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Member Since 14 Dec 2008
Offline Last Active Dec 10 2013 12:25 PM

Topics I've Started

Spherical Harminics: Need Help :-(

23 October 2013 - 02:41 PM

Hi All, I've just started reading classical papers on SH (Green and Peter-Pike Sloan papers tbp) 


Our renderer by now just uses "Reflective Shadows Maps" to evaluate VPL and attempt to create a global illumination solution. Problem is that "naive" RSM just can't be used in Real Time applications. So I've started looking at more advanced techniques like LPV and Radiance Hints.


So far I understand that SH are the base of those techniques....I'll try to explain my objectives:


Goal 1: We've a 3D scene with n lights and a 64x64x64 grid over the whole 3D scene. Every "cell" is a light probe and I want to use SH to store incoming illumination from the n lights   


Goal 2: Use the 64x64x64 "probes" texture to interpolate GI for the scene in a final (deferred) renderer pass


Problem: I really really struggling understanding how SH works and how they can help me storing incoming radiance from scene lights.


Can someone help me on that and point me in the right direction?


Thanks in advance

[DX9] RSM + Volume Rendering + GI

10 September 2013 - 03:15 AM

Hi all,


I've just completed a basic support for Global Illumination for our proprietary DX9 based engine. RSM is used to to compute the first bounce of indirect illumination. An interpolation scheme is used to compute the Indirect Illumination for the whole scene. Then the final scene lighting is composed using direct + indirect contribution.....


Next Step for us is to use one of the following tech. to increase performance and quality:


  • Light Propagation Volume
  • Radiance Hints


So here come my question: how and is it possible to render a volume texture in DX9?

I mean, let's say I want to sample the RSM and store the SH into a 3D Grid using a volume texture.....is it possible using DX9 or should we go for DX10-DX11?

The goal is to reuse that computed volume texture for interpolate (indirect) light into the final scene....


If yes...can someone point me into the right direction (papers...link to website)


Thanks in advance




Camera Glow Shader

06 November 2012 - 02:49 PM

Hi All,

I really want to add an effect like this to our 3D Engine:

Posted Image

This is the so-called Mental Ray "Camera Glow Shader". We want it to apply such effects to some objects we have in the level.
Any idea/guideline about implement this?



Packing Data Advice

26 September 2012 - 01:23 PM

Hi All,

During a deferred pass on a D3DFMT_A16B16G16R16F render target I come across this problem:

I'm correctly computing a "in-scatter" value which is a float3 where every component are a 16bit float.

Is there a good way to store (even with a little loss of precision) those 3 values into a single float (16bit)?

Hints/help/link appreciated....thx

EDIT: scatter is a float3 where every component is in the [0,1] range

IoN6 Games

Scissor region from bounding sphere

03 June 2012 - 12:45 PM

Hi All, I've spent all day trying to implement Lengyel method's for computing "Scissor" region for a spehere.


code is for OpenGL and I'm working on Directx. Basically my adaptation is:
  • Compute light pos in camera space and then negate Z component
  • Compute aspect ratio = (screenW/screenH)
  • Compute e (focal lenght) as 1/tan(FOV/2)
  • Invoke Project_Sphere function
  • Set scissor rect based on top function results (scaling them from [-1,1] to screen coords

results are ok If I'm "inside" the light volume or light is not visible: problem arises when intersection are computed.
Basically the returned rect is very small compared to results I'm expecting....any advice?