"With vertexcoords, you can choose to change colors/alpha only when needed!"
It occurs to me that if the alpha is tied to the color, which is to say, it changes at the same rate (but need not have the same minimum and maximum values) then one might be able to optimize things a bit more if one could quickly find free vertcies whch they know were previously set to the values that they want them to be set to, so you don't have to update them. Of course you would still have to update some.
I suspect this would actually be slower from all the extra processing and I wouldn't want to bother with it myself. I did try something similar with blitting 2D... blititng only those pixels that have changed... a "difference buffer" I called it. But it was actually slower than just blitting normally.
It occurs to me that if the alpha is tied to the color, which is to say, it changes at the same rate (but need not have the same minimum and maximum values) then one might be able to optimize things a bit more if one could quickly find free vertcies whch they know were previously set to the values that they want them to be set to, so you don't have to update them. Of course you would still have to update some.
I suspect this would actually be slower from all the extra processing and I wouldn't want to bother with it myself. I did try something similar with blitting 2D... blititng only those pixels that have changed... a "difference buffer" I called it. But it was actually slower than just blitting normally.