Multiple bodies using the same collider

[Spek]

Hi,

A question about creating colliders. I would expect that a single collider can be used for multiple bodies. For example, when
initializing my app I create a collider made of 2 convex point clouds:

Code: Select all

   // build collider
   colliderCount   := 2;
   colliderArray[0]:= NewtonCreateConvexHull( nWorld, mesh[0].vertexCount, @mesh[0].vertex[0][0], 12, mesh[0].localMatrix[0][0] );
   colliderArray[1]:= NewtonCreateConvexHull( nWorld, mesh[1].vertexCount, @mesh[1].vertex[0][0], 12, mesh[1].localMatrix[0][0] );
   
   staticData.nCollider := NewtonCreateCompoundCollision( nWorld, colliderCount, colliderArray );


Later on, I make use of this collider:

Code: Select all

   // build body
   nCol  := staticData.nCollider;
   nBody := NewtonCreateBody( nWorld, nCol );


Everything goes ok for the first body. But when I use the same collider again for a second body it behaves strange. The body falls through the ground, it doesn't collide properly with other objects, it doesn't fall straight downwards, etcetera. As if its collision hull was messed up. However, if I draw the hulls with Newton's debug tools, the shapes are correct though.

The problem is solved when I rebuild the collider for every body again. But... do I really need to rebuild the collider each time again, or can I share a collider between multiple bodies and is there something I'm doing wrong now? By the way, the collider doesn't get released until the program ends.

Greetings,
Rick

[Julio Jerez]

yes

[JernejL]

But only in newton 2.0, in newton 1.x compound collisions made with NewtonCreateCompoundCollision cannot be shared (if you share them they end up with strange glitchy behavour), if you use newton 2.0 you can reuse them as much as you want.

So while newton 1.x can share all other "colliders" just fine, it cannot share compound collision, but in newton 2.0 it can (i use it for massive spaceships so it definetly works in newton 2.0).

[Spek]

That explains. Allright, but Newton 2 is still in 'Beta' stage right? I've downloaded it a while ago, but couldn't compile it as I don't have C++. Is there a binary somewhere? The new SDK promises some nice improvements!

For now, I just recreate the collider then. I suppose each collider also takes some memory to store the point cloud. So when using many many objects (with the same collider), I should be aware of that... or not?

Thanks!
Rick

[JernejL]

it is a very stable beta yes, and it comes only in compiled binary form.