GLVIEWPORT()

NAME

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 ofx andy from normalized device coordinates to window coordinates. Let (xnd,ynd) be normalized device coordinates. Then the window coordinates (xw,yw) are computed as follows:

xw = (xnd+1)
⎛
⎜
⎝width over 2
⎞
⎟
⎠ + x

yw = (ynd+1)
⎛
⎜
⎝height over 2
⎞
⎟
⎠ + y

Viewport width and height are silently clamped

to a range that depends on the implementation. To query this range, call glGet with argument GL_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

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