GLAPI/glHint: Difference between revisions
m Renaming category: 'API Reference 4' to 'Core API Reference'. |
m Bot: Adding better formatting. |
||
| Line 8: | Line 8: | ||
== Function Definition == | == Function Definition == | ||
void '''glHint'''(GLenum | void '''glHint'''(GLenum {{param|target}}, GLenum {{param|mode}}); | ||
; target | ; target | ||
| Line 17: | Line 17: | ||
== Description == | == Description == | ||
Certain aspects of GL behavior, when there is room for interpretation, can be controlled with hints. A hint is specified with two arguments. | Certain aspects of GL behavior, when there is room for interpretation, can be controlled with hints. A hint is specified with two arguments. {{param|target}} is a symbolic constant indicating the behavior to be controlled, and {{param|mode}} is another symbolic constant indicating the desired behavior. The initial value for each {{param|target}} is {{code|GL_DONT_CARE}}. {{param|mode}} can be one of the following: | ||
; {{code|GL_FASTEST}} | ; {{code|GL_FASTEST}} | ||
| Line 28: | Line 28: | ||
: | : | ||
No preference. | No preference. | ||
Though the implementation aspects that can be hinted are well defined, the interpretation of the hints depends on the implementation. The hint aspects that can be specified with | Though the implementation aspects that can be hinted are well defined, the interpretation of the hints depends on the implementation. The hint aspects that can be specified with {{param|target}}, along with suggested semantics, are as follows: | ||
; {{code|GL_FRAGMENT_SHADER_DERIVATIVE_HINT}} | ; {{code|GL_FRAGMENT_SHADER_DERIVATIVE_HINT}} | ||
| Line 41: | Line 41: | ||
; {{code|GL_TEXTURE_COMPRESSION_HINT}} | ; {{code|GL_TEXTURE_COMPRESSION_HINT}} | ||
: | : | ||
Indicates the quality and performance of the compressing texture images. Hinting {{code|GL_FASTEST}} indicates that texture images should be compressed as quickly as possible, while {{code|GL_NICEST}} indicates that texture images should be compressed with as little image quality loss as possible. {{code|GL_NICEST}} should be selected if the texture is to be retrieved by | Indicates the quality and performance of the compressing texture images. Hinting {{code|GL_FASTEST}} indicates that texture images should be compressed as quickly as possible, while {{code|GL_NICEST}} indicates that texture images should be compressed with as little image quality loss as possible. {{code|GL_NICEST}} should be selected if the texture is to be retrieved by {{apifunc|glGetCompressedTexImage}} for reuse. | ||
== Notes == | == Notes == | ||
| Line 48: | Line 48: | ||
== Errors == | == Errors == | ||
{{code|GL_INVALID_ENUM}} is generated if either | {{code|GL_INVALID_ENUM}} is generated if either {{param|target}} or {{param|mode}} is not an accepted value. | ||
== Copyright == | == Copyright == | ||
Revision as of 01:22, 29 April 2012
| Core in version | 4.6 | |
|---|---|---|
| Core since version | 1.0 | |
glHint: specify implementation-specific hints
Function Definition
void glHint(GLenum target, GLenum mode);
- target
- Specifies a symbolic constant indicating the behavior to be controlled. GL_LINE_SMOOTH_HINT, GL_POLYGON_SMOOTH_HINT, GL_TEXTURE_COMPRESSION_HINT, and GL_FRAGMENT_SHADER_DERIVATIVE_HINT are accepted.
- mode
- Specifies a symbolic constant indicating the desired behavior. GL_FASTEST, GL_NICEST, and GL_DONT_CARE are accepted.
Description
Certain aspects of GL behavior, when there is room for interpretation, can be controlled with hints. A hint is specified with two arguments. target is a symbolic constant indicating the behavior to be controlled, and mode is another symbolic constant indicating the desired behavior. The initial value for each target is GL_DONT_CARE. mode can be one of the following:
- GL_FASTEST
The most efficient option should be chosen.
- GL_NICEST
The most correct, or highest quality, option should be chosen.
- GL_DONT_CARE
No preference. Though the implementation aspects that can be hinted are well defined, the interpretation of the hints depends on the implementation. The hint aspects that can be specified with target, along with suggested semantics, are as follows:
- GL_FRAGMENT_SHADER_DERIVATIVE_HINT
Indicates the accuracy of the derivative calculation for the GL shading language fragment processing built-in functions: dFdx, dFdy, and fwidth.
- GL_LINE_SMOOTH_HINT
Indicates the sampling quality of antialiased lines. If a larger filter function is applied, hinting GL_NICEST can result in more pixel fragments being generated during rasterization.
- GL_POLYGON_SMOOTH_HINT
Indicates the sampling quality of antialiased polygons. Hinting GL_NICEST can result in more pixel fragments being generated during rasterization, if a larger filter function is applied.
- GL_TEXTURE_COMPRESSION_HINT
Indicates the quality and performance of the compressing texture images. Hinting GL_FASTEST indicates that texture images should be compressed as quickly as possible, while GL_NICEST indicates that texture images should be compressed with as little image quality loss as possible. GL_NICEST should be selected if the texture is to be retrieved by glGetCompressedTexImage for reuse.
Notes
The interpretation of hints depends on the implementation. Some implementations ignore glHint settings.
Errors
GL_INVALID_ENUM is generated if either target or mode is not an accepted value.
Copyright
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.