View Full Version : Spirtes and expressions

01 January 2011, 10:17 PM
Hi so i'm sitting with a particle system of sprites, which seems to be ignoring everything i tell it through expressions, unless it's me who's doing it wrong - which is more than likely as i'm not very good at expressions and dynamics really.

i'm trying to get the particle system to smit out sprites, in random size, which picks up a random frame from the sequence of images assigned to the shader i applied to the sprite.
on top of this, i also want the sprites not all to face the camera and be a bit more 'random facing... these are the expressions i wrote, which maya seem to ignore completely, despite that fact that maya is not complaining about them being wrong..

particleShape1.radiusPP = rand (0.01,2);
particleShape1.rotationPP = <<rand (0,200), rand (0,200), rand (0,200)>>;

it picks up the shader image sequence just fine, it just doesn't randomize the frame, just goes through the sequence for the first 10 frames (theres only 10 frames) then goes back and sticks frame 1 onto all the sprites for the rest of the animation

any n all suggestions would be much appreciated.

01 January 2011, 06:15 AM
The sprite particle type uses the "spriteScaleXPP" and "spriteScaleYPP" to control their scales as a sprite is a 2 dimensional image.

Sprites will always face your camera this is why they are sprites and not cards. So not much you can do about that unless you switch to instanced planes onto your particles.

The image sequence thing you have partially right, you have to turn on interactive image sequencing and then remove the expression controlling the image number, then set a key on your start frame with the first number of your sequence, and move ahead 9 frames in your case and set a key for the last image number. Now your sprites should cycle through your image sequence properly.

Hope this helps.

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01 January 2011, 06:15 AM
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