/// <summary>
/// Construye la grilla
/// </summary>
private GrillaRegularNode[, ,] buildGrid(List<TgcMesh> modelos, TgcBoundingBox sceneBounds, Vector3 cellDim)
{
Vector3 sceneSize = sceneBounds.calculateSize();
int gx = (int)FastMath.Ceiling(sceneSize.X / cellDim.X) + 1;
int gy = (int)FastMath.Ceiling(sceneSize.Y / cellDim.Y) + 1;
int gz = (int)FastMath.Ceiling(sceneSize.Z / cellDim.Z) + 1;
GrillaRegularNode[, ,] grid = new GrillaRegularNode[gx, gy, gz];
//Construir grilla
for (int x = 0; x < gx; x++)
{
for (int y = 0; y < gy; y++)
{
for (int z = 0; z < gz; z++)
{
//Crear celda
GrillaRegularNode node = new GrillaRegularNode();
//Crear BoundingBox de celda
Vector3 pMin = new Vector3(sceneBounds.PMin.X + x * cellDim.X, sceneBounds.PMin.Y + y * cellDim.Y, sceneBounds.PMin.Z + z * cellDim.Z);
Vector3 pMax = Vector3.Add(pMin, cellDim);
node.BoundingBox = new TgcBoundingBox(pMin, pMax);
//Cargar modelos en celda
node.Models = new List<TgcMesh>();
addModelsToCell(node, modelos);
grid[x, y, z] = node;
}
}
}
return grid;
}
/// <summary>
/// Indica si un Cilindro colisiona con un AABB.
/// Solo indica si hay colision o no. No va mas en detalle.
/// </summary>
/// <param name="box">AABB</param>
/// <param name="cylinder">Cilindro alineado</param>
/// <returns>True si hay colision</returns>
public static bool testAABBCylinder(TgcBoundingBox box, TgcFixedYBoundingCylinder cylinder)
{
//datos del aabb
Vector3 boxCenter = box.calculateBoxCenter();
Vector3 boxHalfSize = box.calculateSize() * 0.5f;
//datos del cilindro
Vector3 cylCenter = cylinder.Center;
float cylHalfLength = cylinder.HalfLength;
float cylRadius = cylinder.Radius;
//vector de distancias
Vector3 distances = new Vector3(
FastMath.Abs(boxCenter.X - cylCenter.X),
FastMath.Abs(boxCenter.Y - cylCenter.Y),
FastMath.Abs(boxCenter.Z - cylCenter.Z));
//si el aabb esta muy arriba o muy abajo no hay colision
if (distances.Y > boxHalfSize.Y + cylHalfLength) return false;
//si el aabb esta muy lejos en x o en z no hay colision
if (distances.X > boxHalfSize.X + cylRadius) return false;
if (distances.Z > boxHalfSize.Z + cylRadius) return false;
//si el centro del cilindro esta dentro del aabb hay colision
if (distances.X <= boxHalfSize.X) return true;
if (distances.Z <= boxHalfSize.Z) return true;
//si el cilindro toca alguno de los extremos hay colision
float cornerDistanceSq =
FastMath.Pow2(distances.X - boxHalfSize.X) +
FastMath.Pow2(distances.Z - boxHalfSize.Z);
return (cornerDistanceSq <= FastMath.Pow2(cylRadius));
}
/// <summary>
/// Indica si existe colision con un AABB rapidamente, perdiendo precision.
/// Eso se debe a que trata al cilindro como un cubo para ganar performance obviando colisiones raras.
/// </summary>
public bool fastThereIsCollisionCyBB(TgcBoundingBox aabb)
{
Vector3 boxDimensions = aabb.calculateSize() * 0.5f;
Vector3 boxCenter = aabb.Position + boxDimensions;
Vector3 centerToCenter = new Vector3(this.Position.X - boxCenter.X, 0, this.Position.Z - boxCenter.Z);
Vector3 absCenterToCenter = new Vector3();
absCenterToCenter.X = FastMath.Abs(centerToCenter.X);
absCenterToCenter.Z = FastMath.Abs(centerToCenter.Z);
//vemos si esta muy lejos
if (absCenterToCenter.X > (boxDimensions.X + this.radius)) return false;
if (absCenterToCenter.Z > (boxDimensions.Z + this.radius)) return false;
return true;
}
/// <summary>
/// Indica si existe colision con un AABB. En tal caso devuelve la normal de colision.
/// </summary>
public bool thereIsCollisionCyBB(TgcBoundingBox aabb, out Vector3 n)
{
n = Vector3.Empty;
Vector3 boxDimensions = aabb.calculateSize() * 0.5f;
Vector3 boxCenter = aabb.Position + boxDimensions;
Vector3 centerToCenter = new Vector3(this.Position.X - boxCenter.X, 0, this.Position.Z - boxCenter.Z);
Vector3 absCenterToCenter = new Vector3();
absCenterToCenter.X = FastMath.Abs(centerToCenter.X);
absCenterToCenter.Z = FastMath.Abs(centerToCenter.Z);
//vemos si esta muy lejos
if (absCenterToCenter.X > (boxDimensions.X + this.radius)) return false;
if (absCenterToCenter.Z > (boxDimensions.Z + this.radius)) return false;
//vemos si esta dentro del aabb
if (absCenterToCenter.X <= boxDimensions.X) goto calculateNormal;
if (absCenterToCenter.Z <= boxDimensions.Z) goto calculateNormal;
//vemos si toca una esquina
float cornerDistance = FastMath.Pow2(absCenterToCenter.X - boxDimensions.X) + FastMath.Pow2(absCenterToCenter.Z - boxDimensions.Z);
if (cornerDistance <= FastMath.Pow2(this.radius)) goto calculateNormal;
return false;
calculateNormal:
Vector2 boxDimensions2d = fromVector3(boxDimensions);
Vector2 centerToCenter2d = fromVector3(absCenterToCenter);
float cross = Vector2.Ccw(centerToCenter2d, boxDimensions2d);
if (cross > 0) n = new Vector3(centerToCenter.X, 0, 0);
else if (cross < 0) n = new Vector3(0, 0, centerToCenter.Z);
else n = new Vector3(centerToCenter.X * boxDimensions2d.Y, 0, centerToCenter.Z * boxDimensions2d.X);
n.Normalize();
return true;
}