public Vector3 ProcessCollision(IPhysicsProxy physics)
{
// Early out if no ground contact since last check
if (this.GroundContact == null)
{
this.state = ControllerState.Falling;
return(EngineGlobals.Up);
}
// Handle landing from a fall
if (this.state == ControllerState.Falling)
{
this.state = ControllerState.Walking;
}
// TODO: handle walking|sprinting -> sliding
// - If velocity exceeds some threshold, transition to sliding
// - If we're climbing too steep, transition to sliding
// TODO: handle sliding -> walking
// - If we're slding and drop below threshold and not too steep, transition back to walking
var contactNormal = GroundContact.Normal;
GroundContact = null;
return(contactNormal);
}
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;
}
}
private void TryJump(IPhysicsProxy physics, Vector3 jumpDirection)
{
if (state != ControllerState.Falling)
{
var velocity = Vector3.Multiply(jumpSpeed, jumpDirection);
physics.AddVelocity(velocity);
state = ControllerState.Falling;
}
}
// 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);
}
public void Move(IPhysicsProxy physics,
Vector3 inputVector,
Vector3 forward,
Vector3 strafe)
{
var groundNormal = ProcessCollision(physics);
// align our movement vectors with the ground normal (ground normal = 'up')
Vector3 newForward = VectorExtensions.OrthoNormalize(groundNormal, forward);
Vector3 newStrafe = VectorExtensions.OrthoNormalize(groundNormal, strafe);
// Calculate movement direction
var desiredMovement = Vector3.Normalize((inputVector.X * newForward) + (inputVector.Y * newStrafe));
HandleMovement(physics, desiredMovement);
// Jump
if (inputVector.Z > 0f)
{
TryJump(physics, EngineGlobals.Up);
}
}