Re: Re: RE: Depth of field style blur shader + global illum/soft shadow shader?

I was looking at the different messages that you can send to jit.gl.render, and I saw something that I cant find again, but it was somethign along the lines of capture depth buffer... or something like that.. is there a way to get the depth buffer into a texture or matrix?

wow finally links and images... I could go without the smilies...

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-~=:!{[,,___________ ,.-~=:!ili!({[{[{[ www.axiom-crux.net ]}]}]})!ili!:=~-.,___________,,]}!:=~-
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Axiom-Crux wrote on Sat, 21 February 2009 19:07
wow finally links and images... I could go without the smilies...

It's not permanent. Remember that you can turn them off in your post ("Disable smilies in this post").

After it got to 24 hours, I figured people would rather have an imperfect, yet being worked on forum back rather than no forum at all.

w

are you referring to the smilies or the other tools as well? I quite like having images and html links... I think those speed up things alot, no more copy paste, just click. Images are nice too so we can show patch stills and such without also having to copy paste a link.

Axiom-Crux wrote on Sun, 22 February 2009 03:07is there a way to get the depth buffer into a texture or matrix

Yes, there's a depth_grab message that copies the contents of the depth buffer to a named texture.

We've been using it to create depth of field type effect where the blur amount is based on the distance of the pixel from the focal point - this is a common technique for most games, imo.

After some investigation, we found out that depth_grab is pretty expensive operation, so we made a shader that writes depth info to gl_FragColor and render the whole scene twice, which in our case proved to be far more efficient that depth_grab.

can I check out your depth of field effect? I have been looking for something like that. I am trying to learn shaders to do it myself but its taking a while to get up to speed.

Thank you either way nesa, your always a big help!

also, any thoughts on the technique on this page near the bottom:http://fly.srk.fer.hr/~unreal/theredbook/chapter10.html

looks like they use the frame accumulation buffer to draw the frame a few times from slight different camera positions and that makes it slightly blurred ish.. I dont know if thats realistic for complex scenes in reatime.. maybe your technique with shaders is best.

I would definitely recommend writing out depth information via a shader. This is how most real-time graphics engines do it these days (as opposed to using the depth buffer). Aside from potential performance issues, the reason for going this route is to have a linear encoding of distance. The depth buffer is non-linear for reasons I won't go into suffice to say that it's difficult/expensive to apply certain operations when the data is nonlinear.

If you're going to try this out, be sure to set your texture type to float32 otherwise depth values will be clamped to [0, 1].

wes

Axiom-Crux wrote on Sat, 21 February 2009 21:54are you referring to the smilies or the other tools as well?

Just the smilies.

Axiom-Crux wrote on Mon, 23 February 2009 01:24can I check out your depth of field effect?

Well, the problem is that our shaders do a lot of stuff that's particular to the system we're building that it would make more sense to write new shader. Unfortunately at the moment I don't have time to do it...
But I'd be glad to help you with building your own!

For the depth grabing shader you could use:

gl_FragCoord.z (more info here)

and use it to calculate gl_FragColor.

Then you apply this shader to whole scene and capture it to the texture that will contain depth info.

After this, you render&capture the whole scene again, but without 'depthshader'

Now you can send both textures to a modified blur shader that changes the width of blur kernel based on the values from depth texture.

So there's a lot of things to do to make DOF shader, even more to make it look good, but for start I would suggest just writing a simple shader that displays depth of each pixel, and when that is working we can continue for next step.

Quote:also, any thoughts on the technique on this page near the bottom:http://fly.srk.fer.hr/~unreal/theredbook/chapter10.html

This is how my grandpa would do it. And he would still get one WHAO! from me.