Jitter with gravity

Scripting Issues
1

Hi all,

I’m getting some mad jitter in my game since adding gravity. At first, I thought it might have been my update player routine - so I commented that out (stationary player), same result.

So I pondered by update camera routine - but that also looks fine.

Then I pondered my collision handling, disabled that, no luck.

…and now I’m guessing I’ve just done something dumb in the code… :slight_smile:

Physics setup:

    def setupPhysics(self):
        base.enableParticles() # enables physics

        # create a physics node, put in a node path, parent with player
        Node = NodePath(PandaNode("PhysicsNode"))
        Node.reparentTo(self.render)
        an = ActorNode("player-physics")
        # an.getPhysicsObject().setMass(1361.077)
        anp = Node.attachNewNode(an)
        self.player.reparentTo(anp)

        # create a force (gravity)
        gravityFN = ForceNode('world-gravity')
        gravityFNP = self.render.attachNewNode(gravityFN)
        gravityForce = LinearVectorForce(0,0,-0.81)
        gravityFN.addForce(gravityForce)

        base.physicsMgr.attachPhysicalNode(an)
        base.physicsMgr.addLinearForce(gravityForce)

And the camera:

    def updateCamera(self):
        # player flies faster - camera backs off
        percent = (self.speed/self.maxspeed)
        self.camera.setPos(self.player, 19.6225+(10*percent), 3.8807, 10.2779)
        self.camera.setHpr(self.player,94.8996,-12.6549, 1.55508)

Any ideas?

Cheers,
Gary

2

Huh, I also note that the acceleration just keeps on coming… the longer I play the faster I drop.

Somehow think I’m using the completely wrong approach for a flight game! lol

~G

3

Are you using a PhysicsCollisionHandler, and not just a CollisionHandlerPusher? A PhysicsCollisionHandler will act like a regular pusher, but also stop the acceleration from physics. Otherwise your object will keep accelerating even when it’s sitting on the floor, until it eventually busts through.

David

4

Um, I’m not using either. My collisions:

    def setupCollisions(self):
        self.collTrav = CollisionTraverser()

        self.playerGroundSphere = CollisionSphere(0,1.5,-1.5,1.5)
        self.playerGroundCol = CollisionNode('playerSphere')
        self.playerGroundCol.addSolid(self.playerGroundSphere)

        # bitmasks       self.playerGroundCol.setFromCollideMask(BitMask32.bit(0))
        self.playerGroundCol.setIntoCollideMask(BitMask32.allOff())
        self.world.setCollideMask(BitMask32.bit(0))
        self.water.setCollideMask(BitMask32.bit(0))

        # and done
        self.playerGroundColNp = self.player.attachNewNode(self.playerGroundCol)
        self.playerGroundHandler = CollisionHandlerQueue()
        self.collTrav.addCollider(self.playerGroundColNp, self.playerGroundHandler)

        # DEBUG as per video:
        if (self.debug == True):
            self.playerGroundColNp.show()
            self.collTrav.showCollisions(self.render)

Cheers,
~G

5

Since you’re rolling your own collision reaction, you’ll have to deal with the physics too. Whenever you detect a collision, remember to set your physics object’s velocity to 0.

David

6

Ah, I see. Thanks David, you are wealth of information. :slight_smile:

Cheers,
Gary