Bart Kuipers' Blog

In the last tutorial of this series, I will try to explain how to create your own shadow mapping shaders. We’ve already seen the shadows of truevision3d, now it’s time to create our own system. This is by no means the best type of shadowing, it is just good to get an understanding of what is actually happening. The system we’ll make is for a point light. The basic idea behind it is to place 6 camera’s on the place of the light, each facing outwards, so you’ve got a complete view from the camera. This is a cubemap. We’ll render the depth of the object the camera sees to the cubemaps’ faces. This then allows us to do a lookup in the direction of the pixel we’re rendering, to see if the distance of the cubemap is lower than the real distance. If it is, we have a shadow.

Everyone knows this phenomena, you can see it about the tarmac or even something as simple as a candle. A heat haze. What is happening in nature? The air above something that is hot is rising. There are pressure differences and that means the breaking index of the air is difference, in other words; the light rays bend a little. This effect is really cool to have in our scene as well, so we’ll do that. We will take the post-effect approach. What will we do? We will render the scene without the heat haze to a texture, then we’ll render the heat haze (being particles) on to another texture. Then we’ll combine it in a shader to draw it to the screen.

We’ve seen an object shader already, but now we’re going to do something more interesting. In tutorial 4 (per pixel lighting), we’ve seen some per pixel lighting already. It would be good to try and replicate or even improve this effect. We are going to do this in this tutorial. Before you continue, make sure you at least have an idea of what tangent space and parallax mapping might be.

Everyone will have seen black and white films/pictures, sepia pictures, pictures or movies with film grain etc. To get such an effect in the 3D world, we normally use a technique called post-effects. This means we apply some kind of filter after (post) rendering. This means we don’t have to do the effect on every object that’s hidden, we only apply the filter on the pixels that are actually visible. This can be really usefull and good, especially when adding some more calculation heavy stuff.

Now for the more advanced TV3D tutorials. The next 6 tutorials will be about shader and how to work with them. I’m not going to explain all about shaders, there are a lot of good resources for that already. Take a look at this wiki page: wiki. In this first tutorial we’re going to create a simple shader that will just output the cube with a texture. This can be the template for any object shader you’re going to write.

There is a light phenomena that we haven’t discussed yet. It is seen everywhere around you. Shadows. You might think we’ve already covered this, since a cube doesn’t get light when it’s not facing the light, but that’s not what we’re going to do right now. What if a light shines on that cube and there’s something below the cube? That would cast a shadow. In Truevision3D, it is not too hard to add shadows. It’s actually quite easy. It doesn’t suit all purposes and doesn’t always look like the most high end shadow solution, but it’s decent and well worth looking at.

How cool would it be to be able to render smoke? Or fire? Everyone will need some kind of particle system eventually. In this case we will make some nice smoke. You might ask yourself what a particle system is. If you wonder about that, take a look at this wiki page. In this case, we are using a billboard particle system. A billboard is like a camera oriented plane. It will always face the camera. This makes it easier to create the textures to place on it. The particle system will spawn some billboards, apply textures on them and move them around based on some rules you can set, like gravity.