Monday, May 3, 2010

Still alive here

3D:

Shadow Maps
This is pretty much the standards for doing shadows in games nowdays, and the dafacto standard for doing them for movies, Shadow buffers in difference form shadow volumes is image based and can therefore handle alpha masked polygons like a fence, It also allows techniques for blurring or otherwise distorting the shadows.

Percentage Closer Filtering 
A problem with shadow maps is that they easily get pixelized even with the best intentions. Percentage closer filtering is a technique to combat those jaggies and making your shadow edges soft, We will look at different implementations for example randomised kernel rotation with a poisson disc.

Percentage Closer Soft Shadows
In the real world shadows become softer and softer the further they come from the object casting the shadow. This is how to do the same in games using a technique that builds on the Percentage Closer Filtering technique.



I was supposed to get out a post for this Monday but between the volcanic ash cloud forcing me to to stay an week in paris and nordic game conference time has been slim. But now things are normalizing. I have some interesting subjects lined up to write about.

AI:


Automatically balancing decision trees.

This is a simple and effective way to model the strategic level thinking part of an enemy that works by balancing out needs based on a personality with an assessment of the actual situation  and the resources current available to determine the next logical course of action.



3D:

Shadow Maps
This is pretty much the standards for doing shadows in games nowdays, and the dafacto standard for doing them for movies, Shadow buffers in difference form shadow volumes is image based and can therefore handle alpha masked polygons like a fence, It also allows techniques for blurring or otherwise distorting the shadows.

Percentage Closer Filtering 
A problem with shadow maps is that they easily get pixelized even with the best intentions. Percentage closer filtering is a technique to combat those jaggies and making your shadow edges soft, We will look at different implementations for example randomised kernel rotation with a poisson disc.

Percentage Closer Soft Shadows
In the real world shadows become softer and softer the further they come from the object casting the shadow. This is how to do the same in games using a technique that builds on the Percentage Closer Filterign technique.

Parallel split shadow maps aka Cascaded Shadow maps
With all the above optimizations there are still problems with shadow map resolution. Various techniques has been invented to combat this problem all building on a distortion of the perspective matrixes (Perspective shadow mapping, trapezoid shadow mapping ,light space shadow mapping etc) but all of these have problems and requires a lot of tweaking. Cascade shadow mapping tries to solve these problems by using multiple shadow maps.

Deferred Rendering ( 3 lesson series)
Deferred rendering is a technique to decouple lighting from the geometry allowing thousands of lights visible in the screen with decent performance and without need of extensive culling schemes. We willl talk about it's advantages and disadvantages and look at different implementations in games today and what people are doing with the techniques like Prelightining, light idnexed renderer and so on. This Series will bridge at least 3 lessons and require quite a bit of prior knowledge.

Screen Space Ambient Occlusion
As made popular by crysis. This technique models the ambient occlusion terms we have been showing earlier but allows calculation of them in real time instead. This allows us to have correct dynamic occlusion with moving objects in a living world.We might even go on to Screen Space Directional Occlusion.




So these are the ideas I have lined up right now, They are quite 3D heavy at the moment, but as always I will gladly take suggestions or even votes no which of these that seem the more interesting.

At worst we will start with one of these on next monday but I might get out an update before that pending on my time schedule.

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