OpenGL man pages
glClearIndex - specify the clear value for the color index buffers
void glClearIndex( GLfloat c )
c Specifies the index used when the color index buffers are cleared. The
default value is zero.
glClearIndex specifies the index used by glClear to clear the color index
buffers. c is not clamped. Rather, c is converted to a fixed-point value
with unspecified precision to the right of the binary point. The integer
part of this value is then masked with 2m-1, where m is the number of bits
in a color index stored in the frame buffer.
GL_INVALID_OPERATION is generated if glClearIndex is executed between the
execution of glBegin and the corresponding execution of glEnd.
glGet with argument GL_INDEX_CLEAR_VALUE
glGet with argument GL_INDEX_BITS
Fri Dec 6 11:18:03 EST 1996
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