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particle velocity

Anya Ristow
Vengeance Studio
Join date: 21 Sep 2006
Posts: 1,243
01-23-2007 23:16
I'd like to make a glowing rod. Simple, right?

The following gives me an oblong glow:

llParticleSystem([PSYS_PART_FLAGS, PSYS_PART_EMISSIVE_MASK, PSYS_PART_START_SCALE, <.2,1.,1.>, PSYS_PART_START_COLOR, <1,0,0>]);

But it is oriented straight up, and I want it to orient to the prim. Here's a Q/A from the wiki:

Q: How do I make the rotation of the particle match the source prim with PSYS_SRC_PATTERN_DROP?
A: If you use PSYS_SRC_PATTERN_DROP then all particles are rezzed with the same orientation that ignores the source prim. You can change the rotation using PSYS_PART_FOLLOW_VELOCITY_MASK but this is a one time setting that applies to all particles. This can be faked though by using PSYS_SRC_PATTERN_ANGLE with a <0,0,0> velocity. Using PSYS_SRC_PATTERN_ANGLE causes the particles to match the orientation of the source prim.

So, I try to use PSYS_PART_FOLLOW_VELOCITY_MASK, as follows:

llParticleSystem([PSYS_PART_FLAGS, PSYS_PART_EMISSIVE_MASK | PSYS_PART_FOLLOW_VELOCITY_MASK, PSYS_PART_START_SCALE, <.2,1.,1.>, PSYS_SRC_PATTERN, PSYS_SRC_PATTERN_ANGLE, PSYS_PART_START_COLOR, <1,0,0>]);

But this gives the particles a velocity. I want them to stay still, as they were with the first example. I don't see a way to specify a velocity vector, so I don't know how to follow the instructions in the Q/A. The closest thing I see is PSYS_SRC_BURST_SPEED_MIN and PSYS_SRC_BURST_SPEED_MAX. When I set those to 0 and 0, respectively, I get a non-zero and *variable* velocity.

How, pray tell, so I specify both a rotation that follows the prim *and* a zero velocity?

Thanks,
Anya
Anya Ristow
Vengeance Studio
Join date: 21 Sep 2006
Posts: 1,243
01-23-2007 23:23
I think I found the answer. Apparently, the particles *must* have a velocity with VELOCITY_MASK, but that velocity can be very low, and with a finite life, a low velocity achieves zero movement.