particles passing through objects

I have created a mist for a castle moat, using the steam particle script from the Particle Laboratory. The particles are ejected horizontally using a cone, which seems to give all around mist which is what is wanted.
Unfortunately the mist also goes through the castle walls into the castle. Is there any way to prevent this, my knowledge with particles is still at the 101 level.

Sorry if this issue has been posted anywhere else, a search didnt help.

No collisions are calculated for particles. They will simply continue to travel along their velocity- and/or force-defined paths until expiration, unless targeted on a specific object/avatar, but that is a point destination, not a plane or solid intersection such as you are looking for.

Thank you for that quick reply. It will save me the headaches of trying to work out what is not possible. I will still consider alternative ways, essentially of getting a semicircular spray of particles, in the horizontal plane only, directed away from the castle ...

You can figure out the maximum radius the particles will travel before dying. If you use the following parameters for your particles:

[ ...
PSYS_SRC_BURST_RADIUS, startRadius,
PSYS_SRC_BURST_SPEED_MAX, maxSpeed,
PSYS_PART_MAX_AGE, particleAge,
PSYS_PART_END_SCALE, endScale,
... ]

Then the maximum radius of the particles from the emitter origin should generally be about: startRadius+maxSpeed*particleAge+0.5*max(endScale.x, endScale,y, endScale.z

So if you place your emitters that far away from the wall, none of the particles should leak into the castle. You might have to place quite a few emitters to try to cover the area right next to the wall though.

In other news, try PSYS_SRC_PATTERN_ANGLE if you truly want a flat semi-circle.

The PSYS_SRC_PATTERN_ANGLE approach appears to have worked fine.

Thank you all for your valued feedback and input.