glHint

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Specify implementation-specific hints.

C Specification[edit]

void glHint( GLenum target, GLenum mode );


Parameters[edit]

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[edit]

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[edit]

The interpretation of hints depends on the implementation. Some implementations ignore glHint settings.


Errors[edit]

 GL_INVALID_ENUM is generated if either target or mode is not an accepted value.


Version Support[edit]

 glHint  2.0+

See Also[edit]

Copyright[edit]

Copyright© 1991-2006 Silicon Graphics, Inc. Copyright© 2010-2014 Khronos Group. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.