public void HandleMovement(IPhysicsProxy physics, Vector3 movement)
{
var xyMovement = Vector3.Normalize(new Vector3(movement.X, movement.Y, 0));
var xyMagSquared = xyMovement.LengthSquared();
if (float.IsNaN(xyMagSquared) || xyMagSquared <= 0)
{
return;
}
if (this.state == ControllerState.Walking)
{
var velocityChange = GetVelocityChange(physics, xyMovement, desiredGroundSpeed, deltaGroundSpeed);
if (velocityChange.LengthSquared() > 0)
{
physics.AddVelocity(velocityChange);
}
}
else if (this.state == ControllerState.Falling)
{
/*
* goal: allow, at maximum, desiredAirSpeed velocity while falling
* edge case: when jumping from movement, or sliding off edge, don't limit speed down to desiredAirSpeed
*/
Vector3 currentVelocity = physics.GetVelocity();
var likeness = Vector3.Dot(xyMovement, Vector3.Normalize(currentVelocity));
if (float.IsNaN(likeness))
{
likeness = 0f;
}
var currentVelocityInDesiredDirection = currentVelocity * likeness;
var deltaMagnitude = desiredAirSpeed - currentVelocityInDesiredDirection.Length();
if (deltaMagnitude != 0)
{
var change = xyMovement * MathExt.Clamp(deltaMagnitude, 0, deltaAirSpeed);
if (change.LengthSquared() > 0)
{
physics.AddVelocity(change);
}
}
}
else
{
// TODO: handle sprinting and sliding movement
// TODO: desired feel during sliding is 0 friction in the movement direction
return;
}
}
// BUG: can get 'stuck' at the top edge of a ramp
private Vector3 GetVelocityChange(IPhysicsProxy physics, Vector3 movement, float desiredMagnitude, float deltaMagnitude)
{
Vector3 currentVelocity = physics.GetVelocity();
movement *= desiredMagnitude;
// TODO: figure out a better limiting method? velocity going up slopes is limited
Vector3 velocityChange = (movement - currentVelocity);
velocityChange.X = MathExt.Clamp(velocityChange.X, -deltaMagnitude, deltaMagnitude);
velocityChange.Y = MathExt.Clamp(velocityChange.Y, -deltaMagnitude, deltaMagnitude);
velocityChange.Z = 0;
return(velocityChange);
}