Vector3<float> CollisionConvexHullShape::computeLocalInertia(float mass) const
{
AABBox<float> aabbox = toAABBox(PhysicsTransform());
float width = 2.0 * aabbox.getHalfSize(0);
float height = 2.0 * aabbox.getHalfSize(1);
float depth = 2.0 * aabbox.getHalfSize(2);
float localInertia1 = (1.0/12.0) * mass * (height*height + depth*depth);
float localInertia2 = (1.0/12.0) * mass * (width*width + depth*depth);
float localInertia3 = (1.0/12.0) * mass * (width*width + height*height);
return Vector3<float>(localInertia1, localInertia2, localInertia3);
}
void ShapeToAABBoxTest::boxConversion()
{
CollisionBoxShape collisionBox(Vector3<float>(1.0, 2.0, 1.0)); //box 1x2x1
PhysicsTransform transform(urchin::Point3<float>(0.0, 0.0, 0.0), //move 0 unit on X, Y and Z axis
urchin::Quaternion<float>(urchin::Vector3<float>(0.0, 0.0, 1.0), 3.14159265358979/4)); //rotate 45° on Z axis
AABBox<float> box = collisionBox.toAABBox(transform);
AssertHelper::assertFloatEquals(box.getHalfSize(0), 2.12132034356);
AssertHelper::assertFloatEquals(box.getHalfSize(1), 2.12132034356);
AssertHelper::assertFloatEquals(box.getHalfSize(2), 1.0);
AssertHelper::assertPoint3FloatEquals(box.getMin(), Point3<float>(-2.12132034356, -2.12132034356, -1.0));
AssertHelper::assertPoint3FloatEquals(box.getMax(), Point3<float>(2.12132034356, 2.12132034356, 1.0));
}
/**
* Split the bounding box in several bounding boxes at limitSize.
* If original box doesn't exceed limit size, the original box is returned.
*/
std::vector<AABBox<float>> SplitBoundingBox::split(const AABBox<float> &aabbox) const
{
std::vector<float> axisSplits[3];
for(unsigned int axis=0; axis<3; ++axis)
{
float size = aabbox.getHalfSize(axis) * 2.0f;
axisSplits[axis].push_back(aabbox.getMin()[axis]);
auto nbSplits = static_cast<int>(std::ceil(size/limitSize));
float maxValue = aabbox.getMax()[axis];
for(int split = 0; split < nbSplits; ++split)
{
float splitValue = std::min(aabbox.getMin()[axis] + limitSize*(split+1), maxValue);
axisSplits[axis].push_back(splitValue);
}
}
std::vector<AABBox<float>> splittedBoundingBox;
for(unsigned int x=1; x<axisSplits[0].size(); ++x)
{
for(unsigned int y=1; y<axisSplits[1].size(); ++y)
{
for(unsigned int z=1; z<axisSplits[2].size(); ++z)
{
Point3<float> minPoint(axisSplits[0][x-1], axisSplits[1][y-1], axisSplits[2][z-1]);
Point3<float> maxPoint(axisSplits[0][x], axisSplits[1][y], axisSplits[2][z]);
splittedBoundingBox.emplace_back(AABBox<float>(minPoint, maxPoint));
}
}
}
return splittedBoundingBox;
}
void ShapeToAABBoxTest::convexHullConversion()
{
Point3<float> boxPointsTab[] = {
Point3<float>(-1.0, -2.0, 1.0), Point3<float>(1.0, -2.0, 1.0), Point3<float>(1.0, 2.0, 1.0), Point3<float>(-1.0, 2.0, 1.0),
Point3<float>(-1.0, -2.0, -1.0), Point3<float>(1.0, -2.0, -1.0), Point3<float>(1.0, 2.0, -1.0), Point3<float>(-1.0, 2.0, -1.0),
};
std::vector<Point3<float>> boxPoints(boxPointsTab, boxPointsTab+sizeof(boxPointsTab)/sizeof(Point3<float>));
CollisionConvexHullShape collisionConvexHull(0.0, boxPoints);
PhysicsTransform transform(urchin::Point3<float>(0.0, 0.0, 0.0), //move 0 unit on X, Y and Z axis
urchin::Quaternion<float>(urchin::Vector3<float>(0.0, 0.0, 1.0), -3.14159265358979/4)); //rotate 45° on Z axis
AABBox<float> box = collisionConvexHull.toAABBox(transform);
AssertHelper::assertFloatEquals(box.getHalfSize(0), 2.12132034356);
AssertHelper::assertFloatEquals(box.getHalfSize(1), 2.12132034356);
AssertHelper::assertFloatEquals(box.getHalfSize(2), 1.0);
AssertHelper::assertPoint3FloatEquals(box.getMin(), Point3<float>(-2.12132034356, -2.12132034356, -1.0));
AssertHelper::assertPoint3FloatEquals(box.getMax(), Point3<float>(2.12132034356, 2.12132034356, 1.0));
}