glPixelTexGenParameterSGIS(3G) OpenGL Reference
glPixelTexGenParameterfSGIS, glPixelTexGenParameteriSGIS,
glPixelTexGenParameterfvSGIS, glPixelTexGenParameterivSGIS - affects the
generation of texture coordinates in pixel operations
void glPixelTexGenParameterfSGIS( GLenum pname,
GLfloat param )
void glPixelTexGenParameteriSGIS( GLenum pname,
GLint param )
pname Specifies the symbolic name of the parameter to be set, which
must be either GL_PIXEL_FRAGMENT_RGB_SOURCE_SGIS or
GL_PIXEL_FRAGMENT_ALPHA_SOURCE_SGIS.
param Specifies a symbolic constant, which must be either
GL_CURRENT_RASTER_COLOR or GL_PIXEL_GROUP_COLOR_SGIS.
void glPixelTexGenParameterfvSGIS( GLenum pname,
const GLfloat *params )
void glPixelTexGenParameterivSGIS( GLenum pname,
const GLint *params )
pname
Specifies the symbolic name of the parameter to be set, which must
be either GL_PIXEL_FRAGMENT_RGB_SOURCE_SGIS or
GL_PIXEL_FRAGMENT_ALPHA_SOURCE_SGIS.
params
Specifies a pointer to an array where the value of pname is stored.
The value must be either GL_CURRENT_RASTER_COLOR or
GL_PIXEL_GROUP_COLOR_SGIS.
The pixel texture function is enabled by calling glEnable and disabled by
calling glDisable with GL_PIXEL_TEXTURE_SGIS. Pixel texture affects the
result of glDrawPixels and glCopyPixels operations by converting color
components into texture coordinates. Because texture mapping is
essentially a multidimensional table lookup, this conversion supports
multidimensional color lookups for images. Such multidimensional lookups
can be used to implement very accurate color space conversions.
When pixel texture is enabled, the red, green, blue, and alpha components
are used to generate s, t, r, and q texture coordinates, respectively.
If a valid texture has been defined, and texture-mapping enabled, these
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glPixelTexGenParameterSGIS(3G) OpenGL Reference
texture coordinates will produce, in effect, a function of the color
components, which can then be blended with the original color components,
according to the texture environment blend function.
Texture coordinates can be generated from either the pixel color or the
current raster position's color values. The source of the red, green,
and blue values can be selected separately from the source of the alpha
values by calling glPixelTexGenParameterSGIS with different values of
pname:
GL_PIXEL_FRAGMENT_RGB_SOURCE_SGIS [Toc] [Back]
params selects which red, green, and blue values are used to
generate the s, t, and r texture coordinates. If params is
GL_PIXEL_GROUP_COLOR_SGIS then s, t, and r will be generated
from the pixel color data. If params is
GL_CURRENT_RASTER_COLOR then s, t, and r will be generated from
the current raster position color. The default is
GL_PIXEL_GROUP_COLOR_SGIS.
GL_PIXEL_FRAGMENT_ALPHA_SOURCE_SGIS [Toc] [Back]
params selects which alpha values are used to generate the q
texture coordinates. If params is GL_PIXEL_GROUP_COLOR_SGIS
then q will be generated from the pixel alpha data. If params
is GL_CURRENT_RASTER_COLOR then q will be generated from the
current raster position alpha value. The default is
GL_PIXEL_GROUP_COLOR_SGIS.
GL_INVALID_ENUM is generated when pname is not an accepted defined value.
GL_INVALID_ENUM is generated when params is not an accepted defined
value.
GL_INVALID_OPERATION is generated if glPixelTexGenParameterSGIS is
executed between the execution of glBegin and the execution of the
corresponding glEnd.
glGetPixelTexGenParameterSGIS
glIsEnabled with argument GL_PIXEL_TEXTURE_SGIS
MACHINE DEPENDENCIES
glPixelTexGenParameterSGIS is supported only on Octane2 VPro systems.
Octane2 VPro systems support only the GL_PIXEL_GROUP_COLOR_SGIS mode for
GL_PIXEL_FRAGMENT_RGB_SOURCE_SGIS and
GL_PIXEL_FRAGMENT_ALPHA_SOURCE_SGIS.
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glPixelTexGenParameterSGIS(3G) OpenGL Reference
glDisable, glEnable, glGetPixelTexGenParameterSGIS, glIsEnabled
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