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