Rendering fire in OpenGL

Question

I want to render a fire effect in OpenGL based on a particle simulation. I have hundreds of particles which have a position and a temperature (and therefore a color) as well as with all their other properties. Simply rendering a solidSphere using glut doesn't look very realistic, as the particles are spread too wide. How can I draw the fire based on the particles information?

Answer 1

If you are just trying to create a realistic fire effect I would use some kind of re-existing library as recommended in other answers. But it seems to me you that you are after a display of the simulation.

A direct solution worth trying might be replace your current spheres with billboards (i.e. graphic image that always faces toward the camera) which are solid white in the middle and fade to transparent towards the edges - obviously positioning and colouring the images according to your particles.

A better solution I feel is to approach the flame as a set of 2D Grids on which you can control the transparency and colour of each vertex on the grid. One could do this in OpenGL by constructing a plane from quads and use you particle system to calculate (via interpolation from the nearest particles you have) the colour and transparency of each vertex. OpenGL will interpolate each pixel between vertexes for you and give you a smooth looking picture of the 'average particles in the area'.

Answer 2

You probably want to use a particle system to render a fire effect, here's a NeHe tutorial on how to do just that: http://nehe.gamedev.net/data/lessons/lesson.asp?lesson=19