Sunday, January 31, 2010

Volume Light Rendering

So I took a slight detour from my rendering plans. I dived into volume lights instead of writing that Blinn shader. I initially thought that it would be easy, but it really was not. I had a lot to understand about how the different shaders work together to make this work. In most other 3d programs my experience is that the volume light is a function of the light. However in 3delight this is not the case. It's a bit more cumbersome but I can sort of see why you would want to do it this way for one important reason, it's a volume in space and you can limit it much better and have more control over it, if it's separate. But the work flow to make it works like this:

1. Make  a scene with a back wall and put something in front of it.
2. Make a light that cast a deep shadow.
3. Make another object, give it some geo properties so it is transparent, assign and interior smoke shader to it.
4. Make sure the volume object is bigger than your back wall.
5. Turn on all the check boxes in the shadow map section in renderglobals

So yeah a convoluted, but worth it. No I just have to see about making it render faster because I'm sure my settings are not good. Time to look in to that step size parameter.

Saturday, January 30, 2010

Soft area shadows from a single shadow map

I knew you could create soft shadows from mulitple shadow maps and doing some averaging to blend them into a single soft shadow. But I didnt know you could do it with only a single shadow map. But Bertrand Bry-Marfing found a way and put the shader up on his site:

So now I've been able to compile the shader and use it in maya with 3delight. I was going to try for something like this after I got the occlusion stuff to work but since he had the shader already I figured I could give it a go. It also works with deep shadowmaps !

Thursday, January 28, 2010

I wrote a point cloud!

I rendered out a point cloud from maya! I know! Exciting! So know I just have to make a shader that uses that to make an occlusion pass and I've succeded in step one of my renderman goals.

My next step is to create a blinn shader that willl bake out it's own lighting and shading into the point cloud so I can use that to start doing some fake GI bounces. This is all very exciting to me. I'm so used to ray tracing everything and having to worry about fitting things in to memory but now I will not really have to worry so much about that. I'll be able to render trees and grass and still have occlusion and some form of GI color bleeding, very fun. I should write a tutorial up soon.