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Visible Mesh collision "breaking" when scaling?


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Hello,


So, the title pretty much sums it up. I have a custom mesh I've imported into T3D, and I set the collision to "visible mesh" (I intend to create proper collision meshes at a later time, but this is just for set-up/mock-up work). I notice that I can rotate the model how ever I want and collision works fine. However, when I scale it, the collision breaks and my character runs right through it. I have multiple duplicates of the same object in my scene right now, and the ones kept at, or very near original size work fine. The ones I've scaled notably larger lose their collision.


Is there a way to fix this, or kind of "refresh" the collision to work on the larger mesh size on those objects?



And while I'm at it, a second question, can you have multiple collision meshes per object? Since collision meshes need to be convex, it would make it difficult to create a convincing looking collision mesh for an object that has an overhang or is otherwise concave in shape, without the player hitting an "invisible wall".


Thanks!

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For the first part: do you know if it stays broken if you scale the object, save, exit and reload? Or does it work if the object is created with the new scale? That'd help narrow things down


For the second part, yeah, you can either have collision meshes in the art file itself, which follow a naming convention(I beleive it's if the submesh is named Col-*, where the * is a number).

Alternatively, you can load the shape up in the shape editor and use the collision tab to automatically generate convex hull collision meshes. It's easier than doing it in a modelling program, but because it's automated, may not give the preferred results.


Either way, either of these methods will work.

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For the first part: do you know if it stays broken if you scale the object, save, exit and reload? Or does it work if the object is created with the new scale? That'd help narrow things down

 

Hi there,


I meant to include that in the previous message, but forgot to add it. No, saving, closing and re-opening the file doesn't help. Not sure how you mean creating it with the new scale? You mean create a larger version of the object in Blender and then import that?

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Okay, I just noticed something.


When I scale up the object, the visible mesh is increasing, but the collision size is staying the same. So, the larger I make it, I'm able to run further into the visible mesh before I hit the collision.


Now, I've tried finding a way to update the collision mesh after increasing it, but have not been able to do this.


I've also tried adding it as a new object, from the original DAE file, increasing the size first, *then* setting the collision, but that isn't working either. Still getting the same effect. The collision mesh is being created at the original size of the object.

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Here's a video I just recorded showing what's happening. This is the process I've used for any other object I've imported, etc, and this is the first time it's doing this, at least that I can recall.


http://tinyurl.com/zp272zv


Maybe someone will see a clue in the video as to what's happening. Apologies for the awful frame-rate. Apparently Corel VideoStudio's recorder isn't very good for 3D games, and NVidia's recorder wasn't cooperating with me. Still, it gets the idea across.

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I just tested myself and for me it works.

What build are you using? Are you using bullet or physX?

 

It's 3.8, and I'm using Physx.


I'd confirm which PhysX version, but now T3D won't get past the "loading datablocks" stage so I can get into the game/editor. Ugh lol.

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Thanks for the details MiToVo.


I'll fire it up with PhysX and have a look. Most likely thing is when the object scale changes, that's not applied to the physics rep, so it never passes along to the physics sim.


I'll let you know what I find.

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Thanks for the details MiToVo.


I'll fire it up with PhysX and have a look. Most likely thing is when the object scale changes, that's not applied to the physics rep, so it never passes along to the physics sim.


I'll let you know what I find.

 

Sounds good! Thanks!

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Looks like whatever issue you're running into with the scale not applying got fixed at some point in devhead. I spawned a static mesh, visible collision, and tested it in stock, bullet and physx3.3 and it worked in all 3 cases to scale the mesh and have collisions update appropriately.


Will need to eyeball the changes to the physics stuff to see what changes were in play there from 3.8.

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