glScissor — define the scissor box
void glScissor( | GLint | x, |
GLint | y, | |
GLsizei | width, | |
GLsizei | height) ; |
x
, y
Specify the lower left corner of the scissor box. Initially (0, 0).
width
, height
Specify the width and height of the scissor box.
When a GL context is first attached to a window,
width
and height
are set to the dimensions of that
window.
glScissor
defines a rectangle, called the scissor box,
in window coordinates.
The first two arguments,
x
and y
,
specify the lower left corner of the box.
width
and height
specify the width and height of the box.
To enable and disable the scissor test, call
glEnable and glDisable with argument
GL_SCISSOR_TEST
. The test is initially disabled.
While the test is enabled, only pixels that lie within the scissor box
can be modified by drawing commands.
Window coordinates have integer values at the shared corners of
frame buffer pixels.
glScissor(0,0,1,1)
allows modification of only the lower left
pixel in the window, and glScissor(0,0,0,0)
doesn't allow
modification of any pixels in the window.
When the scissor test is disabled, it is as though the scissor box includes the entire window.
GL_INVALID_VALUE
is generated if either width
or height
is negative.
GL_INVALID_OPERATION
is generated if glScissor
is executed between the execution of glBegin
and the corresponding execution of glEnd.
Copyright © 1991-2006 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.