| Name |
| |
| ANGLE_get_image |
| |
| Name Strings |
| |
| GL_ANGLE_get_image |
| |
| Contributors |
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| Jamie Madill |
| |
| Contact |
| |
| Jamie Madill (jmadill 'at' google.com) |
| |
| Notice |
| |
| Copyright (c) 2019 The Khronos Group Inc. Copyright terms at |
| http://www.khronos.org/registry/speccopyright.html |
| |
| Status |
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| Draft |
| |
| Version |
| |
| Version 2, Sept 15, 2021 |
| |
| Number |
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| OpenGL ES Extension #?? |
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| Dependencies |
| |
| Requires OpenGL ES 2.0 |
| |
| Written against the OpenGL ES 3.2 specification. |
| |
| Overview |
| |
| This extension allows the OpenGL application to query and read back Texture |
| and Renderbuffer pixel data. The OpenGL context exposes new queries for the |
| implementation pixel format and type similar to glReadPixels. The context |
| also exposes new commands to read back pixel data with these parameters. |
| |
| New Procedures and Functions |
| |
| void GetTexImageANGLE(GLenum target, GLint level, GLenum format, GLenum type, |
| void *pixels); |
| |
| void GetCompressedTexImageANGLE(enum target, int level, void *pixels); |
| |
| void GetRenderbufferImageANGLE(GLenum target, GLint level, GLenum format, |
| GLenum type, void *pixels); |
| |
| New Tokens |
| |
| None |
| |
| Additions to the OpenGL ES Specification |
| |
| Update section 8.11.2 "Texture Parameter Queries": |
| |
| Change "<pname> must be one of IMAGE_FORMAT_COMPATIBILITY_TYPE, TEXTURE_- |
| IMMUTABLE_FORMAT, TEXTURE_IMMUTABLE_LEVELS, or one of the symbolic |
| values in table 8.19." to "<pname> must be one of IMAGE_FORMAT_COMPATIBILITY_- |
| TYPE, TEXTURE_IMMUTABLE_FORMAT, TEXTURE_IMMUTABLE_LEVELS, IMPLEMENTATION_- |
| COLOR_READ_TYPE, IMPLEMENTATION_COLOR_READ_FORMAT or one of the symbolic |
| values in table 8.19.". |
| |
| Add a paragrah: "Querying <pname> with IMPLEMENTATION_COLOR_READ_TYPE or |
| IMPLEMENTATION_COLOR_READ_FORMAT returns the implementation-dependent read |
| format and type for use with GetTexImageANGLE." |
| |
| Update section 9.2.6 "Renderbuffer Object Queries": |
| |
| Add a paragraph: "If <pname> is IMPLEMENTATION_COLOR_READ_TYPE or |
| IMPLEMENTATION_COLOR_READ_FORMAT then <params> will contain the |
| implementation-dependent read format and type for use with |
| GetRenderbufferImageANGLE." |
| |
| Add a section "Texture and Renderbuffer Image Queries": |
| |
| Texture and Renderbuffer images may be obtained from a Texture or |
| Renderbuffer with the commands |
| |
| void GetTexImageANGLE(GLenum target, GLint level, GLenum format, GLenum type, |
| void *pixels); |
| |
| void GetCompressedTexImageANGLE(GLenum target, GLint level, void *pixels); |
| |
| void GetRenderbufferImageANGLE(GLenum target, GLenum format, GLenum type, |
| void *pixels); |
| |
| For GetTexImageANGLE and GetCompressedTexImageANGLE, <target> specifies the |
| target to which the texture object is bound. target must be one of |
| TEXTURE_2D, TEXTURE_3D, TEXTURE_2D_ARRAY, TEXTURE_CUBE_MAP_ARRAY, indicating |
| a two- or three-dimensional, two-dimensional array, cube map array |
| respectively. <target> may also be one of the targets from table 8.20, |
| indicating the corresponding face of a cube map texture. |
| |
| For GetRenderbufferImageANGLE, <target> must be RENDERBUFFER. |
| |
| <level> is a level-of-detail number, <format> is a pixel format from table 8.5, |
| and <type> is a pixel type from table 8.4. |
| |
| GetTexImageANGLE and GetRenderbufferImageANGLE obtain component groups |
| from a texture or renderbuffer image with the indicated level-of-detail. |
| If <format> is a color format then the components are assigned among R, |
| G, B, and A, starting with the first group in the first row, and |
| continuing by obtaining groups in order from each row and proceeding from |
| the first row to the last, and from the first image to the last for |
| three-dimensional textures. Two-dimensional array and cube map array |
| textures are treated as three-dimensional images, where the layers are |
| treated as rows or images. Cube map textures are treated as |
| three-dimensional images with a depth of 6, where the cube map faces are |
| ordered as image layers as shown in table 8.24. |
| |
| 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. |
| |
| These groups are then packed and placed in client or pixel buffer object memory. |
| If a pixel pack buffer is bound (as indicated by a non-zero value of PIXEL_- |
| PACK_BUFFER_BINDING), <pixels> is an offset into the pixel pack buffer; |
| otherwise, <pixels> is a pointer to client memory. Pixel storage modes that are |
| applicable to ReadPixels are applied, as described in table 16.1 and section |
| 16.1.2. |
| |
| When called, GetCompressedTexImageANGLE writes n ubytes of compressed |
| image data to the pixel pack buffer or client memory pointed to by pixels. |
| n is the value of TEXTURE_COMPRESSED_IMAGE_SIZE for the texture image. The |
| compressed image data is formatted according to the definition of the texture's |
| internal format. |
| |
| For three-dimensional, two-dimensional array, cube map array, and cube map |
| 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. The correspondence of texels |
| to memory locations is as defined for TexImage3D in section 8.5. |
| |
| The row length, number of rows, image depth, and number of images are determined |
| by the size of the texture or renderbuffer image (including any borders). |
| |
| Errors: |
| |
| An INVALID_ENUM error is generated by GetTexImage if <target> is |
| not one of TEXTURE_2D, TEXTURE_3D, TEXTURE_2D_ARRAY, TEXTURE_CUBE_MAP_ARRAY, |
| or one of the targets from table 8.20. |
| |
| An INVALID_ENUM error is generated by GetRenderbufferImage is <target> is not |
| RENDERBUFFER. |
| |
| An INVALID_VALUE error is generated if <level> is negative or larger than |
| the maximum allowable level. |
| |
| An INVALID_OPERATION error is generated if any of the following mismatches |
| between <format> and the internal format of the texture or renderbuffer image |
| exist: |
| |
| * <format> is a color format (one of the formats in table 8.3 whose target is |
| the color buffer) and the base internal format of the texture or renderbuffer |
| image is not a color format. |
| |
| * <format> is DEPTH_COMPONENT and the base internal format is not |
| DEPTH_COMPONENT or DEPTH_STENCIL. |
| |
| * <format> is DEPTH_STENCIL and the base internal format is not DEPTH_- |
| STENCIL. |
| |
| * <format> is STENCIL_INDEX and the base internal format is not |
| STENCIL_INDEX or DEPTH_STENCIL. |
| |
| * <format> is one of the integer formats in table 8.5 and the internal format |
| of the texture or renderbuffer image is not integer, or <format> is not one |
| of the integer formats in table 8.5 and the internal format is integer. |
| |
| An INVALID_OPERATION error is generated if a pixel pack buffer object |
| is bound and packing the texture or renderbuffer image into the buffer’s |
| memory would exceed the size of the buffer. |
| |
| An INVALID_OPERATION error is generated if a pixel pack buffer object |
| is bound and <pixels> is not evenly divisible by the number of basic machine |
| units needed to store in memory the GL data type corresponding to type (see |
| table 8.4). |
| |
| An INVALID_OPERATION error is generated by GetCompressedTexImageANGLE if the |
| texture image is stored with an uncompressed internal format. |
| |
| Dependencies on ARB_texture_rectangle |
| |
| TEXTURE_RECTANGLE is accepted by GetTexImageANGLE and GetRenderbufferImageANGLE. |
| |
| An INVALID_VALUE error is generated if <level> is non-zero and the effective |
| <target> is TEXTURE_RECTANGLE. |
| |
| New State |
| |
| Add to table 21.10 "Textures (state per texture object)": |
| |
| Get Value Type Get Command Initial Value Description Section |
| -------------------------------- ---- ----------- ------------- --------------------------- ------- |
| IMPLEMENTATION_COLOR_READ_FORMAT E GetTextureParameteriv empty Implementation pixel format 8.11.2 |
| IMPLEMENTATION_COLOR_READ_TYPE E GetTextureParameteriv empty Implementation pixel type 8.11.2 |
| |
| Add to table 21.17 "Renderbuffer (state per renderbuffer object)": |
| |
| Get Value Type Get Command Initial Value Description Section |
| -------------------------------- ---- ----------- ------------- --------------------------- ------- |
| IMPLEMENTATION_COLOR_READ_FORMAT E GetRenderbufferParameteriv empty Implementation pixel format 9.2.6 |
| IMPLEMENTATION_COLOR_READ_TYPE E GetRenderbufferParameteriv empty Implementation pixel type 9.2.6 |
| |
| Issues |
| |
| 1) Should GetTexImageANGLE/GetRenderbufferImageANGLE only accept IMPLEMENTATION- |
| _COLOR_READ_FORMAT/TYPE or should they behave the same as GetTexImage in GL? |
| |
| Resolved: Keep the spec wording closer to the desktop GL version. It should |
| not involve much additional implementation work except for validation. |
| |
| Revision History |
| |
| Rev. Date Author Changes |
| ---- ------------- --------- ---------------------------------------- |
| 2 Sept 15, 2021 jmadill Add GetCompressedTexImageANGLE |
| 1 Oct 24, 2019 jmadill Initial version |
