/// <summary>
/// Get the intersection point between the bounding box and a ray.
/// </summary>
/// <param name="box"></param>
/// <returns></returns>
public Vector3f Intersect(Ray ray)
{
const float epsilon = 1e-6f;
float tMin = float.NaN, tMax = float.NaN;
if (System.Math.Abs(ray.Direction.X) < epsilon)
{
if (ray.Position.X < Min.X || ray.Position.X > Max.X)
return Vector3f.NaN;
}
else
{
tMin = (Min.X - ray.Position.X) / ray.Direction.X;
tMax = (Max.X - ray.Position.X) / ray.Direction.X;
if (tMin > tMax)
{
float temp = tMin;
tMin = tMax;
tMax = temp;
}
}
if (System.Math.Abs(ray.Direction.Y) < epsilon)
{
if (ray.Position.Y < Min.Y || ray.Position.Y > Max.Y)
return Vector3f.NaN;
}
else
{
float tMinY = (Min.Y - ray.Position.Y) / ray.Direction.Y;
float tMaxY = (Max.Y - ray.Position.Y) / ray.Direction.Y;
if (tMinY > tMaxY)
{
float temp = tMinY;
tMinY = tMaxY;
tMaxY = temp;
}
if ((tMin != float.NaN && tMin > tMaxY) || (tMax != float.NaN && tMinY > tMax))
return Vector3f.NaN;
if (tMin == float.NaN || tMinY > tMin) tMin = tMinY;
if (tMax == float.NaN || tMaxY < tMax) tMax = tMaxY;
}
if (System.Math.Abs(ray.Direction.Z) < epsilon)
{
if (ray.Position.Z < Min.Z || ray.Position.Z > Max.Z)
return Vector3f.NaN;
}
else
{
float tMinZ = (Min.Z - ray.Position.Z) / ray.Direction.Z;
float tMaxZ = (Max.Z - ray.Position.Z) / ray.Direction.Z;
if (tMinZ > tMaxZ)
{
float temp = tMinZ;
tMinZ = tMaxZ;
tMaxZ = temp;
}
if ((tMin != float.NaN && tMin > tMaxZ) || (tMax != float.NaN && tMinZ > tMax))
return Vector3f.NaN;
if (tMin == float.NaN || tMinZ > tMin) tMin = tMinZ;
if (tMax == float.NaN || tMaxZ < tMax) tMax = tMaxZ;
}
if ((tMin == float.NaN && tMin < 0) && tMax > 0) return Vector3f.NaN;
if (tMin < 0) return Vector3f.NaN;
return ray.Position.Add(ray.Direction.Multiply(tMin));
}
/// <summary>
/// </summary>
/// <returns>
/// Returns a new ray which can be used to intersect objects in the scene.
/// </returns>
public Ray GetCameraRay(int mx, int my)
{
Vector3f origin = Translation;
Vector3f unprojected = Unproject(mx, my);
unprojected.MultiplyStore(1000f);
Ray ray = new Ray(unprojected, origin);
return ray;
}