I decided to use a club to kick a ball and let it roll on the turf in RealityKit, but now I can only let it slide but can not roll.
I add collision on the turf(static), club (kinematic) and the ball(dynamic), and set some parameters: radius, mass.
Using these parameters calculate linear damping, inertia, besides, use time between frames and the club position to calculate speed. Code like these:
let radius: Float = 0.025
let mass: Float = 0.04593 // 质量,单位:kg
var inertia = 2/5 * mass * pow(radius, 2)
let currentPosition = entity.position(relativeTo: nil)
let distance = distance(currentPosition, rgfc.lastPosition)
let deltaTime = Float(context.deltaTime)
let speed = distance / deltaTime
let C_d: Float = 0.47 //阻力系数
let linearDamping = 0.5 * 1.2 * pow(speed, 2) * .pi * pow(radius, 2) * C_d //线性阻尼(1.2表示空气密度)
entity.components[PhysicsBodyComponent.self]?.massProperties.inertia = SIMD3<Float>(inertia, inertia, inertia)
entity.components[PhysicsBodyComponent.self]?.linearDamping = linearDamping
// force
let acceleration = speed / deltaTime
let forceDirection = normalize(currentPosition - rgfc.lastPosition)
let forceMultiplier: Float = 1.0
let appliedForce = forceDirection * mass * acceleration * forceMultiplier
entityCollidedWith.addForce(appliedForce, at: rgfc.hitPosition, relativeTo: nil)
Also I try to applyImpulse but not addForce, like:
let linearImpulse = forceDirection * speed * forceMultiplier * mass
No matter how I adjust the friction(static, dynamic) and restitution, using addForce or applyImpulse, the ball can only slide. How can I solve this problem?