Welding glow

# 1 30-11-2002 , 07:42 PM

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I've been fooling around trying to make a realistic laser welding, but it is quite hard to make the the color on the weld fade from glowing yellow\orange to the dark gray weld when it has cooled down. The idea is to animate the welding cooling down at a certain rate. The way I have tried to acheive this, is to "spawn" a series of sphere(sw) particles along the same path as the laser beam is aiming at, and set a per-particle color ramp. The only problem is that it won't work on software rendered sphere particles. Is there a way to get around this issue?

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# 2 01-12-2002 , 12:37 AM

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Re: Welding glow

sphere is a hardware render type for particles (at least in my maya 4.5 maybe your maya can do spheres in software). and i think on hardware particles you cannot use a ramp. what you want to to is use a cloud (s/w), limit the number of particles, and give them constant lifetime. this will let the emitter shoot single laser beams out (if you put the right force to the particles) and if they die, there is a new shot from emitter. the color ramp works great on a shader, just connect the ramp to the life color. just make it from yellow->orange->grey and make another from black->white and connect this to life transparency. incalandescence needs to be put up higher as well, so the laser is lit - probably also with a ramp. and dont forget to make the lifetime endless (if you use "life forever" the color wont change with time for one particle).

hope that gets you started.

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# 3 01-12-2002 , 01:53 AM

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Re: Re: Welding glow

Originally posted by BabyDuck
and i think on hardware particles you cannot use a ramp.

Originally Posted by

Babyduck: Sure you can use ramps with hw particles. Just add rgpPP attribute to the particleShape and map a ramp to it. By default the particle color is then taken from the ramp based on it's age.

DukerX: Why don't you use the hardware renderer for the particles and composite it with the other stuff in your scene?

Kari
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# 4 09-12-2002 , 08:53 PM

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Hardware/Software

I dont care if it's hardware or software. I've discovered some problems using spheres, because they apear somewhat strange when animated by a "motion path".

The deal is that I'll just use a semi-transparent red poly-cylinder with a glow-effect added to it to make the laser beam, and when the laser beam moves along a path, wich is planar on a "metal" surface, it's shooting sparks and stuff from a particle emitter, wich is animated by the same "motion path".
This is the simple part. (Really!).

The hard part is to make the moving laser beam leave a glowing trail as it moves across the metal plate. For those of you that have seen Matrix (I beleive most of you have), I'm trying to "copy" the effect used when the squid-creatures are cutting throuh the hull of the hovercraft. There you can see the cutted metal edges are glowing. White just where the laser beam was, and more yellow-ish on the edges that have cooled off some, and if you would watch the cutted edges over some time (more than the 2 seconds in the movie) you could see the glowing edges fading from bright yellow through orange and back to gray/black, and this would happen in a linear fashion across the time-line, so the beginning of the cut would be orange and the end of the cut would be bright yellow, because it has not cooled off as much as the beginning of the cut.

That's a simple...? description of what I want to animate. I have acheived this partially by using hardware-rendered sphere particles with a PPrgb ramp, and the emitter folowing the same motion path as the laser beam (or did I use SW cloud on top of the spheres..? Can't remember) The problem is when the motion path has a curve, that moves towards the camera, and then away from the camera, the particle closest to the camera apear as the first sphere in the row, so the geometry looks odd. (Try animating a particle emitter with speed set to 0 and density set high enough to make the spheres overlap (5-10 spheres overlaping eachother) and animathe the emitter with a curved motion path. It looks odd!

Blobby (SW) particles behave in a much more welding-like manner, but I'm unable to apply a per-particle color ramp to make the cooling metal effect that I want.

Ill bring some pictures later. (MAYA@home Internet@work)

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Welding glow

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