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glScissor function

Applies to: desktop apps only

The glScissor function defines the scissor box.

Syntax

void WINAPI glScissor(
  GLint x,
  GLint y,
  GLsizei width,
  GLsizei height
);

Parameters

x

The x (vertical axis) coordinate for the lower-left corner of the scissor box.

y

The y (horizontal axis) coordinate for the lower-left corner of the scissor box. Together, x and y specify the lower-left corner of the scissor box. Initially (0,0).

width

The width of the scissor box.

height

The height of the scissor box. When an OpenGL context is first attached to a window, width and height are set to the dimensions of that window.

Return value

This function does not return a value.

Error codes

The following error code can be retrieved by the glGetError function.

NameMeaning
GL_INVALID_VALUE

Either width or height was negative.

GL_INVALID_OPERATION

The function was called between a call to glBegin and the corresponding call to glEnd.

Remarks

The glScissor function defines a rectangle, called the scissor box, in window coordinates. The first two parameters, x and y, specify the lower-left corner of the box. The width and height parameters specify the width and height of the box.

The scissor test is enabled and disabled using glEnable and glDisable with argument GL_SCISSOR_TEST. While the 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 framebuffer pixels, so glScissor(0,0,1,1) allows only the lower-left pixel in the window to be modified, and glScissor(0,0,0,0) disallows modification to all pixels in the window.

When the scissor test is disabled, it is as though the scissor box includes the entire window.

The following functions retrieve information related to glScissor:

glGet with argument GL_SCISSOR_BOX

glIsEnabled with argument GL_SCISSOR_TEST

Requirements

Minimum supported client

Windows 2000 Professional

Minimum supported server

Windows 2000 Server

Header

Gl.h

Library

Opengl32.lib

DLL

Opengl32.dll

See also

glBegin
glEnable
glEnd
glIsEnabled
glViewport

 

 

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Build date: 3/6/2012

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