Name EXT_texture_cube_map Name Strings GL_EXT_texture_cube_map Notice Copyright NVIDIA Corporation, 1999. Version March 29, 2001 Number ARB_ version is "ARB extension #6" Because this extension was promoted from an EXT to ARB extension before an extension number was assigned, this extension has no extension number. Dependencies None. Written based on the wording of the OpenGL 1.2 specification but not dependent on it. Forward Compatibility This extension is superceded by the ARB_texture_cube_map extension that is officially sanctioned by the OpenGL Architectural Review Board. Enumerant values for EXT_texture_cube_map and ARB_texture_cube_map are identical. The two extensions are operationally identical; the only difference is the change of identifier from EXT to ARB. Because the enumerants are identical for the two extensions and because there are no new entry points, an application that detects either the "GL_EXT_texture_cube_map" or "GL_ARB_texture_cube_map" extension name will operate correctly using either extension. NVIDIA's Release 4 drivers and early versions of NVIDIA's Release 5 drivers advertised the EXT_texture_cube_map without also advertising the ARB_texture_cube_map extension because the ARB version of the extension was not then available. To ensure that your applications operate correctly with these older drivers, NVIDIA recommends that you query for either the EXT_texture_cube_map or ARB_texture_cube_map extension to determine when texture cube map functionality is available. Because the enumerants and functionality is unchanged, programs written to use ARB_texture_cube_map need only recognize EXT_texture_cube_map to operate correctly. Overview This extension provides a new texture generation scheme for cube map textures. Instead of the current texture providing a 1D, 2D, or 3D lookup into a 1D, 2D, or 3D texture image, the texture is a set of six 2D images representing the faces of a cube. The (s,t,r) texture coordinates are treated as a direction vector emanating from the center of a cube. At texture generation time, the interpolated per-fragment (s,t,r) selects one cube face 2D image based on the largest magnitude coordinate (the major axis). A new 2D (s,t) is calculated by dividing the two other coordinates (the minor axes values) by the major axis value. Then the new (s,t) is used to lookup into the selected 2D texture image face of the cube map. Unlike a standard 1D, 2D, or 3D texture that have just one target, a cube map texture has six targets, one for each of its six 2D texture image cube faces. All these targets must be consistent, complete, and have a square dimension. This extension also provides two new texture coordinate generation modes for use in conjunction with cube map texturing. The reflection map mode generates texture coordinates (s,t,r) matching the vertex's eye-space reflection vector. The reflection map mode is useful for environment mapping without the singularity inherent in sphere mapping. The normal map mode generates texture coordinates (s,t,r) matching the vertex's transformed eye-space normal. The normal map mode is useful for sophisticated cube map texturing-based diffuse lighting models. The intent of the new texgen functionality is that an application using cube map texturing can use the new texgen modes to automatically generate the reflection or normal vectors used to look up into the cube map texture. An application note: When using cube mapping with dynamic cube maps (meaning the cube map texture is re-rendered every frame), by keeping the cube map's orientation pointing at the eye position, the texgen-computed reflection or normal vector texture coordinates can be always properly oriented for the cube map. However if the cube map is static (meaning that when view changes, the cube map texture is not updated), the texture matrix must be used to rotate the texgen-computed reflection or normal vector texture coordinates to match the orientation of the cube map. The rotation can be computed based on two vectors: 1) the direction vector from the cube map center to the eye position (both in world coordinates), and 2) the cube map orientation in world coordinates. The axis of rotation is the cross product of these two vectors; the angle of rotation is the arcsin of the dot product of these two vectors. Issues Should we place the normal/reflection vector in the (s,t,r) texture coordinates or (s,t,q) coordinates? RESOLUTION: (s,t,r). Even if hardware uses "q" for the third component, the API should claim to support generation of (s,t,r) and let the texture matrix (through a concatenation with the user-supplied texture matrix) move "r" into "q". Should the texture coordinate generation functionality for cube mapping be specified as a distinct extension from the actual cube map texturing functionality? RESOLUTION: NO. Real applications and real implementations of cube mapping will tie the texgen and texture generation functionality together. Applications won't have to query two separate extensions then. While applications will almost always want to use the texgen functionality for automatically generating the reflection or normal vector as texture coordinates (s,t,r), this extension does permit an application to manually supply the reflection or normal vector through glTexCoord3f explicitly. Note that the NV_texgen_reflection extension does "unbundle" the texgen functionality from cube maps. Should you be able to have some texture coordinates computing REFLECTION_MAP_EXT and others not? Same question with NORMAL_MAP_EXT. RESOLUTION: YES. This is the way that SPHERE_MAP works. It is not clear that this would ever be useful though. Should something special be said about the handling of the q texture coordinate for this spec? RESOLUTION: NO. But the following paragraph is useful for implementors concerned about the handling of q. The REFLECTION_MAP_EXT and NORMAL_MAP_EXT modes are intended to supply reflection and normal vectors for cube map texturing hardware. When these modes are used for cube map texturing, the generated texture coordinates can be thought of as an reflection vector. The value of the q texture coordinate then simply scales the vector but does not change its direction. Because only the vector direction (not the vector magnitude) matters for cube map texturing, implementations are free to leave q undefined when any of the s, t, or r texture coordinates are generated using REFLECTION_MAP_EXT or NORMAL_MAP_EXT. How should the cube faces be labeled? RESOLUTION: Match the render man specification's names of "px" (positive X), "nx" (negative x), "py", "ny", "pz", and "nz". There does not actually need to be an "ordering for the faces" (Direct3D 7.0 does number their cube map faces.) For this extension, the symbolic target names (TEXTURE_CUBE_MAP_POSITIVE_X_EXT, etc) is sufficient without requiring any specific ordering. What coordinate system convention should be used? LHS or RHS? RESOLUTION: The coordinate system is left-handed if you think of yourself within the cube. The coordinate system is right-handed if you think of yourself outside the cube. This matches the convention of the RenderMan interface. If you look at Figure 12.8 (page 265) in "The RenderMan Companion", think of the cube being folded up with the observer inside the cube. Then the coordinate system convention is left-handed. The spec just linearly interpolates the reflection vectors computed per-vertex across polygons. Is there a problem interpolating reflection vectors in this way? Probably. The better approach would be to interpolate the eye vector and normal vector over the polygon and perform the reflection vector computation on a per-fragment basis. Not doing so is likely to lead to artifacts because angular changes in the normal vector result in twice as large a change in the reflection vector as normal vector changes. The effect is likely to be reflections that become glancing reflections too fast over the surface of the polygon. Note that this is an issue for REFLECTION_MAP_EXT, but not NORMAL_MAP_EXT. What happens if an (s,t,q) is passed to cube map generation that is close to (0,0,0), ie. a degenerate direction vector? RESOLUTION: Leave undefined what happens in this case (but may not lead to GL interruption or termination). Note that a vector close to (0,0,0) may be generated as a result of the per-fragment interpolation of (s,t,r) between vertices. Do we need a distinct proxy texture mechanism for cube map textures? RESOLUTION: YES. Cube map textures take up six times the memory as a conventional 2D image texture so proxy 2D texture determinations won't be of value for a cube map texture. Cube maps need their own proxy target. Should we require the 2D texture image width and height to be identical (ie, square only)? RESOLUTION: YES. This limitation is quite a reasonable limitation and DirectX 7 has the same limitation. This restriction is enforced by generating an INVALID_VALUE when calling TexImage2D or CopyTexImage2D with a non-equal width and height. Some consideration was given to enforcing the "squarness" constraint as a texture consistency constraint. This is confusing however since the squareness is known up-front at texture image specification time so it seems confusing to silently report the usage error as a texture consistency issue. Texture consistency still says that all the level 0 textures of all six faces must have the same square size. If some combination of 1D, 2D, 3D, and cube map texturing is enabled, which really operates? RESOLUTION: Cube map texturing. In OpenGL 1.2, 3D takes priority over 2D takes priority over 1D. Cube mapping should take priority over all conventional n-dimensional texturing schemes. Does anything need to be said about combining cube mapping with multitexture? RESOLUTION: NO. Cube mapping should be available on either texture unit. The hardware should fully orthogonal in its handling of cube map textures. Does it make sense to support borders for cube map textures. Actually, it does. It would be nice if the texture border pixels match the appropriate texels from the edges of the other cube map faces that they junction with. For this reason, we'll leave the texture border capability implicitly supported. How does mipmap level-of-detail selection work for cube map textures? The existing spec's language about LOD selection is fine. Should the implementation dependent value for the maximum texture size for a cube map be the same as MAX_TEXTURE_SIZE? RESOLUTION: NO. OpenGL 1.2 has a different MAX_3D_TEXTURE_SIZE for 3D textures, and cube maps should take six times more space than a 2D texture map of the same width & height. The implementation dependent MAX_CUBE_MAP_TEXTURE_SIZE_EXT constant should be used for cube maps then. Note that the proxy cube map texture provides a better way to find out the maximum cube map texture size supported since the proxy mechanism can take into account the internal format, etc. In section 3.8.10 when the "largest magnitude coordinate direction" is choosen, what happens if two or more of the coordinates (rx,ry,rz) have the identical magnitude? RESOLUTION: Implementations can define their own rule to choose the largest magnitude coordinate direction whne two or more of the coordinates have the identical magnitude. The only restriction is that the rule must be deterministic and depend only on (rx,ry,rz). In practice, (s,t,r) is interpolated across polygons so the cases where |s|==|t|, etc. are pretty arbitary (the equality depends on interpolation precision). This extension could mandate a particular rule, but that seems heavy-handed and there is no good reason that multiple vendors should be forced to implement the same rule. Should there be limits on the supported border modes for cube maps? RESOLUTION: NO. The specificiation is written so that cube map texturing proceeds just like conventional 2D texture mapping once the face determination is made. Therefore, all OpenGL texture wrap modes should be supported though some modes are clearly inappropriate for cube maps. The WRAP mode is almost certainly incorrect for cube maps. Likewise, the CLAMP mode without a texture border is almost certainly incorrect for cube maps. CLAMP when a texture border is present and CLAMP_TO_EDGE are both reasonably suited for cube maps. Ideally, CLAMP with a texture border works best if the cube map edges can be replicated in the approriate texture borders of adjacent cube map faces. In practice, CLAMP_TO_EDGE works reasonably well in most circumstances. Perhaps another extension could support a special cube map wrap mode that automatically wraps individual texel fetches to the appropriate adjacent cube map face. The benefit from such a mode is small and the implementation complexity is involved so this wrap mode should not be required for a basic cube map texture extension. How is mipmap LOD selection handled for cube map textures? RESOLUTION: The specification is written so that cube map texturing proceeds just like conventional 2D texture mapping once the face determination is made. Thereforce, the partial differentials in Section 3.8.5 (page 126) should be evaluated for the u and v parameters based on the post-face determination s and t. In Section 2.10.3 "Normal Transformation", there are several versions of the eye-space normal vector to choose from. Which one should the NORMAL_MAP_ARB texgen mode use? RESOLUTION: nf. The nf vector is the final normal, post-rescale normal and post-normalize. In practice, the rescale normal and normalize operations do not change the direction of the vector so the choice of which version of transformed normal is used is not important for cube maps. New Procedures and Functions None New Tokens Accepted by the parameters of TexGend, TexGenf, and TexGeni when parameter is TEXTURE_GEN_MODE: NORMAL_MAP_EXT 0x8511 REFLECTION_MAP_EXT 0x8512 When the parameter of TexGendv, TexGenfv, and TexGeniv is TEXTURE_GEN_MODE, then the array may also contain NORMAL_MAP_EXT or REFLECTION_MAP_EXT. Accepted by the parameter of Enable, Disable, IsEnabled, and by the parameter of GetBooleanv, GetIntegerv, GetFloatv, and GetDoublev, and by the parameter of BindTexture, GetTexParameterfv, GetTexParameteriv, TexParameterf, TexParameteri, TexParameterfv, and TexParameteriv: TEXTURE_CUBE_MAP_EXT 0x8513 Accepted by the parameter of GetBooleanv, GetIntegerv, GetFloatv, and GetDoublev: TEXTURE_BINDING_CUBE_MAP_EXT 0x8514 Accepted by the parameter of GetTexImage, GetTexLevelParameteriv, GetTexLevelParameterfv, TexImage2D, CopyTexImage2D, TexSubImage2D, and CopySubTexImage2D: TEXTURE_CUBE_MAP_POSITIVE_X_EXT 0x8515 TEXTURE_CUBE_MAP_NEGATIVE_X_EXT 0x8516 TEXTURE_CUBE_MAP_POSITIVE_Y_EXT 0x8517 TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT 0x8518 TEXTURE_CUBE_MAP_POSITIVE_Z_EXT 0x8519 TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT 0x851a Accepted by the parameter of GetTexLevelParameteriv, GetTexLevelParameterfv, GetTexParameteriv, and TexImage2D: PROXY_TEXTURE_CUBE_MAP_EXT 0x851b Accepted by the parameter of GetBooleanv, GetDoublev, GetIntegerv, and GetFloatv: MAX_CUBE_MAP_TEXTURE_SIZE_EXT 0x851c Additions to Chapter 2 of the 1.2 Specification (OpenGL Operation) -- Section 2.10.4 "Generating Texture Coordinates" Change the last sentence in the 1st paragraph to: "If is TEXTURE_GEN_MODE, then either points to or is an integer that is one of the symbolic constants OBJECT_LINEAR, EYE_LINEAR, SPHERE_MAP, REFLECTION_MAP_EXT, or NORMAL_MAP_EXT." Add these paragraphs after the 4th paragraph: "If TEXTURE_GEN_MODE indicates REFLECTION_MAP_EXT, compute the reflection vector r as described for the SPHERE_MAP mode. Then the value assigned to an s coordinate (the first TexGen argument value is S) is s = rx; the value assigned to a t coordinate is t = ry; and the value assigned to a r coordinate is r = rz. Calling TexGen with a of Q when indicates REFLECTION_MAP_EXT generates the error INVALID_ENUM. If TEXTURE_GEN_MODE indicates NORMAL_MAP_EXT, compute the normal vector nf as described in section 2.10.3. Then the value assigned to an s coordinate (the first TexGen argument value is S) is s = nfx; the value assigned to a t coordinate is t = nfy; and the value assigned to a r coordinate is r = nfz. (The values nfx, nfy, and nfz are the components of nf.) Calling TexGen with a of Q when indicates NORMAL_MAP_EXT generates the error INVALID_ENUM. The last paragraph's first sentence should be changed to: "The state required for texture coordinate generation comprises a five-valued integer for each coordinate indicating coordinate generation mode, ..." Additions to Chapter 3 of the 1.2 Specification (Rasterization) -- Section 3.6.5 "Pixel Transfer Operations" under "Convolution" Change this paragraph to say: ... "If CONVOLUTION_2D is enabled, the two-dimensional convolution filter is applied only to the two-dimensional images passed to DrawPixels, CopyPixels, ReadPixels, TexImage2D, TexSubImage2D, CopyTexImage2D, CopyTexSubImage2D, and CopyTexSubImage3D, and returned by GetTexImage with one of the targets TEXTURE_2D, TEXTURE_CUBE_MAP_POSITIVE_X_EXT, TEXTURE_CUBE_MAP_NEGATIVE_X_EXT, TEXTURE_CUBE_MAP_POSITIVE_Y_EXT, TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT, TEXTURE_CUBE_MAP_POSITIVE_Z_EXT, or TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT." -- Section 3.8.1 "Texture Image Specification" Change the first full sentence on page 117 to: " must be one of TEXTURE_2D for a 2D texture, or one of TEXTURE_CUBE_MAP_POSITIVE_X_EXT, TEXTURE_CUBE_MAP_NEGATIVE_X_EXT, TEXTURE_CUBE_MAP_POSITIVE_Y_EXT, TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT, TEXTURE_CUBE_MAP_POSITIVE_Z_EXT, or TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT for a cube map texture. Additionally, can be either PROXY_TEXTURE_2D for a 2D proxy texture or PROXY_TEXTURE_CUBE_MAP_EXT for a cube map proxy texture as discussed in section 3.8.7." Add the following paragraphs after the first paragraph on page 117: "A 2D texture consists of a single 2D texture image. A cube map texture is a set of six 2D texture images. The six cube map texture targets form a single cube map texture though each target names a distinct face of the cube map. The TEXTURE_CUBE_MAP_*_EXT targets listed above update their appropriate cube map face 2D texture image. Note that the six cube map 2D image tokens such as TEXTURE_CUBE_MAP_POSITIVE_X_EXT are used when specifying, updating, or querying, one of a cube map's six 2D image, but when enabling cube map texturing or binding to a cube map texture object (that is when the cube map is accessed as a whole as opposed to a particular 2D image), the TEXTURE_CUBE_MAP_EXT target is specified. When the target parameter to TexImage2D is one of the six cube map 2D image targets, the error INVALID_VALUE is generated if the width and height parameters are not equal. If cube map texturing is enabled at the time a primitive is rasterized and if the set of six targets are not "cube complete", then it is as if texture mapping were disabled. The targets of a cube map texture are "cube complete" if the array 0 of all six targets have identical and square dimensions, the array 0 of all six targets were specified with the same internalformat, and the array 0 of all six targets have the same border width." After the 14th paragraph add: "In a similiar fashion, the maximum allowable width and height (they must be the same) of a cube map texture must be at least 2^(k-lod)+2bt for image arrays level 0 through k, where k is the log base 2 of MAX_CUBE_MAP_TEXTURE_SIZE_EXT." -- Section 3.8.2 "Alternate Texture Image Specification Commands" Update the second paragraph (page 120) to say: ... "Currently, must be TEXTURE_2D, TEXTURE_CUBE_MAP_POSITIVE_X_EXT, TEXTURE_CUBE_MAP_NEGATIVE_X_EXT, TEXTURE_CUBE_MAP_POSITIVE_Y_EXT, TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT, TEXTURE_CUBE_MAP_POSITIVE_Z_EXT, or TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT." ... Add after the second paragraph (page 120), the following: "When the target parameter to CopyTexImage2D is one of the six cube map 2D image targets, the error INVALID_VALUE is generated if the width and height parameters are not equal." Update the fourth paragraph (page 121) to say: ... "Currently the target arguments of TexSubImage1D and CopyTexSubImage1D must be TEXTURE_1D, the arguments of TexSubImage2D and CopyTexSubImage2D must be one of TEXTURE_2D, TEXTURE_CUBE_MAP_POSITIVE_X_EXT, TEXTURE_CUBE_MAP_NEGATIVE_X_EXT, TEXTURE_CUBE_MAP_POSITIVE_Y_EXT, TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT, TEXTURE_CUBE_MAP_POSITIVE_Z_EXT, or TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT, and the arguments of TexSubImage3D and CopyTexSubImage3D must be TEXTURE_3D." ... -- Section 3.8.3 "Texture Parameters" Change paragraph one (page 124) to say: ... " is the target, either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, or TEXTURE_CUBE_MAP_EXT." ... Add a final paragraph saying: "Texture parameters for a cube map texture apply to cube map as a whole; the six distinct 2D texture images use the texture parameters of the cube map itself. -- Section 3.8.5 "Texture Minification" under "Mipmapping" Change the first full paragraph on page 130 to: ... "If texturing is enabled for one-, two-, or three-dimensional texturing but not cube map texturing (and TEXTURE_MIN_FILTER is one that requires a mipmap) at the time a primitive is rasterized and if the set of arrays TEXTURE_BASE_LEVEL through q = min{p,TEXTURE_MAX_LEVEL} is incomplete, based on the dimensions of array 0, then it is as if texture mapping were disabled." Follow the first full paragraph on page 130 with: "If cube map texturing is enabled and TEXTURE_MIN_FILTER is one that requires mipmap levels at the time a primitive is rasterized and if the set of six targets are not "mipmap cube complete", then it is as if texture mapping were disabled. The targets of a cube map texture are "mipmap cube complete" if the six cube map targets are "cube complete" and the set of arrays TEXTURE_BASE_LEVEL through q are not incomplete (as described above)." -- Section 3.8.7 "Texture State and Proxy State" Change the first sentence of the first paragraph (page 131) to say: "The state necessary for texture can be divided into two categories. First, there are the nine sets of mipmap arrays (three for the one-, two-, and three-dimensional texture targets and six for the cube map texture targets) and their number." ... Change the second paragraph (page 132) to say: "In addition to the one-, two-, three-dimensional, and the six cube map sets of image arrays, the partially instantiated one-, two-, and three-dimensional and one cube map sets of proxy image arrays are maintained." ... After the third paragraph (page 132) add: "The cube map proxy arrays are operated on in the same manner when TexImage2D is executed with the field specified as PROXY_TEXTURE_CUBE_MAP_EXT with the addition that determining that a given cube map texture is supported with PROXY_TEXTURE_CUBE_MAP_EXT indicates that all six of the cube map 2D images are supported. Likewise, if the specified PROXY_TEXTURE_CUBE_MAP_EXT is not supported, none of the six cube map 2D images are supported." Change the second sentence of the fourth paragraph (page 132) to: "Therefore PROXY_TEXTURE_1D, PROXY_TEXTURE_2D, PROXY_TEXTURE_3D, and PROXY_TEXTURE_CUBE_MAP_EXT cannot be used as textures, and their images must never be queried using GetTexImage." ... -- Section 3.8.8 "Texture Objects" Change the first sentence of paragraph one (page 133) to say: "In addition to the default textures TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, and TEXTURE_CUBE_MAP_EXT, named one-, two-, and three-dimensional texture objects and cube map texture objects can be created and operated on." ... Change the second paragraph (page 133) to say: "A texture object is created by binding an unused name to TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, or TEXTURE_CUBE_MAP_EXT." ... "If the new texture object is bound to TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, or TEXTURE_CUBE_MAP_EXT, it remains a one-, two-, three-dimensional, or cube map texture until it is deleted." Change the third paragraph (page 133) to say: "BindTexture may also be used to bind an existing texture object to either TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, or TEXTURE_CUBE_MAP_EXT." Change paragraph five (page 133) to say: "In the initial state, TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, and TEXTURE_CUBE_MAP have one-dimensional, two-dimensional, three-dimensional, and cube map state vectors associated with them respectively." ... "The initial, one-dimensional, two-dimensional, three-dimensional, and cube map texture is therefore operated upon, queried, and applied as TEXTURE_1D, TEXTUER_2D, TEXTURE_3D, and TEXTURE_CUBE_MAP_EXT respectively while 0 is bound to the corresponding targets." Change paragraph six (page 134) to say: ... "If a texture that is currently bound to one of the targets TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, or TEXTURE_CUBE_MAP_EXT is deleted, it is as though BindTexture has been executed with the same and zero." ... -- Section 3.8.10 "Texture Application" Replace the beginning sentences of the first paragraph (page 136) with: "Texturing is enabled or disabled using the generic Enable and Disable commands, respectively, with the symbolic constants TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, or TEXTURE_CUBE_MAP_EXT to enable the one-dimensional, two-dimensional, three-dimensional, or cube map texturing 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 texturing is disabled, a rasterized fragment is passed on unaltered to the next stage of the GL (although its texture coordinates may be discarded). Otherwise, a texture value is found according to the parameter values of the currently bound texture image of the appropriate dimensionality. However, when cube map texturing is enabled, the rules are more complicated. For cube map texturing, the (s,t,r) texture coordinates are treated as a direction vector (rx,ry,rz) emanating from the center of a cube. (The q coordinate can be ignored since it merely scales the vector without affecting the direction.) At texture application time, the interpolated per-fragment (s,t,r) selects one of the cube map face's 2D image based on the largest magnitude coordinate direction (the major axis direction). If two or more coordinates have the identical magnitude, the implementation may define the rule to disambiguate this situation. The rule must be deterministic and depend only on (rx,ry,rz). The target column in the table below explains how the major axis direction maps to the 2D image of a particular cube map target. major axis direction target sc tc ma ---------- ------------------------------- --- --- --- +rx TEXTURE_CUBE_MAP_POSITIVE_X_EXT -rz -ry rx -rx TEXTURE_CUBE_MAP_NEGATIVE_X_EXT +rz -ry rx +ry TEXTURE_CUBE_MAP_POSITIVE_Y_EXT +rx +rz ry -ry TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT +rx -rz ry +rz TEXTURE_CUBE_MAP_POSITIVE_Z_EXT +rx -ry rz -rz TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT -rx -ry rz Using the sc, tc, and ma determined by the major axis direction as specified in the table above, an updated (s,t) is calculated as follows s = ( sc/|ma| + 1 ) / 2 t = ( tc/|ma| + 1 ) / 2 If |ma| is zero or very nearly zero, the results of the above two equations need not be defined (though the result may not lead to GL interruption or termination). This new (s,t) is used to find a texture value in the determined face's 2D texture image using the rules given in sections 3.8.5 and 3.8.6." ... Additions to Chapter 4 of the 1.2 Specification (Per-Fragment Operations and the Frame Buffer) None Additions to Chapter 5 of the 1.2 Specification (Special Functions) -- Section 5.4 "Display Lists" In the second to the last paragraph (page 179), add PROXY_TEXTURE_CUBE_MAP_EXT to the list of PROXY_* tokens. Additions to Chapter 6 of the 1.2 Specification (State and State Requests) -- Section 6.1.3 "Enumerated Queries" Change the fourth paragraph (page 183) to say: "The GetTexParameter parameter may be one of TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, or TEXTURE_CUBE_MAP_EXT, indicating the currently bound one-dimensional, two-dimensional, three-dimensional, or cube map texture object. For GetTexLevelParameter, may be one of TEXTURE_1D, TEXTURE_2D, TEXTURE_3D, TEXTURE_CUBE_MAP_POSITIVE_X_EXT, TEXTURE_CUBE_MAP_NEGATIVE_X_EXT, TEXTURE_CUBE_MAP_POSITIVE_Y_EXT, TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT, TEXTURE_CUBE_MAP_POSITIVE_Z_EXT, TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT, PROXY_TEXTURE_1D, PROXY_TEXTURE_2D, PROXY_TEXTURE_3D, or PROXY_TEXTURE_CUBE_MAP_EXT, indicating the one-dimensional, two-dimensional, three-dimensional texture object, or distinct cube map texture 2D image, or one-dimensional, two-dimensional, three-dimensional, or cube map proxy state vector. Note that TEXTURE_CUBE_MAP_EXT is not a valid parameter for GetTexLevelParameter because it does not specify a particular cube map face." -- Section 6.1.4 "Texture Queries" Change the first paragraph to read: ... "It is somewhat different from the other get commands; 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 indicates a one-dimensional texture, TEXTURE_2D indicates a two-dimensional texture, TEXTURE_3D indicates a three-dimensional texture, and TEXTURE_CUBE_MAP_POSITIVE_X_EXT, TEXTURE_CUBE_MAP_NEGATIVE_X_EXT, TEXTURE_CUBE_MAP_POSITIVE_Y_EXT, TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT, TEXTURE_CUBE_MAP_POSITIVE_Z_EXT, and TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT indicate the respective face of a cube map texture. Additions to the GLX Specification None Errors INVALID_ENUM is generated when TexGen is called with a of Q when indicates REFLECTION_MAP_EXT or NORMAL_MAP_EXT. INVALID_VALUE is generated when the target parameter to TexImage2D or CopyTexImage2D is one of the six cube map 2D image targets and the width and height parameters are not equal. New State (table 6.12, p202) add the following entries: Get Value Type Get Command Initial Value Description Sec Attribute --------- ---- ----------- ------------- ----------- ------ -------------- TEXTURE_CUBE_MAP_EXT B IsEnabled False True if cube map 3.8.10 texture/enable texturing is enabled TEXTURE_BINDING_CUBE_MAP_EXT Z+ GetIntegerv 0 Texture object 3.8.8 texture for TEXTURE_CUBE_MAP TEXTURE_CUBE_MAP_POSITIVE_X_EXT nxI GetTexImage see 3.8 positive x face 3.8 - cube map texture image at lod i TEXTURE_CUBE_MAP_NEGATIVE_X_EXT nxI GetTexImage see 3.8 negative x face 3.8 - cube map texture image at lod i TEXTURE_CUBE_MAP_POSITIVE_Y_EXT nxI GetTexImage see 3.8 positive y face 3.8 - cube map texture image at lod i TEXTURE_CUBE_MAP_NEGATIVE_Y_EXT nxI GetTexImage see 3.8 negative y face 3.8 - cube map texture image at lod i TEXTURE_CUBE_MAP_POSITIVE_Z_EXT nxI GetTexImage see 3.8 positive z face 3.8 - cube map texture image at lod i TEXTURE_CUBE_MAP_NEGATIVE_Z_EXT nxI GetTexImage see 3.8 negative z face 3.8 - cube map texture image at lod i (table 6.14, p204) change the entry for TEXTURE_GEN_MODE to: Get Value Type Get Command Initial Value Description Sec Attribute --------- ---- ----------- ------------- ----------- ------ --------- TEXTURE_GEN_MODE 4xZ5 GetTexGeniv EYE_LINEAR Function used for 2.10.4 texture texgen (for s,t,r, and q) (the type changes from 4xZ3 to 4xZ5) New Implementation Dependent State (table 6.24, p214) add the following entry: Get Value Type Get Command Minimum Value Description Sec Attribute --------- ---- ----------- ------------- ----------- ------ -------------- MAX_CUBE_MAP_TEXTURE_SIZE_EXT Z+ GetIntegerv 16 Maximum cube map 3.8.1 - texture image dimension