| 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: 2012/03/29 17:22:08 $ $Revision: 1.1.1.1 $ |
| |
| 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.|| |
