| Name |
| |
| ARB_texture_stencil8 |
| |
| Name Strings |
| |
| GL_ARB_texture_stencil8 |
| |
| Contact |
| |
| Jeff Bolz, NVIDIA Corporation (jbolz 'at' nvidia.com) |
| |
| Contributors |
| |
| Piers Daniell, NVIDIA |
| Daniel Koch, NVIDIA |
| Jon Leech |
| |
| Notice |
| |
| Copyright (c) 2013 The Khronos Group Inc. Copyright terms at |
| http://www.khronos.org/registry/speccopyright.html |
| |
| Specification Update Policy |
| |
| Khronos-approved extension specifications are updated in response to |
| issues and bugs prioritized by the Khronos OpenGL Working Group. For |
| extensions which have been promoted to a core Specification, fixes will |
| first appear in the latest version of that core Specification, and will |
| eventually be backported to the extension document. This policy is |
| described in more detail at |
| https://www.khronos.org/registry/OpenGL/docs/update_policy.php |
| |
| Status |
| |
| Complete. Approved by the ARB on June 3, 2013. |
| Ratified by the Khronos Board of Promoters on July 19, 2013. |
| |
| Version |
| |
| Last Modified Date: August 26, 2013 |
| Revision: 5 |
| |
| Number |
| |
| ARB Extension #150 |
| |
| Dependencies |
| |
| This extension is written against the OpenGL 4.3 specification |
| (Compatibility Profile). |
| |
| Overview |
| |
| This extension accepts STENCIL_INDEX8 as a texture internal format, and |
| adds STENCIL_INDEX8 to the required internal format list. This removes the |
| need to use renderbuffers if a stencil-only format is desired. |
| |
| New Procedures and Functions |
| |
| None. |
| |
| New Tokens |
| |
| Accepted by the <format> parameter of TexImage3D, TexImage2D, TexImage1D, |
| TexSubImage3D, TexSubImage2D, TexSubImage1D, or GetTexImage: |
| |
| STENCIL_INDEX 0x1901 /* existing enum */ |
| |
| Accepted by the <internalformat> parameter of TexImage3D, TexImage2D, |
| TexImage1D, CopyTexImage2D, CopyTexImage1D, TexStorage3D, TexStorage2D, |
| TexStorage1D, TexImage3DMultisample, TexImage2DMultisample, |
| TexStorage3DMultisample, TexStorage2DMultisample: |
| |
| STENCIL_INDEX8 0x8D48 /* existing enum */ |
| |
| Additions to Chapter 8 of the OpenGL 4.3 (Compatibility Profile) Specification |
| (Textures and Samplers) |
| |
| Modify Section 8.5 Texture Image Specification, p. 205 |
| |
| In the first paragraph, replace "The <format> STENCIL_INDEX is not allowed" |
| with "An INVALID_OPERATION error is generated if the <format> is |
| STENCIL_INDEX and the base internal format is not STENCIL_INDEX." |
| |
| |
| Modify the last paragraph of p. 207 to include STENCIL_INDEX: |
| |
| "Textures with a base internal format of DEPTH_COMPONENT, DEPTH_STENCIL, |
| or STENCIL_INDEX are supported by texture image specification commands |
| only if <target> is TEXTURE_1D, TEXTURE_2D, TEXTURE_1D_ARRAY, |
| TEXTURE_2D_ARRAY, TEXTURE_RECTANGLE, TEXTURE_CUBE_MAP, |
| TEXTURE_CUBE_MAP_ARRAY, TEXTURE_2D_MULTISAMPLE, |
| TEXTURE_2D_MULTISAMPLE_ARRAY, PROXY_TEXTURE_1D, PROXY_TEXTURE_2D, |
| PROXY_TEXTURE_1D_ARRAY, PROXY_TEXTURE_2D_ARRAY, PROXY_TEXTURE_RECTANGLE, |
| PROXY_TEXTURE_CUBE_MAP, PROXY_TEXTURE_CUBE_MAP_ARRAY, |
| PROXY_TEXTURE_2D_MULTISAMPLE or PROXY_TEXTURE_2D_MULTISAMPLE_ARRAY." |
| |
| Add a row to Table 8.18: Conversion from RGBA, depth, and stencil pixel |
| components to internal texture, table, or filter components |
| |
| Base Internal Format RGBA, Depth, and Stencil Values Internal Components |
| |
| STENCIL_INDEX Stencil S |
| |
| |
| Add to the list of required texture internal formats: |
| |
| - Stencil formats: STENCIL_INDEX8 |
| |
| |
| Add rows to Table 8.21: Correspondence of sized internal depth and stencil |
| formats to base internal formats, internal data type, and desired component |
| resolutions for each sized internal format |
| |
| Sized Internal Format Base Internal Format D bits S bits |
| |
| STENCIL_INDEX8 STENCIL_INDEX <blank> 8 |
| |
| Modify Section 8.6 Alternate Texture Image Specification Commands, p. 222 |
| |
| ...The image is taken from the framebuffer exactly as if these arguments |
| were passed to CopyPixels (see section 18.3) with argument type set to |
| COLOR, DEPTH, DEPTH_STENCIL, or STENCIL_INDEX, depending on internalformat, |
| stopping after pixel transfer processing is complete. |
| |
| Modify Section 8.11 Texture Queries, p. 246 |
| |
| If format is DEPTH_COMPONENT, DEPTH_STENCIL, or STENCIL_INDEX then each |
| depth component and/or stencil index is assigned with the same ordering of |
| rows and images. |
| |
| Modifications to the errors section for GetTexImage, p. 247, |
| |
| Delete the following error: |
| |
| An INVALID_ENUM error is generated if <format> is STENCIL_INDEX. |
| |
| Add a bullet to the list of reasons for INVALID_OPERATION error: |
| |
| - <format> is STENCIL_INDEX and the base internal format is not |
| STENCIL_INDEX or DEPTH_STENCIL. |
| |
| Modify 8.17 Texture Completeness, p. 263 |
| |
| Modify the bullet point on p. 263 describing required texture filter |
| modes for an integer texture in order to determine texture completeness, |
| to add STENCIL_INDEX textures explicitly: |
| |
| - The internal format of the texture is integer (see tables 8.19-8.20) |
| or STENCIL_INDEX, and either the magnification filter is not NEAREST, |
| or the minification filter is neither NEAREST nor |
| NEAREST_MIPMAP_NEAREST. |
| |
| Modify 8.22.1 Depth Texture Comparison Mode, p. 278 |
| |
| - If the base internal format is STENCIL_INDEX, then r = St |
| |
| Additions to Chapter 11 of the OpenGL 4.3 (Compatibility Profile) Specification |
| (Programmable Vertex Processing) |
| |
| Modify 11.1.3.5 Texture Access p. 390 |
| |
| Texture lookups involving texture objects with an internal format of DEPTH_- |
| STENCIL can read the stencil value as described in section 8.22 by setting |
| the DEPTH_STENCIL_TEXTURE_MODE to STENCIL_COMPONENT. Textures with a |
| STENCIL_INDEX base internal format may also be used to read stencil data. |
| The stencil value is read as an integer and assigned to Rt. An unsigned |
| integer sampler must be used to lookup the stencil component, otherwise |
| the results are undefined. |
| |
| |
| Additions to Chapter 15 of the OpenGL 4.3 (Compatibility Profile) Specification |
| (Programmable Fragment Processing) |
| |
| Modify 15.2.1 Texture Access, p.510 |
| |
| Repace the paragraph "The stencil index texture internal component is |
| ignored if the base internal format is DEPTH_STENCIL" with: |
| |
| Texture lookups involving textures with stencil index data generate a |
| texture base color Cb by using stencil values St directly, if either the |
| texture has a base internal format of STENCIL_INDEX or the texture has a |
| base internal format of DEPTH_STENCIL and a DEPTH_STENCIL_TEXTURE_MODE |
| of STENCIL_COMPONENT. |
| |
| |
| New Implementation Dependent State |
| |
| None. |
| |
| New State |
| |
| None. |
| |
| Additions to the AGL/GLX/WGL Specifications |
| |
| None. |
| |
| GLX Protocol |
| |
| None. |
| |
| Modifications to the OpenGL Shading Language Specification, Version 4.30 |
| |
| None. |
| |
| Errors |
| |
| An INVALID_OPERATION error is generated by GetTexImage if <format> |
| is STENCIL_INDEX and the base internal format is not STENCIL_INDEX or |
| DEPTH_STENCIL. |
| |
| An INVALID_OPERATION error is generated by TexImage3D, TexImage2D, |
| TexImage1D, TexSubImage3D, TexSubImage2D, or TexSubImage1D |
| if <format> is STENCIL_INDEX and the base internal format is not |
| <STENCIL_INDEX>. |
| |
| An INVALID_OPERATION error is generated by TexImage3D, TexImage2D, |
| TexImage1D, TexSubImage3D, TexSubImage2D, or TexSubImage1D if |
| <format> is STENCIL_INDEX and <target> is not one of TEXTURE_1D, |
| TEXTURE_2D, TEXTURE_1D_ARRAY, TEXTURE_2D_ARRAY, TEXTURE_RECTANGLE, |
| TEXTURE_CUBE_MAP, TEXTURE_CUBE_MAP_ARRAY, PROXY_TEXTURE_1D, |
| PROXY_TEXTURE_2D, PROXY_TEXTURE_1D_ARRAY, PROXY_TEXTURE_2D_ARRAY, |
| PROXY_TEXTURE_RECTANGLE, PROXY_TEXTURE_CUBE_MAP, or |
| PROXY_TEXTURE_CUBE_MAP_ARRAY. |
| |
| Issues |
| |
| |
| (1) What is the interaction with ARB_stencil_texturing's |
| DEPTH_STENCIL_TEXTURE_MODE? |
| |
| RESOLVED: That piece of state is ignored because the base internal format |
| of a STENCIL_INDEX texture is not DEPTH_STENCIL. |
| |
| (2) Does the presence of this extension imply that the implementation |
| supports a true 8-bit stencil buffer? |
| |
| RESOLVED: No, some OpenGL implementations may internally expand a |
| format like STENCIL_INDEX8 to DEPTH24_STENCIL8, but will make such a format |
| behave as if there were no depth bits. Additionally, implementations may |
| not support independent depth and stencil attachments; a framebuffer with a |
| STENCIL_INDEX8 stencil attachment and a DEPTH_COMPONENT24 depth attachment |
| may be treated as unsupported (FRAMEBUFFER_UNSUPPORTED). |
| |
| (3) Should we support stencil formats that have a number of bits that is |
| not exactly supported in the implementation? 8-bits is universally |
| supported, but 1/4/16-bits are not. |
| |
| RESOLVED: Only accept STENCIL_INDEX8, which is universally supported. |
| |
| Revision History |
| |
| Rev. Date Author Changes |
| ---- -------- -------- ----------------------------------------------- |
| 1 03/20/13 jbolz Internal revisions. |
| 2 05/30/13 dgkoch Add tokens and errors section. |
| Update errors for GetTexImage. |
| 3 06/28/13 Jon Leech Fix dates in revision history. Change filter |
| modes for texture completeness (Bug 10372). |
| 4 08/08/13 pdaniell Fix the functions that accept STENCIL_INDEX8 as |
| an <internalformat> parameter (Bug 10558). |
| 5 08/26/13 pdaniell Fix the list of texture targets that support |
| stencil (and depth and depth/stencil) textures |
| to include the multisample targets (Bug 10558). |
