2011-2013
Khronos Group.
glGetInternalformat
3G

# glGetInternalformat

retrieve information about implementation-dependent support for internal formats

## C Specification

                    void glGetInternalformativ
                    GLenum target
                    GLenum internalformat
                    GLenum pname
                    GLsizei bufSize
                    GLint *params

                    void glGetInternalformati64v
                    GLenum target
                    GLenum internalformat
                    GLenum pname
                    GLsizei bufSize
                    GLint64 *params

## Parameters

`target`

  Indicates the usage of the internal format. `target` must be `GL_TEXTURE_1D`, `GL_TEXTURE_1D_ARRAY`, `GL_TEXTURE_2D`, `GL_TEXTURE_2D_ARRAY`, `GL_TEXTURE_3D`, `GL_TEXTURE_CUBE_MAP`, `GL_TEXTURE_CUBE_MAP_ARRAY`, `GL_TEXTURE_RECTANGLE`, `GL_TEXTURE_BUFFER`, `GL_RENDERBUFFER`, `GL_TEXTURE_2D_MULTISAMPLE` or `GL_TEXTURE_2D_MULTISAMPLE_ARRAY`.

`internalformat`

  Specifies the internal format about which to retrieve information.

`pname`

  Specifies the type of information to query.

`bufSize`

  Specifies the maximum number of basic machine units that may be written to `params` by the function.

`params`

  Specifies the address of a variable into which to write the retrieved information.

## Description

`glGetInternalformativ` and `glGetInternalformati64v` retrieve information about implementation-dependent support for internal formats. `target` indicates the target with which the internal format will be used and must be one of `GL_RENDERBUFFER`, `GL_TEXTURE_2D_MULTISAMPLE`, or `GL_TEXTURE_2D_MULTISAMPLE_ARRAY`, corresponding to usage as a renderbuffer, two-dimensional multisample texture or two-dimensional multisample array texture, respectively.

`internalformat` specifies the internal format about which to retrieve information and must be a color-renderable, depth-renderable or stencil-renderable format.

The information retrieved will be written to memory addressed by the pointer specified in `params`. No more than `bufSize` basic machine units will be written to this memory.

If `pname` is `GL_NUM_SAMPLE_COUNTS`, the number of sample counts that would be returned by querying `GL_SAMPLES` will be returned in `params`.

If `pname` is `GL_SAMPLES`, the sample counts supported for `internalformat` and `target` are written into `params` in descending numeric order. Only positive values are returned. Querying `GL_SAMPLES` with `bufSize` of one will return just the maximum supported number of samples for this format. The maximum value in `GL_SAMPLES` is guaranteed to be at least the lowest of the following:

- The value of `GL_MAX_INTEGER_SAMPLES` if `internalformat` is a signed or unsigned integer format.

- The value of `GL_MAX_DEPTH_TEXTURE_SAMPLES` if `internalformat` is a depth- or stencil-renderable format and `target` is `GL_TEXTURE_2D_MULTISAMPLE`, `GL_TEXTURE_2D_MULTISAMPLE_ARRAY`.

- The value of `GL_MAX_COLOR_TEXTURE_SAMPLES` if `internalformat` is a color-renderable format and `target` is `GL_TEXTURE_2D_MULTISAMPLE` or `GL_TEXTURE_2D_MULTISAMPLE_ARRAY`.

- The value of `GL_MAX_SAMPLES`.

If `pname` is `GL_INTERNALFORMAT_SUPPORTED`, `params` is set to `GL_TRUE` if `internalFormat` is a supported internal format for `target` and to `GL_FALSE` otherwise.

If `pname` is `GL_INTERNALFORMAT_PREFERRED`, `params` is set to `GL_TRUE` if `internalFormat` is an format for `target` that is preferred by the implementation and to `GL_FALSE` otherwise.

If `pname` is `GL_INTERNALFORMAT_RED_SIZE`, `GL_INTERNALFORMAT_GREEN_SIZE`, `GL_INTERNALFORMAT_BLUE_SIZE`, `GL_INTERNALFORMAT_ALPHA_SIZE`, `GL_INTERNALFORMAT_DEPTH_SIZE`, `GL_INTERNALFORMAT_STENCIL_SIZE`, or `GL_INTERNALFORMAT_SHARED_SIZE` then `params` is set to the actual resolutions that would be used for storing image array components for the resource for the red, green, blue, alpha, depth, stencil and shared channels respectively. If `internalFormat` is a compressed internal format, then `params` is set to the component resolution of an uncompressed internal format that produces an image of roughly the same quality as the compressed algorithm. If the internal format is unsupported, or if a particular component is not present in the format, 0 is written to `params`.

If `pname` is `GL_INTERNALFORMAT_RED_TYPE`, `GL_INTERNALFORMAT_GREEN_TYPE`, `GL_INTERNALFORMAT_BLUE_TYPE`, `GL_INTERNALFORMAT_ALPHA_TYPE`, `GL_INTERNALFORMAT_DEPTH_TYPE`, or `GL_INTERNALFORMAT_STENCIL_TYPE` then `params` is set to a token identifying the data type used to store the respective component. If the `internalFormat` represents a compressed internal format then the types returned specify how components are interpreted after decompression.

If `pname` is `GL_MAX_WIDTH`, `GL_MAX_HEIGHT`, `GL_MAX_DEPTH`, or `GL_MAX_LAYERS` then `pname` is filled with the maximum width, height, depth or layer count for textures with internal format `internalFormat`, respectively. If `pname` is `GL_MAX_COMBINED_DIMENSIONS` then `pname` is filled with the maximum combined dimensions of a texture of the specified internal format.

If `pname` is `GL_COLOR_COMPONENTS` then `params` is set to the value `GL_TRUE` if the internal format contains any color component (i.e., red, green, blue or alpha) and to `GL_FALSE` otherwise. If `pname` is `GL_DEPTH_COMPONENTS` or `GL_STENCIL_COMPONENTS` then `params` is set to `GL_TRUE` if the internal format contains a depth or stencil component, respectively, and to `GL_FALSE` otherwise.

If `pname` is `GL_COLOR_RENDERABLE`, `GL_DEPTH_RENDERABLE` or `GL_STENCIL_RENDERABLE` then `params` is set to `GL_TRUE` if the specified internal format is color, depth or stencil renderable, respectively, and to `GL_FALSE` otherwise.

If `pname` is `GL_FRAMEBUFFER_RENDERABLE` or `GL_FRAMEBUFFER_RENDERABLE_LAYERED` then `params` is set to one of `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT` or `GL_NONE` to indicate that framebuffer attachments (layered attachments in the case of `GL_FRAMEBUFFER_RENDERABLE_LAYERED`) with that internal format are either renderable with no restrictions, renderable with some restrictions or not renderable at all.

If `pname` is `GL_FRAMEBUFFER_BLEND`, `params` is set to `GL_TRUE` to indicate that the internal format is supported for blending operations when attached to a framebuffer, and to `GL_FALSE` otherwise.

If `pname` is `GL_READ_PIXELS` then `params` is set to `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT` or `GL_NONE` to that either full support, limited support or no support at all is supplied for reading pixels from framebuffer attachments in the specified internal format.

If `pname` is `GL_READ_PIXELS_FORMAT` or `GL_READ_PIXELS_TYPE` then `params` is filled with the format or type, respectively, most recommended to obtain the highest image quality and performance. For `GL_READ_PIXELS_FORMAT`, the value returned in `params` is a token that is accepted for the `format` argument to glReadPixels. For `GL_READ_PIXELS_TYPE`, the value returned in `params` is a token that is accepted for the `type` argument to glReadPixels.

If `pname` is `GL_TEXTURE_IMAGE_FORMAT` or `GL_TEXTURE_IMAGE_TYPE` then `params` is filled with the implementation-recommended format or type to be used in calls to glTexImage2D and other similar functions. For `GL_TEXTURE_IMAGE_FORMAT`, `params` is filled with a token suitable for use as the `format` argument to glTexImage2D. For `GL_TEXTURE_IMAGE_TYPE`, `params` is filled with a token suitable for use as the `type` argument to glTexImage2D.

If `pname` is `GL_GET_TEXTURE_IMAGE_FORMAT` or `GL_GET_TEXTURE_IMAGE_TYPE` then `params` is filled with the implementation-recommended format or type to be used in calls to glGetTexImage2D and other similar functions. For `GL_GET_TEXTURE_IMAGE_FORMAT`, `params` is filled with a token suitable for use as the `format` argument to glGetTexImage2D. For `GL_GET_TEXTURE_IMAGE_TYPE`, `params` is filled with a token suitable for use as the `type` argument to glGetTexImage2D.

If `pname` is `GL_MIPMAP` then `pname` is set to `GL_TRUE` to indicate that the specified internal format supports mipmaps and to `GL_FALSE` otherwise.

If `pname` is `GL_GENERATE_MIPMAP` or `GL_AUTO_GENERATE_MIPMAP` then `params` is indicates the level of support for manual or automatic mipmap generation for the specified internal format, respectively. Returned values may be one of `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT` and `GL_NONE` to indicate either full support, limited support or no support at all.

If `pname` is `GL_COLOR_ENCODING` then the color encoding for the resource is returned in `params`. Possible values for color buffers are `GL_LINEAR` or `GL_SRGB`, for linear or sRGB-encoded color components, respectively. For non-color formats (such as depth or stencil), or for unsupported resources, the value `GL_NONE` is returned.

If `pname` is `GL_SRGB_READ`, or `GL_SRGB_WRITE` then `params` indicates the level of support for reading and writing to sRGB encoded images, respectively. For `GL_SRGB_READ`, support for converting from sRGB colorspace on read operations is returned in `params` and for `GL_SRGB_WRITE`, support for converting to sRGB colorspace on write operations to the resource is returned in `params`. `params` may be set to `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT`, or `GL_NONE` to indicate full support, limited support or no support at all, respecitively.

If `pname` is `GL_FILTER` the `params` is set to either `GL_TRUE` or `GL_FALSE` to indicate support or lack thereof for filter modes other than `GL_NEAREST` or `GL_NEAREST_MIPMAP` for the specified internal format.

If `pname` is `GL_VERTEX_TEXTURE`, `GL_TESS_CONTROL_TEXTURE`, `GL_TESS_EVALUATION_TEXTURE`, `GL_GEOMETRY_TEXTURE`, `GL_FRAGMENT_TEXTURE`, or `GL_COMPUTE_TEXTURE`, then the value written to `params` indicates support for use of the resource as a source of texturing in the vertex, tessellation control, tessellation evaluation, geometry, fragment and compute shader stages, respectively. `params` may be set to `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT` or `GL_NONE` to indicate full support, limited support or no support at all, respectively.

If `pname` is `GL_TEXTURE_SHADOW`, `GL_TEXTURE_GATHER` or `GL_TEXTURE_GATHER_SHADOW` then the value written to `params` indicates the level of support for using the resource with a shadow sampler, in gather operations or as a shadow sampler in gather operations, respectively. Returned values may be `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT` or `GL_NONE` to indicate full support, limited support or no support at all, respectively.

If `pname` is `GL_SHADER_IMAGE_LOAD`, `GL_SHADER_IMAGE_STORE` or `GL_SHADER_IMAGE_ATOMIC` then the value returned in `params` indicates the level of support for image loads, stores and atomics for resources of the specified internal format. Returned values may be `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT` or `GL_NONE` to indicate full support, limited support or no support at all, respectively.

If `pname` is `GL_IMAGE_TEXEL_SIZE` then the size of a texel when the resource when used as an image texture is returned in `params`. If the resource is not supported for image textures zero is returned.

If `pname` is `GL_IMAGE_COMPATIBILITY_CLASS` then the compatibility class of the resource when used as an image texture is returned in `params`. The possible values returned are `GL_IMAGE_CLASS_4_X_32`, `GL_IMAGE_CLASS_2_X_32`, `GL_IMAGE_CLASS_1_X_32`, `GL_IMAGE_CLASS_4_X_16`, `GL_IMAGE_CLASS_2_X_16`, `GL_IMAGE_CLASS_1_X_16`, `GL_IMAGE_CLASS_4_X_8`, `GL_IMAGE_CLASS_2_X_8`, `GL_IMAGE_CLASS_1_X_8`, `GL_IMAGE_CLASS_11_11_10`, and `GL_IMAGE_CLASS_10_10_10_2`, which correspond to the 4x32, 2x32, 1x32, 4x16, 2x16, 1x16, 4x8, 2x8, 1x8, the class (a) 11/11/10 packed floating-point format, and the class (b) 10/10/10/2 packed formats, respectively. If the resource is not supported for image textures, `GL_NONE` is returned.

If `pname` is `GL_IMAGE_PIXEL_FORMAT` or `GL_IMAGE_PIXEL_TYPE` then the pixel format or type of the resource when used as an image texture is returned in `params`, respectively. In either case, the resource is not supported for image textures `GL_NONE` is returned.

If `pname` is `GL_IMAGE_FORMAT_COMPATIBILITY_TYPE`, the matching criteria use for the resource when used as an image textures is returned in `params`. Possible values returned in `params` are `GL_IMAGE_FORMAT_COMPATIBILITY_BY_SIZE` or `GL_IMAGE_FORMAT_COMPATIBILITY_BY_CLASS`. If the resource is not supported for image textures, `GL_NONE` is returned.

If `pname` is `GL_SIMULTANEOUS_TEXTURE_AND_DEPTH_TEST` or `GL_SIMULTANEOUS_TEXTURE_AND_STENCIL_TEST`, support for using the resource both as a source for texture sampling while it is bound as a buffer for depth or stencil test, respectively, is written to `params`. Possible values returned are `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT`, or `GL_NONE` to indicate full support, limited support or no support at all. If the resource or operation is not supported, `GL_NONE` is returned.

If `pname` is `GL_SIMULTANEOUS_TEXTURE_AND_DEPTH_WRITE` or `GL_SIMULTANEOUS_TEXTURE_AND_STENCIL_WRITE`, support for using the resource both as a source for texture sampling while performing depth or stencil writes to the resources, respectively, is written to `params`. Possible values returned are `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT`, or `GL_NONE` to indicate full support, limited support or no support at all. If the resource or operation is not supported, `GL_NONE` is returned.

If `pname` is `GL_TEXTURE_COMPRESSED` then `GL_TRUE` is returned in `params` if `internalformat` is a compressed internal format. `GL_FALSE` is returned in `params` otherwise.

If `pname` is `GL_TEXTURE_COMPRESSED_BLOCK_WIDTH`, `GL_TEXTURE_COMPRESSED_BLOCK_HEIGHT` or `GL_TEXTURE_COMPRESSED_BLOCK_SIZE` then the width, height or total size, respectively of a block (in basic machine units) is returned in `params`. If the internal format is not compressed, or the resource is not supported, 0 is returned.

If `pname` is `GL_CLEAR_BUFFER`, the level of support for using the resource with glClearBufferData and glClearBufferSubData is returned in `params`. Possible values returned are `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT`, or `GL_NONE` to indicate full support, limited support or no support at all, respectively. If the resource or operation is not supported, `GL_NONE` is returned.

If `pname` is `GL_TEXTURE_VIEW`, the level of support for using the resource with the glTextureView command is returned in `params`. Possible values returned are `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT`, or `GL_NONE` to indicate full support, limited support or no support at all, respectively. If the resource or operation is not supported, `GL_NONE` is returned.

If `pname` is `GL_VIEW_COMPATIBILITY_CLASS` then the compatibility class of the resource when used as a texture view is returned in `params`. The possible values returned are `GL_VIEW_CLASS_128_BITS`, `GL_VIEW_CLASS_96_BITS`, `GL_VIEW_CLASS_64_BITS`, `GL_VIEW_CLASS_48_BITS`, `GL_VIEW_CLASS_32_BITS`, `GL_VIEW_CLASS_24_BITS`, `GL_VIEW_CLASS_16_BITS`, `GL_VIEW_CLASS_8_BITS`, `GL_VIEW_CLASS_S3TC_DXT1_RGB`, `GL_VIEW_CLASS_S3TC_DXT1_RGBA`, `GL_VIEW_CLASS_S3TC_DXT3_RGBA`, `GL_VIEW_CLASS_S3TC_DXT5_RGBA`, `GL_VIEW_CLASS_RGTC1_RED`, `GL_VIEW_CLASS_RGTC2_RG`, `GL_VIEW_CLASS_BPTC_UNORM`, and `GL_VIEW_CLASS_BPTC_FLOAT`.

If `pname` is `GL_CLEAR_TEXTURE` then the presence of support for using the glClearTexImage and glClearTexSubImage commands with the resource is written to `params`. Possible values written are `GL_FULL_SUPPORT`, `GL_CAVEAT_SUPPORT`, or `GL_NONE` to indicate full support, limited support or no support at all, respectively. If the resource or operation is not supported, `GL_NONE` is returned.

## Notes

`glGetInternalformativ` is available only if the GL version is 4.2 or higher.

The tokens `GL_INTERNALFORMAT_SUPPORTED`, `GL_INTERNALFORMAT_PREFERRED`, `GL_INTERNALFORMAT_RED_SIZE`, `GL_INTERNALFORMAT_GREEN_SIZE`, `GL_INTERNALFORMAT_BLUE_SIZE`, `GL_INTERNALFORMAT_ALPHA_SIZE`, `GL_INTERNALFORMAT_DEPTH_SIZE`, `GL_INTERNALFORMAT_STENCIL_SIZE`, `GL_INTERNALFORMAT_SHARED_SIZE`, `GL_INTERNALFORMAT_RED_TYPE`, `GL_INTERNALFORMAT_GREEN_TYPE`, `GL_INTERNALFORMAT_BLUE_TYPE`, `GL_INTERNALFORMAT_ALPHA_TYPE`, `GL_INTERNALFORMAT_DEPTH_TYPE`, `GL_INTERNALFORMAT_STENCIL_TYPE`, `GL_MAX_WIDTH`, `GL_MAX_HEIGHT`, `GL_MAX_DEPTH`, `GL_MAX_LAYERS`, `GL_MAX_COMBINED_DIMENSIONS`, `GL_COLOR_COMPONENTS`, `GL_DEPTH_COMPONENTS`, `GL_STENCIL_COMPONENTS`, `GL_COLOR_RENDERABLE`, `GL_DEPTH_RENDERABLE`, `GL_STENCIL_RENDERABLE`, `GL_FRAMEBUFFER_RENDERABLE`, `GL_FRAMEBUFFER_RENDERABLE_LAYERED`, `GL_FRAMEBUFFER_BLEND`, `GL_READ_PIXELS`, `GL_READ_PIXELS_FORMAT`, `GL_READ_PIXELS_TYPE`, `GL_TEXTURE_IMAGE_FORMAT`, `GL_TEXTURE_IMAGE_TYPE`, `GL_GET_TEXTURE_IMAGE_FORMAT`, `GL_GET_TEXTURE_IMAGE_TYPE`, `GL_MIPMAP`, `GL_GENERATE_MIPMAP`, `GL_AUTO_GENERATE_MIPMAP`, `GL_COLOR_ENCODING`, `GL_SRGB_READ`, `GL_SRGB_WRITE`, `GL_SRGB_DECODE_ARB`, `GL_FILTER`, `GL_VERTEX_TEXTURE`, `GL_TESS_CONTROL_TEXTURE`, `GL_TESS_EVALUATION_TEXTURE`, `GL_GEOMETRY_TEXTURE`, `GL_FRAGMENT_TEXTURE`, `GL_COMPUTE_TEXTURE`, `GL_TEXTURE_SHADOW`, `GL_TEXTURE_GATHER`, `GL_TEXTURE_GATHER_SHADOW`, `GL_SHADER_IMAGE_LOAD`, `GL_SHADER_IMAGE_STORE`, `GL_SHADER_IMAGE_ATOMIC`, `GL_IMAGE_TEXEL_SIZE`, `GL_IMAGE_COMPATIBILITY_CLASS`, `GL_IMAGE_PIXEL_FORMAT`, `GL_IMAGE_PIXEL_TYPE`, `GL_IMAGE_FORMAT_COMPATIBILITY_TYPE`, `GL_SIMULTANEOUS_TEXTURE_AND_DEPTH_TEST`, `GL_SIMULTANEOUS_TEXTURE_AND_STENCIL_TEST`, `GL_SIMULTANEOUS_TEXTURE_AND_DEPTH_WRITE`, `GL_SIMULTANEOUS_TEXTURE_AND_STENCIL_WRITE`, `GL_TEXTURE_COMPRESSED`, `GL_TEXTURE_COMPRESSED_BLOCK_WIDTH`, `GL_TEXTURE_COMPRESSED_BLOCK_HEIGHT`, `GL_TEXTURE_COMPRESSED_BLOCK_SIZE`, `GL_CLEAR_BUFFER`, `GL_TEXTURE_VIEW`, and `GL_VIEW_COMPATIBILITY_CLASS` are supported only if the GL version is 4.3 or higher.

The `GL_CLEAR_TEXTURE` token is accepted for `pname` only if the GL version is 4.4 or higher.

## Errors

`GL_INVALID_VALUE` is generated if `bufSize` is negative.

`GL_INVALID_ENUM` is generated if `pname` is not `GL_SAMPLES` or `GL_NUM_SAMPLE_COUNTS`.

`GL_INVALID_ENUM` is generated if `internalformat` is not color-, depth-, or stencil-renderable.

`GL_INVALID_ENUM` is generated if `target` is not one of `GL_TEXTURE_2D_MULTISAMPLE`, `GL_TEXTURE_2D_MULTISAMPLE_ARRAY` or `GL_RENDERBUFFER`.

## See Also

glGet

## Copyright

Copyright 2011-2013 Khronos Group. This material may be distributed subject to the terms and conditions set forth in the Open Publication License, v 1.0, 8 June 1999. http://opencontent.org/openpub/.