GLDETAILTEXFUNCSGIS(3GL)GLDETAILTEXFUNCSGIS(3GL)NAME
glDetailTexFuncSGIS - defines detail texture function.
C SPECIFICATION
void glDetailTexFuncSGIS ( GLenum target,
GLsizein, const GLfloat* points)
PARAMETERS
target The target texture. Must be GL_TEXTURE_2D.
sizei Number of LOD, value pairs in points array.
points Pointer to array of data containing LOD, value pairs.
DESCRIPTION
glDetailTexFuncSGIS,
Passes in array of LOD, value pairs which define the detail function.
The detail function is part of the SGIS_detail_texture extension,
which defines
a texture magnification filter that blends
between the level 0 texture and a separately defined detail image.
The first value of each value pair in <points> specifies a value of
LOD, and the second value of each value pair specifies the correspond‐
ing function value. The order in which the points are specified is not
significant. The <n> value pairs in <points> completely specify the
function, replacing any previous specification that may have existed.
Since negative values of LOD correspond to magnification and positive
values correspond to minification, the points should have negative val‐
ues for LOD (though it is not an error to specify positive values).
Function F is evaluated by sorting the value pairs specified by glDe‐
tailTexFuncSGIS by LOD value, then fitting a curve through these
points. This curve may be linear between adjacent points, or it may be
smoothed, but it will pass exactly through the points, limited only by
the resolution of the implementation. The value pair with the lowest
LOD value specifies the function value F for all values of LOD less
than or equal to that pair's LOD. Likewise, the value pair with the
greatest LOD value specifies the function value F for all values of LOD
greater than or equal to that pair's LOD. F is undefined if two or
more value pairs have the same LOD value.
The current contents of the detail function tables are queried using
glGetDetailTexFuncSGIS. <target> must be GL_TEXTURE_2D.
ERRORS
GL_INVALID_ENUM is generated if glDetailTexFuncSGIS parameter <target>
is not GL_TEXTURE_2D.
GL_INVALID_VALUE is generated if glDetailTexFuncSGIS parameter <n> is
negative.
GL_INVALID_OPERATION is generated if glDetailTexFuncSGIS is executed
between execution of glBegin and the corresponding glEnd.
ASSOCIATED CALLS
glGetDetailTexFuncSGIS.
SEE ALSO
glGetTexLevelParameter, glGetTexImage, glGetTexParameter, glCopyTexIm‐
age2D, glTexImage2D, glCopyTexSubImage2D, glBindTexture, glTexParame‐
ter, glGet.
30 May 01 GLDETAILTEXFUNCSGIS(3GL)
