glViewport - set the viewport
void glViewport( GLint x, GLint y, GLsizei width, GLsizei height )
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.
glViewport specifies the affine transformation of x and y from normalized device coordinates to window coordinates. Let (x , y ) be normalized nd nd device coordinates. Then the window coordinates x , y ) are computed as follows: w w width x = (x +1)----- + x w nd 2 height y = (y +1)------ + y w nd 2 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.
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.
glGet with argument GL_VIEWPORT glGet with argument GL_MAX_VIEWPORT_DIMS
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Fri Dec 6 11:18:03 EST 1996
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