How to render smooth alpha transistion between two objects? I want to smooth the intersection between two objects, similar to the soft particle effect seen in many games:



Here's an example in blender where you would want to use this effect:



I want to smooth the intersection between these two planes to simulate clouds crossing each other. Considering the node system has access to geometry data and such, would this be possible? I'm using blender render if that matters (but the theory is universal i'm guessing).
Yes the renderer has access to geometry data, but the Z-channel clipping is still sharp no matter what.

You would have to make the ground plane transparent where the particles are crossing behind it, which one can do, but it would be pointless because it's not the effect you are looking for - any geometry behind ground could be seen.

What you need to do is to render smaller particles closer to the camera that don't intersect the ground.