NAME¶
glHint - specify implementation-specific hints
C SPECIFICATION¶
void
glHint(GLenum target,
GLenum mode);
PARAMETERS¶
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
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/.