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cobalt / cobalt / 286dd7840608e9cf78bc4a603ff2ec2ee39750c5 / . / src / third_party / angle / extensions / ANGLE_lossy_etc_decode.txt
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David Ghandeharib1536522017-05-24 00:01:15 -0700[diff] [blame]1Name
2
3 ANGLE_lossy_etc_decode
4
5Name Strings
6
7 GL_ANGLE_lossy_etc_decode
8
9Contributors
10
11 Minmin Gong (mgong 'at' microsoft.com)
12
13Contacts
14
15 Minmin Gong (mgong 'at' microsoft.com)
16
17Status
18
19 Draft
20
21Version
22
23 Last Modified Date: Nov 25, 2015
24 Author Revision: 1
25
26Number
27
28 TBD
29
30Dependencies
31
32 Requires OpenGL ES 3.0 for ETC2 and EAC formats, or OpenGL ES 2.0 and
33 OES_compressed_ETC1_RGB8_texture for ETC1 format.
34 The extension is written against the OpenGL ES 2.0 specification.
35
36Overview
37
38 Both the OpenGL ES 3.0 specification and OES_compressed_ETC1_RGB8_texture
39 specify that Ericsson Texture Compression (ETC) decoding must not be lossy.
40 The goal of this extension is to allow a lossy decode of
41 compressed textures in the ETC formats in OpenGL ES, for lower memory
42 and bandwidth consumption.
43
44 This extension uses the same ETC compression format as OpenGL ES 3.0
45 and OES_compressed_ETC1_RGB8_texture, with the restriction that the texture
46 dimensions must be a multiple of four (except for mip levels where the
47 dimensions are either 2 or 1). And the requirement that ETC decoding must
48 not be lossy is relaxed.
49
50 See OES_compressed_ETC1_RGB8_texture for a description of the ETC1 format.
51 Also see OpenGL ES 3.0 specification appendix C.2 (ETC Compressed Texture
52 ImageFormats) for a description of ETC2 and EAC formats.
53
54IP Status
55
56 See Ericsson's "IP Statement"
57
58New Procedures and Functions
59
60 None.
61
62New Types
63
64 None.
65
66New Tokens
67
68 Accepted by the <internalformat> parameter of CompressedTexImage2D
69 and the <format> parameter of CompressedTexSubImage2D:
70
71 ETC1_RGB8_LOSSY_DECODE_ANGLE 0x9690
72 COMPRESSED_R11_LOSSY_DECODE_EAC_ANGLE 0x9691
73 COMPRESSED_SIGNED_R11_LOSSY_DECODE_EAC_ANGLE 0x9692
74 COMPRESSED_RG11_LOSSY_DECODE_EAC_ANGLE 0x9693
75 COMPRESSED_SIGNED_RG11_LOSSY_DECODE_EAC_ANGLE 0x9694
76 COMPRESSED_RGB8_LOSSY_DECODE_ETC2_ANGLE 0x9695
77 COMPRESSED_SRGB8_LOSSY_DECODE_ETC2_ANGLE 0x9696
78 COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_LOSSY_DECODE_ETC2_ANGLE 0x9697
79 COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_LOSSY_DECODE_ETC2_ANGLE 0x9698
80 COMPRESSED_RGBA8_LOSSY_DECODE_ETC2_EAC_ANGLE 0x9699
81 COMPRESSED_SRGB8_ALPHA8_LOSSY_DECODE_ETC2_EAC_ANGLE 0x969A
82
83Additions to Chapter 3 of the OpenGL ES 2.0 Specification (Rasterization)
84
85 Add the following to Section 3.7.3 (Compressed Texture Images)
86 (at the end of the description of the CompressedTexImage2D command):
87
88 Compressed Internal Format Base Internal Format
89 ========================== ====================
90 ETC1_RGB8_LOSSY_DECODE_ANGLE RGB
91 COMPRESSED_R11_LOSSY_DECODE_EAC_ANGLE R
92 COMPRESSED_SIGNED_R11_LOSSY_DECODE_EAC_ANGLE R
93 COMPRESSED_RG11_LOSSY_DECODE_EAC_ANGLE RG
94 COMPRESSED_SIGNED_RG11_LOSSY_DECODE_EAC_ANGLE RG
95 COMPRESSED_RGB8_LOSSY_DECODE_ETC2_ANGLE RGB
96 COMPRESSED_SRGB8_LOSSY_DECODE_ETC2_ANGLE RGB
97 COMPRESSED_RGB8_PUNCHTHROUGH_ALPHA1_LOSSY_DECODE_ETC2_ANGLE RGBA
98 COMPRESSED_SRGB8_PUNCHTHROUGH_ALPHA1_LOSSY_DECODE_ETC2_ANGLE RGBA
99 COMPRESSED_RGBA8_LOSSY_DECODE_ETC2_EAC_ANGLE RGBA
100 COMPRESSED_SRGB8_ALPHA8_LOSSY_DECODE_ETC2_EAC_ANGLE RGBA
101
102 Table 3.x: Specific Compressed Internal Formats
103
104 If <internalformat> is one of the ETC lossy decode formats listed in
105 Table 3.x, the compressed texture is stored in an unspecified compressed
106 texture format, that may introduce losses of precision in the texture data.
107 The GL and the ETC texture compression algorithm support only 2D images
108 without borders.
109
110 CompressedTexImage2D will produce the INVALID_OPERATION error when
111 <internalformat> is one of the lossy decode ETC-format values from
112 Table 3.x under the following conditions:
113
114 * <border> is non-zero.
115 * <width> is not one, two, nor a multiple of four.
116 * <height> is not one, two, nor a multiple of four.
117
118 Add the following to Section 3.7.3 (Compressed Texture Images)
119 (at the end of the description of the CompressedTexSubImage2D command):
120
121 If the internal format of the texture image being modified is an ETC-format
122 listed in Table 3.x, the compressed texture is stored in an unspecified
123 compressed texture format. The xoffset and yoffset must also be aligned to
124 4x4 texel block boundaries, since ETC encoding makes it difficult to modify
125 non-aligned regions. CompressedTexSubImage2D will result in an
126 INVALID_OPERATION error only if one of the following conditions occurs:
127
128 * <width> is not a multiple of four nor equal to TEXTURE_WIDTH.
129 * <height> is not a multiple of four nor equal to TEXTURE_HEIGHT.
130 * <xoffset> or <yoffset> is not a multiple of four.
131 * <format> does not match the internal format of the texture image
132 being modified.
133
134Errors
135
136 INVALID_OPERATION is generated by CompressedTexImage2D if
137 lossy decode ETC-format is used and <internalformat> is one of the
138 compressed internal formats from Table 3.x and any of the following apply:
139 - <border> is not equal to zero.
140 - <width> is not one, two, nor a multiple of four.
141 - <height> is not one, two, nor a multiple of four.
142
143 INVALID_OPERATION is generated by CompressedTexSubImage2D if
144 lossy decode ETC-format is used and <format> is one of the compressed
145 interal formats from Table 3.x and any of the following apply:
146 - <width> is not a multiple of four nor equal to TEXTURE_WIDTH;
147 - <height> is not a multiple of four nor equal to TEXTURE_HEIGHT;
148 - <xoffset> or <yoffset> is not a multiple of four;
149 - <format> does not match the internal format of the texture image
150 being modified.
151
152New State
153
154 None.
155
156Revision History
157
158 Revision 1, 2015/11/25 - mgong
159 - Initial revision