예제 #1
0
AABB Triangle::getClippedAABB(const Point *positions, const AABB &aabb) const {
    /* Reserve room for some additional vertices */
    Point3d vertices1[MAX_VERTS], vertices2[MAX_VERTS];
    int nVertices = 3;

    /* The kd-tree code will frequently call this function with
       almost-collapsed AABBs. It's extremely important not to introduce
       errors in such cases, otherwise the resulting tree will incorrectly
       remove triangles from the associated nodes. Hence, do the
       following computation in double precision! */
    for (int i=0; i<3; ++i)
        vertices1[i] = Point3d(positions[idx[i]]);

    for (int axis=0; axis<3; ++axis) {
        nVertices = sutherlandHodgman(vertices1, nVertices, vertices2, axis, aabb.min[axis], true);
        nVertices = sutherlandHodgman(vertices2, nVertices, vertices1, axis, aabb.max[axis], false);
    }

    AABB result;
    for (int i=0; i<nVertices; ++i) {
#if defined(SINGLE_PRECISION)
        for (int j=0; j<3; ++j) {
            /* Now this is really paranoid! */
            double pos_d = vertices1[i][j];
            float  pos_f = (float) pos_d;
            float  pos_roundedDown, pos_roundedUp;

            if (pos_f < pos_d) {
                /* Float value is too small */
                pos_roundedDown = pos_f;
                pos_roundedUp = nextafterf(pos_f,
                                           std::numeric_limits<float>::infinity());
            } else if (pos_f > pos_d) {
                /* Float value is too large */
                pos_roundedUp = pos_f;
                pos_roundedDown = nextafterf(pos_f,
                                             -std::numeric_limits<float>::infinity());
            } else {
                /* Double value is exactly representable */
                pos_roundedDown = pos_roundedUp = pos_f;
            }

            result.min[j] = std::min(result.min[j], pos_roundedDown);
            result.max[j] = std::max(result.max[j], pos_roundedUp);
        }
#else
        result.expandBy(vertices1[i]);
#endif
    }
    result.clip(aabb);

    return result;
}
예제 #2
0
파일: mesh.cpp 프로젝트: UIKit0/nori
BoundingBox3f Mesh::getClippedBoundingBox(uint32_t index, const BoundingBox3f &bbox) const {
	/* Reserve room for some additional vertices */
	Point3d vertices1[NORI_TRICLIP_MAXVERTS], vertices2[NORI_TRICLIP_MAXVERTS];
	int nVertices = 3;

	/* The kd-tree code will frequently call this function with
	   almost-collapsed bounding boxes. It's extremely important not to introduce
	   errors in such cases, otherwise the resulting tree will incorrectly
	   remove triangles from the associated nodes. Hence, do the
	   following computation in double precision! */
	for (int i=0; i<3; ++i) 
		vertices1[i] = m_vertexPositions[m_indices[3*index+i]].cast<double>();

	for (int axis=0; axis<3; ++axis) {
		nVertices = sutherlandHodgman(vertices1, nVertices, vertices2, axis, bbox.min[axis], true);
		nVertices = sutherlandHodgman(vertices2, nVertices, vertices1, axis, bbox.max[axis], false);
	}

	BoundingBox3f result;
	for (int i=0; i<nVertices; ++i) 
		result.expandBy(vertices1[i].cast<float>());
	result.clip(bbox);
	return result;
}