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 ( $x_{\mathrm{nd}}$ , $y_{\mathrm{nd}}$ ) be normalized device coordinates. Then the window coordinates ( $x_w$ , $y_w$ ) are computed as follows:

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

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

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(3G)