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What is a collision Prim?

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    What is a collision Prim?

    Working on a shotgun that uses a loop to spawn multiple particles.

    I have had a ton of problems
    https://forums.unrealengine.com/deve...ll-projectiles

    Thinking it might be some way performance related i picked the smallest mesh i could find...the 1x1x1 cube in the engine and it worked except it doesnt collide with anything to generate hit events

    So i made a cube the same size in blender and imported it and i was back to the old problem of limiting 1-3 spawns on the loop.
    Playing around I found I could spawn 30+ of a foliage I have with it's materials and everything.

    Only thing I can see when I glance at the files is the foliage and cube that work share that they have " collision prim: 0"
    while everything else has atlease 1.

    What is a collision prim? why would it cause this?
    and what can I do to fix this issue?

    #2
    collision prim, AKA: collision primitives. the 1x1x1 cube does have collision on it. im guessing your spawns are colliding with each other so they don't spawn, try setting them to always spawn.
    CEO of Prydetech

    https://www.artstation.com/ixicalibur

    Originally posted by ixicalibur
    Here you go, this is a link to every tutorial you could ever need plus instructions to access all the collective knowledge of mankind: [Super massive awesome link that every amazing game developer uses to instantly learn to be super awesome at making stuff]

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      #3
      Originally posted by ixicalibur View Post
      collision prim, AKA: collision primitives. the 1x1x1 cube does have collision on it. im guessing your spawns are colliding with each other so they don't spawn, try setting them to always spawn.
      Thank you for answering...I actually came up with a solution finally....shouldve updated these board....

      It's not the actual 1x1x1 M cube. In the engine files there is a really small 1x1x1 (i think it is a CM ) that has xyzPiviot on end of it's name.
      I did find out that primitive were. Not what I expected as primitive usually means simple...and it's the more complex of the collisions.

      To get the system to work:
      I made a copy of the little material less, primitiveless cube.
      Moved it over where I keep my bullet meshes. And opened it. I added a simple cube collision.
      And they work perfect.

      doing a quick read in to documentation it seems that primitives can be set to varying degree of accuracy for objects. When I imported a Small UV sphere from Blender and it have convex collisions they probably take a bit to process.
      The loop though is basically instant. So when the spawning finished, the actor probably spawned where the loop WAS at that time. which would explain only getting 1-2 and TYPICALLY toward the end rotations spread.

      Experimenting a bit, i loaded up other objects with convex primitives I had attempted (things from blender) and removed all collisions and applied a simple cube. They would now work fine, even attempting spawns up to 50+

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