Area shadow with shadow map

[Mzigaib]

I am sorry if I already ask about it here but since I didn't find it here it goes.

Anyone knows if there's something on mantra for shadow maps that works like this?

http://www.3db-site.com/html/softShadow.php

Thanks.

[Mzigaib]

Anyone?

[edward]

I'm probably missing something. You're given the source code to the RSL shader(s?) already. Can't you just convert it to VEX?

[Mzigaib]

I'm probably missing something. You're given the source code to the RSL shader(s?) already. Can't you just convert it to VEX?

Thanks for the feedback!

My bad if I wasn't clear enough, my question is if Houdini have something like that shadow shader builded in, I didn't find anything that work like that on shops but I could be missing something, and since you mention it if I want to convert it, since I am not a expert on shade writing I don't think that just copying and paste the code on VEX would work, would it?

Thanks.

[old school]

No, copying and pasting this code won't work. It's rsl and you have to convert to vex or use VOPs. There is the Light Builder Shader SHOP that you can dive in and create if you so wish. You need to add a Light Template Object and supply the light shader SHOP on this light. I would target just the MicroPolygon and Raytrace Mantra engines and not PBR with this light shader.

There is an ASAD Light shader that you can grab and modify if you wish. It's written in code btw.

No Houdini doesn't support this method of blurring opacity shadow maps. It is a pretty specialized shader and is questionable with PBR renders. And then there is shadow bias and changing scene sizes to dial in. Certainly not a plug-n-play light shader. This was also Siggraph 2006. I suspect that with today's hardware and the dramatic improvements with raytrace engines, the disparity between z-depth map soft shadows and ray traced shadows would have closed up enough to make this a tougher sell in a generic lighting pipeline. Just look at the latest direction RenderMan is moving to underscore the above point.

Not dissuading you from writing your own light shader though. If you are in to writing shaders, absolutely go for it.

[symek]

We used to re-implemented this shader in VEX somewhere around H10 or so, and it was terribly slow (which might be our fault, but this is where we ended up). Definitely not worth its efforts with PBR rendering at hand, unless you really can't ray trace your scene.

[Mzigaib]

Thank you so much for the feedback and explanations Symek and Oldschool, I really feel in debt with this forum I always learn a lot here, odforce community rocks!

Back to the shadow issue, yes I agree with you guys that with the advances today it's kind of pointless to try to create a shader to do something that is naturally created for you in raytrace unless it's a difficult shot to raytrace, the reason for my question is to learn more about shadow shaders and also it seemed to be a very useful and optimized shader technique and would be really nice to try to reproduce it in Mantra but it seems that mantra has some limitations on blurring shadow maps right?

The use for this shader would be definitely with micropolygon would be pointless to use it with raytrace.

What is really weird for me is since mantra is very similar to renderman in micropolygon why it can't do some stuff that rederman naturally can?

Anyway thanks again for the feedback!

Edited June 5, 2012 by Mzigaib