Greetings.
Blender 2.44 on SUSE Linux 10.2
Am I doing something wrong, or have I found a bug?
I want to animate hair colour going from red to yellow from frame 1 to frame 50.
So I do this:
I select the hair emitting mesh.
I enable particles, and set them static and vect and som initial speed.
On frame 1 I set the material colour to red and make an RGB key.
On frame 50 I set the material colour to yellow and make an RGB key.
Now, no matter what frame I am on the rendered hair is yellow. Also on frame 1 with the red key.
When I walk through the animation with the frame counter in the GUI, I see that the color sliders do the right thing – shifting from red to yellow over the 50 frames.
If I delete the particle system from the mesh, the mesh colour animates fra red to yellow as expected.
So it is like if the rendering system does not properly pick up the colour animation, when the mesh is used as a particle emitter.
Can anyone confirm the bug, or tell me what I do wrong?
Best regards 
Johnny
assuming you have no geometry dupli’d to your emitter, and that you’re using a basic material, it works as expected for me. Remember though, that the keyed color changes with respect to particle age, not absolute time. (OS X py 2.3 build)
edit: works on linux i386 32bit build as well.
check out http://www.peerlessproductions.com/tuts/pages/Particles.html for animating particle colors…
Change the particles from static back into halos an it will probably work just fine. You will probably have to animate the effect in the nodes compositor. Once you convert to particles the color change is designed to occur over time AND space. When you convert to static the normal speed is lost and the effect breaks. You’ll need to multiply the alpha channel from the particles by some color that you want to change them to (they need to be on their own, separate render layer to do this…make sure you enable only Solid and All Z on the top set of buttons on the render layer tab). Plug the alpha channel into the top yellow socket of the mix node and set the number to 1.0 and the type to multiply then set the color on the bottom channel of the node to the color you want the particles to change to. Now you need to use a time node to difference the the render layer image output by your newly redefined particle color but I’m going to let you use the wiki to figure out how to do that part for yourself. You’re also going to have to use the wiki to discover how to recombine render layers for yourself if someone else doesn’t come along to help you. I just think you’ll get a whole lot more under your belt this way.
http://wiki.blender.org/index.php/Manual/Compositing_Nodes
Thank you dschnell289 and RamboBaby.
dschnell289, could you perhaps tell me exactly how you achieved the effect?
I just can’t get it to work, and the tutorial video contains nothing about animating the colour of static vect particles.
RamboBaby, thank you for your pointers. I may have to sit down and learn how to use the node system.
It strikes me as a very complicated way to do a very simple thing.
But if it’s the only way…
I just got the idea that perhaps in this particular situation a simpler solution, than a bunch of nodes, would be a tiny script that changes the emitter colour on each frame change.
Any advice on that?
Best regards
Johnny
Well, if you enable the “Mesh” option in the particles buttons and press ALT+A in the 3D window you will see that the base mesh DOES change color. It’s like Dschnell mentioned…“Remember though, that the keyed color changes with respect to particle age, not absolute time.”…The problem here is that static particles have an INFINITE lifetime, and the NOR factor no longer controls their speed, it controls their length. The node set up that I mentioned is really not complicated at all. Ya gotta work wit wat ya gots, mang!
B4 Blender hade the nodes this really WAS a complicated affair.
Sorry Johnny - I didn’t click the static button - what I tried earlier was for plain particles.
I don’t have time to play and test, but there may be a way to control the effect with the material node (not composite node), and a colorband on a blend texture mapped to strand. (similar for hair). Then figure out how to animate the blend texture. Might be as simple as animating the ofsZ value. Check out Cog’s tutorials for these as well. (cogfilms.com).