I’m trying to model a rainbow and I’d like it to fade out at the edges. I can get the colors I want with a ramp, but up to now I’m not able to get a variable alpha value at the edges.
Unfortunately, it does not work to set the alpha value of the material to zero and use ‘add’ mode with a color ramp (with different alpha values). The alpha of the material seems to be constant all the way. Multiplying does not work, too.
Is there another way to get the desired effect? I know it would be possible with textures mapped to alpha, but the correct coordinate mapping seems to require a lot of effort.