glViewport example c c++ objc java

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 surface (e.g. window), width and height are set to the dimensions of that surface.

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:

xw = ( xnd + 1 ) width/2 + x

yw = ( ynd + 1 ) height/2 + y

Viewport width and height are silently clamped to a range that depends on the implementation. To query this range, call glGetInteger with argument GL_MAX_VIEWPORT_DIMS.

Errors

GL_INVALID_VALUE is generated if either width or height is negative.

Associated Gets

glGetInteger with argument GL_MAX_VIEWPORT_DIMS

Copyright

Copyright © 2003 Silicon Graphics, Inc.
This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.

See Also

glDepthRange, glGetInteger

Example of glViewport

void reshape(int width, int height)
{
 glClearColor(1.0, 1.0, 1.0, 0.0);
 glMatrixMode(GL_PROJECTION);
 glViewport(0, 0, width, height);
 glLoadIdentity();
 gluOrtho2D(-0.5,0.5,-0.5,0.5);
 printf("reshape function called. ");
}