Um, the source code on the linked site is not helping? I don't know about openGL ES, but that link would have been the first link I would have posted. I'd be surprised if ES didn't support r,q coordinates.
OpenGL ES does not work with the fixed pipe line. So I can't use glTexCoord4f.
Also, ES does not supports Quads ( Only Tri's ).
Is there a way to achieve this effect on OGL ES ?
I have read about the algorithm "[background=rgb(247, 247, 247)][font="verdana, helvetica, sans-serif"][size="2"][color="#000000"]Direct Linear Transform" but I'm not sure it is possible for a quad that built up from 2 triangles.[/font][/background]
The issues you brought up are not issues at all. A texture coordinate is a texture coordinate, so even if you cannot use glTexCoord, you still have access yo vertex arrays, and whether or not you draw quads or triangles, the effect is still the same given the same coordinates.
You're not setting the q-value of the texture coordinate as described in the link. I would say the value for the narrow part of the quad should be 0.5, not 1.0, since that part is half the size of the opposite side of the quad.
edit: The s and t coordinates need to be 0.5 as well, not only the q-coordinate.
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