BEPUphysics

Hi!

I need to create a physic entity loading a 3d model for shape and mass and other variable from file.
It's possible to do that?

Giulio

Yes, but I've avoided adding in direct serialization for entity types. I would recommend saving and loading the information you know you will need to reconstruct the scene externally.

i didn't understand a thing: how i can apply to a 3d model physics?

If you're just looking to create a physical representation of a loaded 3d model, then you have a few choices.

1) Load the model for graphics only. Create an approximation out of simple primitives for the collision geometry that the physics engine will handle. You can use a CompoundBody containing BoxShapes and SphereShapes, for example. Transform the graphics using the entity's position and orientation.

2) Create convex hulls from the graphics model, or a simplified version of it. A single convex hull could be the collision shape for a whole model if the model is convex enough. If not, a CompoundBody of multiple ConvexHullShapes would be necessary. Note that keeping the geometry simple is important for performance.

3) You can technically create a MobileMesh from a model, but a MobileMesh that handles every triangle individually is going to be a lot slower in collisions than an approximation like #1.

To get an idea of how to construct entities in different ways, I would recommend checking out the BEPUphysicsDemos source in the main BEPUphysics download, in particular the EntityConstructionDemo.

an example?

The EntityConstructionDemo in the BEPUphysicsDemos source (which comes in the main source download over at http://bepuphysics.codeplex.com/SourceC ... changesets) shows a bunch of examples of how to construct entities, including compound entities.

The important parts are setting up a compound's children and then making sure you position the graphic correctly relative to the physical representation. The compound constructors can output a position in various ways that tells you the local offset to apply to the graphic to align it with the physics.