1 Name 2 3 MESA_texture_array 4 5 Name Strings 6 7 GL_MESA_texture_array 8 9 Contact 10 11 Ian Romanick, IBM (idr 'at' us.ibm.com) 12 13 IP Status 14 15 No known IP issues. 16 17 Status 18 19 Shipping in Mesa 7.1 20 21 Version 22 23 24 Number 25 26 TBD 27 28 Dependencies 29 30 OpenGL 1.2 or GL_EXT_texture3D is required. 31 32 Support for ARB_fragment_program is assumed, but not required. 33 34 Support for ARB_fragment_program_shadow is assumed, but not required. 35 36 Support for EXT_framebuffer_object is assumed, but not required. 37 38 Written based on the wording of the OpenGL 2.0 specification and 39 ARB_fragment_program_shadow but not dependent on them. 40 41 Overview 42 43 There are a number of circumstances where an application may wish to 44 blend two textures out of a larger set of textures. Moreover, in some 45 cases the selected textures may vary on a per-fragment basis within 46 a polygon. Several examples include: 47 48 1. High dynamic range textures. The application stores several 49 different "exposures" of an image as different textures. On a 50 per-fragment basis, the application selects which exposures are 51 used. 52 53 2. A terrain engine where the altitude of a point determines the 54 texture applied to it. If the transition is from beach sand to 55 grass to rocks to snow, the application will store each texture 56 in a different texture map, and dynamically select which two 57 textures to blend at run-time. 58 59 3. Storing short video clips in textures. Each depth slice is a 60 single frame of video. 61 62 Several solutions to this problem have been proposed, but they either 63 involve using a separate texture unit for each texture map or using 3D 64 textures without mipmaps. Both of these options have major drawbacks. 65 66 This extension provides a third alternative that eliminates the major 67 drawbacks of both previous methods. A new texture target, 68 TEXTURE_2D_ARRAY, is added that functions identically to TEXTURE_3D in 69 all aspects except the sizes of the non-base level images. In 70 traditional 3D texturing, the size of the N+1 LOD is half the size 71 of the N LOD in all three dimensions. For the TEXTURE_2D_ARRAY target, 72 the height and width of the N+1 LOD is halved, but the depth is the 73 same for all levels of detail. The texture then becomes an array of 74 2D textures. The per-fragment texel is selected by the R texture 75 coordinate. 76 77 References: 78 79 http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011557 80 http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=000516 81 http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011903 82 http://www.delphi3d.net/articles/viewarticle.php?article=terraintex.htm 83 84 New Procedures and Functions 85 86 All functions come directly from EXT_texture_array. 87 88 void FramebufferTextureLayerEXT(enum target, enum attachment, 89 uint texture, int level, int layer); 90 91 New Tokens 92 93 All token names and values come directly from EXT_texture_array. 94 95 Accepted by the <cap> parameter of Enable, Disable, and IsEnabled, by 96 the <pname> parameter of GetBooleanv, GetIntegerv, GetFloatv, and 97 GetDoublev, and by the <target> parameter of TexImage3D, GetTexImage, 98 GetTexLevelParameteriv, GetTexLevelParameterfv, GetTexParameteriv, and 99 GetTexParameterfv: 100 101 TEXTURE_1D_ARRAY_EXT 0x8C18 102 TEXTURE_2D_ARRAY_EXT 0x8C1A 103 104 Accepted by the <target> parameter of TexImage2D, TexSubImage2D, 105 CopyTexImage2D, CopyTexSubImage2D, CompressedTexImage2D, 106 CompressedTexSubImage2D, GetTexLevelParameteriv, and 107 GetTexLevelParameterfv: 108 109 TEXTURE_1D_ARRAY_EXT 110 PROXY_TEXTURE_1D_ARRAY_EXT 0x8C19 111 112 Accepted by the <target> parameter of TexImage3D, TexSubImage3D, 113 CopyTexSubImage3D, CompressedTexImage3D, CompressedTexSubImage3D, 114 GetTexLevelParameteriv, and GetTexLevelParameterfv: 115 116 TEXTURE_2D_ARRAY_EXT 117 PROXY_TEXTURE_2D_ARRAY_EXT 0x8C1B 118 119 Accepted by the <pname> parameter of GetBooleanv, GetIntegerv, 120 GetFloatv, and GetDoublev 121 122 TEXTURE_BINDING_1D_ARRAY_EXT 0x8C1C 123 TEXTURE_BINDING_2D_ARRAY_EXT 0x8C1D 124 MAX_ARRAY_TEXTURE_LAYERS_EXT 0x88FF 125 126 Accepted by the <param> parameter of TexParameterf, TexParameteri, 127 TexParameterfv, and TexParameteriv when the <pname> parameter is 128 TEXTURE_COMPARE_MODE_ARB: 129 130 COMPARE_REF_DEPTH_TO_TEXTURE_EXT 0x884E 131 132 (Note: COMPARE_REF_DEPTH_TO_TEXTURE_EXT is simply an alias for the 133 existing COMPARE_R_TO_TEXTURE token in OpenGL 2.0; the alternate name 134 reflects the fact that the R coordinate is not always used.) 135 136 Accepted by the <internalformat> parameter of TexImage3D and 137 CompressedTexImage3D, and by the <format> parameter of 138 CompressedTexSubImage3D: 139 140 COMPRESSED_RGB_S3TC_DXT1_EXT 141 COMPRESSED_RGBA_S3TC_DXT1_EXT 142 COMPRESSED_RGBA_S3TC_DXT3_EXT 143 COMPRESSED_RGBA_S3TC_DXT5_EXT 144 145 Accepted by the <pname> parameter of 146 GetFramebufferAttachmentParameterivEXT: 147 148 FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT 0x8CD4 149 150 (Note: FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER is simply an alias for the 151 FRAMEBUFFER_ATTACHMENT_TEXTURE_3D_ZOFFSET_EXT token provided in 152 EXT_framebuffer_object. This extension generalizes the notion of 153 "<zoffset>" to include layers of an array texture.) 154 155 Additions to Chapter 2 of the OpenGL 2.0 Specification (OpenGL Operation) 156 157 None 158 159 Additions to Chapter 3 of the OpenGL 2.0 Specification (Rasterization) 160 161 -- Section 3.8.1 "Texture Image Specification" 162 163 Change the first paragraph (page 150) to say (spec changes identical to 164 EXT_texture_array): 165 166 "The command 167 168 void TexImage3D(enum target, int level, int internalformat, 169 sizei width, sizei height, sizei depth, int border, 170 enum format, enum type, void *data); 171 172 is used to specify a three-dimensional texture image. target must be one 173 one of TEXTURE_3D for a three-dimensional texture or 174 TEXTURE_2D_ARRAY_EXT for an two-dimensional array texture. 175 Additionally, target may be either PROXY_TEXTURE_3D for a 176 three-dimensional proxy texture, or PROXY_TEXTURE_2D_ARRAY_EXT for a 177 two-dimensional proxy array texture." 178 179 Change the fourth paragraph on page 151 to say (spec changes identical 180 to EXT_texture_array): 181 182 "Textures with a base internal format of DEPTH_COMPONENT are supported 183 by texture image specification commands only if target is TEXTURE_1D, 184 TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, TEXTURE_2D_ARRAY_EXT, 185 PROXY_TEXTURE_1D, PROXY_TEXTURE_2D, PROXY_TEXTURE_1D_ARRAY_EXT, or 186 PROXY_TEXTURE_2D_ARRAY_EXT. Using this format in conjunction with any 187 other target will result in an INVALID_OPERATION error." 188 189 190 Change the fourth paragraph on page 156 to say (spec changes identical 191 to EXT_texture_array): 192 193 "The command 194 195 void TexImage2D(enum target, int level, 196 int internalformat, sizei width, sizei height, 197 int border, enum format, enum type, void *data); 198 199 is used to specify a two-dimensional texture image. target must be one 200 of TEXTURE_2D for a two-dimensional texture, TEXTURE_1D_ARRAY_EXT for a 201 one-dimensional array texture, or one of TEXTURE_CUBE_MAP_POSITIVE_X, 202 TEXTURE_CUBE_MAP_NEGATIVE_X, TEXTURE_CUBE_MAP_POSITIVE_Y, 203 TEXTURE_CUBE_MAP_NEGATIVE_Y, TEXTURE_CUBE_MAP_POSITIVE_Z, or 204 TEXTURE_CUBE_MAP_NEGATIVE_Z for a cube map texture. Additionally, 205 target may be either PROXY_TEXTURE_2D for a two-dimensional proxy 206 texture, PROXY_TEXTURE_1D_ARRAY_EXT for a one-dimensional proxy array 207 texture, or PROXY TEXTURE_CUBE_MAP for a cube map proxy texture in the 208 special case discussed in section 3.8.11. The other parameters match 209 the corresponding parameters of TexImage3D. 210 211 For the purposes of decoding the texture image, TexImage2D is 212 equivalent to calling TexImage3D with corresponding arguments and depth 213 of 1, except that 214 215 * The border depth, d_b, is zero, and the depth of the image is 216 always 1 regardless of the value of border. 217 218 * The border height, h_b, is zero if <target> is 219 TEXTURE_1D_ARRAY_EXT, and <border> otherwise. 220 221 * Convolution will be performed on the image (possibly changing its 222 width and height) if SEPARABLE 2D or CONVOLUTION 2D is enabled. 223 224 * UNPACK SKIP IMAGES is ignored." 225 226 -- Section 3.8.2 "Alternate Texture Image Specification Commands" 227 228 Change the second paragraph (page 159) (spec changes identical 229 to EXT_texture_array): 230 231 "The command 232 233 void CopyTexImage2D(enum target, int level, 234 enum internalformat, int x, int y, sizei width, 235 sizei height, int border); 236 237 defines a two-dimensional texture image in exactly the manner of 238 TexImage2D, except that the image data are taken from the framebuffer 239 rather than from client memory. Currently, target must be one of 240 TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, TEXTURE_CUBE_MAP_POSITIVE_X, 241 TEXTURE_CUBE_MAP_NEGATIVE_X, TEXTURE_CUBE MAP_POSITIVE_Y, 242 TEXTURE_CUBE_MAP_NEGATIVE_Y, TEXTURE_CUBE_MAP_POSITIVE_Z, or 243 TEXTURE_CUBE_MAP_NEGATIVE_Z. 244 245 246 Change the last paragraph on page 160 to say (spec changes identical 247 to EXT_texture_array): 248 249 "Currently the target arguments of TexSubImage1D and CopyTexSubImage1D 250 must be TEXTURE_1D, the target arguments of TexSubImage2D and 251 CopyTexSubImage2D must be one of TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, 252 TEXTURE_CUBE_MAP_POSITIVE_X, TEXTURE_CUBE_MAP_NEGATIVE_X, 253 TEXTURE_CUBE_MAP_POSITIVE_Y, TEXTURE_CUBE_MAP_NEGATIVE_Y, 254 TEXTURE_CUBE_MAP_POSITIVE_Z, or TEXTURE_CUBE_MAP_NEGATIVE_Z, and the 255 target arguments of TexSubImage3D and CopyTexSubImage3D must be 256 TEXTURE_3D or TEXTURE_2D_ARRAY_EXT. ..." 257 258 259 -- Section 3.8.4 "Texture Parameters" 260 261 Change the first paragraph (page 166) to say: 262 263 "Various parameters control how the texel array is treated when 264 specified or changed, and when applied to a fragment. Each parameter is 265 set by calling 266 267 void TexParameter{if}(enum target, enum pname, T param); 268 void TexParameter{if}v(enum target, enum pname, T params); 269 270 target is the target, either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, 271 TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT." 272 273 274 -- Section 3.8.8 "Texture Minification" in the section "Scale Factor and Level of Detail" 275 276 Change the first paragraph (page 172) to say: 277 278 "Let s(x,y) be the function that associates an s texture coordinate 279 with each set of window coordinates (x,y) that lie within a primitive; 280 define t(x,y) and r(x,y) analogously. Let u(x,y) = w_t * s(x,y), 281 v(x,y) = h_t * t(x,y), and w(x,y) = d_t * r(x,y), where w_t, h_t, 282 and d_t are as defined by equations 3.15, 3.16, and 3.17 with 283 w_s, h_s, and d_s equal to the width, height, and depth of the 284 image array whose level is level_base. For a one-dimensional 285 texture or a one-dimensional array texture, define v(x,y) = 0 and 286 w(x,y) = 0; for a two-dimensional texture or a two-dimensional array 287 texture, define w(x,y) = 0..." 288 289 -- Section 3.8.8 "Texture Minification" in the section "Mipmapping" 290 291 Change the third paragraph (page 174) to say: 292 293 "For a two-dimensional texture, two-dimensional array texture, or 294 cube map texture," 295 296 Change the fourth paragraph (page 174) to say: 297 298 "And for a one-dimensional texture or a one-dimensional array texture," 299 300 After the first paragraph (page 175) add: 301 302 "For one-dimensional array textures, h_b and d_b are treated as 1, 303 regardless of the actual values, when performing mipmap calculations. 304 For two-dimensional array textures, d_b is always treated as one, 305 regardless of the actual value, when performing mipmap calculations." 306 307 -- Section 3.8.8 "Automatic Mipmap Generation" in the section "Mipmapping" 308 309 Change the third paragraph (page 176) to say (spec changes identical 310 to EXT_texture_array): 311 312 "The contents of the derived arrays are computed by repeated, filtered 313 reduction of the level_base array. For one- and two-dimensional array 314 textures, each layer is filtered independently. ..." 315 316 -- Section 3.8.8 "Manual Mipmap Generation" in the section "Mipmapping" 317 318 Change first paragraph to say (spec changes identical to 319 EXT_texture_array): 320 321 "Mipmaps can be generated manually with the command 322 323 void GenerateMipmapEXT(enum target); 324 325 where <target> is one of TEXTURE_1D, TEXTURE_2D, TEXTURE_CUBE_MAP, 326 TEXTURE_3D, TEXTURE_1D_ARRAY, or TEXTURE_2D_ARRAY. Mipmap generation 327 affects the texture image attached to <target>. ..." 328 329 -- Section 3.8.10 "Texture Completeness" 330 331 Change the second paragraph (page 177) to say (spec changes identical 332 to EXT_texture_array): 333 334 "For one-, two-, or three-dimensional textures and one- or 335 two-dimensional array textures, a texture is complete if the following 336 conditions all hold true:" 337 338 -- Section 3.8.11 "Texture State and Proxy State" 339 340 Change the second and third paragraphs (page 179) to say (spec changes 341 identical to EXT_texture_array): 342 343 "In addition to image arrays for one-, two-, and three-dimensional 344 textures, one- and two-dimensional array textures, and the six image 345 arrays for the cube map texture, partially instantiated image arrays 346 are maintained for one-, two-, and three-dimensional textures and one- 347 and two-dimensional array textures. Additionally, a single proxy image 348 array is maintained for the cube map texture. Each proxy image array 349 includes width, height, depth, border width, and internal format state 350 values, as well as state for the red, green, blue, alpha, luminance, 351 and intensity component resolutions. Proxy image arrays do not include 352 image data, nor do they include texture properties. When TexImage3D is 353 executed with target specified as PROXY_TEXTURE_3D, the 354 three-dimensional proxy state values of the specified level-of-detail 355 are recomputed and updated. If the image array would not be supported 356 by TexImage3D called with target set to TEXTURE 3D, no error is 357 generated, but the proxy width, height, depth, border width, and 358 component resolutions are set to zero. If the image array would be 359 supported by such a call to TexImage3D, the proxy state values are set 360 exactly as though the actual image array were being specified. No pixel 361 data are transferred or processed in either case. 362 363 Proxy arrays for one- and two-dimensional textures and one- and 364 two-dimensional array textures are operated on in the same way when 365 TexImage1D is executed with target specified as PROXY_TEXTURE_1D, 366 TexImage2D is executed with target specified as PROXY_TEXTURE_2D or 367 PROXY_TEXTURE_1D_ARRAY_EXT, or TexImage3D is executed with target 368 specified as PROXY_TETXURE_2D_ARRAY_EXT." 369 370 -- Section 3.8.12 "Texture Objects" 371 372 Change section (page 180) to say (spec changes identical to 373 EXT_texture_array): 374 375 "In addition to the default textures TEXTURE_1D, TEXTURE_2D, 376 TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and TEXTURE_2D_EXT, 377 named one-, two-, and three-dimensional, cube map, and one- and 378 two-dimensional array texture objects can be created and operated upon. 379 The name space for texture objects is the unsigned integers, with zero 380 reserved by the GL. 381 382 A texture object is created by binding an unused name to TEXTURE_1D, 383 TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or 384 TEXTURE_2D_ARRAY_EXT. The binding is effected by calling 385 386 void BindTexture(enum target, uint texture); 387 388 with <target> set to the desired texture target and <texture> set to 389 the unused name. The resulting texture object is a new state vector, 390 comprising all the state values listed in section 3.8.11, set to the 391 same initial values. If the new texture object is bound to TEXTURE_1D, 392 TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or 393 TEXTURE_2D_ARRAY_EXT, it is and remains a one-, two-, 394 three-dimensional, cube map, one- or two-dimensional array texture 395 respectively until it is deleted. 396 397 BindTexture may also be used to bind an existing texture object to 398 either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, 399 TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT. The error 400 INVALID_OPERATION is generated if an attempt is made to bind a texture 401 object of different dimensionality than the specified target. If the 402 bind is successful no change is made to the state of the bound texture 403 object, and any previous binding to target is broken. 404 405 While a texture object is bound, GL operations on the target to which 406 it is bound affect the bound object, and queries of the target to which 407 it is bound return state from the bound object. If texture mapping of 408 the dimensionality of the target to which a texture object is bound is 409 enabled, the state of the bound texture object directs the texturing 410 operation. 411 412 In the initial state, TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, 413 TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and TEXTURE_2D_ARRAY_EXT have 414 one-, two-, three-dimensional, cube map, and one- and two-dimensional 415 array texture state vectors respectively associated with them. In order 416 that access to these initial textures not be lost, they are treated as 417 texture objects all of whose names are 0. The initial one-, two-, 418 three-dimensional, cube map, one- and two-dimensional array textures 419 are therefore operated upon, queried, and applied as TEXTURE_1D, 420 TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and 421 TEXTURE_2D_ARRAY_EXT respectively while 0 is bound to the corresponding 422 targets. 423 424 Change second paragraph on page 181 to say (spec changes identical to 425 EXT_texture_array): 426 427 "... If a texture that is currently bound to one of the targets 428 TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, 429 TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT is deleted, it is as 430 though BindTexture had been executed with the same target and texture 431 zero. ..." 432 433 Change second paragraph on page 182 to say (spec changes identical to 434 EXT_texture_array): 435 436 "The texture object name space, including the initial one-, two-, and 437 three dimensional, cube map, and one- and two-dimensional array texture 438 objects, is shared among all texture units. ..." 439 440 441 -- Section 3.8.14 "Depth Texture Comparison Modes" in "Texture Comparison Modes" 442 443 Change second through fourth paragraphs (page 188) to say: 444 445 "Let D_t be the depth texture value, in the range [0, 1]. For 446 texture lookups from one- and two-dimensional, rectangle, and 447 one-dimensional array targets, let R be the interpolated <r> 448 texture coordinate, clamped to the range [0, 1]. For texture lookups 449 from two-dimensional array texture targets, let R be the interpolated 450 <q> texture coordinate, clamped to the range [0, 1]. Then the 451 effective texture value L_t, I_t, or A_t is computed as follows: 452 453 If the value of TEXTURE_COMPARE_MODE is NONE, then 454 455 r = Dt 456 457 If the value of TEXTURE_COMPARE_MODE is 458 COMPARE_REF_DEPTH_TO_TEXTURE_EXT), then r depends on the texture 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 <optionName> ::= "MESA_texture_array" 487 488 <texTarget> ::= "1D" 489 | "2D" 490 | "3D" 491 | "CUBE" 492 | "RECT" 493 | <arrayTarget> (if program option is present) 494 | <shadowTarget> (if program option is present) 495 496 <arrayTarget> ::= "ARRAY1D" 497 | "ARRAY2D" 498 499 <shadowTarget> ::= "SHADOW1D" 500 | "SHADOW2D" 501 | "SHADOWRECT" 502 | <shadowArrayTarget> (if program option is present) 503 504 <shadowArrayTarget> ::= "SHADOWARRAY1D" 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 <texTarget> rule is modified to add the texture targets 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 <coord> 533 are used by all texture targets. Component usage for each <texTarget> 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 <texTarget>, and 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. <layer> is an integer indicating the 580 layer number, and is treated identically to the <zoffset> parameter in 581 FramebufferTexture3DEXT. The error INVALID_VALUE is generated if 582 <layer> is negative. The error INVALID_OPERATION is generated if 583 <texture> is non-zero and is not the name of a three dimensional 584 texture or one- or two-dimensional array texture. Unlike 585 FramebufferTexture3D, no <textarget> parameter is accepted. 586 587 If <texture> is non-zero and the command does not result in an error, 588 the framebuffer attachment state corresponding to <attachment> is 589 updated as in the other FramebufferTexture commands, except that 590 FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT is set to <layer>." 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 <pname> is FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT and the 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 <params> will contain the number of texture layer attached to the 630 attachment point. Otherwise, <params> will contain the value zero." 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 <target> is TEXTURE_2D_ARRAY_EXT, each layer is stored independently 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.|| 805
