///<summary>
///Transforms a point from world space to the agent's local space
///</summary>
///<param name="point"></param>
///<param name="agentHeading"></param>
///<param name="agentSide"></param>
///<param name="agentPosition"></param>
///<returns>the transformed point</returns>
public static Vector2 PointToLocalSpace(
Vector2 point,
Vector2 agentHeading,
Vector2 agentSide,
Vector2 agentPosition)
{
//make a copy of the point
Vector2 transformedPoint = point; //TODO: why copy?
//create a transformation matrix
Matrix2 transformationMatrix = new Matrix2();
float tx = Vector2.Dot(-agentPosition, agentHeading);
float ty = Vector2.Dot(-agentPosition, agentSide);
//create the transformation matrix
transformationMatrix.E11 = agentHeading.X;
transformationMatrix.E12 = agentSide.X;
transformationMatrix.E21 = agentHeading.Y;
transformationMatrix.E22 = agentSide.Y;
transformationMatrix.E31 = tx;
transformationMatrix.E32 = ty;
//now transform the vertices
transformationMatrix.TransformVector2(ref transformedPoint);
return transformedPoint;
}
///<summary>
///Transforms a point from the agent's local space into world space
///</summary>
///<param name="point"></param>
///<param name="agentHeading"></param>
///<param name="agentSide"></param>
///<param name="agentPosition"></param>
///<returns>the transformed point</returns>
public static Vector2 PointToWorldSpace(
Vector2 point,
Vector2 agentHeading,
Vector2 agentSide,
Vector2 agentPosition)
{
//make a copy of the point
Vector2 transformedPoint = point; //TODO: why copy?
//create a transformation matrix
Matrix2 transformationMatrix = new Matrix2();
//rotate
transformationMatrix.Rotate(agentHeading, agentSide);
//and translate
transformationMatrix.Translate(agentPosition.X, agentPosition.Y);
//now transform the point
transformationMatrix.TransformVector2(ref transformedPoint);
return transformedPoint;
}
///<summary>
///given a target position, this method rotates the bot's facing vector
///by an amount not greater than <see cref="MovingEntity.MaxTurnRate"/>
///until it directly faces the target.
///</summary>
///<param name="target">the target position</param>
///<returns>
///true when the heading is facing in the desired direction
/// </returns>
public bool RotateFacingTowardPosition(Vector2 target)
{
Vector2 toTarget = Vector2.Normalize(target - Position);
float dot = Vector2.Dot(Facing, toTarget);
//clamp to rectify any rounding errors
dot = MathHelper.Clamp(dot, -1, 1);
//determine the angle between the heading vector and the target
float angle = (float) Math.Acos(dot);
//return true if the bot's facing is within WeaponAimTolerance
//radians of facing the target
//TODO: should be a parameter (different than BotAimAccuracy??)
const float weaponAimTolerance = 0.01f; //2 degs approx
if (angle < weaponAimTolerance)
{
Facing = toTarget;
return true;
}
//clamp the amount to turn to the max turn rate
if (angle > MaxTurnRate) angle = MaxTurnRate;
//The next few lines use a rotation matrix to rotate the player's
//facing vector accordingly
Matrix2 rotationMatrix = new Matrix2();
//notice how the direction of rotation has to be determined when
//creating the rotation matrix
rotationMatrix.Rotate(angle*Vector2Util.Sign(Facing, toTarget));
Facing = rotationMatrix.TransformVector2(Facing);
return false;
}
///<summary>
///rotates a vector <paramref name="angle"/> radians around the origin
///</summary>
///<param name="v">vector to rotate around the origin</param>
///<param name="angle">rotation angle in radians</param>
public static void RotateVectorAroundOrigin(ref Vector2 v, float angle)
{
//create a transformation matrix
Matrix2 transformationMatrix = new Matrix2();
//rotate
transformationMatrix.Rotate(angle);
//now transform the object's vertices
transformationMatrix.TransformVector2(ref v);
}
///<summary>
///given a list of 2D vectors, a position and orientation, this
///function transforms the 2D vectors into the object's world space
///</summary>
///<param name="points"></param>
///<param name="position"></param>
///<param name="forward"></param>
///<param name="side"></param>
///<returns>list of transformed points</returns>
public static List<Vector2> WorldTransform(
List<Vector2> points,
Vector2 position,
Vector2 forward,
Vector2 side)
{
//copy the original points into the list about to be transformed
List<Vector2> transformedPoints = new List<Vector2>(points);
//create a transformation matrix
Matrix2 transformationMatrix = new Matrix2();
//rotate
transformationMatrix.Rotate(forward, side);
//and translate
transformationMatrix.Translate(position.X, position.Y);
//now transform the points
transformationMatrix.TransformVector2(transformedPoints);
return transformedPoints;
}
///<summary>
///rotates a vector <paramref name="angle"/> radians around the origin
///</summary>
///<param name="v">vector to rotate around the origin</param>
///<param name="p"></param>
///<param name="angle">rotation angle in radians</param>
///<returns>the rotated vector</returns>
public static void RotateVectorAroundPoint(ref Vector2 v, Vector2 p, float angle)
{
//create a transformation matrix
Matrix2 transformationMatrix = new Matrix2();
transformationMatrix.Translate(-p.X, -p.Y);
transformationMatrix.Rotate(angle);
transformationMatrix.Translate(p.X, p.Y);
//now transform the object's vertices
transformationMatrix.TransformVector2(ref v);
}
