public MeshTriangle(MeshVertex vertex1, MeshVertex vertex2, MeshVertex vertex3)
{
this.Vertex1 = vertex1;
this.Vertex2 = vertex2;
this.Vertex3 = vertex3;
this.visible = true;
this.CurrentBarycentricCoordinate = BarycentricCoordinate.Zero;
this.material = null;
}
//From http://jgt.akpeters.com/papers/GuigueDevillers03/ray_triangle_intersection.html
public bool FindIntersection(Ray ray, out Intersection intersect)
{
intersect = new Intersection();
Vector3D vect0, vect1, nvect;
float det, inv_det;
vect0 = this.Vertex2.Position - this.Vertex1.Position;
vect1 = this.Vertex3.Position - this.Vertex1.Position;
Vector3D normalNonNormalized = vect0 ^ vect1;
/* orientation of the ray with respect to the triangle's normal,
also used to calculate output parameters*/
det = -(ray.Direction * normalNonNormalized);
#if TEST_CULL
/* define TEST_CULL if culling is desired */
if (det < MathUtil.Epsilon) return false;
/* calculate vector from ray origin to this.vertex1 */
vect0 = this.Vertex1.Position - ray.Origin;
/* vector used to calculate u and v parameters */
nvect = ray.Direction ^ vect0;
/* calculate vector from ray origin to this.vertex2*/
vect1 = this.Vertex2.Position - ray.Origin;
/* calculate unnormalized v parameter and test bounds */
float v = -(vect1 * nvect);
if (v < 0.0 || v > det) return false;
/* calculate vector from ray origin to this.vertex3*/
vect1 = this.Vertex3.Position - ray.Origin;
/* calculate unnormalized v parameter and test bounds */
float u = vect1 * nvect;
if (u < 0.0 || u + v > det) return false;
/* calculate unormalized t parameter */
float t = -(vect0 * normalNonNormalized);
inv_det = 1.0f / det;
/* calculate u v t, ray intersects triangle */
u = u * inv_det;
v = v * inv_det;
t = t * inv_det;
#else
/* the non-culling branch */
/* if determinant is near zero, ray is parallel to the plane of triangle */
if (det.NearZero()) {
return false;
}
/* calculate vector from ray origin to this.vertex1 */
vect0 = this.Vertex1.Position - ray.Origin;
/* normal vector used to calculate u and v parameters */
nvect = ray.Direction ^ vect0;
inv_det = 1.0f / det;
/* calculate vector from ray origin to this.vertex2*/
vect1 = this.Vertex2.Position - ray.Origin;
/* calculate v parameter and test bounds */
float v = -(vect1 * nvect) * inv_det;
if (v < 0.0f || v > 1.0f) {
return false;
}
/* calculate vector from ray origin to this.vertex3*/
vect1 = this.Vertex3.Position - ray.Origin;
/* calculate v parameter and test bounds */
float u = (vect1 * nvect) * inv_det;
if (u < 0.0f || u + v > 1.0f) {
return false;
}
/* calculate t, ray intersects triangle */
float t = -(vect0 * normalNonNormalized) * inv_det;
#endif
//if (t < 100)
// return false;
// return 1;
//if (t < 100) //FIXME: the correct is t < 0, but dont work, why? tell me you! =P
//{
// return false;
//}
if (t >= 0) {
intersect.TMin = t;
intersect.Normal = Vector3D.Normal(this.Vertex1.Position, this.Vertex2.Position, this.Vertex3.Position);
intersect.HitPoint = ray.Origin + (t * ray.Direction);
this.CurrentBarycentricCoordinate = new BarycentricCoordinate(1.0f - (u + v), u, v);
intersect.HitPrimitive = this;
return true;
}
return false;
}
