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Bas Zalmstra

Member Since 11 Aug 2004
Offline Last Active Oct 14 2012 10:39 AM

Topics I've Started

O'Neil Atmospheric scattering scale function

17 May 2011 - 03:21 PM

Hey all,

I have implemented O'Neils atmospheric scattering from space as described in GPU Gems 2. I have got it working the way I want except that I having trouble making the atmosphere larger/bigger. O'Neils implementation uses a predefined scale function which limits the atmosphere to be 2.5% larger than the planet itself. Currently this is what I have:

Posted Image

What I want to achieve is a larger atmosphere, as seen in Spore for instance:

Posted Image

It is obvious that in the screenshot above the atmosphere is much larger than 2.5% of the planet..

So my question is: how to adapt O'Neil atmospheric scattering approach to account for a larger atmosphere.


07 August 2008 - 11:37 PM

I know that C# doesn't nativly support SSE SIMD instructions. C++ however does. What if a person was to implement a wrapper to do SSE instructions in managed c++. You'd be able to use SSE instructions. 2 options: Wrap SSE instructions: Create an object to represents a SSE datatype. This object implements default SSE instructions like addps, etc. I figured that the problem with this is that the compiler doesn't know how to optimize the SSE intructions, if we would chain them together in C#, or any other .NET language for that matter. (or does it?) So we need to find a way to optimize these instructions in an earlier stage. Create specialized objects: Another way is to implement specialized data types, in managed c++, that internally handles SSE datatypes and operate on them. Examples are matrices, vectors, packages of vectors, you name it. This allows the c++ compiler to optimize the SSE code for us, right? I could find very little information on the matter on the web. What do you think about the subject? Regards, Bas

Faked dynamicly animated water

20 June 2008 - 10:39 AM

Hey there, I have a question regarding the implementation of a very big lake. I'm trying to create a rather large water surface. Water is only reflective (not refractive.) I am moving rowing boats over this water plane. With all settings on high (regarding the water) I want the water to feature boat wakes eg. dynamic waves caused by a moving boat. I also want the water to interact with the paddles of the boat when they hit the water. I figured that because I only have two sorts of interaction, circular-(by the paddles) and boat waves, I do not need to implement a fully dynamic system. My idea was to update the height or normal map of the water by just rendering the (prerendered) wave formations into a map. Also, I have artifacts caused by the reflection being cut of. I tried to solve the problem by moving the clipping plane a bit. This solved the problem but then the reflection looked kind of unrealistic. I read a thread here on gamedev stating the same problem but the author of that thread said the problem was caused by refraction instead of reflection. I must also note that I am trying to keep the tesselation count of the plane, which I use as the water surface, as low as possible. I don't want very big occean waves because I want a kind of flat surface for the boats to cruise on. Just a nice looking distorsion. Does anyone have a good idea of how I could implement this the best way? Do you think I should go for a fully dynamic animated water mesh, like described by Yann in his lecture about water? Or is there a simpler way I cant get my head around? Bas

Fast Depth of Field Rendering with Surface Splatting

18 April 2007 - 08:46 PM

Im currently working on getting Depth of Field to work. I found a great paper from ATI and implemented this. But I soon found that a problem occures when using transparent objects. For instance, you have a window and behind it is a box. When focussed on the box the window should be blurred and when focussed on the window the box should be blurred through the window. After a while I found this paper. But I could not make a lot of sence of it. Did anyone implement DOF as presented in this paper and who would like to share the details with me? Or does someone know an other solution for this problem? GBS

3D Studio max Fur artifacts

21 March 2007 - 09:09 AM

I have a problem with fur rendering. I made a small grass plane. A character is in front of the grass. The camera starts between the two. You see the back of the character. Then the camera starts rotating around the character. When the grass is almost visible the whole background is colored in the colors of my grass. Looks like some strange artifacts. Does anyone have a clue? GBS