glScissor(3G) OpenGL Reference glScissor(3G)
NAME
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. 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.
DESCRIPTION
The glScissor routine 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.
The scissor test is enabled and disabled using glEnable and glDisable
with argument GLSCISSORTEST. 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 frame buffer 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.
ERRORS
GLINVALIDVALUE is generated if either width or height is negative.
GLINVALIDOPERATION is generated if glScissor is executed between the
execution of glBegin and the corresponding execution of glEnd.
ASSOCIATED GETS
glGet with argument GLSCISSORBOX
glIsEnabled with argument GLSCISSORTEST
SEE ALSO
glEnable, glViewport
Page 1