public void PerpendicularVector2DTest()
{
Vector test = new Vector(3, 2);
Vector perpendicular = test.PerpendicularVector2D();
Assert.AreEqual(0, test.DotProduct(perpendicular), "Error: the dot product of orthoginal vectors should be 0.");
Assert.AreEqual(test.Magnitude, perpendicular.Magnitude, "Error: the magnitude of orthoginal vectors should be the same.");
}
public static void ProjectPolygon(Vector axis, Polygon polygon, ref double min, ref double max)
{
double dotProduct = axis.DotProduct(polygon.Vertices[0].ToVector());
min = dotProduct;
max = dotProduct;
for (int i = 0; i < polygon.Vertices.Count; i++)
{
dotProduct = polygon.Vertices[i].ToVector().DotProduct(axis);
if (dotProduct < min)
{
min = dotProduct;
}
else if (dotProduct > max)
{
max = dotProduct;
}
}
}
public static void ProjectPolygon(Vector axis, Polygon polygon, ref double min, ref double max)
{
double dotProduct = axis.DotProduct(polygon.Vertices[0].ToVector());
min = dotProduct;
max = dotProduct;
for(int i = 0; i < polygon.Vertices.Count; i++)
{
dotProduct = polygon.Vertices[i].ToVector().DotProduct(axis);
if(dotProduct < min)
{
min = dotProduct;
}
else if(dotProduct > max)
{
max = dotProduct;
}
}
}
public static PolygonCollisionResult PolygonCollision(Polygon a, Polygon b, Vector velocity)
{
PolygonCollisionResult result = new PolygonCollisionResult();
result.WillIntersect = true;
result.Intersect = true;
int edgeCountA = a.Edges.Count;
int edgeCountB = b.Edges.Count;
double minIntervalDistance = double.PositiveInfinity;
Vector traslationAxis = new Vector();
Vector edge;
for (int edgeIndex = 0; edgeIndex < edgeCountA + edgeCountB; edgeIndex++)
{
if (edgeIndex < edgeCountA)
{
edge = a.Edges[edgeIndex];
}
else
{
edge = b.Edges[edgeIndex - edgeCountA];
}
Vector axis = edge.PerpendicularVector2D();
axis = axis.Unit;
double minA = 0;
double maxA = 0;
double minB = 0;
double maxB = 0;
ProjectPolygon(axis, a, ref minA, ref maxA);
ProjectPolygon(axis, b, ref minB, ref maxB);
if (IntervalDisance(minA, maxA, minB, maxB) > 0)
{
result.Intersect = false;
}
double velosityProjection = axis.DotProduct(velocity);
if (velosityProjection < 0)
{
minA += velosityProjection;
}
else
{
maxA += velosityProjection;
}
double intervalDistance = IntervalDisance(minA, maxA, minB, maxB);
if (intervalDistance > 0)
{
result.WillIntersect = false;
}
if (!result.Intersect && !result.WillIntersect)
{
break;
}
intervalDistance = Math.Abs(intervalDistance);
if (intervalDistance < minIntervalDistance)
{
minIntervalDistance = intervalDistance;
traslationAxis = axis;
Point d = a.Centroid - b.Centroid;
if (d.ToVector().DotProduct(traslationAxis) < 0)
{
traslationAxis = traslationAxis * -1;
}
}
}
if (result.WillIntersect)
{
result.MinimumTranslationVector = traslationAxis * minIntervalDistance;
}
return(result);
}
