View Full Version : Electric arcs...

05-06-2001, 11:57 AM
I'm trying to render some electric arc but I can't find a good method...
The problem is that I want the arc to look good from any angle of view, and also to have the core brighter, and fading around...
I tried using 2 ortho tri strips that looks good when you see it horiz/vert, but in the same direction of the arc I see a lot of + + +...
Hope you understand... thanks in advance

05-06-2001, 01:30 PM
Capping the ends when viewed nearly axially might help a bit. Still would look a little odd though.

05-07-2001, 11:38 AM
Mmmh... I think this will not resolve my problem: supposing the arc to draw a 'dune', in axial direction the top will show the trick of billboarding... and I think it will be too expensive to draw an orthogonal quad on every point between the segments...
I tried with multiple GL_LINES and it will not be bad, but larger lines have not good connections between segments...
How do you think the guy that wrote the demo in the picture did this? This is similar to what I want!
His site is here (bigger image) but now I can't access it: http://www.lysator.liu.se/~sdw/opengl/
It seems to draw multiple line with a little random displacement...
Another question: drawing lines is slow? Now I'm using few of these, and I can't see how perf is affected.
Thanks alllll...

05-07-2001, 12:38 PM
Ok, I looked at that demo, and it does not draw any lines. The arc is composed of 16 blended triangle strips (ignoring the reflected arc). I haven't examined the frame coherence yet, but it looks like, the strips are nearly coincident and are varied by some type of procedural noise, most likely Perlin noise. Essentially it does the same thing you describe you were doing, except multiplied by a factor of 8.

05-07-2001, 01:56 PM
Thanks! ... this may be a solution.
I'm looking at GLScene, too. There might be what I'm looking for.
Thanks again!