GLAPI/glGetTexLevelParameter: Difference between revisions
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: Specifies the level-of-detail number of the desired image. Level 0 is the base image level. Level ''n'' is the ''n''th mipmap reduction image. | : Specifies the level-of-detail number of the desired image. Level 0 is the base image level. Level ''n'' is the ''n''th mipmap reduction image. | ||
; pname | ; pname | ||
: Specifies the symbolic name of a texture parameter | : Specifies the symbolic name of a texture parameter. | ||
; params | ; params | ||
: Returns the requested data. | : Returns the requested data. | ||
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'''glGetTexLevelParameter''' returns in {{param|params}} texture parameter values for a specific level-of-detail value, specified as {{param|level}}. {{param|target}} defines the target texture, either {{enum|GL_TEXTURE_1D}}, {{enum|GL_TEXTURE_2D}}, {{enum|GL_TEXTURE_3D}}, {{enum|GL_PROXY_TEXTURE_1D}}, {{enum|GL_PROXY_TEXTURE_2D}}, {{enum|GL_PROXY_TEXTURE_3D}}, {{enum|GL_TEXTURE_CUBE_MAP_POSITIVE_X}}, {{enum|GL_TEXTURE_CUBE_MAP_NEGATIVE_X}}, {{enum|GL_TEXTURE_CUBE_MAP_POSITIVE_Y}}, {{enum|GL_TEXTURE_CUBE_MAP_NEGATIVE_Y}}, {{enum|GL_TEXTURE_CUBE_MAP_POSITIVE_Z}}, {{enum|GL_TEXTURE_CUBE_MAP_NEGATIVE_Z}}, or {{enum|GL_PROXY_TEXTURE_CUBE_MAP}}. | '''glGetTexLevelParameter''' returns in {{param|params}} texture parameter values for a specific level-of-detail value, specified as {{param|level}}. {{param|target}} defines the target texture, either {{enum|GL_TEXTURE_1D}}, {{enum|GL_TEXTURE_2D}}, {{enum|GL_TEXTURE_3D}}, {{enum|GL_PROXY_TEXTURE_1D}}, {{enum|GL_PROXY_TEXTURE_2D}}, {{enum|GL_PROXY_TEXTURE_3D}}, {{enum|GL_TEXTURE_CUBE_MAP_POSITIVE_X}}, {{enum|GL_TEXTURE_CUBE_MAP_NEGATIVE_X}}, {{enum|GL_TEXTURE_CUBE_MAP_POSITIVE_Y}}, {{enum|GL_TEXTURE_CUBE_MAP_NEGATIVE_Y}}, {{enum|GL_TEXTURE_CUBE_MAP_POSITIVE_Z}}, {{enum|GL_TEXTURE_CUBE_MAP_NEGATIVE_Z}}, or {{enum|GL_PROXY_TEXTURE_CUBE_MAP}}. | ||
{{enum|GL_MAX_TEXTURE_SIZE}}, and {{enum|GL_MAX_3D_TEXTURE_SIZE}} are not really descriptive enough. It has to report the largest square texture image that can be accommodated with mipmaps | {{enum|GL_MAX_TEXTURE_SIZE}}, and {{enum|GL_MAX_3D_TEXTURE_SIZE}} are not really descriptive enough. It has to report the largest square texture image that can be accommodated with mipmaps but a long skinny texture, or a texture without mipmaps may easily fit in texture memory. The proxy targets allow the user to more accurately query whether the GL can accommodate a texture of a given configuration. If the texture cannot be accommodated, the texture state variables, which may be queried with '''glGetTexLevelParameter''', are set to 0. If the texture can be accommodated, the texture state values will be set as they would be set for a non-proxy target. | ||
{{param|pname}} specifies the texture parameter whose value or values will be returned. | {{param|pname}} specifies the texture parameter whose value or values will be returned. | ||
| Line 31: | Line 31: | ||
; {{enum|GL_TEXTURE_WIDTH}} | ; {{enum|GL_TEXTURE_WIDTH}} | ||
: | : {{param|params}} returns a single value, the width of the texture image. This value includes the border of the texture image. The initial value is 0. | ||
{{param|params}} returns a single value, the width of the texture image. This value includes the border of the texture image. The initial value is 0. | |||
; {{enum|GL_TEXTURE_HEIGHT}} | ; {{enum|GL_TEXTURE_HEIGHT}} | ||
: | : {{param|params}} returns a single value, the height of the texture image. This value includes the border of the texture image. The initial value is 0. | ||
{{param|params}} returns a single value, the height of the texture image. This value includes the border of the texture image. The initial value is 0. | |||
; {{enum|GL_TEXTURE_DEPTH}} | ; {{enum|GL_TEXTURE_DEPTH}} | ||
: | : {{param|params}} returns a single value, the depth of the texture image. This value includes the border of the texture image. The initial value is 0. | ||
{{param|params}} returns a single value, the depth of the texture image. This value includes the border of the texture image. The initial value is 0. | ; {{enum|GL_TEXTURE_SAMPLES}} | ||
: {{param|params}} returns a single value, the number of samples in a multisample image. For non-multisample textures, this is 0. | |||
; {{enum|GL_TEXTURE_FIXED_SAMPLE_LOCATIONS}} | |||
: {{param|params}} returns a boolean value. {{enum|GL_TRUE}} if the sample locations are fixed, and {{enum|GL_FALSE}} otherwise. | |||
; {{enum|GL_TEXTURE_INTERNAL_FORMAT}} | ; {{enum|GL_TEXTURE_INTERNAL_FORMAT}} | ||
: | : {{param|params}} returns a single value, the internal format of the texture image. | ||
{{param|params}} returns a single value, the internal format of the texture image. | ; {{enum|GL_TEXTURE_RED_TYPE}}, {{enum|GL_TEXTURE_GREEN_TYPE}}, {{enum|GL_TEXTURE_BLUE_TYPE}}, {{enum|GL_TEXTURE_ALPHA_TYPE}}, {{enum|GL_TEXTURE_DEPTH_TYPE}} | ||
; {{enum|GL_TEXTURE_RED_TYPE}}, | ; {{enum|GL_TEXTURE_RED_SIZE}}, {{enum|GL_TEXTURE_GREEN_SIZE}}, {{enum|GL_TEXTURE_BLUE_SIZE}}, {{enum|GL_TEXTURE_ALPHA_SIZE}}, {{enum|GL_TEXTURE_DEPTH_SIZE}}, {{enum|GL_TEXTURE_STENCIL_SIZE}} | ||
: The internal storage resolution of an individual component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of {{apifunc|glTexImage1D}}, {{apifunc|glTexImage2D}}, {{apifunc|glTexImage3D}}, {{apifunc|glCopyTexImage1D}}, and {{apifunc|glCopyTexImage2D}}. The initial value is 0. | |||
; {{enum|GL_TEXTURE_SHARED_SIZE}} | |||
: {{param|params}} will store a single value, the number of bits in the shared exponent of the [[Image Format]]. If the image format doesn't have a shared exponent, then it is 0. | |||
: The data type used to store the component. The types {{enum|GL_NONE}}, {{enum|GL_SIGNED_NORMALIZED}}, {{enum|GL_UNSIGNED_NORMALIZED}}, {{enum|GL_FLOAT}}, {{enum|GL_INT}}, and {{enum|GL_UNSIGNED_INT}} may be returned to indicate signed normalized fixed-point, unsigned normalized fixed-point, floating-point, integer unnormalized, and unsigned integer unnormalized components, respectively. | |||
: | |||
The internal storage resolution of an individual component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of {{apifunc|glTexImage1D}}, {{apifunc|glTexImage2D}}, {{apifunc|glTexImage3D}}, {{apifunc|glCopyTexImage1D}}, and {{apifunc|glCopyTexImage2D}}. The initial value is 0. | |||
; {{enum|GL_TEXTURE_COMPRESSED}} | ; {{enum|GL_TEXTURE_COMPRESSED}} | ||
: | : {{param|params}} returns a single boolean value indicating if the texture image is stored in a compressed internal format. The initiali value is {{enum|GL_FALSE}}. | ||
{{param|params}} returns a single boolean value indicating if the texture image is stored in a compressed internal format. The initiali value is {{enum|GL_FALSE}}. | |||
; {{enum|GL_TEXTURE_COMPRESSED_IMAGE_SIZE}} | ; {{enum|GL_TEXTURE_COMPRESSED_IMAGE_SIZE}} | ||
: | : {{param|params}} returns a single integer value, the number of unsigned bytes of the compressed texture image that would be returned from {{apifunc|glGetCompressedTexImage}}. | ||
{{param|params}} returns a single integer value, the number of unsigned bytes of the compressed texture image that would be returned from {{apifunc|glGetCompressedTexImage}}. | ; {{enum|GL_TEXTURE_BUFFER_DATA_STORE_BINDING}} | ||
: For [[Buffer Texture]]s, the buffer object (if any) attached to this mipmap level. For non-buffer textures, this is 0. | |||
; {{enum|GL_TEXTURE_BUFFER_OFFSET}} | ; {{enum|GL_TEXTURE_BUFFER_OFFSET}} | ||
: | : {{param|params}} returns a single integer value, the offset into the data store of the buffer bound to a buffer texture. {{apifunc|glTexBufferRange}}. | ||
{{param|params}} returns a single integer value, the offset into the data store of the buffer bound to a buffer texture. {{apifunc|glTexBufferRange}}. | |||
; {{enum|GL_TEXTURE_BUFFER_SIZE}} | ; {{enum|GL_TEXTURE_BUFFER_SIZE}} | ||
: | : {{param|params}} returns a single integer value, the size of the range of a data store of the buffer bound to a buffer texture. {{apifunc|glTexBufferRange}}. | ||
{{param|params}} returns a single integer value, the size of the range of a data store of the buffer bound to a buffer texture. {{apifunc|glTexBufferRange}}. | |||
== Notes == | == Notes == | ||
| Line 94: | Line 85: | ||
== Copyright == | == Copyright == | ||
Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010- | Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2013 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see [https://khronos.org/registry/OpenGL-Refpages/LICENSES/LicenseRef-FreeB.txt LicenseRef-FreeB]. | ||
[[Category:Core API Reference|GetTexLevelParameter]] | [[Category:Core API Reference|GetTexLevelParameter]] | ||
[[Category:Core API Ref Texturing|GetTexLevelParameter]] | [[Category:Core API Ref Texturing|GetTexLevelParameter]] | ||
[[Category:Texture Object API State Functions|GetTexLevelParameter]] | |||
Latest revision as of 22:14, 5 February 2021
| Core in version | 4.6 | |
|---|---|---|
| Core since version | 1.0 | |
glGetTexLevelParameter: return texture parameter values for a specific level of detail
Function Definition
void glGetTexLevelParameterfv(GLenum target, GLint level, GLenum pname, GLfloat * params); void glGetTexLevelParameteriv(GLenum target, GLint level, GLenum pname, GLint * params);
- target
- Specifies the symbolic name of the target texture, one of GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D, GL_TEXTURE_1D_ARRAY, GL_TEXTURE_2D_ARRAY, GL_TEXTURE_RECTANGLE, GL_TEXTURE_2D_MULTISAMPLE, GL_TEXTURE_2D_MULTISAMPLE_ARRAY, GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, GL_PROXY_TEXTURE_1D, GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_3D, GL_PROXY_TEXTURE_1D_ARRAY, GL_PROXY_TEXTURE_2D_ARRAY, GL_PROXY_TEXTURE_RECTANGLE, GL_PROXY_TEXTURE_2D_MULTISAMPLE, GL_PROXY_TEXTURE_2D_MULTISAMPLE_ARRAY, GL_PROXY_TEXTURE_CUBE_MAP, or GL_TEXTURE_BUFFER.
- level
- Specifies the level-of-detail number of the desired image. Level 0 is the base image level. Level n is the nth mipmap reduction image.
- pname
- Specifies the symbolic name of a texture parameter.
- params
- Returns the requested data.
Description
glGetTexLevelParameter returns in params texture parameter values for a specific level-of-detail value, specified as level. target defines the target texture, either GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D, GL_PROXY_TEXTURE_1D, GL_PROXY_TEXTURE_2D, GL_PROXY_TEXTURE_3D, GL_TEXTURE_CUBE_MAP_POSITIVE_X, GL_TEXTURE_CUBE_MAP_NEGATIVE_X, GL_TEXTURE_CUBE_MAP_POSITIVE_Y, GL_TEXTURE_CUBE_MAP_NEGATIVE_Y, GL_TEXTURE_CUBE_MAP_POSITIVE_Z, GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, or GL_PROXY_TEXTURE_CUBE_MAP.
GL_MAX_TEXTURE_SIZE, and GL_MAX_3D_TEXTURE_SIZE are not really descriptive enough. It has to report the largest square texture image that can be accommodated with mipmaps but a long skinny texture, or a texture without mipmaps may easily fit in texture memory. The proxy targets allow the user to more accurately query whether the GL can accommodate a texture of a given configuration. If the texture cannot be accommodated, the texture state variables, which may be queried with glGetTexLevelParameter, are set to 0. If the texture can be accommodated, the texture state values will be set as they would be set for a non-proxy target.
pname specifies the texture parameter whose value or values will be returned.
The accepted parameter names are as follows:
- GL_TEXTURE_WIDTH
- params returns a single value, the width of the texture image. This value includes the border of the texture image. The initial value is 0.
- GL_TEXTURE_HEIGHT
- params returns a single value, the height of the texture image. This value includes the border of the texture image. The initial value is 0.
- GL_TEXTURE_DEPTH
- params returns a single value, the depth of the texture image. This value includes the border of the texture image. The initial value is 0.
- GL_TEXTURE_SAMPLES
- params returns a single value, the number of samples in a multisample image. For non-multisample textures, this is 0.
- GL_TEXTURE_FIXED_SAMPLE_LOCATIONS
- params returns a boolean value. GL_TRUE if the sample locations are fixed, and GL_FALSE otherwise.
- GL_TEXTURE_INTERNAL_FORMAT
- params returns a single value, the internal format of the texture image.
- GL_TEXTURE_RED_TYPE, GL_TEXTURE_GREEN_TYPE, GL_TEXTURE_BLUE_TYPE, GL_TEXTURE_ALPHA_TYPE, GL_TEXTURE_DEPTH_TYPE
- GL_TEXTURE_RED_SIZE, GL_TEXTURE_GREEN_SIZE, GL_TEXTURE_BLUE_SIZE, GL_TEXTURE_ALPHA_SIZE, GL_TEXTURE_DEPTH_SIZE, GL_TEXTURE_STENCIL_SIZE
- The internal storage resolution of an individual component. The resolution chosen by the GL will be a close match for the resolution requested by the user with the component argument of glTexImage1D, glTexImage2D, glTexImage3D, glCopyTexImage1D, and glCopyTexImage2D. The initial value is 0.
- GL_TEXTURE_SHARED_SIZE
- params will store a single value, the number of bits in the shared exponent of the Image Format. If the image format doesn't have a shared exponent, then it is 0.
- The data type used to store the component. The types GL_NONE, GL_SIGNED_NORMALIZED, GL_UNSIGNED_NORMALIZED, GL_FLOAT, GL_INT, and GL_UNSIGNED_INT may be returned to indicate signed normalized fixed-point, unsigned normalized fixed-point, floating-point, integer unnormalized, and unsigned integer unnormalized components, respectively.
- GL_TEXTURE_COMPRESSED
- params returns a single boolean value indicating if the texture image is stored in a compressed internal format. The initiali value is GL_FALSE.
- GL_TEXTURE_COMPRESSED_IMAGE_SIZE
- params returns a single integer value, the number of unsigned bytes of the compressed texture image that would be returned from glGetCompressedTexImage.
- GL_TEXTURE_BUFFER_DATA_STORE_BINDING
- For Buffer Textures, the buffer object (if any) attached to this mipmap level. For non-buffer textures, this is 0.
- GL_TEXTURE_BUFFER_OFFSET
- params returns a single integer value, the offset into the data store of the buffer bound to a buffer texture. glTexBufferRange.
- GL_TEXTURE_BUFFER_SIZE
- params returns a single integer value, the size of the range of a data store of the buffer bound to a buffer texture. glTexBufferRange.
Notes
If an error is generated, no change is made to the contents of params.
glGetTexLevelParameter returns the texture level parameters for the active texture unit.
GL_TEXTURE_BUFFER_OFFSET and GL_TEXTURE_BUFFER_SIZE are available only if the GL version is 4.3 or greater.
Errors
GL_INVALID_ENUM is generated if target or pname is not an accepted value.
GL_INVALID_VALUE is generated if level is less than 0.
GL_INVALID_VALUE may be generated if level is greater than log2(max), where max is the returned value of GL_MAX_TEXTURE_SIZE.
GL_INVALID_VALUE is generated if target is GL_TEXTURE_BUFFER and level is not zero.
GL_INVALID_OPERATION is generated if GL_TEXTURE_COMPRESSED_IMAGE_SIZE is queried on texture images with an uncompressed internal format or on proxy targets.
See Also
glActiveTexture, glBindTexture, glGetTexParameter
Copyright
Copyright © 1991-2006 Silicon Graphics, Inc. Copyright © 2010-2013 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see LicenseRef-FreeB.