Physics Simulation Forum

Hi,

I have been trying to get a vehicle working within Cocos3d on IOS.

I have a vehicle that I can move around but the wheels go all over the place.

I thought maybe it is to do with my coordinate getting muddled up but I'm not sure

In cocos 3d.

Forward = Negative Z
Up = Positive Y
Right = Positive X

For my vehicle I have

int rightIndex = 0;
int upIndex = 1;
int forwardIndex = 2;
physicsObject.m_vehicle->setCoordinateSystem(rightIndex, upIndex, forwardIndex);//X，Y，Z

and for my wheels I have

btVector3 wheelDirectionCS0(0,-1,0);
btVector3 wheelAxleCS(-1,0,0);

They are then attached as follows

btVector3 connectionPointCS0(0.88f,connectionHeight,1.6f);
carChassis.m_vehicle->addWheel(connectionPointCS0,wheelDirectionCS0,wheelAxleCS,suspensionRestLength,wheelRadius,carChassis.mTuning,isFrontWheel);

etc

They are all placed correctly but when I turn left or right, they rotate on their side originally, instead of left and right.
and then as i move the vehicle forward as soon as I start to turn they just go all over the place..

I update the rendering of my wheels as follows


btQuaternion btq = object.m_vehicle->getWheelInfo(i).m_worldTransform.getRotation();
btVector3 wPos = object.m_vehicle->getWheelInfo(i).m_worldTransform.getOrigin();
CC3Vector4 quaternion;
quaternion.x = btq.x();
quaternion.y = btq.y();
quaternion.z = btq.z();
quaternion.w = btq.w();
//wheel.quaternion = quaternion;


switch (i) {
case 0:
wheel = object.Wheel1;
break;
case 1:
wheel = object.Wheel2;
break;
case 2:
wheel = object.Wheel3;
break;
case 3:
wheel = object.Wheel4;
break;
default:
break;
}

wheel.location = CC3VectorMake(wPos.getX(), wPos.getY(), wPos.getZ());
wheel.quaternion = quaternion;


Any pointers in the right direction would be hand,

Many thanks

Duncan.

I figured out that all my issues were to do with the steering.

After making a few alterations I managed to get it working with cocos3d.

I've documented the changes here.

http://ios-app-development.blogspot.co. ... cos3d.html