/// <summary>
/// Performs a bounce collision (a collision which modifies velocity and acceleration), and separates the objects if so.
/// </summary>
/// <param name="sphere">The Sphere to perform collision against.</param>
/// <param name="thisMass">The mass of this instance.</param>
/// <param name="otherMass">Th e mass of the argument cube.</param>
/// <param name="elasticity">The ratio of velocity to preserve.</param>
/// <returns>Whether a collision occurred.</returns>
public bool CollideAgainstBounce(Sphere sphere, float thisMass, float otherMass, float elasticity)
{
#if DEBUG
if (thisMass == 0 && otherMass == 0)
{
throw new ArgumentException("Both masses cannot be 0. For equal masses pick a non-zero value");
}
#endif
if (CollideAgainstMove(sphere, thisMass, otherMass))
{
// Get the relative velocity of this circle to the argument circle:
Vector3 relativeVelocity = new Vector3(
this.TopParent.XVelocity - sphere.TopParent.XVelocity,
this.TopParent.YVelocity - sphere.TopParent.YVelocity,
this.TopParent.ZVelocity - sphere.TopParent.ZVelocity);
#if FRB_MDX
float velocityNormalDotResult = Vector3.Dot(relativeVelocity, LastMoveCollisionReposition);
#else
float velocityNormalDotResult;
Vector3.Dot(ref relativeVelocity, ref LastMoveCollisionReposition, out velocityNormalDotResult);
#endif
if (velocityNormalDotResult >= 0)
{
return(true);
}
#if FRB_MDX
//Vector2 tangentVector = new Vector2((float)mLastCollisionTangent.X, (float)mLastCollisionTangent.Y);
// Perform the bounce if the relative velocity and the tangent are the opposite direction.
Vector3 reverseNormal = -Vector3.Normalize(LastMoveCollisionReposition);
float length = Vector3.Dot(relativeVelocity, reverseNormal);
Vector3 velocityOnNormal = Vector3.Multiply(reverseNormal, length);
#else
Vector3 reverseNormal = -LastMoveCollisionReposition;
reverseNormal.Normalize();
float length = Vector3.Dot(relativeVelocity, reverseNormal);
Vector3 velocityOnNormal;
Vector3.Multiply(ref reverseNormal, length, out velocityOnNormal);
#endif
sphere.TopParent.Velocity.X += (1 + elasticity) * thisMass / (thisMass + otherMass) * velocityOnNormal.X;
sphere.TopParent.Velocity.Y += (1 + elasticity) * thisMass / (thisMass + otherMass) * velocityOnNormal.Y;
sphere.TopParent.Velocity.Z += (1 + elasticity) * thisMass / (thisMass + otherMass) * velocityOnNormal.Z;
this.TopParent.Velocity.X -= (1 + elasticity) * otherMass / (thisMass + otherMass) * velocityOnNormal.X;
this.TopParent.Velocity.Y -= (1 + elasticity) * otherMass / (thisMass + otherMass) * velocityOnNormal.Y;
this.TopParent.Velocity.Z -= (1 + elasticity) * otherMass / (thisMass + otherMass) * velocityOnNormal.Z;
return(true);
}
return(false);
}
/// <summary>
/// Larger comes first.
/// </summary>
/// <param name="first">The first instance.</param>
/// <param name="second">The second instance.</param>
/// <returns>-1 if the first comes first, 1 if the second comes first, 0 if they're equal.</returns>
#endregion
public int Compare(IDrawableBatch first, IDrawableBatch second)
{
Vector3 firstCameraRelativePosition = new Vector3(
first.X - mCamera.X,
first.Y - mCamera.Y,
first.Z - mCamera.Z);
Vector3 secondCameraRelativePosition = new Vector3(
second.X - mCamera.X,
second.Y - mCamera.Y,
second.Z - mCamera.Z);
float firstDistance;
#if FRB_MDX
Vector3 forwardVector = mCamera.RotationMatrix.Forward();
Vector3Extensions.Dot(ref firstCameraRelativePosition, ref forwardVector, out firstDistance);
float secondDistance;
Vector3Extensions.Dot(ref secondCameraRelativePosition, ref forwardVector, out secondDistance);
#else
Vector3 forwardVector = mCamera.RotationMatrix.Forward;
Vector3.Dot(ref firstCameraRelativePosition, ref forwardVector, out firstDistance);
float secondDistance;
Vector3.Dot(ref secondCameraRelativePosition, ref forwardVector, out secondDistance);
#endif
if (firstDistance < secondDistance)
{
return(1);
}
else if (firstDistance > secondDistance)
{
return(-1);
}
else
{
return(0);
}
}
