| What is a shader ? |
| What do we need to render a three dimensional object; 2D on your monitor? We start off by building some sort of structure that has a surface, that surface is being built from triangles and why triangles? They are quick to calculate. How's each triangle being processed? Each triangle has to be transformed according to its relative position and orientation to the viewer. Each of the three vertices the triangle is made up of is transformed to its proper view space position. The next step is to light the triangle by taking the transformed vertices and applying a lighting calculation for every light defined in the scene. At last the triangle needs to be projected to the screen in order to rasterize it. During rasterization the triangle will be shaded and textured.
Graphic processors like the GeForce series are able to perform a certain amount of these tasks. The first generation was able to draw shaded and textured triangles in hardware. The CPU still had the burden to feed the graphics processor with transformed and lit vertices, triangle gradients for shading and texturing, etc. Integrating the triangle setup into the chip logic was the next step and finally even transformation and lighting (TnL) was possible in hardware, reducing the CPU load considerably (GeForce 256). The big disadvantage was that a game programmer had no direct (i.e. program driven) control over transformation, lighting and pixel rendering because all the calculation models were fixed on the chip. And now we finally get to the stage where we can explain Shaders. Vertex and Pixel shaders allow developers to code customized transformation and lighting calculations as well as pixel coloring functionality. Each shader is basically nothing more than a relatively small program executed on the graphics processor to control either vertex or pixel processing |
As always, after the technical specs we're at the point where we quickly discuss Shader Model 3 and another hot feature of the new Series 7 products.
Talking about Shader Model 3
If you program or play computer games or even recently attempted to purchase a video card, then you will have no doubt heard the terms "Vertex Shader" and "Pixel Shader". The step from 2.0 towards 3.0 was a small one and most Shader Model 2.0 games can easily be upgraded towards Model 3.0, which can bring more performance to that gaming experience. DirectX 9 was recently updated and we are going to see more and more support for 3.0 Shaders.
Is SM 3.0 technology a huge visual advantage over 2.0? Nope, not even the slightest bit. Yet any technological advantage is always welcome and preferred over a previous generation's development. What you need to remember about Shaders 3.0 it that it can and will be used only in several critical places where it can give a performance boost and graphics cards are all about performance my friends. Both ATI and NVIDIA now offer shader model 3 support in the new products. GeForce series 6 and upwards and for ATi their X1000 series and upwards.
Talking about HDR
Another big trendy implementation that will bring games closer to a movie like quality experience is HDR.
Both ATI and NVIDIA
have been focusing extremely hard on HDR. They put a lot of money into their technology to support HDR in the best possible way, and they should as it just is a fantastic effect that brings so much more to the your gameplay experience. HDR is something you all know from games like Far Cry. It's extremely bright lighting that brings a really cool cinematic effect to gaming. This effect is becoming extraordinarily popular.
Valve recently released a new HL2 level in the form of Half Life 2: Lost Coast. Go download it as it'll show and amaze you what HDR can do. The difference is obvious. HDR means High Dynamic Range. HDR facilitates the use of color values way beyond the normal range of the color palette in an effort to produce a more extreme form of lighting rendering. Typically this trick is used to contrast really dark scenery. Extreme sunlight, over-saturation or over exposure is a good example of what exactly is possible. The most simple way to describe it would be controlling the amount of light used present in a certain position in a 3D scene.
Half Life 2 - Lost Coast level. If you bought the game it's available for free via Steam.
HDR is already present in Far Cry, Splinter Cell: Chaos Theory and in Half Life 2: Lost Coast. It will be available in Unreal 3 and likely a large number of other games, not to mention 3DMark06. Let the screenshots do the talking and click away.
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