HP Workstation zx2000 OpenGL 1.1 Reference for HP-UX 11.x - Page 385

R glRect Description glRect supports efficient specification of rectangles as two corner points. Each rectangle command takes four arguments, organized either as two consecutive pairs of (x,y) coordinates, or as two pointers to arrays, each containing an (x, y) pair. The resulting rectangle is defined in the z = 0 plane. glRect(x1, y1, x2, y2) is exactly equivalent to the following sequence: glBegin(GL_POLYGON); glVertex2(x1, y1); glVertex2(x2, y1); glVertex2(x2, y2); glVertex2(x1, y2); glEnd(); Note that if the second vertex is above and to the right of the first vertex, the rectangle is constructed with a counter-clockwise winding. Errors • GL_INVALID_OPERATION is generated if glRect is executed between the execution of glBegin and the corresponding execution of glEnd. See Also glBegin, glVertex Chapter 16 385