The scissor test determines if lies within the scissor rectangle defined by four values. These values are set with
void Scissor ( int left, int bottom, sizei width, sizei height ) ;
If and , then the scissor test passes. Otherwise, the test fails and the fragment is discarded. The test is enabled or disabled using Enable or Disable using the constant SCISSOR_TEST. When disabled, it is as if the scissor test always passes. If either width or height is less than zero, then the error INVALID_VALUE is generated. The state required consists of four integer values and a bit indicating whether the test is enabled or disabled. In the initial state left = bottom = 0; width and height are determined by the size of the GL window. Initially, the scissor test is disabled.