STATIC SUB ClearIndex ( Value AS Float )
Gl.ClearIndex specifies the index used by Gl.Clear to clear the color index buffers. Value is not clamped. Rather, Value 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 2 m - 1, where m is the number of bits in a color index stored in the frame buffer.
Gl.GL_INVALID_OPERATION is generated if Gl.ClearIndex is called between a call to Gl.Begin and the corresponding call to Gl.End.
Gl.GetIndexClearValue
Gl.GetIndexBits