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 default is (0, 0).
width, height: Specify the width and height, respectively, 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 (xnd, ynd) be normalized device coordinates. Then the window coordinates (xw, yw) are computed as follows:

$x_w = \left(x_{nd}+1\right)\left(\frac{width}{2}\right)+x$

$y_w = \left(y_{nd}+1\right)\left(\frac{height}{2}\right)+y$

Viewport width and height are silently clamped to a range that depends on the implementation. This range is queried by calling 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