public void Move(List <IPolygon> polygons, Vector2 velocity)
{
Vector2 translation = velocity;
foreach (Polygon polygon in polygons)
{
CollisionResult result = Simulate(polygon, velocity);
if (result.WillIntersect && this.IsTangible && polygon.IsTangible)
{
translation += result.MinimumTranslation;
//break;
}
if (result.AreIntersecting)
{
this.OnCollide?.Invoke(this, polygon);
polygon.OnCollide?.Invoke(polygon, this);
}
}
Position += translation;
}
/// <summary>
/// Simulate collision between this polygon and another <paramref name="polygon"/> with <paramref name="velocity"/>
/// </summary>
/// <param name="polygon"></param>
/// <param name="velocity"></param>
/// <returns></returns>
public CollisionResult Simulate(IPolygon polygon, Vector2 velocity)
{
CollisionResult result = new CollisionResult();
result.AreIntersecting = true;
result.WillIntersect = true;
int edgeCountA = this.Edges.Count;
int edgeCountB = polygon.Edges.Count;
float minimumInterval = float.PositiveInfinity;
Vector2 translationAxis = Vector2.Zero;
Vector2 edge = Vector2.Zero;
// loop through edges of both polygons
for (int edgeIndex = 0; edgeIndex < edgeCountA + edgeCountB; edgeIndex++)
{
if (edgeIndex < edgeCountA)
{
edge = this.Edges[edgeIndex];
}
else
{
edge = polygon.Edges[edgeIndex - edgeCountA];
}
// find if the polygons are intersecting.
// find the axis perpendicular to the current edge
Vector2 axis = new Vector2(-edge.Y, edge.X);
axis.Normalize();
// find the projection of the axis
float minA = 0, minB = 0, maxA = 0, maxB = 0;
projectPolygon(axis, this, ref minA, ref maxA);
projectPolygon(axis, polygon, ref minB, ref maxB);
// check if projections are intersecting
if (intervalDistance(minA, maxA, minB, maxB) > 0)
{
result.AreIntersecting = false;
}
// find if polygons _will_ intersect
float velocityProjection = Vector2.Dot(axis, velocity);
// get the projection of this poly during movement
if (velocityProjection < 0)
{
minA += velocityProjection;
}
else
{
maxA += velocityProjection;
}
// same test for new projection
float interval = intervalDistance(minA, maxA, minB, maxB);
if (interval > 0)
{
result.WillIntersect = false;
}
if (!result.AreIntersecting && !result.WillIntersect)
{
break;
}
// check if the current interval is the minimum one
interval = Math.Abs(interval);
if (interval < minimumInterval)
{
minimumInterval = interval;
translationAxis = axis;
Vector2 d = this.Center - polygon.Center;
if (Vector2.Dot(d, translationAxis) < 0)
{
translationAxis = -translationAxis;
}
}
}
if (result.WillIntersect)
{
result.MinimumTranslation = translationAxis * minimumInterval;
}
return(result);
}
