I’m trying to create a bubble particle system. Right now the emitter is generating the point sprites with an image I’m loading in and everything is working. I was hoping to use glScale on the texture matrix to make the bubbles look like they were transforming instead of just being stagnant pictures but to no avail. Since I’m using the gl point sprite arb I’m not really sure where I’d need to transform the texture coordinates since I’m not specifying texture coordinates. Can I use the texture matrix to do this or do I need to go into the shader? Any suggestions, work arounds?
You’ll need to go into the pixel shader as far as I know. The texture coordinates for point sprites are generated in the rasterization stage, so the texture matrix won’t be used (cause its applied in the vertex stage).
In the pixel shader you’ll get coordinates that are 0,0->1,1, you’ll need to manually change those.
Thanks MalcolmB, that worked out. I just used the texcoordinates in the frag shader and multiplied it by the texture matrix I was modifying in the app.