glScissor: define the scissor box.
C Specification |
Associated Gets |
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.
- x, y
- Specify the lower left corner of the scissor box. Initially (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.
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.
glGet with argument
- 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.
glIsEnabled with argument