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I understand what polygons, edges, verticies and textures are. I understand bump mapping. I have a good understanding of 3D world coordinates etc.

What I can't seem to figure out is this: What are shaders? I've seen examples of what they can do on Nvidia's and DBPro's website.

Is it a piece of code that describes the surface of material but doesn't acually have a texture? What the difference between pixel and vertex shaders?

Pixel Shaders make objects look beautiful (here's an screenshot from morrowind)

As I understand it......

Pixel shaders change the appearance (think of them as a programable texture)

Vertex shaders change the shape (think of them as programs that animate the shape)

The vertex and pixel shaders often work together,look at the bubble shader example in the help files, it undulates because the vertex shader (a program realy) cycles the shape to make it move like a bubble, and the appearance is altered by a pixel shader, the two work in unison to give that reflective-transparent-wobbly bubble effect where the highlight moves about.

You can make 400 bubbles as simply as making 400 spheres and adding the shader to them (pity the shader ignores the z buffer....it seems to have a programming error) , as for where you get them, try Nvidia`s dedicated shader site and ATI`s site may have some, there are also shader sites that talk about and display demo`s of nothing but shaders.

AFAIK you need to make a few alterations to make them work in DB, but it`s just altering a few of the initial lines or something, (not tried em myself yet...apart from the DB examples).

The reason you get the shader to do the work rather than the program or running an animation, is that the GFX card has specialised registers and mini cpu blocks just for handling colour and 3D data that mean the GFX card can take all the load out of handling the shapes automaticaly, and the PC can get on with running the game.

Also the card may have a slower GPU clock speed than your PC`s CPU but it can do the calculations faster than any CPU could do since it is made just to do 3D and colour, the CPU couldn`t even come close to the speed of the GPU on a graphics card (think of how much slower and worse software renderd images are compared to what the same images look like rendered on even a pretty basic ATI or Fx card)

Some of the video card researchers are currently developing cards that will do realtime raytraceing (caustics and refraction etc) in the hardware, as well as including instruction sets to allow them to handle physics and collision from properties supplied to the shader data for that shape, that should increase the speed and realism of the next-but-one generation of cards even further.

Mentor.

I was able to open a .fx file in notepad and see the code. Now I understand the basics...Very cool thanks!

This is the bit I get stuck on....what alterations?
Its not documented anywhere i can find, i really dont get how people are using these things.

What is the URL to Nvidia's shader site? I can't find it..

out of those two screenies i like the bottom one better... it fits in so much more witht the rest of scenery, it does look almost real but it seems to broken up and distracting.

http://developer.nvidia.com/page/home

and

http://www.cgshaders.org/

as for the modifications, you just need to alter the header a bit or something, it`s getting fixed in a later patch I think, it was mentioned on the forum a few times so if you can get the search to work then you may be able to find the thread.

Mentor.

There are two different types of shaders, fragment and vertex. Vertex shaders operate on every vertex in a model and can change their position, color and normal. Fragment shaders operate on every pixel in the scene and can change each pixels color(some advanced porfiles can also change depth).