Basics

Now let's talk about a very important and mostly underestimated attribute of particles, the my_bright option.
If you turn this flag ON, the particle bitmaps are not normally drawn over or mixed (transparent parts) with the background anymore, their colors are added to the background. 
If you know what the additive color synthesis is, then you'll have a good idea of what I mean. Ofcourse it's not a good simulation of the synthesis, but you can achieve similar effects with some tweaking.

Simply said, the particles can only lighten the background, never darken it, so they recieve a 'glowing' effect.

Let's put the line

my_bright = ON;

into our function and see what happens...

We also increase the particle size to 750 in order to get more particle-overlappings and fortify the glowing effect.

You can find the modified files 'tut3.wdl' and 'tut3.wmp' in the tutorial-templates directory. Build and run the level and watch our improved effect!

If you look closely, you will notice that the colors of the dark blue particles add up all the way to a bright white if enough particles overlap.

So .. with all this basic knowledge, you are ready to process to the fire tutorial .. have fun there :)