2003-2004 Silicon Graphics, Inc.
glScissor 3G
glScissor define the scissor box

## C Specification

void `glScissor` GLint x GLint y GLsizei width GLsizei height

## Parameters

x, y

  Specify the lower left corner of the scissor box, in pixels. The initial value is (0, 0).

width, height

  Specify the width and height of the scissor box. When a GL context is first attached to a surface (e.g. window), width and height are set to the dimensions of that surface.

## Description

`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 scissor test is initially disabled. While scissor 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.

## Errors

`GL_INVALID_VALUE` is generated if either width or height is negative.

## See Also

glEnable, glViewport

## Copyright

Copyright 2003-2004 Silicon Graphics, Inc. This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.