GLPOINTPARAMETER(3G) OpenGL Manual GLPOINTPARAMETER(3G)NAME
glPointParameter - specify point parameters
C SPECIFICATION
void glPointParameterf(GLenum pname, GLfloat param);
void glPointParameteri(GLenum pname, GLint param);
PARAMETERS
pname
Specifies a single-valued point parameter. GL_POINT_FADE_THRESHOLD_SIZE, and GL_POINT_SPRITE_COORD_ORIGIN are accepted.
param
Specifies the value that pname will be set to.
C SPECIFICATION
void glPointParameterfv(GLenum pname, const GLfloat * params);
void glPointParameteriv(GLenum pname, const GLint * params);
PARAMETERS
pname
Specifies a point parameter. GL_POINT_FADE_THRESHOLD_SIZE, and GL_POINT_SPRITE_COORD_ORIGIN are accepted.
params
Specifies the value to be assigned to pname..
DESCRIPTION
The following values are accepted for pname:
GL_POINT_FADE_THRESHOLD_SIZE
params is a single floating-point value that specifies the threshold value to which point sizes are clamped if they exceed the
specified value. The default value is 1.0.
GL_POINT_SPRITE_COORD_ORIGIN
params is a single enum specifying the point sprite texture coordinate origin, either GL_LOWER_LEFT or GL_UPPER_LEFT. The default value
is GL_UPPER_LEFT.
ERRORS
GL_INVALID_VALUE is generated if the value specified for GL_POINT_FADE_THRESHOLD_SIZE is less than zero.
GL_INVALID_ENUM is generated If the value specified for GL_POINT_SPRITE_COORD_ORIGIN is not GL_LOWER_LEFT or GL_UPPER_LEFT.
ASSOCIATED GETS
glGet() with argument GL_POINT_FADE_THRESHOLD_SIZE
glGet() with argument GL_POINT_SPRITE_COORD_ORIGIN
SEE ALSO
glPointSize()
COPYRIGHT
Copyright (C) 1991-2006 Silicon Graphics, Inc. Copyright (C) 2010 Khronos Group. This document is licensed under the SGI Free Software B
License. For details, see http://oss.sgi.com/projects/FreeB/.
AUTHORS
opengl.org
opengl.org 06/10/2014 GLPOINTPARAMETER(3G)
Check Out this Related Man Page
GLFOG(3G) OpenGL Manual GLFOG(3G)NAME
glFog - specify fog parameters
C SPECIFICATION
void glFogf(GLenum pname, GLfloat param);
void glFogi(GLenum pname, GLint param);
PARAMETERS
pname
Specifies a single-valued fog parameter. GL_FOG_MODE, GL_FOG_DENSITY, GL_FOG_START, GL_FOG_END, GL_FOG_INDEX, and GL_FOG_COORD_SRC are
accepted.
param
Specifies the value that pname will be set to.
C SPECIFICATION
void glFogfv(GLenum pname, const GLfloat * params);
void glFogiv(GLenum pname, const GLint * params);
PARAMETERS
pname
Specifies a fog parameter. GL_FOG_MODE, GL_FOG_DENSITY, GL_FOG_START, GL_FOG_END, GL_FOG_INDEX, GL_FOG_COLOR, and GL_FOG_COORD_SRC are
accepted.
params
Specifies the value or values to be assigned to pname. GL_FOG_COLOR requires an array of four values. All other parameters accept an
array containing only a single value.
DESCRIPTION
Fog is initially disabled. While enabled, fog affects rasterized geometry, bitmaps, and pixel blocks, but not buffer clear operations. To
enable and disable fog, call glEnable() and glDisable() with argument GL_FOG.
glFog assigns the value or values in params to the fog parameter specified by pname. The following values are accepted for pname:
GL_FOG_MODE
params is a single integer or floating-point value that specifies the equation to be used to compute the fog blend factor, f. Three
symbolic constants are accepted: GL_LINEAR, GL_EXP, and GL_EXP2. The equations corresponding to these symbolic constants are defined
below. The initial fog mode is GL_EXP.
GL_FOG_DENSITY
params is a single integer or floating-point value that specifies density, the fog density used in both exponential fog equations. Only
nonnegative densities are accepted. The initial fog density is 1.
GL_FOG_START
params is a single integer or floating-point value that specifies start, the near distance used in the linear fog equation. The initial
near distance is 0.
GL_FOG_END
params is a single integer or floating-point value that specifies end, the far distance used in the linear fog equation. The initial
far distance is 1.
GL_FOG_INDEX
params is a single integer or floating-point value that specifies i f, the fog color index. The initial fog index is 0.
GL_FOG_COLOR
params contains four integer or floating-point values that specify C f, the fog color. Integer values are mapped linearly such that the
most positive representable value maps to 1.0, and the most negative representable value maps to -1.0. Floating-point values are mapped
directly. After conversion, all color components are clamped to the range 0 1. The initial fog color is (0, 0, 0, 0).
GL_FOG_COORD_SRC
params contains either of the following symbolic constants: GL_FOG_COORD or GL_FRAGMENT_DEPTH. GL_FOG_COORD specifies that the current
fog coordinate should be used as distance value in the fog color computation. GL_FRAGMENT_DEPTH specifies that the current fragment
depth should be used as distance value in the fog computation.
Fog blends a fog color with each rasterized pixel fragment's post-texturing color using a blending factor f. Factor f is computed in one of
three ways, depending on the fog mode. Let c be either the distance in eye coordinate from the origin (in the case that the
GL_FOG_COORD_SRC is GL_FRAGMENT_DEPTH) or the current fog coordinate (in the case that GL_FOG_COORD_SRC is GL_FOG_COORD). The equation for
GL_LINEAR fog is f = end - c end - start
The equation for GL_EXP fog is f = e - density . c
The equation for GL_EXP2 fog is f = e - density . c 2
Regardless of the fog mode, f is clamped to the range 0 1 after it is computed. Then, if the GL is in RGBA color mode, the fragment's red,
green, and blue colors, represented by C r, are replaced by
C r '' = f x C r + 1 - f x C f
Fog does not affect a fragment's alpha component.
In color index mode, the fragment's color index i r is replaced by
i r '' = i r + 1 - f x i f
NOTES
GL_FOG_COORD_SRC is available only if the GL version is 1.4 or greater.
ERRORS
GL_INVALID_ENUM is generated if pname is not an accepted value, or if pname is GL_FOG_MODE and params is not an accepted value.
GL_INVALID_VALUE is generated if pname is GL_FOG_DENSITY and params is negative.
GL_INVALID_OPERATION is generated if glFog is executed between the execution of glBegin() and the corresponding execution of glEnd().
ASSOCIATED GETS
glIsEnabled() with argument GL_FOG
glGet() with argument GL_FOG_COLOR
glGet() with argument GL_FOG_INDEX
glGet() with argument GL_FOG_DENSITY
glGet() with argument GL_FOG_START
glGet() with argument GL_FOG_END
glGet() with argument GL_FOG_MODE
SEE ALSO
glEnable()
COPYRIGHT
Copyright (C) 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/.
AUTHORS
opengl.org
opengl.org 06/10/2014 GLFOG(3G)