Simple particle direction

Hi all.

I have a prim that emits particles. It is a gun barrel.

the particles shoot straight and fast... problem: They do NOT emit in the direction the barrel is pointing at.... excatly 90 degrees off.

Imagine pointing a gun straight out away from you, pulling the trigger, and blowing off your foot.

That is my dilemma.

My code for the direction is:

PSYS_SRC_ANGLE_BEGIN, 0.0,
PSYS_SRC_ANGLE_END, 0.0,

changing the values to PI shoots upward.

Other values give wild spreads...


it seems that the axis of the prim is the issue... but dammit, barrels have a direction, so I can't change that, and also, I can NOT add prims.

how to get these particle bullets to point along the barrel?

Thanks!

Particles emit in the direction of the Z axis of the prim. i would assume the barrel would be a cylinder, in which case, the Z axis would be the correct one. if it some other shape prim, i would simply attempt to turn it so the axis faces the correct direction. a bit hard to say without seeing the gun in question.

did you try the FOLLOW_MASK flag?

See /54/4f/209783/1.html

which gives an explanation of and simple example of how to set up PSYS_PART_FOLLOW_SRC_MASK and getting particles to emit in a specific direction.

I'd guess your using a tube rather than a cylinder since a tubes Z axis is not along its length, if you can edit linked parts (which I figure you might not be able to sinceyou can't add prims?) you can bring up the stretch controls and the blue boxes show z axis.

Switchign the tube for a hollowed cylinder would be the easy option if you can without messing up the build

Make the barrel of the gun out of a cylinder (not a tube) and set to appropriate sizes, say

x = 0.05
y = 0.05
z = 1.25

set the rotation to:

x = 0.00
y = 90.00
z = 0.00

Use the following llParticleSystem call:



The particles will shoot in the direction that the end of the gun barrel is facing.
Keep PSYS_PART_FOLLOW_SRC_MASK in place but add any other necessary flags for the effect that you are trying to create; change the texture, colour, speed etc etc to suit.

The above llParticleSystem call provides a handy template for any 'directional' particle effects

As stated above, the only solution is to fix the emitter prim to point in the correct direction, or use another tiny, invisible prim which is, if you can't change the build. Chances are, if you are using a cylinder as the barrel, you can put the particle system script in it and control it with link messages, if the root prim with the rest of the code is elsewhere.

PSYS_PART_FOLLOW_SRC_MASK isn't a good choice for guns, because it will move the whole particle stream with the gun and avatar, but not like people think it does. It won't change the direction of the particles at all, only their path of movement in a wholesale fashion. Basically it works like this:

Emit Particle:
Base_Position = Emitter_Position;
Offset = (initial transformations using the emitter position as the origin);
Particle_Position = Base_Position + Offset;

Update_Particle:
Offset = (updated transformations);
if (PSYS_PART_FOLLOW_SRC_MASK is set)
Base_Position = Emitter_Position; // Make the particle position "follow" the emitter position; note that rotation is NOT included!
Particle_Position = Base_Position + Offset;

Actually, it is a tube... a vastly more useable cylindrical shape.

I do not have the option of using a different prim.
I do not have the option of adding a prim.

The Tube seems to be the crux of the issue!

Indeed, I've used tube extensively, but i never noticed the Z Axis doesn't take the same direction as the Cylinder. How unfortunate. :\

The maths are beyond me, but it should be possible to set PSYS_SRC_ACCEL based on the rotation of the barrel to accelerate the particles in the correct direction.