V
glViewport
Chapter 20
479
glViewport
glViewport: set the viewport.
C Specification
void glViewport(
GLint x,
GLint y,
GLsizei width,
GLsizei height)
Parameters
x, y Specify the lower left corner of the viewport rectangle, in pixels. The
initial value is (0, 0).
width, height Specify the width and height of the viewport. When a GL context is
first attached to a window, width and height are set to the dimensions
of that window.
Description
glViewport specifies the affine transformation of x and y from normalized device
coordinates to window coordinates. Let (x
nd’
,y
nd
) be normalized device coordinates. Then
the window coordinates (x
w’
, y
w
) are computed as follows:
x
w
= (x
nd
+ 1) · (width / 2) + x
y
w
= (y
nd
+ 1) · (height / 2) + y
Viewport width and height are silently clamped to a range that depends on the
implementation. To query this range, call glGet with
argumentGL_MAX_VIEWPORT_DIMS.
Errors
• GL_INVALID_VALUE is generated if either width or height is negative.
• GL_INVALID_OPERATION is generated if glViewport is executed between the
execution of glBegin and the corresponding execution of glEnd.
Associated Gets
glGet with argument GL_VIEWPORT
glGet with argument GL_MAX_VIEWPORT_DIMS
See Also
glDepthRange
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