSED_RG11_LOSSY_DECODE_EAC_ANGLE RG COMPRESSED_SIGNED_RG11_LOSSY_DECODE_EAC_ANGLE RG COMPRESSED_RGB8_LOSSY_DECODE_ETC2_ANGLE RGB COMPRESSED_SRGB8_LOSSY_DECODE_ETC2_ANGLE RGB COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_LOSSY_DECODE_ETC2_ANGLE RGBA COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_LOSSY_DECODE_ETC2_ANGLE RGBA COMPRESSED_RGBA8_LOSSY_DECODE_ETC2_EAC_ANGLE RGBA COMPRESSED_SRGB8_ALPHA8_LOSSY_DECODE_ETC2_EAC_ANGLE RGBA Table 3.x: Specific Compressed Internal Formats If <internalformat> is one of the ETC lossy decode formats listed in Table 3.x, the compressed texture is stored in an unspecified compressed texture format, that may introduce losses of precision in the texture data. The GL and the ETC texture compression algorithm support only 2D images without borders. CompressedTexImage2D will produce the INVALID_OPERATION error when <internalformat> is one of the lossy decode ETC-format values from Table 3.x under the following conditions: * <border> is non-zero. * <width> is not one, two, nor a multiple of four. * <height> is not one, two, nor 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 an ETC-format listed in Table 3.x, the compressed texture is stored in an unspecified compressed texture format. The xoffset and yoffset must also be aligned to 4x4 texel block boundaries, since ETC encoding makes it difficult to modify non-aligned regions. CompressedTexSubImage2D will result in an INVALID_OPERATION error only if one of the following conditions occurs: * <width> is not a multiple of four nor equal to TEXTURE_WIDTH. * <height> is not a multiple of four nor 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. Errors INVALID_OPERATION is generated by CompressedTexImage2D if lossy decode ETC-format is used and <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, nor a multiple of four. - <height> is not one, two, nor a multiple of four. INVALID_OPERATION is generated by CompressedTexSubImage2D if lossy decode ETC-format is used and <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 nor equal to TEXTURE_WIDTH; - <height> is not a multiple of four nor 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. Revision History Revision 1, 2015/11/25 - mgong - Initial revision