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# allingm

Member Since 30 Oct 2009
Offline Last Active Jun 10 2015 11:11 PM

### In Topic: Screen-Space Subsurface Scattering artifacts (help)

28 June 2014 - 07:55 PM

It's possible you are having depth precision issues.  If you tweak your near and far plane does the banding change size?  If this is a problem you could possibly take a different approach and only change your blur width based on the first sample.  I know the original Jimenez paper did a ddx and ddy calculation on the first sample of depth to figure out the slope.

Edit:

Oh, also, just for testing, try sampling the alpha of your specular map on each blur sample and reject the color if the resulting sample is greater than 0.  (I'm thinking my previous comment is wrong now, but I'll keep it just in case.)

### In Topic: The 3D graphics pipeline: I don't understand why clip space is a cube, or...

22 October 2013 - 11:57 PM

Personally I prefer to understand this from a mathematical perspective.  There seems to be a decent explanation here:
http://www.codeguru.com/cpp/misc/misc/graphics/article.php/c10123/Deriving-Projection-Matrices.htm#page-3

### In Topic: Object distortions on the edges of window

19 September 2013 - 06:05 PM

Shouldn't this line...

float xScale = 1.0f / tanf(0.5f * fovy);

...be:

float xScale = 1.0f / tanf(0.5f * fovx);

?

### In Topic: Fast exp2() function in shader

13 July 2013 - 01:16 AM

exp2
http://msdn.microsoft.com/en-us/library/windows/desktop/bb509596%28v=vs.85%29.aspx

The only way to find out the answer to your question is to test performance.  You can also get an idea by looking at the token assembly of your shader.

Also, integers operations were emulated with floats in DirectX 9, but 10 requires full integer support.  I don't see how they could simulate it with a float, and if they did you would notice a huge performance impact.

### In Topic: RPG Shadows, CSM, TSM, what else?

10 July 2013 - 04:12 PM

For RTW is it possible to use the previous frame's shadow map to compute the warping maps?

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