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diff method for capping convex hull point count

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Andrew Meadows 2016-06-03 09:18:40 -07:00
parent c73757f740
commit f17330ea82
1 changed files with 80 additions and 7 deletions
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87
libraries/physics/src/ShapeFactory.cpp
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@ -17,6 +17,54 @@
#include "ShapeFactory.h"
#include "BulletUtil.h"
// These are the same normalized directions used by the btShapeHull class.
// 12 points for the face centers of a duodecohedron plus another 30 points
// for the midpoints the edges, for a total of 42.
const uint32_t NUM_UNIT_SPHERE_DIRECTIONS = 42;
static const btVector3 _unitSphereDirections[NUM_UNIT_SPHERE_DIRECTIONS] = {
btVector3(btScalar(0.000000) , btScalar(-0.000000),btScalar(-1.000000)),
btVector3(btScalar(0.723608) , btScalar(-0.525725),btScalar(-0.447219)),
btVector3(btScalar(-0.276388) , btScalar(-0.850649),btScalar(-0.447219)),
btVector3(btScalar(-0.894426) , btScalar(-0.000000),btScalar(-0.447216)),
btVector3(btScalar(-0.276388) , btScalar(0.850649),btScalar(-0.447220)),
btVector3(btScalar(0.723608) , btScalar(0.525725),btScalar(-0.447219)),
btVector3(btScalar(0.276388) , btScalar(-0.850649),btScalar(0.447220)),
btVector3(btScalar(-0.723608) , btScalar(-0.525725),btScalar(0.447219)),
btVector3(btScalar(-0.723608) , btScalar(0.525725),btScalar(0.447219)),
btVector3(btScalar(0.276388) , btScalar(0.850649),btScalar(0.447219)),
btVector3(btScalar(0.894426) , btScalar(0.000000),btScalar(0.447216)),
btVector3(btScalar(-0.000000) , btScalar(0.000000),btScalar(1.000000)),
btVector3(btScalar(0.425323) , btScalar(-0.309011),btScalar(-0.850654)),
btVector3(btScalar(-0.162456) , btScalar(-0.499995),btScalar(-0.850654)),
btVector3(btScalar(0.262869) , btScalar(-0.809012),btScalar(-0.525738)),
btVector3(btScalar(0.425323) , btScalar(0.309011),btScalar(-0.850654)),
btVector3(btScalar(0.850648) , btScalar(-0.000000),btScalar(-0.525736)),
btVector3(btScalar(-0.525730) , btScalar(-0.000000),btScalar(-0.850652)),
btVector3(btScalar(-0.688190) , btScalar(-0.499997),btScalar(-0.525736)),
btVector3(btScalar(-0.162456) , btScalar(0.499995),btScalar(-0.850654)),
btVector3(btScalar(-0.688190) , btScalar(0.499997),btScalar(-0.525736)),
btVector3(btScalar(0.262869) , btScalar(0.809012),btScalar(-0.525738)),
btVector3(btScalar(0.951058) , btScalar(0.309013),btScalar(0.000000)),
btVector3(btScalar(0.951058) , btScalar(-0.309013),btScalar(0.000000)),
btVector3(btScalar(0.587786) , btScalar(-0.809017),btScalar(0.000000)),
btVector3(btScalar(0.000000) , btScalar(-1.000000),btScalar(0.000000)),
btVector3(btScalar(-0.587786) , btScalar(-0.809017),btScalar(0.000000)),
btVector3(btScalar(-0.951058) , btScalar(-0.309013),btScalar(-0.000000)),
btVector3(btScalar(-0.951058) , btScalar(0.309013),btScalar(-0.000000)),
btVector3(btScalar(-0.587786) , btScalar(0.809017),btScalar(-0.000000)),
btVector3(btScalar(-0.000000) , btScalar(1.000000),btScalar(-0.000000)),
btVector3(btScalar(0.587786) , btScalar(0.809017),btScalar(-0.000000)),
btVector3(btScalar(0.688190) , btScalar(-0.499997),btScalar(0.525736)),
btVector3(btScalar(-0.262869) , btScalar(-0.809012),btScalar(0.525738)),
btVector3(btScalar(-0.850648) , btScalar(0.000000),btScalar(0.525736)),
btVector3(btScalar(-0.262869) , btScalar(0.809012),btScalar(0.525738)),
btVector3(btScalar(0.688190) , btScalar(0.499997),btScalar(0.525736)),
btVector3(btScalar(0.525730) , btScalar(0.000000),btScalar(0.850652)),
btVector3(btScalar(0.162456) , btScalar(-0.499995),btScalar(0.850654)),
btVector3(btScalar(-0.425323) , btScalar(-0.309011),btScalar(0.850654)),
btVector3(btScalar(-0.425323) , btScalar(0.309011),btScalar(0.850654)),
btVector3(btScalar(0.162456) , btScalar(0.499995),btScalar(0.850654))
};
btConvexHullShape* ShapeFactory::createConvexHull(const QVector<glm::vec3>& points) {
@ -66,15 +114,40 @@ btConvexHullShape* ShapeFactory::createConvexHull(const QVector<glm::vec3>& poin
hull->addPoint(btVector3(correctedPoint[0], correctedPoint[1], correctedPoint[2]), false);
}
if (points.size() > MAX_HULL_POINTS) {
// create hull approximation
btShapeHull shapeHull(hull);
shapeHull.buildHull(margin);
uint32_t numPoints = (uint32_t)hull->getNumPoints();
if (numPoints > MAX_HULL_POINTS) {
// we have too many points, so we compute point projections along canonical unit vectors
// and keep the those that project the farthest
btVector3 btCenter = glmToBullet(center);
btVector3* shapePoints = hull->getUnscaledPoints();
std::vector<uint32_t> finalIndices;
finalIndices.reserve(NUM_UNIT_SPHERE_DIRECTIONS);
for (uint32_t i = 0; i < NUM_UNIT_SPHERE_DIRECTIONS; ++i) {
uint32_t bestIndex = 0;
btScalar maxDistance = _unitSphereDirections[i].dot(shapePoints[0] - btCenter);
for (uint32_t j = 1; j < numPoints; ++j) {
btScalar distance = _unitSphereDirections[i].dot(shapePoints[j] - btCenter);
if (distance > maxDistance) {
maxDistance = distance;
bestIndex = j;
}
}
bool keep = true;
for (uint32_t j = 0; j < finalIndices.size(); ++j) {
if (finalIndices[j] == bestIndex) {
keep = false;
break;
}
}
if (keep) {
finalIndices.push_back(bestIndex);
}
}
// we cannot copy Bullet shapes so we must create a new one...
btConvexHullShape* newHull = new btConvexHullShape();
const btVector3* newPoints = shapeHull.getVertexPointer();
for (int i = 0; i < shapeHull.numVertices(); ++i) {
newHull->addPoint(newPoints[i], false);
for (uint32_t i = 0; i < finalIndices.size(); ++i) {
newHull->addPoint(shapePoints[finalIndices[i]], false);
}
// ...and delete the old one
delete hull;