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starting to implement PoissonDisk sampling

This commit is contained in:
Massimiliano Corsini 2009-01-11 15:43:58 +00:00
parent 44aa343da6
commit abbf0d60ce
1 changed files with 122 additions and 18 deletions
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140
vcg/complex/trimesh/point_sampling.h
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@ -47,9 +47,7 @@ namespace tri
{
/// Trivial Sampler, an example sampler object that show the required interface used by the sampling class.
/// Most of the sampling classes call the AddFace method with the face containing the sample and its baricentric coord.
/// Most of the sampling classes call the AddFace method with the face containing the sample and its barycentric coord.
template <class MeshType>
class TrivialSampler
{
@ -72,7 +70,7 @@ class TrivialSampler
void AddTextureSample(const FaceType &, const CoordType &, const Point2i &)
{
// Retrieve the colorof the sample from the face f using the barycentric coord p
// Retrieve the color of the sample from the face f using the barycentric coord p
// and write that color in a texture image at position tp[0],tp[1]
}
}; // end class TrivialSampler
@ -80,17 +78,43 @@ class TrivialSampler
template <class MetroMesh, class VertexSampler>
class SurfaceSampling
{
typedef typename MetroMesh::CoordType CoordType;
typedef typename MetroMesh::ScalarType ScalarType;
typedef typename MetroMesh::CoordType CoordType;
typedef typename MetroMesh::ScalarType ScalarType;
typedef typename MetroMesh::VertexType VertexType;
typedef typename MetroMesh::VertexPointer VertexPointer;
typedef typename MetroMesh::VertexIterator VertexIterator;
typedef typename MetroMesh::FacePointer FacePointer;
typedef typename MetroMesh::FaceIterator FaceIterator;
typedef typename MetroMesh::FaceType FaceType;
typedef typename MetroMesh::FaceContainer FaceContainer;
typedef typename MetroMesh::VertexPointer VertexPointer;
typedef typename MetroMesh::VertexIterator VertexIterator;
typedef typename MetroMesh::FacePointer FacePointer;
typedef typename MetroMesh::FaceIterator FaceIterator;
typedef typename MetroMesh::FaceType FaceType;
typedef typename MetroMesh::FaceContainer FaceContainer;
private:
/// Cell for Poisson Disk sampling.
class Cell
{
public:
Point3<ScalarType> center; // center of the cell
double halfedge; // size (half) of the cell
bool isempty; // false if contains almost one sample
// ctor
Cell() :
center(0.0,0.0,0.0),
halfedge(0.0),
isempty(true)
{
}
vcg::Box3<ScalarType> convertToBBox()
{
vcg::Box<ScalarType> box3(center, halfedge);
return box3;
}
}; // end class Cell
public:
static math::MarsenneTwisterRNG &SamplingRandomGenerator()
{
static math::MarsenneTwisterRNG rnd;
@ -638,21 +662,101 @@ static void SingleFaceRaster(FaceType &f, VertexSampler &ps, const Point2<Scala
}
}
/// Compute a Poisson-disk sampling of the surface
/// The radius of the disk is computed according to the estimated sampling density.
static void Poissondisk(MetroMesh &m, VertexSampler &ps, int sampleNum)
static void subdivideCell(std::vector<Cell *> &activeCellList, Cell *cell)
{
FaceIterator fi;
ScalarType he = cell->halfedge / 2.0;
// first of all computed radius
int coeffs[24] = {
+1,+1,+1,
+1,+1,-1,
+1,-1,+1,
+1,-1,-1,
-1,+1,+1,
-1,+1,-1,
-1,-1,+1,
-1,-1,-1
};
for (int i = 0; i < 8; i++)
{
Cell *newcell = new Cell();
newcell->center[0] = cell->center[0] + coeffs[i*3] * he;
newcell->center[1] = cell->center[1] + coeffs[i*3+1] * he;
newcell->center[2] = cell->center[2] + coeffs[i*3+2] * he;
newcell->halfedge = he;
// discard the cell if it not contains faces
// TODO...
// discard the cell if it is too near to another sample (?!)
// TODO...
}
}
/** Compute a Poisson-disk sampling of the surface.
* The radius of the disk is computed according to the estimated sampling density.
*
* This algorithm is an adaptation of the algorithm of White et al. :
*
* "Poisson Disk Point Set by Hierarchical Dart Throwing"
* K. B. White, D. Cline, P. K. Egbert,
* IEEE Symposium on Interactive Ray Tracing, 2007,
* 10-12 Sept. 2007, pp. 129-132.
*/
static void Poissondisk(MetroMesh &m, VertexSampler &ps, int sampleNum, int version)
{
// active cell list (max 10 levels of subdivisions)
std::vector<Cell *> activeCells[10];
// just in case...
for (int i = 0; i < 10; i++)
activeCells[i].clear();
// first of all, radius is estimated
ScalarType meshArea = Stat<MetroMesh>::ComputeMeshArea(m);
ScalarType r = sqrt(meshArea / (0.7 * 3.1415 * sampleNum)); // 0.7 is a density factor
// setup initial grid
// setup initial grid (initial active cells)
Point3<ScalarType> C = m.bbox.Center();
ScalarType maxdim; // max(dimx,dimy,dimz)
maxdim = std::max(m.bbox.DimX(), std::max(m.bbox.DimY(), m.bbox.DimZ()));
ScalarType cellsize = r / sqrt(2.0);
Cell *cell;
ScalarType xx,yy,zz;
for (zz = m.bbox.min[2]; zz < m.bbox.min[2]; zz += r)
for (yy = m.bbox.min[1]; yy < m.bbox.min[1]; yy += r)
for (xx = m.bbox.min[0]; xx < m.bbox.min[0]; xx += r)
{
cell = new Cell();
cell->center[0] = xx + r/2.0;
cell->center[1] = yy + r/2.0;
cell->center[2] = zz + r/2.0;
cell->halfedge = r/2.0;
activeCells[0].push_back(cell);
}
// sampling algorithm (version 1)
// ------------------------------
//
// - extract a cell (C) from the active cell list (proportional to cell's volume)
// - generate a sample inside C and project it on the mesh
// - if the sample violated the radius constrain discard it, subdivide the cell in eight cells
// and added them to the active cell list
// - iterate until the active cell list is empty or a pre-defined number of subdivisions is reached
//
//
// sampling algorithm (version 2)
// ------------------------------
//
// - extract a cell (C) from the active cell list (proportional to the cell's volume)
// - generate a sample on the triangles inside C
// - if the sample violated the radius constrain discard it, subdivide the cell in eight cells
// and added them to the active cell list
// - iterate until the active cell list is empty or a pre-defined number of subdivisions is reached
}
//template <class MetroMesh>