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 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 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

See Also

glDepthRange