The following IRIS GL viewport functions have no OpenGL equivalent:
With the IRIS GL viewport function, you specify the x coordinates (in pixels) for the left and right of a viewport rectangle and the y coordinates for the top and bottom. With the OpenGL glViewport function, however, you specify the x and y coordinates (in pixels) of the lower-left corner of the viewport rectangle along with its width and height.
The following table lists IRIS GL viewport functions and their equivalent OpenGL functions.
| IRIS GL Function | OpenGL Function | Meaning |
|---|---|---|
| viewport(left, right, bottom, top) |
glViewport(x, y, width, height) | Set the viewport. |
| popviewport pushviewport |
glPopAttrib glPushAttrib(GL_VIEWPORT_BIT) |
Push and pop the stack. |
| getviewport | glGet(GL_VIEWPORT) | Returns viewport dimensions. |