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diff --git a/docs/MESA_texture_array.spec b/docs/MESA_texture_array.spec new file mode 100644 index 00000000000..d3b77521151 --- /dev/null +++ b/docs/MESA_texture_array.spec @@ -0,0 +1,805 @@ +Name + + MESA_texture_array + +Name Strings + + GL_MESA_texture_array + +Contact + + Ian Romanick, IBM (idr 'at' us.ibm.com) + +IP Status + + No known IP issues. + +Status + + Shipping in Mesa 7.1 + +Version + + $Date: 2007/05/16$ $Revision: 0.4$ + +Number + + TBD + +Dependencies + + OpenGL 1.2 or GL_EXT_texture3D is required. + + Support for ARB_fragment_program is assumed, but not required. + + Support for ARB_fragment_program_shadow is assumed, but not required. + + Support for EXT_framebuffer_object is assumed, but not required. + + Written based on the wording of the OpenGL 2.0 specification and + ARB_fragment_program_shadow but not dependent on them. + +Overview + + There are a number of circumstances where an application may wish to + blend two textures out of a larger set of textures. Moreover, in some + cases the selected textures may vary on a per-fragment basis within + a polygon. Several examples include: + + 1. High dynamic range textures. The application stores several + different "exposures" of an image as different textures. On a + per-fragment basis, the application selects which exposures are + used. + + 2. A terrain engine where the altitude of a point determines the + texture applied to it. If the transition is from beach sand to + grass to rocks to snow, the application will store each texture + in a different texture map, and dynamically select which two + textures to blend at run-time. + + 3. Storing short video clips in textures. Each depth slice is a + single frame of video. + + Several solutions to this problem have been proposed, but they either + involve using a separate texture unit for each texture map or using 3D + textures without mipmaps. Both of these options have major drawbacks. + + This extension provides a third alternative that eliminates the major + drawbacks of both previous methods. A new texture target, + TEXTURE_2D_ARRAY, is added that functions identically to TEXTURE_3D in + all aspects except the sizes of the non-base level images. In + traditional 3D texturing, the size of the N+1 LOD is half the size + of the N LOD in all three dimensions. For the TEXTURE_2D_ARRAY target, + the height and width of the N+1 LOD is halved, but the depth is the + same for all levels of detail. The texture then becomes an array of + 2D textures. The per-fragment texel is selected by the R texture + coordinate. + + References: + + http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011557 + http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=000516 + http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=011903 + http://www.delphi3d.net/articles/viewarticle.php?article=terraintex.htm + +New Procedures and Functions + + All functions come directly from EXT_texture_array. + + void FramebufferTextureLayerEXT(enum target, enum attachment, + uint texture, int level, int layer); + +New Tokens + + All token names and values come directly from EXT_texture_array. + + Accepted by the <cap> parameter of Enable, Disable, and IsEnabled, by + the <pname> parameter of GetBooleanv, GetIntegerv, GetFloatv, and + GetDoublev, and by the <target> parameter of TexImage3D, GetTexImage, + GetTexLevelParameteriv, GetTexLevelParameterfv, GetTexParameteriv, and + GetTexParameterfv: + + TEXTURE_1D_ARRAY_EXT 0x8C18 + TEXTURE_2D_ARRAY_EXT 0x8C1A + + Accepted by the <target> parameter of TexImage2D, TexSubImage2D, + CopyTexImage2D, CopyTexSubImage2D, CompressedTexImage2D, + CompressedTexSubImage2D, GetTexLevelParameteriv, and + GetTexLevelParameterfv: + + TEXTURE_1D_ARRAY_EXT + PROXY_TEXTURE_1D_ARRAY_EXT 0x8C19 + + Accepted by the <target> parameter of TexImage3D, TexSubImage3D, + CopyTexSubImage3D, CompressedTexImage3D, CompressedTexSubImage3D, + GetTexLevelParameteriv, and GetTexLevelParameterfv: + + TEXTURE_2D_ARRAY_EXT + PROXY_TEXTURE_2D_ARRAY_EXT 0x8C1B + + Accepted by the <pname> parameter of GetBooleanv, GetIntegerv, + GetFloatv, and GetDoublev + + TEXTURE_BINDING_1D_ARRAY_EXT 0x8C1C + TEXTURE_BINDING_2D_ARRAY_EXT 0x8C1D + MAX_ARRAY_TEXTURE_LAYERS_EXT 0x88FF + + Accepted by the <param> parameter of TexParameterf, TexParameteri, + TexParameterfv, and TexParameteriv when the <pname> parameter is + TEXTURE_COMPARE_MODE_ARB: + + COMPARE_REF_DEPTH_TO_TEXTURE_EXT 0x884E + + (Note: COMPARE_REF_DEPTH_TO_TEXTURE_EXT is simply an alias for the + existing COMPARE_R_TO_TEXTURE token in OpenGL 2.0; the alternate name + reflects the fact that the R coordinate is not always used.) + + Accepted by the <internalformat> parameter of TexImage3D and + CompressedTexImage3D, and by the <format> parameter of + CompressedTexSubImage3D: + + COMPRESSED_RGB_S3TC_DXT1_EXT + COMPRESSED_RGBA_S3TC_DXT1_EXT + COMPRESSED_RGBA_S3TC_DXT3_EXT + COMPRESSED_RGBA_S3TC_DXT5_EXT + + Accepted by the <pname> parameter of + GetFramebufferAttachmentParameterivEXT: + + FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT 0x8CD4 + + (Note: FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER is simply an alias for the + FRAMEBUFFER_ATTACHMENT_TEXTURE_3D_ZOFFSET_EXT token provided in + EXT_framebuffer_object. This extension generalizes the notion of + "<zoffset>" to include layers of an array texture.) + +Additions to Chapter 2 of the OpenGL 2.0 Specification (OpenGL Operation) + + None + +Additions to Chapter 3 of the OpenGL 2.0 Specification (Rasterization) + + -- Section 3.8.1 "Texture Image Specification" + + Change the first paragraph (page 150) to say (spec changes identical to + EXT_texture_array): + + "The command + + void TexImage3D(enum target, int level, int internalformat, + sizei width, sizei height, sizei depth, int border, + enum format, enum type, void *data); + + is used to specify a three-dimensional texture image. target must be one + one of TEXTURE_3D for a three-dimensional texture or + TEXTURE_2D_ARRAY_EXT for an two-dimensional array texture. + Additionally, target may be either PROXY_TEXTURE_3D for a + three-dimensional proxy texture, or PROXY_TEXTURE_2D_ARRAY_EXT for a + two-dimensional proxy array texture." + + Change the fourth paragraph on page 151 to say (spec changes identical + to EXT_texture_array): + + "Textures with a base internal format of DEPTH_COMPONENT are supported + by texture image specification commands only if target is TEXTURE_1D, + TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, TEXTURE_2D_ARRAY_EXT, + PROXY_TEXTURE_1D, PROXY_TEXTURE_2D, PROXY_TEXTURE_1D_ARRAY_EXT, or + PROXY_TEXTURE_2D_ARRAY_EXT. Using this format in conjunction with any + other target will result in an INVALID_OPERATION error." + + + Change the fourth paragraph on page 156 to say (spec changes identical + to EXT_texture_array): + + "The command + + void TexImage2D(enum target, int level, + int internalformat, sizei width, sizei height, + int border, enum format, enum type, void *data); + + is used to specify a two-dimensional texture image. target must be one + of TEXTURE_2D for a two-dimensional texture, TEXTURE_1D_ARRAY_EXT for a + one-dimensional array texture, or one of TEXTURE_CUBE_MAP_POSITIVE_X, + TEXTURE_CUBE_MAP_NEGATIVE_X, TEXTURE_CUBE_MAP_POSITIVE_Y, + TEXTURE_CUBE_MAP_NEGATIVE_Y, TEXTURE_CUBE_MAP_POSITIVE_Z, or + TEXTURE_CUBE_MAP_NEGATIVE_Z for a cube map texture. Additionally, + target may be either PROXY_TEXTURE_2D for a two-dimensional proxy + texture, PROXY_TEXTURE_1D_ARRAY_EXT for a one-dimensional proxy array + texture, or PROXY TEXTURE_CUBE_MAP for a cube map proxy texture in the + special case discussed in section 3.8.11. The other parameters match + the corresponding parameters of TexImage3D. + + For the purposes of decoding the texture image, TexImage2D is + equivalent to calling TexImage3D with corresponding arguments and depth + of 1, except that + + * The border depth, d_b, is zero, and the depth of the image is + always 1 regardless of the value of border. + + * The border height, h_b, is zero if <target> is + TEXTURE_1D_ARRAY_EXT, and <border> otherwise. + + * Convolution will be performed on the image (possibly changing its + width and height) if SEPARABLE 2D or CONVOLUTION 2D is enabled. + + * UNPACK SKIP IMAGES is ignored." + + -- Section 3.8.2 "Alternate Texture Image Specification Commands" + + Change the second paragraph (page 159) (spec changes identical + to EXT_texture_array): + + "The command + + void CopyTexImage2D(enum target, int level, + enum internalformat, int x, int y, sizei width, + sizei height, int border); + + defines a two-dimensional texture image in exactly the manner of + TexImage2D, except that the image data are taken from the framebuffer + rather than from client memory. Currently, target must be one of + TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, TEXTURE_CUBE_MAP_POSITIVE_X, + TEXTURE_CUBE_MAP_NEGATIVE_X, TEXTURE_CUBE MAP_POSITIVE_Y, + TEXTURE_CUBE_MAP_NEGATIVE_Y, TEXTURE_CUBE_MAP_POSITIVE_Z, or + TEXTURE_CUBE_MAP_NEGATIVE_Z. + + + Change the last paragraph on page 160 to say (spec changes identical + to EXT_texture_array): + + "Currently the target arguments of TexSubImage1D and CopyTexSubImage1D + must be TEXTURE_1D, the target arguments of TexSubImage2D and + CopyTexSubImage2D must be one of TEXTURE_2D, TEXTURE_1D_ARRAY_EXT, + TEXTURE_CUBE_MAP_POSITIVE_X, TEXTURE_CUBE_MAP_NEGATIVE_X, + TEXTURE_CUBE_MAP_POSITIVE_Y, TEXTURE_CUBE_MAP_NEGATIVE_Y, + TEXTURE_CUBE_MAP_POSITIVE_Z, or TEXTURE_CUBE_MAP_NEGATIVE_Z, and the + target arguments of TexSubImage3D and CopyTexSubImage3D must be + TEXTURE_3D or TEXTURE_2D_ARRAY_EXT. ..." + + + -- Section 3.8.4 "Texture Parameters" + + Change the first paragraph (page 166) to say: + + "Various parameters control how the texel array is treated when + specified or changed, and when applied to a fragment. Each parameter is + set by calling + + void TexParameter{if}(enum target, enum pname, T param); + void TexParameter{if}v(enum target, enum pname, T params); + + target is the target, either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, + TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT." + + + -- Section 3.8.8 "Texture Minification" in the section "Scale Factor and Level of Detail" + + Change the first paragraph (page 172) to say: + + "Let s(x,y) be the function that associates an s texture coordinate + with each set of window coordinates (x,y) that lie within a primitive; + define t(x,y) and r(x,y) analogously. Let u(x,y) = w_t * s(x,y), + v(x,y) = h_t * t(x,y), and w(x,y) = d_t * r(x,y), where w_t, h_t, + and d_t are as defined by equations 3.15, 3.16, and 3.17 with + w_s, h_s, and d_s equal to the width, height, and depth of the + image array whose level is level_base. For a one-dimensional + texture or a one-dimensional array texture, define v(x,y) = 0 and + w(x,y) = 0; for a two-dimensional texture or a two-dimensional array + texture, define w(x,y) = 0..." + + -- Section 3.8.8 "Texture Minification" in the section "Mipmapping" + + Change the third paragraph (page 174) to say: + + "For a two-dimensional texture, two-dimensional array texture, or + cube map texture," + + Change the fourth paragraph (page 174) to say: + + "And for a one-dimensional texture or a one-dimensional array texture," + + After the first paragraph (page 175) add: + + "For one-dimensional array textures, h_b and d_b are treated as 1, + regardless of the actual values, when performing mipmap calculations. + For two-dimensional array textures, d_b is always treated as one, + regardless of the actual value, when performing mipmap calculations." + + -- Section 3.8.8 "Automatic Mipmap Generation" in the section "Mipmapping" + + Change the third paragraph (page 176) to say (spec changes identical + to EXT_texture_array): + + "The contents of the derived arrays are computed by repeated, filtered + reduction of the level_base array. For one- and two-dimensional array + textures, each layer is filtered independently. ..." + + -- Section 3.8.8 "Manual Mipmap Generation" in the section "Mipmapping" + + Change first paragraph to say (spec changes identical to + EXT_texture_array): + + "Mipmaps can be generated manually with the command + + void GenerateMipmapEXT(enum target); + + where <target> is one of TEXTURE_1D, TEXTURE_2D, TEXTURE_CUBE_MAP, + TEXTURE_3D, TEXTURE_1D_ARRAY, or TEXTURE_2D_ARRAY. Mipmap generation + affects the texture image attached to <target>. ..." + + -- Section 3.8.10 "Texture Completeness" + + Change the second paragaph (page 177) to say (spec changes identical + to EXT_texture_array): + + "For one-, two-, or three-dimensional textures and one- or + two-dimensional array textures, a texture is complete if the following + conditions all hold true:" + + -- Section 3.8.11 "Texture State and Proxy State" + + Change the second and third paragraphs (page 179) to say (spec changes + identical to EXT_texture_array): + + "In addition to image arrays for one-, two-, and three-dimensional + textures, one- and two-dimensional array textures, and the six image + arrays for the cube map texture, partially instantiated image arrays + are maintained for one-, two-, and three-dimensional textures and one- + and two-dimensional array textures. Additionally, a single proxy image + array is maintained for the cube map texture. Each proxy image array + includes width, height, depth, border width, and internal format state + values, as well as state for the red, green, blue, alpha, luminance, + and intensity component resolutions. Proxy image arrays do not include + image data, nor do they include texture properties. When TexImage3D is + executed with target specified as PROXY_TEXTURE_3D, the + three-dimensional proxy state values of the specified level-of-detail + are recomputed and updated. If the image array would not be supported + by TexImage3D called with target set to TEXTURE 3D, no error is + generated, but the proxy width, height, depth, border width, and + component resolutions are set to zero. If the image array would be + supported by such a call to TexImage3D, the proxy state values are set + exactly as though the actual image array were being specified. No pixel + data are transferred or processed in either case. + + Proxy arrays for one- and two-dimensional textures and one- and + two-dimensional array textures are operated on in the same way when + TexImage1D is executed with target specified as PROXY_TEXTURE_1D, + TexImage2D is executed with target specified as PROXY_TEXTURE_2D or + PROXY_TEXTURE_1D_ARRAY_EXT, or TexImage3D is executed with target + specified as PROXY_TETXURE_2D_ARRAY_EXT." + + -- Section 3.8.12 "Texture Objects" + + Change section (page 180) to say (spec changes identical to + EXT_texture_array): + + "In addition to the default textures TEXTURE_1D, TEXTURE_2D, + TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and TEXTURE_2D_EXT, + named one-, two-, and three-dimensional, cube map, and one- and + two-dimensional array texture objects can be created and operated upon. + The name space for texture objects is the unsigned integers, with zero + reserved by the GL. + + A texture object is created by binding an unused name to TEXTURE_1D, + TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or + TEXTURE_2D_ARRAY_EXT. The binding is effected by calling + + void BindTexture(enum target, uint texture); + + with <target> set to the desired texture target and <texture> set to + the unused name. The resulting texture object is a new state vector, + comprising all the state values listed in section 3.8.11, set to the + same initial values. If the new texture object is bound to TEXTURE_1D, + TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or + TEXTURE_2D_ARRAY_EXT, it is and remains a one-, two-, + three-dimensional, cube map, one- or two-dimensional array texture + respectively until it is deleted. + + BindTexture may also be used to bind an existing texture object to + either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, + TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT. The error + INVALID_OPERATION is generated if an attempt is made to bind a texture + object of different dimensionality than the specified target. If the + bind is successful no change is made to the state of the bound texture + object, and any previous binding to target is broken. + + While a texture object is bound, GL operations on the target to which + it is bound affect the bound object, and queries of the target to which + it is bound return state from the bound object. If texture mapping of + the dimensionality of the target to which a texture object is bound is + enabled, the state of the bound texture object directs the texturing + operation. + + In the initial state, TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, + TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and TEXTURE_2D_ARRAY_EXT have + one-, two-, three-dimensional, cube map, and one- and two-dimensional + array texture state vectors respectively associated with them. In order + that access to these initial textures not be lost, they are treated as + texture objects all of whose names are 0. The initial one-, two-, + three-dimensional, cube map, one- and two-dimensional array textures + are therefore operated upon, queried, and applied as TEXTURE_1D, + TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, and + TEXTURE_2D_ARRAY_EXT respectively while 0 is bound to the corresponding + targets. + + Change second paragraph on page 181 to say (spec changes identical to + EXT_texture_array): + + "... If a texture that is currently bound to one of the targets + TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, + TEXTURE_1D_ARRAY_EXT, or TEXTURE_2D_ARRAY_EXT is deleted, it is as + though BindTexture had been executed with the same target and texture + zero. ..." + + Change second paragraph on page 182 to say (spec changes identical to + EXT_texture_array): + + "The texture object name space, including the initial one-, two-, and + three dimensional, cube map, and one- and two-dimensional array texture + objects, is shared among all texture units. ..." + + + -- Section 3.8.14 "Depth Texture Comparison Modes" in "Texture Comparison Modes" + + Change second through fourth paragraphs (page 188) to say: + + "Let D_t be the depth texture value, in the range [0, 1]. For + texture lookups from one- and two-dimesional, rectangle, and + one-dimensional array targets, let R be the interpolated <r> + texture coordinate, clamped to the range [0, 1]. For texture lookups + from two-dimesional array texture targets, let R be the interpolated + <q> texture coordinate, clamped to the range [0, 1]. Then the + effective texture value L_t, I_t, or A_t is computed as follows: + + If the value of TEXTURE_COMPARE_MODE is NONE, then + + r = Dt + + If the value of TEXTURE_COMPARE_MODE is + COMPARE_REF_DEPTH_TO_TEXTURE_EXT), then r depends on the texture + comparison function as shown in table 3.27." + + -- Section 3.8.15 "Texture Application" + + Change the first paragraph (page 189) to say: + + "Texturing is enabled or disabled using the generic Enable and Disable + commands, respectively, with the symbolic constants TEXTURE_1D, + TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP, TEXTURE_1D_ARRAY_EXT, or + TEXTURE_2D_ARRAY_EXT to enable one-, two-, three-dimensional, cube + map, one-dimensional array, or two-dimensional array texture, + respectively. If both two- and one-dimensional textures are enabled, + the two-dimensional texture is used. If the three-dimensional and + either of the two- or one-dimensional textures is enabled, the + three-dimensional texture is used. If the cube map texture and any of + the three-, two-, or one-dimensional textures is enabled, then cube map + texturing is used. If one-dimensional array texture is enabled and any + of cube map, three-, two-, or one-dimensional textures is enabled, + one-dimensional array texturing is used. If two-dimensional array + texture is enabled and any of cube map, three-, two-, one-dimensional + textures or one-dimensional array texture is enabled, two-dimensional + array texturing is used..." + + -- Section 3.11.2 of ARB_fragment_program (Fragment Program Grammar and Restrictions): + + (mostly add to existing grammar rules) + + <optionName> ::= "MESA_texture_array" + + <texTarget> ::= "1D" + | "2D" + | "3D" + | "CUBE" + | "RECT" + | <arrayTarget> (if program option is present) + | <shadowTarget> (if program option is present) + + <arrayTarget> ::= "ARRAY1D" + | "ARRAY2D" + + <shadowTarget> ::= "SHADOW1D" + | "SHADOW2D" + | "SHADOWRECT" + | <shadowArrayTarget> (if program option is present) + + <shadowArrayTarget> ::= "SHADOWARRAY1D" + | "SHADOWARRAY2D" + + + -- Add Section 3.11.4.5.4 "Texture Stack Option" + + "If a fragment program specifies the "MESA_texture_array" program + option, the <texTarget> rule is modified to add the texture targets + ARRAY1D and ARRAY2D (See Section 3.11.2)." + + -- Section 3.11.6 "Fragment Program Texture Instruction Set" + + (replace 1st and 2nd paragraphs with the following paragraphs) + + "The first three texture instructions described below specify the + mapping of 4-tuple input vectors to 4-tuple output vectors. + The sampling of the texture works as described in section 3.8, + except that texture environments and texture functions are not + applicable, and the texture enables hierarchy is replaced by explicit + references to the desired texture target (i.e., 1D, 2D, 3D, cube map, + rectangle, ARRAY1D, ARRAY2D). These texture instructions specify + how the 4-tuple is mapped into the coordinates used for sampling. The + following function is used to describe the texture sampling in the + descriptions below: + + vec4 TextureSample(vec4 coord, float lodBias, int texImageUnit, + enum texTarget); + + Note that not all four components of the texture coordinates <coord> + are used by all texture targets. Component usage for each <texTarget> + is defined in table X. + + coordinates used + texTarget Texture Type s t r layer shadow + ---------------- --------------------- ----- ----- ------ + 1D TEXTURE_1D x - - - - + 2D TEXTURE_2D x y - - - + 3D TEXTURE_3D x y z - - + CUBE TEXTURE_CUBE_MAP x y z - - + RECT TEXTURE_RECTANGLE_ARB x y - - - + ARRAY1D TEXTURE_1D_ARRAY_EXT x - - y - + ARRAY2D TEXTURE_2D_ARRAY_EXT x y - z - + SHADOW1D TEXTURE_1D x - - - z + SHADOW2D TEXTURE_2D x y - - z + SHADOWRECT TEXTURE_RECTANGLE_ARB x y - - z + SHADOWARRAY1D TEXTURE_1D_ARRAY_EXT x - - y z + SHADOWARRAY2D TEXTURE_2D_ARRAY_EXT x y - z w + + Table X: Texture types accessed for each of the <texTarget>, and + coordinate mappings. The "coordinates used" column indicate the + input values used for each coordinate of the texture lookup, the + layer selector for array textures, and the reference value for + texture comparisons." + + -- Section 3.11.6.2 "TXP: Project coordinate and map to color" + + Add to the end of the section: + + "A program will fail to load if the TXP instruction is used in + conjunction with the SHADOWARRAY2D target." + +Additions to Chapter 4 of the OpenGL 2.0 Specification (Per-Fragment Operations) + + -- Section 4.4.2.3 "Attaching Texture Images to a Framebuffer" + + Add to the end of the section (spec changes identical to + EXT_texture_array): + + "The command + + void FramebufferTextureLayerEXT(enum target, enum attachment, + uint texture, int level, int layer); + + operates identically to FramebufferTexture3DEXT, except that it + attaches a single layer of a three-dimensional texture or a one- or + two-dimensional array texture. <layer> is an integer indicating the + layer number, and is treated identically to the <zoffset> parameter in + FramebufferTexture3DEXT. The error INVALID_VALUE is generated if + <layer> is negative. The error INVALID_OPERATION is generated if + <texture> is non-zero and is not the name of a three dimensional + texture or one- or two-dimensional array texture. Unlike + FramebufferTexture3D, no <textarget> parameter is accepted. + + If <texture> is non-zero and the command does not result in an error, + the framebuffer attachment state corresponding to <attachment> is + updated as in the other FramebufferTexture commands, except that + FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT is set to <layer>." + + -- Section 4.4.4.1 "Framebuffer Attachment Completeness" + + Add to the end of the list of completeness rules (spec changes + identical to EXT_texture_array): + + "* If FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE_EXT is TEXTURE and + FRAMEBUFFER_ATTACHMENT_OBJECT_NAME_EXT names a one- or + two-dimensional array texture, then + FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT must be smaller than the + number of layers in the texture." + +Additions to Chapter 5 of the OpenGL 2.0 Specification (Special Functions) + + -- Section 5.4 "Display Lists" + + Change the first paragraphi on page 242 to say (spec changes + identical to EXT_texture_array): + + "TexImage3D, TexImage2D, TexImage1D, Histogram, and ColorTable are + executed immediately when called with the corresponding proxy arguments + PROXY_TEXTURE_3D or PROXY_TEXTURE_2D_ARRAY_EXT; PROXY_TEXTURE_2D, + PROXY_TEXTURE_CUBE_MAP, or PROXY_TEXTURE_1D_ARRAY_EXT; + PROXY_TEXTURE_1D; PROXY_HISTOGRAM; and PROXY_COLOR_TABLE, + PROXY_POST_CONVOLUTION_COLOR_TABLE, or + PROXY_POST_COLOR_MATRIX_COLOR_TABLE." + +Additions to Chapter 6 of the OpenGL 2.0 Specification (State and State Requests) + + -- Section 6.1.3 "Enumerated Queries" + + Add after the line beginning "If the value of + FRAMEBUFFER_ATTACHMENT_OBJECT_TYPE_EXT is TEXTURE" (spec changes + identical to EXT_texture_array): + + "If <pname> is FRAMEBUFFER_ATTACHMENT_TEXTURE_LAYER_EXT and the + texture object named FRAMEBUFFER_ATTACHMENT_OBJECT_NAME_EXT is a + three-dimensional texture or a one- or two-dimensional array texture, + then <params> will contain the number of texture layer attached to the + attachment point. Otherwise, <params> will contain the value zero." + + -- Section 6.1.4 "Texture Queries" + + Change the first three paragraphs (page 248) to say (spec changes + identical to EXT_texture_array): + + "The command + + void GetTexImage(enum tex, int lod, enum format, + enum type, void *img); + + is used to obtain texture images. It is somewhat different from the + other get commands; tex is a symbolic value indicating which texture + (or texture face in the case of a cube map texture target name) is to + be obtained. TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_1D_ARRAY_EXT, + and TEXTURE_2D_ARRAY_EXT indicate a one-, two-, or three-dimensional + texture, or one- or two-dimensional array texture, respectively. + TEXTURE_CUBE_MAP_POSITIVE_X, ... + + GetTexImage obtains... from the first image to the last for + three-dimensional textures. One- and two-dimensional array textures + are treated as two- and three-dimensional images, respectively, where + the layers are treated as rows or images. These groups are then... + + For three-dimensional and two-dimensional array textures, pixel storage + operations are applied as if the image were two-dimensional, except + that the additional pixel storage state values PACK_IMAGE_HEIGHT and + PACK_SKIP_IMAGES are applied. ..." + +Additions to Appendix A of the OpenGL 2.0 Specification (Invariance) + + None + +Additions to the AGL/GLX/WGL Specifications + + None + +GLX Protocol + + None + +Dependencies on ARB_fragment_program + + If ARB_fragment_program is not supported, the changes to section 3.11 + should be ignored. + +Dependencies on EXT_framebuffer_object + + If EXT_framebuffer_object is not supported, the changes to section + 3.8.8 ("Manual Mipmap Generation"), 4.4.2.3, and 6.1.3 should be ignored. + +Dependencies on EXT_texture_compression_s3tc and NV_texture_compression_vtc + + (Identical dependency as EXT_texture_array.) + + S3TC texture compression is supported for two-dimensional array textures. + When <target> is TEXTURE_2D_ARRAY_EXT, each layer is stored independently + as a compressed two-dimensional textures. When specifying or querying + compressed images using one of the S3TC formats, the images are provided + and/or returned as a series of two-dimensional textures stored + consecutively in memory, with the layer closest to zero specified first. + For array textures, images are not arranged in 4x4x4 or 4x4x2 blocks as in + the three-dimensional compression format provided in the + EXT_texture_compression_vtc extension. Pixel store parameters, including + those specific to three-dimensional images, are ignored when compressed + image data are provided or returned, as in the + EXT_texture_compression_s3tc extension. + + S3TC compression is not supported for one-dimensional texture targets in + EXT_texture_compression_s3tc, and is not supported for one-dimensional + array textures in this extension. If compressed one-dimensional arrays + are needed, use a two-dimensional texture with a height of one. + + This extension allows the use of the four S3TC internal format types in + TexImage3D, CompressedTexImage3D, and CompressedTexSubImage3D calls. + +Errors + + None + +New State + + (add to table 6.15, p. 276) + + Initial + Get Value Type Get Command Value Description Sec. Attribute + ---------------------------- ----- ----------- ----- -------------------- ------ --------- + TEXTURE_BINDING_1D_ARRAY_EXT 2*xZ+ GetIntegerv 0 texture object bound 3.8.12 texture + to TEXTURE_1D_ARRAY + TEXTURE_BINDING_2D_ARRAY_EXT 2*xZ+ GetIntegerv 0 texture object bound 3.8.12 texture + to TEXTURE_2D_ARRAY + + +New Implementation Dependent State + + (add to Table 6.32, p. 293) + + Minimum + Get Value Type Get Command Value Description Sec. Attribute + ---------------------------- ---- ----------- ------- ------------------ ----- --------- + MAX_TEXTURE_ARRAY_LAYERS_EXT Z+ GetIntegerv 64 maximum number of 3.8.1 - + layers for texture + arrays + +Issues + + (1) Is "texture stack" a good name for this functionality? + + NO. The name is changed to "array texture" to match the + nomenclature used by GL_EXT_texture_array. + + (2) Should the R texture coordinate be treated as normalized or + un-normalized? If it were un-normalized, floor(R) could be thought + of as a direct index into the array texture. This may be more + convenient for applications. + + RESOLVED. All texture coordinates are normalized. The issue of + un-normalized texture coordinates has been discussed in the ARB + before and should be left for a layered extension. + + RE-RESOLVED. The R coordinate is un-normalized. Accessing an array + using [0, layers-1] coordinates is much more natural. + + (3) How does LOD selection work for stacked textures? + + RESOLVED. For 2D array textures the R coordinate is ignored, and + the LOD selection equations for 2D textures are used. For 1D + array textures the T coordinate is ignored, and the LOD selection + equations for 1D textures are used. The expected usage is in a + fragment program with an explicit LOD selection. + + (4) What is the maximum size of a 2D array texture? Is it the same + as for a 3D texture, or should a new query be added? How about for 1D + array textures? + + RESOLVED. A new query is added. + + (5) How are array textures exposed in GLSL? + + RESOLVED. Use GL_EXT_texture_array. + + (6) Should a 1D array texture also be exposed? + + RESOLVED. For orthogonality, yes. + + (7) How are stacked textures attached to framebuffer objects? + + RESOLVED. Layers of both one- and two-dimensional array textures + are attached using FreambufferTextureLayerEXT. Once attached, the + array texture layer behaves exactly as either a one- or + two-dimensional texture. + + (8) How is this extension related to GL_EXT_texture_array? + + This extension adapats GL_MESAX_texture_stack to the notation, + indexing, and FBO access of GL_EXT_texture_array. This extension + replaces the GLSL support of GL_EXT_texture_array with + GL_ARB_fragment_program support. + + Assembly program support is also provided by GL_NV_gpu_program4. + GL_NV_gpu_program4 also adds support for other features that are + specific to Nvidia hardware, while this extension adds only support + for array textures. + + Much of text of this extension that has changed since + GL_MESAX_texture_stack comes directly from either + GL_EXT_texture_array or GL_NV_gpu_program4. + +Revision History + + ||2005/11/15||0.1||idr||Initial draft MESAX version.|| + ||2005/12/07||0.2||idr||Added framebuffer object interactions.|| + ||2005/12/12||0.3||idr||Updated fragment program interactions.|| + ||2007/05/16||0.4||idr||Converted to MESA_texture_array. Brought in line with EXT_texture_array and NV_gpu_program4.|| |