Determining collision point -- object to object

Search isn't working ATM for me; So if this thread is redundant, I apologize in advance.

I'm looking for information on detecting object to object collision points. All I can see in the wiki is just getting the collider's position via llDetectedPos(). But as far as I can tell from the wiki, only land collisions support returning the actual collision point. Am I just out of luck?

I need this data in order to rez a prim at the collision point, based on the detected collision point's normal. (Imagine a bullet striking a surface and leaving behind a decal in a typical 3D game.)

You've not had a reply, so I'll have a go.

Errr...

Hmm...

I know!!

How about firing 3 bullets out of your gun, all at the same time! and then when each one hits the target's surface. you freeze them and calculate their angle relative to eachother to get the normal. Then stamp your decal down.

Hey, I'm trying!!!


Or:

Err...

Okay, I'm going to bed.

At the point the collision occurs for the bullet its position can be determined by an llGetPos() in a collision_start() event. Depending on the shape of the bullet etc. you might have to add an offset for size of bullet.

That could then be used to define the position to rez the hit "splash" effect.

This sounds like the best way I can think of to do it – on collision, get the velocity the bullet was moving at and our bullet’s size halved… And then use that as an offset and slap down the decal – I don’t know any specific function that tells you the actual exact point of collision…

Eloies: that won't tell you the angle to place the decal at.

Starax' solution is probably the only way you'll be able to do it. To keep the probes close enough, and to avoid having one clip the corner of a prim on the way, you could have the bullet res the probes on impact.

Logan: Using velocity may work... That effectively gives me a direction vector, though there might be issues when the object is bouncing along the floor/ground. (This isn't a bullet, even though I used that as an example, so it's not always moving at high speed.)

I hate to use probes; The mere fact I am rezzing visual effect prims for collisions is enough to give me the willies. (Considering how your typical gun that spews out shells and whatnot can crash a sim!)

Thanks, everybody, for the suggestions. This gives me something to try.