void VoronoiFractureDemo::voronoiConvexHullShatter(const btAlignedObjectArray<btVector3>& points, const btAlignedObjectArray<btVector3>& verts, const btQuaternion& bbq, const btVector3& bbt, btScalar matDensity) {
// points define voronoi cells in world space (avoid duplicates)
// verts = source (convex hull) mesh vertices in local space
// bbq & bbt = source (convex hull) mesh quaternion rotation and translation
// matDensity = Material density for voronoi shard mass calculation
btConvexHullComputer* convexHC = new btConvexHullComputer();
btAlignedObjectArray<btVector3> vertices, chverts;
btVector3 rbb, nrbb;
btScalar nlength, maxDistance, distance;
btAlignedObjectArray<btVector3> sortedVoronoiPoints;
sortedVoronoiPoints.copyFromArray(points);
btVector3 normal, plane;
btAlignedObjectArray<btVector3> planes, convexPlanes;
std::set<int> planeIndices;
std::set<int>::iterator planeIndicesIter;
int numplaneIndices;
int cellnum = 0;
int i, j, k;
// Convert verts to world space and get convexPlanes
int numverts = verts.size();
chverts.resize(verts.size());
for (i=0; i < numverts ;i++) {
chverts[i] = quatRotate(bbq, verts[i]) + bbt;
}
//btGeometryUtil::getPlaneEquationsFromVertices(chverts, convexPlanes);
// Using convexHullComputer faster than getPlaneEquationsFromVertices for large meshes...
convexHC->compute(&chverts[0].getX(), sizeof(btVector3), numverts, 0.0, 0.0);
int numFaces = convexHC->faces.size();
int v0, v1, v2; // vertices
for (i=0; i < numFaces; i++) {
const btConvexHullComputer::Edge* edge = &convexHC->edges[convexHC->faces[i]];
v0 = edge->getSourceVertex();
v1 = edge->getTargetVertex();
edge = edge->getNextEdgeOfFace();
v2 = edge->getTargetVertex();
plane = (convexHC->vertices[v1]-convexHC->vertices[v0]).cross(convexHC->vertices[v2]-convexHC->vertices[v0]).normalize();
plane[3] = -plane.dot(convexHC->vertices[v0]);
convexPlanes.push_back(plane);
}
const int numconvexPlanes = convexPlanes.size();
int numpoints = points.size();
for (i=0; i < numpoints ;i++) {
curVoronoiPoint = points[i];
planes.copyFromArray(convexPlanes);
for (j=0; j < numconvexPlanes ;j++) {
planes[j][3] += planes[j].dot(curVoronoiPoint);
}
maxDistance = SIMD_INFINITY;
sortedVoronoiPoints.heapSort(pointCmp());
for (j=1; j < numpoints; j++) {
normal = sortedVoronoiPoints[j] - curVoronoiPoint;
nlength = normal.length();
if (nlength > maxDistance)
break;
plane = normal.normalized();
plane[3] = -nlength / btScalar(2.);
planes.push_back(plane);
getVerticesInsidePlanes(planes, vertices, planeIndices);
if (vertices.size() == 0)
break;
numplaneIndices = planeIndices.size();
if (numplaneIndices != planes.size()) {
planeIndicesIter = planeIndices.begin();
for (k=0; k < numplaneIndices; k++) {
if (k != *planeIndicesIter)
planes[k] = planes[*planeIndicesIter];
planeIndicesIter++;
}
planes.resize(numplaneIndices);
}
maxDistance = vertices[0].length();
for (k=1; k < vertices.size(); k++) {
distance = vertices[k].length();
if (maxDistance < distance)
maxDistance = distance;
}
maxDistance *= btScalar(2.);
}
if (vertices.size() == 0)
continue;
// Clean-up voronoi convex shard vertices and generate edges & faces
convexHC->compute(&vertices[0].getX(), sizeof(btVector3), vertices.size(),0.0,0.0);
// At this point we have a complete 3D voronoi shard mesh contained in convexHC
// Calculate volume and center of mass (Stan Melax volume integration)
numFaces = convexHC->faces.size();
btScalar volume = btScalar(0.);
btVector3 com(0., 0., 0.);
for (j=0; j < numFaces; j++) {
const btConvexHullComputer::Edge* edge = &convexHC->edges[convexHC->faces[j]];
v0 = edge->getSourceVertex();
v1 = edge->getTargetVertex();
edge = edge->getNextEdgeOfFace();
v2 = edge->getTargetVertex();
while (v2 != v0) {
// Counter-clockwise triangulated voronoi shard mesh faces (v0-v1-v2) and edges here...
btScalar vol = convexHC->vertices[v0].triple(convexHC->vertices[v1], convexHC->vertices[v2]);
volume += vol;
com += vol * (convexHC->vertices[v0] + convexHC->vertices[v1] + convexHC->vertices[v2]);
edge = edge->getNextEdgeOfFace();
v1 = v2;
v2 = edge->getTargetVertex();
}
}
com /= volume * btScalar(4.);
volume /= btScalar(6.);
// Shift all vertices relative to center of mass
int numVerts = convexHC->vertices.size();
for (j=0; j < numVerts; j++)
{
convexHC->vertices[j] -= com;
}
// Note:
// At this point convex hulls contained in convexHC should be accurate (line up flush with other pieces, no cracks),
// ...however Bullet Physics rigid bodies demo visualizations appear to produce some visible cracks.
// Use the mesh in convexHC for visual display or to perform boolean operations with.
// Create Bullet Physics rigid body shards
btCollisionShape* shardShape = new btConvexHullShape(&(convexHC->vertices[0].getX()), convexHC->vertices.size());
shardShape->setMargin(CONVEX_MARGIN); // for this demo; note convexHC has optional margin parameter for this
m_collisionShapes.push_back(shardShape);
btTransform shardTransform;
shardTransform.setIdentity();
shardTransform.setOrigin(curVoronoiPoint + com); // Shard's adjusted location
btDefaultMotionState* shardMotionState = new btDefaultMotionState(shardTransform);
btScalar shardMass(volume * matDensity);
btVector3 shardInertia(0.,0.,0.);
shardShape->calculateLocalInertia(shardMass, shardInertia);
btRigidBody::btRigidBodyConstructionInfo shardRBInfo(shardMass, shardMotionState, shardShape, shardInertia);
btRigidBody* shardBody = new btRigidBody(shardRBInfo);
m_dynamicsWorld->addRigidBody(shardBody);
cellnum ++;
}
printf("Generated %d voronoi btRigidBody shards\n", cellnum);
}
std::list<VoronoiShard>
voronoi_convex_hull_shatter(const gl::MeshPtr &the_mesh,
const std::vector<glm::vec3>& the_voronoi_points)
{
// points define voronoi cells in world space (avoid duplicates)
// verts = source (convex hull) mesh vertices in local space
std::list<VoronoiShard> ret;
std::vector<glm::vec3> mesh_verts = the_mesh->geometry()->vertices();
auto convexHC = std::make_shared<btConvexHullComputer>();
btAlignedObjectArray<btVector3> vertices;
btVector3 rbb, nrbb;
btScalar nlength, maxDistance, distance;
std::vector<glm::vec3> sortedVoronoiPoints = the_voronoi_points;
btVector3 normal, plane;
btAlignedObjectArray<btVector3> planes, convexPlanes;
std::set<int> planeIndices;
std::set<int>::iterator planeIndicesIter;
int numplaneIndices;
int i, j, k;
// Normalize verts (numerical stability), convert to world space and get convexPlanes
int numverts = mesh_verts.size();
// auto aabb = the_mesh->boundingBox();
// float scale_val = 1.f;//std::max(std::max(aabb.width(), aabb.height()), aabb.depth());
auto mesh_transform = the_mesh->global_transform() ;//* scale(glm::mat4(), vec3(1.f / scale_val));
std::vector<glm::vec3> world_space_verts;
world_space_verts.resize(mesh_verts.size());
for (i = 0; i < numverts ;i++)
{
world_space_verts[i] = (mesh_transform * vec4(mesh_verts[i], 1.f)).xyz();
}
//btGeometryUtil::getPlaneEquationsFromVertices(chverts, convexPlanes);
// Using convexHullComputer faster than getPlaneEquationsFromVertices for large meshes...
convexHC->compute(&world_space_verts[0].x, sizeof(world_space_verts[0]), numverts, 0.0, 0.0);
int numFaces = convexHC->faces.size();
int v0, v1, v2; // vertices
// get plane equations for the convex-hull n-gons
for (i = 0; i < numFaces; i++)
{
const btConvexHullComputer::Edge* edge = &convexHC->edges[convexHC->faces[i]];
v0 = edge->getSourceVertex();
v1 = edge->getTargetVertex();
edge = edge->getNextEdgeOfFace();
v2 = edge->getTargetVertex();
plane = (convexHC->vertices[v1]-convexHC->vertices[v0]).cross(convexHC->vertices[v2]-convexHC->vertices[v0]).normalize();
plane[3] = -plane.dot(convexHC->vertices[v0]);
convexPlanes.push_back(plane);
}
const int numconvexPlanes = convexPlanes.size();
int numpoints = the_voronoi_points.size();
for (i = 0; i < numpoints ; i++)
{
auto curVoronoiPoint = the_voronoi_points[i];
planes.copyFromArray(convexPlanes);
for (j = 0; j < numconvexPlanes; j++)
{
planes[j][3] += planes[j].dot(type_cast(the_voronoi_points[i]));
}
maxDistance = SIMD_INFINITY;
// sort voronoi points
std::sort(sortedVoronoiPoints.begin(), sortedVoronoiPoints.end(), pointCmp(curVoronoiPoint));
for (j=1; j < numpoints; j++)
{
normal = type_cast(sortedVoronoiPoints[j] - curVoronoiPoint);
nlength = normal.length();
if (nlength > maxDistance)
break;
plane = normal.normalized();
plane[3] = -nlength / btScalar(2.);
planes.push_back(plane);
getVerticesInsidePlanes(planes, vertices, planeIndices);
if (vertices.size() == 0) break;
numplaneIndices = planeIndices.size();
if (numplaneIndices != planes.size())
{
planeIndicesIter = planeIndices.begin();
for (k=0; k < numplaneIndices; k++)
{
if (k != *planeIndicesIter)
planes[k] = planes[*planeIndicesIter];
planeIndicesIter++;
}
planes.resize(numplaneIndices);
}
maxDistance = vertices[0].length();
for (k=1; k < vertices.size(); k++)
{
distance = vertices[k].length();
if (maxDistance < distance)
maxDistance = distance;
}
maxDistance *= btScalar(2.);
}
if (vertices.size() == 0)
continue;
// Clean-up voronoi convex shard vertices and generate edges & faces
convexHC->compute(&vertices[0].getX(), sizeof(btVector3), vertices.size(),0.0,0.0);
// At this point we have a complete 3D voronoi shard mesh contained in convexHC
// Calculate volume and center of mass (Stan Melax volume integration)
numFaces = convexHC->faces.size();
btScalar volume = btScalar(0.);
btVector3 com(0., 0., 0.);
for (j = 0; j < numFaces; j++)
{
const btConvexHullComputer::Edge* edge = &convexHC->edges[convexHC->faces[j]];
v0 = edge->getSourceVertex();
v1 = edge->getTargetVertex();
edge = edge->getNextEdgeOfFace();
v2 = edge->getTargetVertex();
while (v2 != v0)
{
// Counter-clockwise triangulated voronoi shard mesh faces (v0-v1-v2) and edges here...
btScalar vol = convexHC->vertices[v0].triple(convexHC->vertices[v1], convexHC->vertices[v2]);
volume += vol;
com += vol * (convexHC->vertices[v0] + convexHC->vertices[v1] + convexHC->vertices[v2]);
edge = edge->getNextEdgeOfFace();
v1 = v2;
v2 = edge->getTargetVertex();
}
}
com /= volume * btScalar(4.);
volume /= btScalar(6.);
// Shift all vertices relative to center of mass
int numVerts = convexHC->vertices.size();
for (j = 0; j < numVerts; j++)
{
convexHC->vertices[j] -= com;
}
// now create our output geometry with indices
std::vector<gl::Face3> outer_faces, inner_faces;
std::vector<glm::vec3> outer_vertices, inner_vertices;
int cur_outer_index = 0, cur_inner_index = 0;
for (j = 0; j < numFaces; j++)
{
const btConvexHullComputer::Edge* edge = &convexHC->edges[convexHC->faces[j]];
v0 = edge->getSourceVertex();
v1 = edge->getTargetVertex();
edge = edge->getNextEdgeOfFace();
v2 = edge->getTargetVertex();
// determine if it is an inner or outer face
btVector3 cur_plane = (convexHC->vertices[v1] - convexHC->vertices[v0]).cross(convexHC->vertices[v2]-convexHC->vertices[v0]).normalize();
cur_plane[3] = -cur_plane.dot(convexHC->vertices[v0]);
bool is_outside = false;
for(uint32_t q = 0; q < convexPlanes.size(); q++)
{
if(is_equal(convexPlanes[q], cur_plane, 0.01f)){ is_outside = true; break;}
}
std::vector<gl::Face3> *shard_faces = &outer_faces;
std::vector<glm::vec3> *shard_vertices = &outer_vertices;
int *shard_index = &cur_outer_index;
if(!is_outside)
{
shard_faces = &inner_faces;
shard_vertices = &inner_vertices;
shard_index = &cur_inner_index;
}
int face_start_index = *shard_index;
// advance index
*shard_index += 3;
// first 3 verts of n-gon
glm::vec3 tmp[] = { type_cast(convexHC->vertices[v0]),
type_cast(convexHC->vertices[v1]),
type_cast(convexHC->vertices[v2])};
shard_vertices->insert(shard_vertices->end(), tmp, tmp + 3);
shard_faces->push_back(gl::Face3(face_start_index,
face_start_index + 1,
face_start_index + 2));
// add remaining triangles of face (if any)
while (true)
{
edge = edge->getNextEdgeOfFace();
v1 = v2;
v2 = edge->getTargetVertex();
// end of n-gon
if(v2 == v0) break;
shard_vertices->push_back(type_cast(convexHC->vertices[v2]));
shard_faces->push_back(gl::Face3(face_start_index,
*shard_index - 1,
*shard_index));
(*shard_index)++;
}
}
// entry construction
gl::Mesh::Entry e0, e1;
// outer entry
e0.num_vertices = outer_vertices.size();
e0.num_indices = outer_faces.size() * 3;
e0.material_index = 0;
// inner entry
e1.base_index = e0.num_indices;
e1.base_vertex = e0.num_vertices;
e1.num_vertices = inner_vertices.size();
e1.num_indices = inner_faces.size() * 3;
e1.material_index = 1;
// create gl::Mesh object for the shard
auto inner_geom = gl::Geometry::create(), outer_geom = gl::Geometry::create();
// append verts and indices
outer_geom->append_faces(outer_faces);
outer_geom->vertices() = outer_vertices;
outer_geom->compute_face_normals();
inner_geom->append_faces(inner_faces);
inner_geom->append_vertices(inner_vertices);
inner_geom->compute_face_normals();
// merge geometries
outer_geom->append_vertices(inner_geom->vertices());
outer_geom->append_normals(inner_geom->normals());
outer_geom->append_indices(inner_geom->indices());
outer_geom->faces().insert(outer_geom->faces().end(),
inner_geom->faces().begin(), inner_geom->faces().end());
outer_geom->compute_bounding_box();
auto inner_mat = gl::Material::create();
auto m = gl::Mesh::create(outer_geom, gl::Material::create());
m->entries() = {e0, e1};
m->materials().push_back(inner_mat);
m->set_position(curVoronoiPoint + type_cast(com));
// m->transform() *= glm::scale(mat4(), vec3(scale_val));
// compute projected texcoords (outside)
gl::project_texcoords(the_mesh, m);
// compute box mapped texcoords for inside vertices
auto &indices = m->geometry()->indices();
auto &vertices = m->geometry()->vertices();
// aabb
auto out_aabb = the_mesh->bounding_box();
vec3 aabb_extents = out_aabb.halfExtents() * 2.f;
uint32_t base_vertex = m->entries()[1].base_vertex;
uint32_t k = m->entries()[1].base_index, kl = k + m->entries()[1].num_indices;
for(;k < kl; k += 3)
{
gl::Face3 f(indices[k] + base_vertex,
indices[k] + base_vertex + 1,
indices[k] + base_vertex + 2);
// normal
const vec3 &v0 = vertices[f.a];
const vec3 &v1 = vertices[f.b];
const vec3 &v2 = vertices[f.c];
vec3 n = glm::normalize(glm::cross(v1 - v0, v2 - v0));
float abs_vals[3] = {fabsf(n[0]), fabsf(n[1]), fabsf(n[2])};
// get principal direction
int principle_axis = std::distance(abs_vals, std::max_element(abs_vals, abs_vals + 3));
// switch (principle_axis)
// {
// // X-axis
// case 0:
// //ZY plane
// m->geometry()->texCoords()[f.a] = vec2(v0.z - out_aabb.min.z / aabb_extents.z,
// v0.y - out_aabb.min.y / aabb_extents.y);
// m->geometry()->texCoords()[f.b] = vec2(v1.z - out_aabb.min.z / aabb_extents.z,
// v1.y - out_aabb.min.y / aabb_extents.y);
// m->geometry()->texCoords()[f.c] = vec2(v2.z - out_aabb.min.z / aabb_extents.z,
// v2.y - out_aabb.min.y / aabb_extents.y);
// break;
//
// // Y-axis
// case 1:
// // XZ plane
// m->geometry()->texCoords()[f.a] = vec2(v0.x - out_aabb.min.x / aabb_extents.x,
// v0.z - out_aabb.min.z / aabb_extents.z);
// m->geometry()->texCoords()[f.b] = vec2(v1.x - out_aabb.min.x / aabb_extents.x,
// v1.z - out_aabb.min.z / aabb_extents.z);
// m->geometry()->texCoords()[f.c] = vec2(v2.x - out_aabb.min.x / aabb_extents.x,
// v2.z - out_aabb.min.z / aabb_extents.z);
// break;
//
// // Z-axis
// case 2:
// //XY plane
// m->geometry()->texCoords()[f.a] = vec2(v0.x - out_aabb.min.x / aabb_extents.x,
// v0.y - out_aabb.min.y / aabb_extents.y);
// m->geometry()->texCoords()[f.b] = vec2(v1.x - out_aabb.min.x / aabb_extents.x,
// v1.y - out_aabb.min.y / aabb_extents.y);
// m->geometry()->texCoords()[f.c] = vec2(v2.x - out_aabb.min.x / aabb_extents.x,
// v2.y - out_aabb.min.y / aabb_extents.y);
// break;
//
// default:
// break;
// }
}
// push to return structure
ret.push_back({m, volume});
}
LOG_DEBUG << "Generated " << ret.size() <<" voronoi shards";
return ret;
}
