private MeshTriangle(MeshTriangle other, Vector3 translate)
{
Id = other.Id;
P0 = other.P0 + translate;
P1 = other.P1 + translate;
P2 = other.P2 + translate;
Points = new List<Vector3>{P0, P1, P2};
U = other.U;
V = other.V;
Normal = other.Normal;
Direction = other.Direction;
UU = other.UU;
VV = other.VV;
UV = other.UV;
D = other.D;
}
private bool SplitPoints(MeshTriangle[] triangles, out List<Vector3> lineA, out List<Vector3> lineB)
{
var gradients = new Vector3[4][];
lineA = lineB = null;
for (var i = 0; i < 4; ++i)
{
gradients[i] = new Vector3[3];
for (var j = 0; j < 3; ++j)
{
gradients[i][j] = (triangles[i].Points[j] - triangles[i].Points[(j + 1)%3]).NormalizeRet();
}
}
var lines = new List<List<Vector3>>();
// now find the gradients that are the same on different triangles & where
// the start & end points are the same...
for (var triangleAIndex = 0; triangleAIndex < 4; ++triangleAIndex)
{
for (var triangleBIndex = 0; triangleBIndex < 4; ++triangleBIndex)
{
for (var lineAIndex = 0; lineAIndex < 3; ++lineAIndex)
{
for (var lineBIndex = 0; lineBIndex < 3; ++lineBIndex)
{
if (gradients[triangleAIndex][lineAIndex] == gradients[triangleBIndex][lineBIndex] &&
(triangles[triangleAIndex].Points[(lineAIndex + 1)%3] ==
triangles[triangleBIndex].Points[lineBIndex]))
{
lines.Add(new List<Vector3>
{
triangles[triangleAIndex].Points[lineAIndex],
triangles[triangleAIndex].Points[(lineAIndex + 1)%3],
triangles[triangleBIndex].Points[(lineBIndex + 1)%3]
});
}
}
}
}
}
if (lines.Count != 2)
return false;
lineA = lines[0];
lineB = lines[1];
return true;
}
// attempt to merge the (4) given triangles. if they can be merged then the result is populated
private bool AttemptMergeTriangles(MeshTriangle[] toTryToMerge, out MeshTriangle[] result)
{
// for 4 triangles to merge - then between the 4 triangles there should be only 6 unique points
result = null;
var points = new HashSet<Vector3>();
foreach (var triangle in toTryToMerge)
{
points.Add(triangle.P0);
points.Add(triangle.P1);
points.Add(triangle.P2);
}
if (points.Count != 6)
return false;
// we need 2 lots of 3 sets of points to be able to merge, so the 6 points are to be split
// and the 2 lines can be merged into new triangles.
List<Vector3> lineA;
List<Vector3> lineB;
if (SplitPoints(toTryToMerge, out lineA, out lineB))
{
result = new MeshTriangle[2];
result[0] = new MeshTriangle(toTryToMerge[0].Id, lineA[0], lineA[2], lineB[2]);
result[1] = new MeshTriangle(toTryToMerge[0].Id, lineB[0], lineB[2], lineA[2]);
return true;
}
return false;
}
private void MergeTriangles(List<MeshTriangle> triangles)
{
var startCount = triangles.Count;
//Logger.Write("Attempting to merge triangles in mesh - starting with " + startCount, LoggerLevel.Trace);
var toExamine = new MeshTriangle[4];
var newTriangles = new List<MeshTriangle>();
var position = 0;
for (; position < triangles.Count - 4; ++position)
{
for (var count = 0; count < 4; ++count)
{
toExamine[count] = triangles[position + count];
}
MeshTriangle[] result;
if (!AttemptMergeTriangles(toExamine, out result))
{
newTriangles.Add(triangles[position]);
continue;
}
position += 3;
newTriangles.AddRange(result);
}
for (; position < triangles.Count; ++position)
newTriangles.Add(triangles[position]);
triangles.Clear();
triangles.AddRange(newTriangles);
var endCount = triangles.Count;
if (endCount != startCount)
MergeTriangles(triangles);
//Logger.Write("Completed merge triangles in mesh - finished with " + endCount, LoggerLevel.Trace);
}
public virtual void AddTriangle(MeshTriangle meshTriangle)
{
Triangles.Add(new MeshTriangle(meshTriangle.Id, meshTriangle.P0, meshTriangle.P1, meshTriangle.P2));
_maxX = _maxY = _maxZ = _minX = _minY = _minZ = null;
}
public override void AddTriangle(MeshTriangle meshTriangle)
{
Triangles.Add(new MeshTriangle(meshTriangle.Id, meshTriangle.P0, meshTriangle.P1, meshTriangle.P2).Rotate(_actualRotation));
}
private void UpdateCollisionData(MeshCollisionData data, float distance, CollisionResult result, MeshTriangle triangle)
{
if (!data.HasCollided ||
distance < data.CollisionDistance)
{
data.CollisionDistance = distance;
data.CollisionResult = result;
data.CollisionId = triangle.Id;
data.Triangle = triangle;
data.HasCollided = true;
}
}
public MeshCollisionResult(CollisionResult rayCollisionResult, byte triangleId = 0, MeshTriangle hit = null)
{
RayCollisionResult = rayCollisionResult;
TriangleId = triangleId;
Triangle = hit;
}
private CollisionResult CollideTriangleWithRay(MeshTriangle triangle, Vector3 point, Vector3 direction)
{
var n = triangle.Normal;
var b = n.Dot(direction);
if (b >= 0.00000)
return new CollisionResult { HasCollided = false };
var w0 = point - triangle.P0;
var a = -n.Dot(w0);
var r = a / b;
if (r < 0)
return new CollisionResult { HasCollided = false };
var I = point + r * direction;
var w = I - triangle.P0;
var wu = w.Dot(triangle.U);
var wv = w.Dot(triangle.V);
var s = (triangle.UV * wv - triangle.VV * wu) / triangle.D;
if (s < 0 || s > 1)
return new CollisionResult { HasCollided = false };
var t = (triangle.UV * wu - triangle.UU * wv) / triangle.D;
if (t < 0 || (s + t) > 1)
return new CollisionResult { HasCollided = false };
return new CollisionResult { HasCollided = true, CollisionPoint = I };
}