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Krzysztof Narkowicz

Member Since 13 Aug 2010
Online Last Active Today, 01:11 PM

Posts I've Made

In Topic: Transparent shadow casters with 'Translucency Map'

20 December 2014 - 03:41 PM

Crytek's approach has only one drawback - transparent surfaces can't cast shadows onto other transparent surfaces.

It works as follows:
1. Draw opaque surfaces into shadowmap
2. Clear translucency map to white
3. Draw translucents into translucency map with opaque shadow map as depth buffer and depth writes disabled
4. In order to apply shadows sample shadow map and translucency map. Shadow = Min(ShadowMapDepthTest, TranslucencyMap).

So if translucent shadow caster is behind the opaque one it will be discarded by the depth test. In other case it will modify translucency map, but it won't matter as depth test result will override this value during shadow evaluation.

In Topic: automatic light probes positioning

09 November 2014 - 04:01 PM

You could try using some heuristic to place more probes where it matters. For example you could use navmesh or height above ground.


In Topic: Grass Rendering Questions

07 July 2014 - 02:41 PM

You can use pixel shader input VFACE / SV_IsFrontFace / gl_FrontFacing to check if current pixel belongs to a front facing or to a back facing triangle. It it's back facing then just flip normal and shade as usually.


In Topic: UE4 IBL / shading confusion

29 June 2014 - 09:11 AM

Metallic works like Tessellator wrote, but it's also has an additional specular parameter (which is equal 0.5 by default). Mentioned specular parameter is driven by a cavity map (single channel).

BaseColor = Cavity * OldBaseColor
Specular = Cavity * 0.5

DiffuseColor = lerp( BaseColor, 0, Metallic )
SpecularColor = lerp( 0.08 * Specular, BaseColor, Metallic )

https://forums.unrealengine.com/archive/index.php/t-3869.html

https://docs.unrealengine.com/latest/INT/Engine/Rendering/Materials/PhysicallyBased/index.html

 

As for split sum aproximation try comparing with an reference shader, which takes hundreds of samples per pixel in real time.


In Topic: Doing local fog (again)

27 May 2014 - 02:47 PM

For an interesting general volumetric fog solution check out Assasin Creed 4 presentations by Bart Wroński: http://bartwronski.com/publications/


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