Hi all,
I am drawing some 2d explosions using OpenGL triangle strips.

http://2.bp.blogspot.com/_vMC6A9wL7B...Screenshot.png

I would like to make the explosions look more like this (with shock-wave ring, ignore rest of explosion):



Here is the code I currently use:

[pascal]Procedure TExplosion.Draw;
Const
cSegments = 20;

Var
p : Integer;
t : Single;
a : Single;
r2 : Single;
r1 : Single;
ex : Single;
ey : Single;
Begin
If Time < 0 Then Exit;
t := Time / TTL;
r2 := MinRadius + MaxRadius * (1 - t);
r1 := r2 - 25;
If r1 < 0 Then r1 := 0;

glPushMatrix;
glTranslatef(x,y,0);
glBegin(GL_TRIANGLE_STRIP);
For p := 0 To cSegments Do
Begin
a := p * 2 * PI / cSegments;
ex := Cos(a);
ey := Sin(a);
// outer ring edge
glColor4f(1,0.2,0,t);
glVertex3f(r2 * ex,r2 * ey,0);
// inner ring edge
glColor4f(1,1,0,t / 2);
glVertex3f(r1 * ex,r1 * ey,0);
End;
glEnd;
glPopMatrix;
End;
[/pascal]

Any ideas?

I'm sure I could make a nice texture, but I am not sure what U,V coordinates I would use inside the code when doing the triangle strip...

cheers,
Paul