Changeset 2466 for code/branches/presentation/src/orxonox/objects/Scene.cc

Timestamp:

Dec 15, 2008, 4:33:50 PM (15 years ago)

Author:

rgrieder

Message:

Added callback for collisions. Every WorldEntity that collides against another will be called with the following function:
virtual bool collidesAgainst(WorldEntity* otherObject, btManifoldPoint& contactPoint);
btManifoldPoint is from Bullet and tells you more about the contact point, like position.

Per default, the callback is disabled. Enable it with this→enableCollisionCallback(), for instance in your derived class constructor.
Note that if you activate the callback for e.g. SpaceShips, but not for MovableEntities, then collidesAgainst will only be called in the SpaceShip. This could be changed however, just ask me.

File:

• code/branches/presentation/src/orxonox/objects/Scene.cc (modified) (2 diffs)

code/branches/presentation/src/orxonox/objects/Scene.cc

@@ -206 +206 @@
             this->physicalWorld_   = new btDiscreteDynamicsWorld(this->dispatcher_, this->broadphase_, this->solver_, this->collisionConfig_);
             this->physicalWorld_->setGravity(omni_cast<btVector3>(this->gravity_));
+
+            // also set the collision callback variable.
+            // Note: This is a global variable which we assign a static function.
+            // TODO: Check whether this (or anything about Bullet) works with multiple physics engine instances.
+            gContactAddedCallback = &Scene::collisionCallback;
         }
         else if (!wantPhysics && hasPhysics())
@@ -337 +342 @@
             this->physicalWorld_->removeRigidBody(object->getPhysicalBody());
     }
+
+    /*static*/ bool Scene::collisionCallback(btManifoldPoint& cp, const btCollisionObject* colObj0, int partId0,
+                                             int index0, const btCollisionObject* colObj1, int partId1, int index1)
+    {
+        // get the WorldEntity pointers
+        WorldEntity* object0 = (WorldEntity*)colObj0->getUserPointer();
+        assert(dynamic_cast<WorldEntity*>(object0));
+        WorldEntity* object1 = (WorldEntity*)colObj1->getUserPointer();
+        assert(dynamic_cast<WorldEntity*>(object1));
+
+        // false means that bullet will assume we didn't modify the contact
+        bool modified = false;
+        if (object0->isCollisionCallbackActive())
+        {
+            modified |= object0->collidesAgainst(object1, cp);
+            if (object1->isCollisionCallbackActive())
+                modified |= object1->collidesAgainst(object0, cp);
+        }
+        else
+            modified |= object1->collidesAgainst(object0, cp);
+
+        return modified;
+    }
 }