Okay, I have my Sprites in Houdini looking good in the GL Viewport, but when I do a flipbook and save them out, the Alphas become this hard edged clamped thing that follow the shape of the sprite textures, but with no soft falloff. The Alpha must be good for the textures to overlay so nicely in the GL window, but I can't figure out how to get the proper Alpha out as the Alpha in my Flipbook images.

Any ideas?

Thanks,
Craig

The alpha in the flipbook images is computed from the colour buffers. I'm not tamiliar with the details but that's almost certainly the reason the alpha is not as nice as you might hope for.

I think one of the rules behind the sprites rendering ( actually for most of the FX stuff ) is to not mess too mutch with the alpha channels. Just create another variation of your shaders and tweak them a bit until you get a result close enough to what you think should look as your alpha. Then render two image sequences and merge the color/alpha channels in compositing.

Actually in many cases is enough to render only the color channel, then just extract the alpha with keying. Should work fine.