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5564 | serge | 1 | Name |
2 | |||
3 | MESA_texture_array |
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4 | |||
5 | Name Strings |
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6 | |||
7 | GL_MESA_texture_array |
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8 | |||
9 | Contact |
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10 | |||
11 | Ian Romanick, IBM (idr 'at' us.ibm.com) |
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12 | |||
13 | IP Status |
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14 | |||
15 | No known IP issues. |
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16 | |||
17 | Status |
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18 | |||
19 | DEPRECATED - Support removed in Mesa 10.1. |
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20 | |||
21 | Version |
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22 | |||
23 | |||
24 | Number |
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25 | |||
26 | TBD |
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27 | |||
28 | Dependencies |
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29 | |||
30 | OpenGL 1.2 or GL_EXT_texture3D is required. |
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31 | |||
32 | Support for ARB_fragment_program is assumed, but not required. |
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33 | |||
34 | Support for ARB_fragment_program_shadow is assumed, but not required. |
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35 | |||
36 | Support for EXT_framebuffer_object is assumed, but not required. |
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37 | |||
38 | Written based on the wording of the OpenGL 2.0 specification and |
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39 | ARB_fragment_program_shadow but not dependent on them. |
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40 | |||
41 | Overview |
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42 | |||
43 | There are a number of circumstances where an application may wish to |
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44 | blend two textures out of a larger set of textures. Moreover, in some |
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45 | cases the selected textures may vary on a per-fragment basis within |
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46 | a polygon. Several examples include: |
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47 | |||
48 | 1. High dynamic range textures. The application stores several |
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49 | different "exposures" of an image as different textures. On a |
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50 | per-fragment basis, the application selects which exposures are |
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51 | used. |
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52 | |||
53 | 2. A terrain engine where the altitude of a point determines the |
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54 | texture applied to it. If the transition is from beach sand to |
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55 | grass to rocks to snow, the application will store each texture |
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56 | in a different texture map, and dynamically select which two |
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57 | textures to blend at run-time. |
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58 | |||
59 | 3. Storing short video clips in textures. Each depth slice is a |
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60 | single frame of video. |
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61 | |||
62 | Several solutions to this problem have been proposed, but they either |
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63 | involve using a separate texture unit for each texture map or using 3D |
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64 | textures without mipmaps. Both of these options have major drawbacks. |
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65 | |||
66 | This extension provides a third alternative that eliminates the major |
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67 | drawbacks of both previous methods. A new texture target, |
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68 | TEXTURE_2D_ARRAY, is added that functions identically to TEXTURE_3D in |
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69 | all aspects except the sizes of the non-base level images. In |
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70 | traditional 3D texturing, the size of the N+1 LOD is half the size |
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71 | of the N LOD in all three dimensions. For the TEXTURE_2D_ARRAY target, |
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72 | the height and width of the N+1 LOD is halved, but the depth is the |
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73 | same for all levels of detail. The texture then becomes an array of |
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74 | 2D textures. The per-fragment texel is selected by the R texture |
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75 | coordinate. |
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76 | |||
77 | References: |
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78 | |||
79 | http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011557 |
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80 | http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=000516 |
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81 | http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011903 |
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82 | http://www.delphi3d.net/articles/viewarticle.php?article=terraintex.htm |
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83 | |||
84 | New Procedures and Functions |
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85 | |||
86 | All functions come directly from EXT_texture_array. |
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87 | |||
88 | void FramebufferTextureLayerEXT(enum target, enum attachment, |
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89 | uint texture, int level, int layer); |
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90 | |||
91 | New Tokens |
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92 | |||
93 | All token names and values come directly from EXT_texture_array. |
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94 | |||
95 | Accepted by the |
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96 | the |
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97 | GetDoublev, and by the |
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98 | GetTexLevelParameteriv, GetTexLevelParameterfv, GetTexParameteriv, and |
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99 | GetTexParameterfv: |
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100 | |||
101 | TEXTURE_1D_ARRAY_EXT 0x8C18 |
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102 | TEXTURE_2D_ARRAY_EXT 0x8C1A |
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103 | |||
104 | Accepted by the |
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105 | CopyTexImage2D, CopyTexSubImage2D, CompressedTexImage2D, |
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106 | CompressedTexSubImage2D, GetTexLevelParameteriv, and |
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107 | GetTexLevelParameterfv: |
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108 | |||
109 | TEXTURE_1D_ARRAY_EXT |
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110 | PROXY_TEXTURE_1D_ARRAY_EXT 0x8C19 |
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111 | |||
112 | Accepted by the |
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113 | CopyTexSubImage3D, CompressedTexImage3D, CompressedTexSubImage3D, |
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114 | GetTexLevelParameteriv, and GetTexLevelParameterfv: |
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115 | |||
116 | TEXTURE_2D_ARRAY_EXT |
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117 | PROXY_TEXTURE_2D_ARRAY_EXT 0x8C1B |
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118 | |||
119 | Accepted by the |
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120 | GetFloatv, and GetDoublev |
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121 | |||
122 | TEXTURE_BINDING_1D_ARRAY_EXT 0x8C1C |
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123 | TEXTURE_BINDING_2D_ARRAY_EXT 0x8C1D |
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124 | MAX_ARRAY_TEXTURE_LAYERS_EXT 0x88FF |
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125 | |||
126 | Accepted by the parameter of TexParameterf, TexParameteri, |
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127 | TexParameterfv, and TexParameteriv when the |
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128 | TEXTURE_COMPARE_MODE_ARB: |
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129 | |||
130 | COMPARE_REF_DEPTH_TO_TEXTURE_EXT 0x884E |
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131 | |||
132 | (Note: COMPARE_REF_DEPTH_TO_TEXTURE_EXT is simply an alias for the |
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133 | existing COMPARE_R_TO_TEXTURE token in OpenGL 2.0; the alternate name |
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134 | reflects the fact that the R coordinate is not always used.) |
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135 | |||
136 | Accepted by the |
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137 | CompressedTexImage3D, and by the |
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138 | CompressedTexSubImage3D: |
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139 | |||
140 | COMPRESSED_RGB_S3TC_DXT1_EXT |
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141 | COMPRESSED_RGBA_S3TC_DXT1_EXT |
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142 | COMPRESSED_RGBA_S3TC_DXT3_EXT |
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143 | COMPRESSED_RGBA_S3TC_DXT5_EXT |
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144 | |||
145 | Accepted by the |
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146 | GetFramebufferAttachmentParameterivEXT: |
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147 | |||
148 | FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT 0x8CD4 |
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149 | |||
150 | (Note: FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER is simply an alias for the |
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151 | FRAMEBUFFER_ATTACHMENT_TEXTURE_3D_ZOFFSET_EXT token provided in |
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152 | EXT_framebuffer_object. This extension generalizes the notion of |
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153 | " |
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154 | |||
155 | Additions to Chapter 2 of the OpenGL 2.0 Specification (OpenGL Operation) |
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156 | |||
157 | None |
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158 | |||
159 | Additions to Chapter 3 of the OpenGL 2.0 Specification (Rasterization) |
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160 | |||
161 | -- Section 3.8.1 "Texture Image Specification" |
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162 | |||
163 | Change the first paragraph (page 150) to say (spec changes identical to |
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164 | EXT_texture_array): |
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165 | |||
166 | "The command |
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167 | |||
168 | void TexImage3D(enum target, int level, int internalformat, |
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169 | sizei width, sizei height, sizei depth, int border, |
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170 | enum format, enum type, void *data); |
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171 | |||
172 | is used to specify a three-dimensional texture image. target must be one |
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173 | one of TEXTURE_3D for a three-dimensional texture or |
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174 | TEXTURE_2D_ARRAY_EXT for an two-dimensional array texture. |
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175 | Additionally, target may be either PROXY_TEXTURE_3D for a |
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176 | three-dimensional proxy texture, or PROXY_TEXTURE_2D_ARRAY_EXT for a |
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177 | two-dimensional proxy array texture." |
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178 | |||
179 | Change the fourth paragraph on page 151 to say (spec changes identical |
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180 | to EXT_texture_array): |
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181 | |||
182 | "Textures with a base internal format of DEPTH_COMPONENT are supported |
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183 | by texture image specification commands only if target is TEXTURE_1D, |
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184 | TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, TEXTURE_2D_ARRAY_EXT, |
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185 | PROXY_TEXTURE_1D, PROXY_TEXTURE_2D, PROXY_TEXTURE_1D_ARRAY_EXT, or |
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186 | PROXY_TEXTURE_2D_ARRAY_EXT. Using this format in conjunction with any |
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187 | other target will result in an INVALID_OPERATION error." |
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188 | |||
189 | |||
190 | Change the fourth paragraph on page 156 to say (spec changes identical |
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191 | to EXT_texture_array): |
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192 | |||
193 | "The command |
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194 | |||
195 | void TexImage2D(enum target, int level, |
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196 | int internalformat, sizei width, sizei height, |
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197 | int border, enum format, enum type, void *data); |
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198 | |||
199 | is used to specify a two-dimensional texture image. target must be one |
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200 | of TEXTURE_2D for a two-dimensional texture, TEXTURE_1D_ARRAY_EXT for a |
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201 | one-dimensional array texture, or one of TEXTURE_CUBE_MAP_POSITIVE_X, |
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202 | TEXTURE_CUBE_MAP_NEGATIVE_X, TEXTURE_CUBE_MAP_POSITIVE_Y, |
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203 | TEXTURE_CUBE_MAP_NEGATIVE_Y, TEXTURE_CUBE_MAP_POSITIVE_Z, or |
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204 | TEXTURE_CUBE_MAP_NEGATIVE_Z for a cube map texture. Additionally, |
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205 | target may be either PROXY_TEXTURE_2D for a two-dimensional proxy |
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206 | texture, PROXY_TEXTURE_1D_ARRAY_EXT for a one-dimensional proxy array |
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207 | texture, or PROXY TEXTURE_CUBE_MAP for a cube map proxy texture in the |
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208 | special case discussed in section 3.8.11. The other parameters match |
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209 | the corresponding parameters of TexImage3D. |
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210 | |||
211 | For the purposes of decoding the texture image, TexImage2D is |
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212 | equivalent to calling TexImage3D with corresponding arguments and depth |
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213 | of 1, except that |
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214 | |||
215 | * The border depth, d_b, is zero, and the depth of the image is |
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216 | always 1 regardless of the value of border. |
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217 | |||
218 | * The border height, h_b, is zero if |
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219 | TEXTURE_1D_ARRAY_EXT, and |
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220 | |||
221 | * Convolution will be performed on the image (possibly changing its |
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222 | width and height) if SEPARABLE 2D or CONVOLUTION 2D is enabled. |
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223 | |||
224 | * UNPACK SKIP IMAGES is ignored." |
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225 | |||
226 | -- Section 3.8.2 "Alternate Texture Image Specification Commands" |
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227 | |||
228 | Change the second paragraph (page 159) (spec changes identical |
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229 | to EXT_texture_array): |
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230 | |||
231 | "The command |
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232 | |||
233 | void CopyTexImage2D(enum target, int level, |
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234 | enum internalformat, int x, int y, sizei width, |
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235 | sizei height, int border); |
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236 | |||
237 | defines a two-dimensional texture image in exactly the manner of |
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238 | TexImage2D, except that the image data are taken from the framebuffer |
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239 | rather than from client memory. Currently, target must be one of |
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240 | TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, TEXTURE_CUBE_MAP_POSITIVE_X, |
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241 | TEXTURE_CUBE_MAP_NEGATIVE_X, TEXTURE_CUBE MAP_POSITIVE_Y, |
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242 | TEXTURE_CUBE_MAP_NEGATIVE_Y, TEXTURE_CUBE_MAP_POSITIVE_Z, or |
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243 | TEXTURE_CUBE_MAP_NEGATIVE_Z. |
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244 | |||
245 | |||
246 | Change the last paragraph on page 160 to say (spec changes identical |
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247 | to EXT_texture_array): |
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248 | |||
249 | "Currently the target arguments of TexSubImage1D and CopyTexSubImage1D |
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250 | must be TEXTURE_1D, the target arguments of TexSubImage2D and |
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251 | CopyTexSubImage2D must be one of TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, |
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252 | TEXTURE_CUBE_MAP_POSITIVE_X, TEXTURE_CUBE_MAP_NEGATIVE_X, |
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253 | TEXTURE_CUBE_MAP_POSITIVE_Y, TEXTURE_CUBE_MAP_NEGATIVE_Y, |
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254 | TEXTURE_CUBE_MAP_POSITIVE_Z, or TEXTURE_CUBE_MAP_NEGATIVE_Z, and the |
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255 | target arguments of TexSubImage3D and CopyTexSubImage3D must be |
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256 | TEXTURE_3D or TEXTURE_2D_ARRAY_EXT. ..." |
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257 | |||
258 | |||
259 | -- Section 3.8.4 "Texture Parameters" |
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260 | |||
261 | Change the first paragraph (page 166) to say: |
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262 | |||
263 | "Various parameters control how the texel array is treated when |
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264 | specified or changed, and when applied to a fragment. Each parameter is |
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265 | set by calling |
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266 | |||
267 | void TexParameter{if}(enum target, enum pname, T param); |
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268 | void TexParameter{if}v(enum target, enum pname, T params); |
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269 | |||
270 | target is the target, either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, |
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271 | TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT." |
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272 | |||
273 | |||
274 | -- Section 3.8.8 "Texture Minification" in the section "Scale Factor and Level of Detail" |
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275 | |||
276 | Change the first paragraph (page 172) to say: |
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277 | |||
278 | "Let s(x,y) be the function that associates an s texture coordinate |
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279 | with each set of window coordinates (x,y) that lie within a primitive; |
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280 | define t(x,y) and r(x,y) analogously. Let u(x,y) = w_t * s(x,y), |
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281 | v(x,y) = h_t * t(x,y), and w(x,y) = d_t * r(x,y), where w_t, h_t, |
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282 | and d_t are as defined by equations 3.15, 3.16, and 3.17 with |
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283 | w_s, h_s, and d_s equal to the width, height, and depth of the |
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284 | image array whose level is level_base. For a one-dimensional |
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285 | texture or a one-dimensional array texture, define v(x,y) = 0 and |
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286 | w(x,y) = 0; for a two-dimensional texture or a two-dimensional array |
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287 | texture, define w(x,y) = 0..." |
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288 | |||
289 | -- Section 3.8.8 "Texture Minification" in the section "Mipmapping" |
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290 | |||
291 | Change the third paragraph (page 174) to say: |
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292 | |||
293 | "For a two-dimensional texture, two-dimensional array texture, or |
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294 | cube map texture," |
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295 | |||
296 | Change the fourth paragraph (page 174) to say: |
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297 | |||
298 | "And for a one-dimensional texture or a one-dimensional array texture," |
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299 | |||
300 | After the first paragraph (page 175) add: |
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301 | |||
302 | "For one-dimensional array textures, h_b and d_b are treated as 1, |
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303 | regardless of the actual values, when performing mipmap calculations. |
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304 | For two-dimensional array textures, d_b is always treated as one, |
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305 | regardless of the actual value, when performing mipmap calculations." |
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306 | |||
307 | -- Section 3.8.8 "Automatic Mipmap Generation" in the section "Mipmapping" |
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308 | |||
309 | Change the third paragraph (page 176) to say (spec changes identical |
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310 | to EXT_texture_array): |
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311 | |||
312 | "The contents of the derived arrays are computed by repeated, filtered |
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313 | reduction of the level_base array. For one- and two-dimensional array |
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314 | textures, each layer is filtered independently. ..." |
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315 | |||
316 | -- Section 3.8.8 "Manual Mipmap Generation" in the section "Mipmapping" |
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317 | |||
318 | Change first paragraph to say (spec changes identical to |
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319 | EXT_texture_array): |
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320 | |||
321 | "Mipmaps can be generated manually with the command |
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322 | |||
323 | void GenerateMipmapEXT(enum target); |
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324 | |||
325 | where |
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326 | TEXTURE_3D, TEXTURE_1D_ARRAY, or TEXTURE_2D_ARRAY. Mipmap generation |
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327 | affects the texture image attached to |
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328 | |||
329 | -- Section 3.8.10 "Texture Completeness" |
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330 | |||
331 | Change the second paragraph (page 177) to say (spec changes identical |
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332 | to EXT_texture_array): |
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333 | |||
334 | "For one-, two-, or three-dimensional textures and one- or |
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335 | two-dimensional array textures, a texture is complete if the following |
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336 | conditions all hold true:" |
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337 | |||
338 | -- Section 3.8.11 "Texture State and Proxy State" |
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339 | |||
340 | Change the second and third paragraphs (page 179) to say (spec changes |
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341 | identical to EXT_texture_array): |
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342 | |||
343 | "In addition to image arrays for one-, two-, and three-dimensional |
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344 | textures, one- and two-dimensional array textures, and the six image |
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345 | arrays for the cube map texture, partially instantiated image arrays |
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346 | are maintained for one-, two-, and three-dimensional textures and one- |
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347 | and two-dimensional array textures. Additionally, a single proxy image |
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348 | array is maintained for the cube map texture. Each proxy image array |
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349 | includes width, height, depth, border width, and internal format state |
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350 | values, as well as state for the red, green, blue, alpha, luminance, |
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351 | and intensity component resolutions. Proxy image arrays do not include |
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352 | image data, nor do they include texture properties. When TexImage3D is |
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353 | executed with target specified as PROXY_TEXTURE_3D, the |
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354 | three-dimensional proxy state values of the specified level-of-detail |
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355 | are recomputed and updated. If the image array would not be supported |
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356 | by TexImage3D called with target set to TEXTURE 3D, no error is |
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357 | generated, but the proxy width, height, depth, border width, and |
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358 | component resolutions are set to zero. If the image array would be |
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359 | supported by such a call to TexImage3D, the proxy state values are set |
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360 | exactly as though the actual image array were being specified. No pixel |
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361 | data are transferred or processed in either case. |
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362 | |||
363 | Proxy arrays for one- and two-dimensional textures and one- and |
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364 | two-dimensional array textures are operated on in the same way when |
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365 | TexImage1D is executed with target specified as PROXY_TEXTURE_1D, |
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366 | TexImage2D is executed with target specified as PROXY_TEXTURE_2D or |
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367 | PROXY_TEXTURE_1D_ARRAY_EXT, or TexImage3D is executed with target |
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368 | specified as PROXY_TETXURE_2D_ARRAY_EXT." |
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369 | |||
370 | -- Section 3.8.12 "Texture Objects" |
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371 | |||
372 | Change section (page 180) to say (spec changes identical to |
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373 | EXT_texture_array): |
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374 | |||
375 | "In addition to the default textures TEXTURE_1D, TEXTURE_2D, |
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376 | TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and TEXTURE_2D_EXT, |
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377 | named one-, two-, and three-dimensional, cube map, and one- and |
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378 | two-dimensional array texture objects can be created and operated upon. |
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379 | The name space for texture objects is the unsigned integers, with zero |
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380 | reserved by the GL. |
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381 | |||
382 | A texture object is created by binding an unused name to TEXTURE_1D, |
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383 | TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or |
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384 | TEXTURE_2D_ARRAY_EXT. The binding is effected by calling |
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385 | |||
386 | void BindTexture(enum target, uint texture); |
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387 | |||
388 | with |
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389 | the unused name. The resulting texture object is a new state vector, |
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390 | comprising all the state values listed in section 3.8.11, set to the |
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391 | same initial values. If the new texture object is bound to TEXTURE_1D, |
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392 | TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or |
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393 | TEXTURE_2D_ARRAY_EXT, it is and remains a one-, two-, |
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394 | three-dimensional, cube map, one- or two-dimensional array texture |
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395 | respectively until it is deleted. |
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396 | |||
397 | BindTexture may also be used to bind an existing texture object to |
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398 | either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, |
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399 | TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT. The error |
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400 | INVALID_OPERATION is generated if an attempt is made to bind a texture |
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401 | object of different dimensionality than the specified target. If the |
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402 | bind is successful no change is made to the state of the bound texture |
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403 | object, and any previous binding to target is broken. |
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404 | |||
405 | While a texture object is bound, GL operations on the target to which |
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406 | it is bound affect the bound object, and queries of the target to which |
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407 | it is bound return state from the bound object. If texture mapping of |
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408 | the dimensionality of the target to which a texture object is bound is |
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409 | enabled, the state of the bound texture object directs the texturing |
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410 | operation. |
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411 | |||
412 | In the initial state, TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, |
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413 | TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and TEXTURE_2D_ARRAY_EXT have |
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414 | one-, two-, three-dimensional, cube map, and one- and two-dimensional |
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415 | array texture state vectors respectively associated with them. In order |
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416 | that access to these initial textures not be lost, they are treated as |
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417 | texture objects all of whose names are 0. The initial one-, two-, |
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418 | three-dimensional, cube map, one- and two-dimensional array textures |
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419 | are therefore operated upon, queried, and applied as TEXTURE_1D, |
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420 | TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and |
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421 | TEXTURE_2D_ARRAY_EXT respectively while 0 is bound to the corresponding |
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422 | targets. |
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423 | |||
424 | Change second paragraph on page 181 to say (spec changes identical to |
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425 | EXT_texture_array): |
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426 | |||
427 | "... If a texture that is currently bound to one of the targets |
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428 | TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, |
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429 | TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT is deleted, it is as |
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430 | though BindTexture had been executed with the same target and texture |
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431 | zero. ..." |
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432 | |||
433 | Change second paragraph on page 182 to say (spec changes identical to |
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434 | EXT_texture_array): |
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435 | |||
436 | "The texture object name space, including the initial one-, two-, and |
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437 | three dimensional, cube map, and one- and two-dimensional array texture |
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438 | objects, is shared among all texture units. ..." |
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439 | |||
440 | |||
441 | -- Section 3.8.14 "Depth Texture Comparison Modes" in "Texture Comparison Modes" |
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442 | |||
443 | Change second through fourth paragraphs (page 188) to say: |
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444 | |||
445 | "Let D_t be the depth texture value, in the range [0, 1]. For |
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446 | texture lookups from one- and two-dimensional, rectangle, and |
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447 | one-dimensional array targets, let R be the interpolated |
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448 | texture coordinate, clamped to the range [0, 1]. For texture lookups |
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449 | from two-dimensional array texture targets, let R be the interpolated |
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450 | texture coordinate, clamped to the range [0, 1]. Then the |
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451 | effective texture value L_t, I_t, or A_t is computed as follows: |
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452 | |||
453 | If the value of TEXTURE_COMPARE_MODE is NONE, then |
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454 | |||
455 | r = Dt |
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456 | |||
457 | If the value of TEXTURE_COMPARE_MODE is |
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458 | COMPARE_REF_DEPTH_TO_TEXTURE_EXT), then r depends on the texture |
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459 | comparison function as shown in table 3.27." |
||
460 | |||
461 | -- Section 3.8.15 "Texture Application" |
||
462 | |||
463 | Change the first paragraph (page 189) to say: |
||
464 | |||
465 | "Texturing is enabled or disabled using the generic Enable and Disable |
||
466 | commands, respectively, with the symbolic constants TEXTURE_1D, |
||
467 | TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or |
||
468 | TEXTURE_2D_ARRAY_EXT to enable one-, two-, three-dimensional, cube |
||
469 | map, one-dimensional array, or two-dimensional array texture, |
||
470 | respectively. If both two- and one-dimensional textures are enabled, |
||
471 | the two-dimensional texture is used. If the three-dimensional and |
||
472 | either of the two- or one-dimensional textures is enabled, the |
||
473 | three-dimensional texture is used. If the cube map texture and any of |
||
474 | the three-, two-, or one-dimensional textures is enabled, then cube map |
||
475 | texturing is used. If one-dimensional array texture is enabled and any |
||
476 | of cube map, three-, two-, or one-dimensional textures is enabled, |
||
477 | one-dimensional array texturing is used. If two-dimensional array |
||
478 | texture is enabled and any of cube map, three-, two-, one-dimensional |
||
479 | textures or one-dimensional array texture is enabled, two-dimensional |
||
480 | array texturing is used..." |
||
481 | |||
482 | -- Section 3.11.2 of ARB_fragment_program (Fragment Program Grammar and Restrictions): |
||
483 | |||
484 | (mostly add to existing grammar rules) |
||
485 | |||
486 |
|
||
487 | |||
488 |
|
||
489 | | "2D" |
||
490 | | "3D" |
||
491 | | "CUBE" |
||
492 | | "RECT" |
||
493 | | |
||
494 | | |
||
495 | |||
496 |
|
||
497 | | "ARRAY2D" |
||
498 | |||
499 |
|
||
500 | | "SHADOW2D" |
||
501 | | "SHADOWRECT" |
||
502 | | |
||
503 | |||
504 |
|
||
505 | | "SHADOWARRAY2D" |
||
506 | |||
507 | |||
508 | -- Add Section 3.11.4.5.4 "Texture Stack Option" |
||
509 | |||
510 | "If a fragment program specifies the "MESA_texture_array" program |
||
511 | option, the |
||
512 | ARRAY1D and ARRAY2D (See Section 3.11.2)." |
||
513 | |||
514 | -- Section 3.11.6 "Fragment Program Texture Instruction Set" |
||
515 | |||
516 | (replace 1st and 2nd paragraphs with the following paragraphs) |
||
517 | |||
518 | "The first three texture instructions described below specify the |
||
519 | mapping of 4-tuple input vectors to 4-tuple output vectors. |
||
520 | The sampling of the texture works as described in section 3.8, |
||
521 | except that texture environments and texture functions are not |
||
522 | applicable, and the texture enables hierarchy is replaced by explicit |
||
523 | references to the desired texture target (i.e., 1D, 2D, 3D, cube map, |
||
524 | rectangle, ARRAY1D, ARRAY2D). These texture instructions specify |
||
525 | how the 4-tuple is mapped into the coordinates used for sampling. The |
||
526 | following function is used to describe the texture sampling in the |
||
527 | descriptions below: |
||
528 | |||
529 | vec4 TextureSample(vec4 coord, float lodBias, int texImageUnit, |
||
530 | enum texTarget); |
||
531 | |||
532 | Note that not all four components of the texture coordinates |
||
533 | are used by all texture targets. Component usage for each |
||
534 | is defined in table X. |
||
535 | |||
536 | coordinates used |
||
537 | texTarget Texture Type s t r layer shadow |
||
538 | ---------------- --------------------- ----- ----- ------ |
||
539 | 1D TEXTURE_1D x - - - - |
||
540 | 2D TEXTURE_2D x y - - - |
||
541 | 3D TEXTURE_3D x y z - - |
||
542 | CUBE TEXTURE_CUBE_MAP x y z - - |
||
543 | RECT TEXTURE_RECTANGLE_ARB x y - - - |
||
544 | ARRAY1D TEXTURE_1D_ARRAY_EXT x - - y - |
||
545 | ARRAY2D TEXTURE_2D_ARRAY_EXT x y - z - |
||
546 | SHADOW1D TEXTURE_1D x - - - z |
||
547 | SHADOW2D TEXTURE_2D x y - - z |
||
548 | SHADOWRECT TEXTURE_RECTANGLE_ARB x y - - z |
||
549 | SHADOWARRAY1D TEXTURE_1D_ARRAY_EXT x - - y z |
||
550 | SHADOWARRAY2D TEXTURE_2D_ARRAY_EXT x y - z w |
||
551 | |||
552 | Table X: Texture types accessed for each of the |
||
553 | coordinate mappings. The "coordinates used" column indicate the |
||
554 | input values used for each coordinate of the texture lookup, the |
||
555 | layer selector for array textures, and the reference value for |
||
556 | texture comparisons." |
||
557 | |||
558 | -- Section 3.11.6.2 "TXP: Project coordinate and map to color" |
||
559 | |||
560 | Add to the end of the section: |
||
561 | |||
562 | "A program will fail to load if the TXP instruction is used in |
||
563 | conjunction with the SHADOWARRAY2D target." |
||
564 | |||
565 | Additions to Chapter 4 of the OpenGL 2.0 Specification (Per-Fragment Operations) |
||
566 | |||
567 | -- Section 4.4.2.3 "Attaching Texture Images to a Framebuffer" |
||
568 | |||
569 | Add to the end of the section (spec changes identical to |
||
570 | EXT_texture_array): |
||
571 | |||
572 | "The command |
||
573 | |||
574 | void FramebufferTextureLayerEXT(enum target, enum attachment, |
||
575 | uint texture, int level, int layer); |
||
576 | |||
577 | operates identically to FramebufferTexture3DEXT, except that it |
||
578 | attaches a single layer of a three-dimensional texture or a one- or |
||
579 | two-dimensional array texture. |
||
580 | layer number, and is treated identically to the |
||
581 | FramebufferTexture3DEXT. The error INVALID_VALUE is generated if |
||
582 |
|
||
583 |
|
||
584 | texture or one- or two-dimensional array texture. Unlike |
||
585 | FramebufferTexture3D, no |
||
586 | |||
587 | If |
||
588 | the framebuffer attachment state corresponding to |
||
589 | updated as in the other FramebufferTexture commands, except that |
||
590 | FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT is set to |
||
591 | |||
592 | -- Section 4.4.4.1 "Framebuffer Attachment Completeness" |
||
593 | |||
594 | Add to the end of the list of completeness rules (spec changes |
||
595 | identical to EXT_texture_array): |
||
596 | |||
597 | "* If FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE_EXT is TEXTURE and |
||
598 | FRAMEBUFFER_ATTACHMENT_OBJECT_NAME_EXT names a one- or |
||
599 | two-dimensional array texture, then |
||
600 | FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT must be smaller than the |
||
601 | number of layers in the texture." |
||
602 | |||
603 | Additions to Chapter 5 of the OpenGL 2.0 Specification (Special Functions) |
||
604 | |||
605 | -- Section 5.4 "Display Lists" |
||
606 | |||
607 | Change the first paragraph on page 242 to say (spec changes |
||
608 | identical to EXT_texture_array): |
||
609 | |||
610 | "TexImage3D, TexImage2D, TexImage1D, Histogram, and ColorTable are |
||
611 | executed immediately when called with the corresponding proxy arguments |
||
612 | PROXY_TEXTURE_3D or PROXY_TEXTURE_2D_ARRAY_EXT; PROXY_TEXTURE_2D, |
||
613 | PROXY_TEXTURE_CUBE_MAP, or PROXY_TEXTURE_1D_ARRAY_EXT; |
||
614 | PROXY_TEXTURE_1D; PROXY_HISTOGRAM; and PROXY_COLOR_TABLE, |
||
615 | PROXY_POST_CONVOLUTION_COLOR_TABLE, or |
||
616 | PROXY_POST_COLOR_MATRIX_COLOR_TABLE." |
||
617 | |||
618 | Additions to Chapter 6 of the OpenGL 2.0 Specification (State and State Requests) |
||
619 | |||
620 | -- Section 6.1.3 "Enumerated Queries" |
||
621 | |||
622 | Add after the line beginning "If the value of |
||
623 | FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE_EXT is TEXTURE" (spec changes |
||
624 | identical to EXT_texture_array): |
||
625 | |||
626 | "If |
||
627 | texture object named FRAMEBUFFER_ATTACHMENT_OBJECT_NAME_EXT is a |
||
628 | three-dimensional texture or a one- or two-dimensional array texture, |
||
629 | then |
||
630 | attachment point. Otherwise, |
||
631 | |||
632 | -- Section 6.1.4 "Texture Queries" |
||
633 | |||
634 | Change the first three paragraphs (page 248) to say (spec changes |
||
635 | identical to EXT_texture_array): |
||
636 | |||
637 | "The command |
||
638 | |||
639 | void GetTexImage(enum tex, int lod, enum format, |
||
640 | enum type, void *img); |
||
641 | |||
642 | is used to obtain texture images. It is somewhat different from the |
||
643 | other get commands; tex is a symbolic value indicating which texture |
||
644 | (or texture face in the case of a cube map texture target name) is to |
||
645 | be obtained. TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_1D_ARRAY_EXT, |
||
646 | and TEXTURE_2D_ARRAY_EXT indicate a one-, two-, or three-dimensional |
||
647 | texture, or one- or two-dimensional array texture, respectively. |
||
648 | TEXTURE_CUBE_MAP_POSITIVE_X, ... |
||
649 | |||
650 | GetTexImage obtains... from the first image to the last for |
||
651 | three-dimensional textures. One- and two-dimensional array textures |
||
652 | are treated as two- and three-dimensional images, respectively, where |
||
653 | the layers are treated as rows or images. These groups are then... |
||
654 | |||
655 | For three-dimensional and two-dimensional array textures, pixel storage |
||
656 | operations are applied as if the image were two-dimensional, except |
||
657 | that the additional pixel storage state values PACK_IMAGE_HEIGHT and |
||
658 | PACK_SKIP_IMAGES are applied. ..." |
||
659 | |||
660 | Additions to Appendix A of the OpenGL 2.0 Specification (Invariance) |
||
661 | |||
662 | None |
||
663 | |||
664 | Additions to the AGL/GLX/WGL Specifications |
||
665 | |||
666 | None |
||
667 | |||
668 | GLX Protocol |
||
669 | |||
670 | None |
||
671 | |||
672 | Dependencies on ARB_fragment_program |
||
673 | |||
674 | If ARB_fragment_program is not supported, the changes to section 3.11 |
||
675 | should be ignored. |
||
676 | |||
677 | Dependencies on EXT_framebuffer_object |
||
678 | |||
679 | If EXT_framebuffer_object is not supported, the changes to section |
||
680 | 3.8.8 ("Manual Mipmap Generation"), 4.4.2.3, and 6.1.3 should be ignored. |
||
681 | |||
682 | Dependencies on EXT_texture_compression_s3tc and NV_texture_compression_vtc |
||
683 | |||
684 | (Identical dependency as EXT_texture_array.) |
||
685 | |||
686 | S3TC texture compression is supported for two-dimensional array textures. |
||
687 | When |
||
688 | as a compressed two-dimensional textures. When specifying or querying |
||
689 | compressed images using one of the S3TC formats, the images are provided |
||
690 | and/or returned as a series of two-dimensional textures stored |
||
691 | consecutively in memory, with the layer closest to zero specified first. |
||
692 | For array textures, images are not arranged in 4x4x4 or 4x4x2 blocks as in |
||
693 | the three-dimensional compression format provided in the |
||
694 | EXT_texture_compression_vtc extension. Pixel store parameters, including |
||
695 | those specific to three-dimensional images, are ignored when compressed |
||
696 | image data are provided or returned, as in the |
||
697 | EXT_texture_compression_s3tc extension. |
||
698 | |||
699 | S3TC compression is not supported for one-dimensional texture targets in |
||
700 | EXT_texture_compression_s3tc, and is not supported for one-dimensional |
||
701 | array textures in this extension. If compressed one-dimensional arrays |
||
702 | are needed, use a two-dimensional texture with a height of one. |
||
703 | |||
704 | This extension allows the use of the four S3TC internal format types in |
||
705 | TexImage3D, CompressedTexImage3D, and CompressedTexSubImage3D calls. |
||
706 | |||
707 | Errors |
||
708 | |||
709 | None |
||
710 | |||
711 | New State |
||
712 | |||
713 | (add to table 6.15, p. 276) |
||
714 | |||
715 | Initial |
||
716 | Get Value Type Get Command Value Description Sec. Attribute |
||
717 | ---------------------------- ----- ----------- ----- -------------------- ------ --------- |
||
718 | TEXTURE_BINDING_1D_ARRAY_EXT 2*xZ+ GetIntegerv 0 texture object bound 3.8.12 texture |
||
719 | to TEXTURE_1D_ARRAY |
||
720 | TEXTURE_BINDING_2D_ARRAY_EXT 2*xZ+ GetIntegerv 0 texture object bound 3.8.12 texture |
||
721 | to TEXTURE_2D_ARRAY |
||
722 | |||
723 | |||
724 | New Implementation Dependent State |
||
725 | |||
726 | (add to Table 6.32, p. 293) |
||
727 | |||
728 | Minimum |
||
729 | Get Value Type Get Command Value Description Sec. Attribute |
||
730 | ---------------------------- ---- ----------- ------- ------------------ ----- --------- |
||
731 | MAX_TEXTURE_ARRAY_LAYERS_EXT Z+ GetIntegerv 64 maximum number of 3.8.1 - |
||
732 | layers for texture |
||
733 | arrays |
||
734 | |||
735 | Issues |
||
736 | |||
737 | (1) Is "texture stack" a good name for this functionality? |
||
738 | |||
739 | NO. The name is changed to "array texture" to match the |
||
740 | nomenclature used by GL_EXT_texture_array. |
||
741 | |||
742 | (2) Should the R texture coordinate be treated as normalized or |
||
743 | un-normalized? If it were un-normalized, floor(R) could be thought |
||
744 | of as a direct index into the array texture. This may be more |
||
745 | convenient for applications. |
||
746 | |||
747 | RESOLVED. All texture coordinates are normalized. The issue of |
||
748 | un-normalized texture coordinates has been discussed in the ARB |
||
749 | before and should be left for a layered extension. |
||
750 | |||
751 | RE-RESOLVED. The R coordinate is un-normalized. Accessing an array |
||
752 | using [0, layers-1] coordinates is much more natural. |
||
753 | |||
754 | (3) How does LOD selection work for stacked textures? |
||
755 | |||
756 | RESOLVED. For 2D array textures the R coordinate is ignored, and |
||
757 | the LOD selection equations for 2D textures are used. For 1D |
||
758 | array textures the T coordinate is ignored, and the LOD selection |
||
759 | equations for 1D textures are used. The expected usage is in a |
||
760 | fragment program with an explicit LOD selection. |
||
761 | |||
762 | (4) What is the maximum size of a 2D array texture? Is it the same |
||
763 | as for a 3D texture, or should a new query be added? How about for 1D |
||
764 | array textures? |
||
765 | |||
766 | RESOLVED. A new query is added. |
||
767 | |||
768 | (5) How are array textures exposed in GLSL? |
||
769 | |||
770 | RESOLVED. Use GL_EXT_texture_array. |
||
771 | |||
772 | (6) Should a 1D array texture also be exposed? |
||
773 | |||
774 | RESOLVED. For orthogonality, yes. |
||
775 | |||
776 | (7) How are stacked textures attached to framebuffer objects? |
||
777 | |||
778 | RESOLVED. Layers of both one- and two-dimensional array textures |
||
779 | are attached using FreambufferTextureLayerEXT. Once attached, the |
||
780 | array texture layer behaves exactly as either a one- or |
||
781 | two-dimensional texture. |
||
782 | |||
783 | (8) How is this extension related to GL_EXT_texture_array? |
||
784 | |||
785 | This extension adapats GL_MESAX_texture_stack to the notation, |
||
786 | indexing, and FBO access of GL_EXT_texture_array. This extension |
||
787 | replaces the GLSL support of GL_EXT_texture_array with |
||
788 | GL_ARB_fragment_program support. |
||
789 | |||
790 | Assembly program support is also provided by GL_NV_gpu_program4. |
||
791 | GL_NV_gpu_program4 also adds support for other features that are |
||
792 | specific to Nvidia hardware, while this extension adds only support |
||
793 | for array textures. |
||
794 | |||
795 | Much of text of this extension that has changed since |
||
796 | GL_MESAX_texture_stack comes directly from either |
||
797 | GL_EXT_texture_array or GL_NV_gpu_program4. |
||
798 | |||
799 | Revision History |
||
800 | |||
801 | ||2005/11/15||0.1||idr||Initial draft MESAX version.|| |
||
802 | ||2005/12/07||0.2||idr||Added framebuffer object interactions.|| |
||
803 | ||2005/12/12||0.3||idr||Updated fragment program interactions.|| |
||
804 | ||2007/05/16||0.4||idr||Converted to MESA_texture_array. Brought in line with EXT_texture_array and NV_gpu_program4.|| |