Variance Shadow Maps Demo (D3D10)

How do you fetch the raw samples individually in D3D10? A 512x512 render texture with 4xAA has 1024^2 samples in it.

jbizzler, are you trying to get the samples before resolving? I would expect that to look more aliased due to the jittering of the samples. AA works with VSM because the resolving is mathematically correct, and storage/performance penalties are low. You might get better results with your own custom resolve with a bigger kernel.

BTW, did you mean Andy instead of Alex?

 

Yeah, Andy, not Alex, sorry. It has been edited.

I'm confused. Does this mean the other "samples" in the multisampled texture are out an beyond the 512x512 I think about the regular texture? Do I have to, then, use the offset or something to access that info?

 

Maybe this code snippet will help:

http://forum.beyond3d.com/showpost.php?p=963649&postcount=144

Jawed

 

I tried something like that:

Code:

for(int i = 0; i < 4; i++)
[INDENT]moments += Texture.Load(int3(tex.x * 512, tex.y * 512, 0), i).xy;[/INDENT]
moments *= 1.0f / 4;

And it produced the same ugly shadow as before.

Is there something you have to do elseware. Like, after a texture is flagged to multisample, do you have to manually do it in the render loop?

 

I'm afraid I'm seriously outta my depth on this, but I thought you'd like to see another code snippet that accesses the multisamples. Someone else will hopefully help with the VSM specific stuff.

Jawed

 

Oh, I'm sorry if you felt I wasn't thankful for the help. Thanks for the link.

 

Ooh, no need to worry, just sorry I can't help with specifics relating to VSM.

Jawed

 

My problem is, if I just do a regular Sample() call, the shader fails to compile for some reason. It's just a float2 (R32G32_FLOAT), so I don't see why Sample() doens't work. Is there anything special I need to do to the SamplerState?

 

Mintmaster, thanks for solving this problem for me a while back. I had no idea what resolving was, so I didn't try it. But now I do. Thanks so much guys.

 

AndyTX, you're in the now-released GPU Gems 3! Congratulations!

 

congratulations Andy! already ordered my copy on amazon, but it seems it won't arrive before mid September

 

Cool..so moving to california was a good idea, lol
cancelling my order right now and ordering it again from amazon.ca

 

Here an example for your VSM. Much thanks for inpiration. Working in direction SAT and Parallel Split now
http://de.youtube.com/watch?v=xzusuhkST2I
you could select
"watch in high quality" under Video to have a more detailed view

 

Very nice technique. I tested it on my X3100 aswell, it has some issues with the VSM and PSVSM algorithms... at the edges of the softshadow it sometimes has a black border, seems like a wraparound issue... which is no doubt caused by the driver.
The other methods all work with visual artifacts... However, the SAVSM method with fp is really, REALLY slow on the X3100. It runs at about 3 fps, while the int method runs at 12 fps.
Again probably the driver though

Just wanted to throw it in for general reference.

 

problem when going deferred...

Hi guys,

I am performing some tests and implemented a traditional deferred pipeline in my engine.

I am experiencing some issues with my cascade VSM implementation, which worked flawlessly with the forward rendering pipeline.

Using the deferred pipeline, I get some artifacts at polygon edges, as shown below (screenshot showing the result of the shadow being applied, nothing else - no lighting, no texture, no postprocess):



Now, I have checked everything is reconstructed from the G-Buffers correctly: normals, view space position, etc...

The problem definitively comes from the shadow map not being sampled correctly. See the screenshot below, showing the result of the shadow map sampling (I modified the contrast to clearly show the error):



Now, I think this is due to the derivatives used for the texture sampling being wrong. The texture coordinates used for shadow map sampling are constructed in the pixel shader, using the view space position multiplied by shadow light view matrix.

However, the viewspace position is reconstructed using the linear view space depth, which is read from the G-Buffer in the PS.

Hence, the texture coordinates derivatives are not correct.

I am pretty sure I have to manually compute them, however I have no idea how to proceed.

Could anybody help me ?

Thanks,
Greg

[EDIT]:
I found some interesting method here http://visual-computing.intel-research.net/art/publications/sdsm/ (Andy is everywhere )

Now, one last question:

I can reconstruct the view space position of (x,y), of (x+1, y) and of (x, y+1) (x & y being pixels). Call them ViewPos, ViewPosdX, ViewPosdY.

So, I guess I have to transform these 3 coordinates into shadow light space, LightPos, LightPosdX, LightPosdY.

Then, what should I call SampleGrad with ?

I would say :
ddx = LightPosdX - LightPos
ddy = LightPosdY - LightPos

Am I right ?