Generates the collision shape of a model in Panda3D

collision_geom.py

import itertools

from panda3d.core import NodePath
from panda3d.core import TransformState
from panda3d.core import Vec3

from panda3d.bullet import BulletBoxShape
from panda3d.bullet import BulletConeShape
from panda3d.bullet import BulletConvexHullShape
from panda3d.bullet import BulletCylinderShape
from panda3d.bullet import BulletSphereShape
from panda3d.bullet import BulletTriangleMesh
from panda3d.bullet import BulletTriangleMeshShape

class Entity():
    @staticmethod
    def calcSize(model):
        entityModel = loader.loadModel(model)
        return Entity.calcNodeSize(entityModel)

    @staticmethod
    def calcNodeSize(node):
        bottomLeft, topRight = node.getTightBounds()
        width = topRight.x - bottomLeft.x
        depth = topRight.y - bottomLeft.y
        height = topRight.z - bottomLeft.z
        return Vec3(width, depth, height)

    @staticmethod
    def calcTransform(nodePath, root):
        bottomLeft, topRight = nodePath.getTightBounds()
        shapeOrigin = (bottomLeft + topRight)/2
        originOffset = shapeOrigin - nodePath.getPos()
        if root is None:
            # We only needed to calculate the shape offset
            return TransformState.makePos(originOffset)
        else:
            # Combine the shape offset with nodePath's transform to the root node
            transform = nodePath.getTransform(root)
            return transform.setPos(transform.getPos() + originOffset)

    @staticmethod
    def calcCollisionShape(shape, model):
        if shape == "geometry":
            return Entity.calcCollisionGeometryShapes(model)

        modelNode = loader.loadModel(model).find('**/+GeomNode')
        return Entity.calcNodeCollisionShape(shape, modelNode, None)

    @staticmethod
    def calcNodeCollisionShape(shape, nodePath, root):
        width, depth, height = Entity.calcNodeSize(nodePath)
        transform = Entity.calcTransform(nodePath, root)
        if shape == "box":
            return [(BulletBoxShape(Vec3(width/2, depth/2, height/2)), transform)]
        elif shape == "sphere":
            return [(BulletSphereShape(width/2), transform)]
        elif shape == "cylinder":
            return [(BulletCylinderShape(width/2, height, 2), transform)]
        elif shape == "cone":
            return [(BulletConeShape(width/2, height), transform)]
        elif shape == "hull":
            geom = nodePath.node().getGeom(0)
            hull = BulletConvexHullShape()
            hull.addGeom(geom)
            return [(hull, TransformState.makeIdentity())]
        elif shape == "mesh":
            geom = nodePath.node().getGeom(0)
            mesh = BulletTriangleMesh()
            mesh.addGeom(geom)
            return [(BulletTriangleMeshShape(mesh, dynamic=False), TransformState.makeIdentity())]
        else:
            raise AttributeError('Collision type ' + str(shape) + ' does not exist!')

    @staticmethod
    def calcCollisionGeometryShapes(model):
        root = loader.loadModel(model)
        shapes = []
        # Find any collider geometry and transform it into a collision shape
        for shape in ["box", "sphere", "cylinder", "cone", "hull", "mesh"]:
            for child in root.findAllMatches('**/collision_{0}_*'.format(shape)):
                shapes = itertools.chain(shapes, Entity.calcNodeCollisionShape(shape, NodePath(child), root))
                child.removeNode()

        return shapes