glScissor
[New
- Windows 95, OEM Service Release 2]
The glScissor
function defines the scissor box.
void glScissor(
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GLint x, |
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GLint y, |
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GLsizei width, |
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GLsizei height |
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); |
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Parameters
x,
y
The
lower-left corner of the scissor box. Initially (0,0).
width,
height
The width and
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.
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 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.
The following
functions retrieve information related to glScissor:
glGet
with argument GL_SCISSOR_BOX
glIsEnabled with argument GL_SCISSOR_TEST
Error Codes
The following
are the error codes generated and their conditions.
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Error
Code |
Condition |
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GL_INVALID_VALUE
|
either width
or height was negative. |
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GL_INVALID_OPERATION
|
glScissor was called between a call to glBegin and the
corresponding call to glEnd. |
See Also