Comments on: Working on shadows…

By: XNA Bits « XNA Tidbits

XNA Bits « XNA Tidbits — Tue, 15 Jun 2010 18:39:13 +0000

[...] other little tools. This game is again about 30% written, but after seeing Catalin Zima’s 2d shadows I may have to make some changes to my own level [...]

By: John Hampson

John Hampson — Tue, 15 Jun 2010 12:45:37 +0000

Hi Again,

Or are you actually creating the ray in one shader pass and running a texture lookup all along the ray to find the closest occluder?

@ Catalin, a little late, but congratulations on getting married!

By: John Hampson

John Hampson — Mon, 14 Jun 2010 19:52:01 +0000

Hi Brett,
Would you mind explaining how you stored the occlusion information? I’ve been trying for a while now and can’t figure out how to store the distance of the occluders along a ray in such a way that the pixel shader can read them later.

If you wouldn#t mind, it’d be great to see until Catalin has finished his tutorial.
thanks

By: Brett

Brett — Wed, 12 May 2010 00:55:47 +0000

Thanks a lot I went that direction and it works great. Much much more efficient than ray tracing each pixel. Thanks for the idea, you’re a genius.

If anybody is interested I’ll share my code after I add add multiple light sources and optimize it a little

By: Catalin Zima

Catalin Zima — Tue, 11 May 2010 21:56:46 +0000

In the shader

By: Brett

Brett — Tue, 11 May 2010 20:56:12 +0000

Do you do the occlusion checks for each ray on the CPU or in the shader?

By: Борис

Борис — Tue, 27 Apr 2010 12:34:48 +0000

А вы сами так пробовали?

By: Michael

Michael — Fri, 05 Mar 2010 05:22:01 +0000

Ive been trying to work out the same thing, starting by modifying A*, unsuccesfully of course. But i think i may understand your method. You create a ray map by checking each occluding pixel and setting that pixel edges angles and distance from the light source, if its not completely enclosed in an existing ray. next, you render the shadow map by drawing all pixels not even partially obscured by an occluding pixel’s ray. As an added bonus, you can simulate transluscent materials by adding a falloff multiply value and possibly even a colour value to the ray. I havn’t tried this (i am at work) but it seems to work in my head and on paper.

Cheers,
Michael

By: Pnikosis

Pnikosis — Fri, 15 Jan 2010 13:48:33 +0000

Nice sample Chance! I’m totally ignorant about graphics programming, and I’ve been looking for implementing 2D shadows as well, so I’ve been following this thread with big interest.

And thanks Catalin for sharing with us your knowledge (right now I’m using your old 2d shodows method), and for this interesting discussion.

I’ll keep following this comment thread with great interest. Cheers!

By: Catalin Zima

Catalin Zima — Thu, 14 Jan 2010 08:52:05 +0000

Thanks,
I’ll try to take a look at it later