does somebody know, how I let rigid bodies react on fired bullets of my weapon? Something like "add an impulse at one position (where the bullet hit the object) and let all bodies, which where hit by the bullet, move"
I can't explain it better but I think you know what I want
This was taken from the btRigidBody class, impulse is the direction of the shot, and rel_pos is the position where you hit. I never tryed this, but it should work. Hope this help.
ok...thanks. But now I've got a problem: I know the nodes which belongs to the rigid bodies but I don't have a pointer for them. It means that I can't call the addImpulse function directly, I have to get the pointer for the rigid body, which get hit of the bullet but for the scene nodes there isn't a method like "getRigidBody". The rigidBodies have a method called "getNode" or something like this... do I have to save the pointer of every created rigid Body or is there another way?
I dont use IrrBullet so i dont know how it manages rigid bodys. But what i suggest you is to make a dynamic array, where you store your rigid bodys in, and where you can call them when ever you need them.
I think it has a list of them just look for it hard
because irrbullet has to have all of the pointers so it can update every nodes position translation ect.
const int numManifolds = collisionWorld->getDispatcher()->getNumManifolds();
int i;
for (i=0;i<numManifolds;i++)
{
int id[2];
id[0]=id[1]=-1;
btPersistentManifold* contactManifold = collisionWorld->getDispatcher()->getManifoldByIndexInternal(i);
btCollisionObject* obA = static_cast<btCollisionObject*>(contactManifold->getBody0());
btCollisionObject* obB = static_cast<btCollisionObject*>(contactManifold->getBody1());
}
obA, obB are two coliding bodies you could put 'if' statement's in the for loop to check if they are the objects you need, or you could put every object into a list and than make a function that would do that
You do need to use manifolds (in irrBullet I call this ICollisionCallback so that beginners can understand it more easily) for collision callbacks.
Also check in irrBullet "ICollisionObject::hasCollidedWithAttribute(attributeName)" and ICollisionObject::getAttributes() to add a new attribute.
This isn't the fastest way; I recommend using the manifolds (this is how I do it in my own game using irrBullet).
If you have irrBullet 0.1.6, you can see the irrBulletTest's code for both collision detection ways! I will make this an actual collision example in the next release. (I will have lots of new examples in this release in fact!)
Also, comparing a rigid body's scene node with the scene node hit in the ray would be the best way for now (although not the fastest).
Bullet has internally a ray cast method. I'll work on developing an interface for this, but I have a lot of things to do such as working on my game, my game's tools, irrBullet, teaching C++, and school.
The detection happens before that code is reached. After it has been, the collision(s) are held in a list (or vector, I don't know) that you access through world->getCollisionCallback(unsigned int). If you look at the API, and that example that you posted you can find what kind of information you can pull about the collision. Also, that snippet of code you posted shows how to retrieve pointers of the rigid bodies that collided.
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This is my actual code to detect collision between bullets and rigidBodies. I save the bullets in a list and check them if they collided with an rigid body with the attribute "world". When I just check the dynamic objects (which stands around in my world) for collision, all works fine. But when I check the static objects, like the room I'm walking while the game is running, I get the message "COLLISION!!1" not in the moment when the bullet hits the body, I get this message directly after creating the bullet... I don't know why but I think it is because the room, I'm walking in is an dynamic body and the engine thinks I already hit the body...
This gets the first contact point. Sometimes there are multiple contact points in one manifold. You can also step through each contact point, but I usually only take the first one.
What's more, collisions are registered once an object begins to enter the Axis-Aligned Bounding Box of another object. That's why it's registering the collision between your bullet and the enclosed map/level.
This is generally fine for quick collisions for objects whose AABB actually covers only what's collideable, but for levels this isn't the case, so you need to check distance to be sure.
