359 lines
17 KiB
C++
359 lines
17 KiB
C++
/*******************************************************************************
|
|
Copyright (c) 2005-2009 David Williams
|
|
|
|
This software is provided 'as-is', without any express or implied
|
|
warranty. In no event will the authors be held liable for any damages
|
|
arising from the use of this software.
|
|
|
|
Permission is granted to anyone to use this software for any purpose,
|
|
including commercial applications, and to alter it and redistribute it
|
|
freely, subject to the following restrictions:
|
|
|
|
1. The origin of this software must not be misrepresented; you must not
|
|
claim that you wrote the original software. If you use this software
|
|
in a product, an acknowledgment in the product documentation would be
|
|
appreciated but is not required.
|
|
|
|
2. Altered source versions must be plainly marked as such, and must not be
|
|
misrepresented as being the original software.
|
|
|
|
3. This notice may not be removed or altered from any source
|
|
distribution.
|
|
*******************************************************************************/
|
|
|
|
#ifndef __PolyVox_SurfaceExtractor_H__
|
|
#define __PolyVox_SurfaceExtractor_H__
|
|
|
|
#include "Impl/MarchingCubesTables.h"
|
|
#include "Impl/PlatformDefinitions.h"
|
|
|
|
#include "PolyVox/Array.h"
|
|
#include "PolyVox/BaseVolume.h" //For wrap modes... should move these?
|
|
#include "PolyVox/Mesh.h"
|
|
#include "PolyVox/DefaultMarchingCubesController.h"
|
|
#include "PolyVox/Vertex.h"
|
|
|
|
namespace PolyVox
|
|
{
|
|
#ifdef SWIG
|
|
struct MarchingCubesVertex
|
|
#else
|
|
template<typename _DataType>
|
|
struct POLYVOX_API MarchingCubesVertex
|
|
#endif
|
|
{
|
|
typedef _DataType DataType;
|
|
|
|
// Each component of the position is stored using 8.8 fixed-point encoding.
|
|
Vector3DUint16 encodedPosition;
|
|
|
|
// The normal is encoded as a 16-bit unsigned integer using the 'oct16'
|
|
// encoding described here: http://jcgt.org/published/0003/02/01/
|
|
uint16_t encodedNormal;
|
|
|
|
// User data
|
|
DataType data;
|
|
};
|
|
|
|
// Convienient shorthand for declaring a mesh of marching cubes vertices
|
|
// Currently disabled because it requires GCC 4.7
|
|
//template <typename VertexDataType, typename IndexType = DefaultIndexType>
|
|
//using MarchingCubesMesh = Mesh< MarchingCubesVertex<VertexDataType>, IndexType >;
|
|
|
|
/// Decodes a position from a MarchingCubesVertex
|
|
inline Vector3DFloat decodePosition(const Vector3DUint16& encodedPosition)
|
|
{
|
|
Vector3DFloat result(encodedPosition.getX(), encodedPosition.getY(), encodedPosition.getZ());
|
|
result *= (1.0f / 256.0f); // Division is compile-time constant
|
|
return result;
|
|
}
|
|
|
|
inline uint16_t encodeNormal(const Vector3DFloat& normal)
|
|
{
|
|
// The first part of this function is based off the code in Listing 1 of http://jcgt.org/published/0003/02/01/
|
|
// It was rewritten in C++ and is restructued for the CPU rather than the GPU.
|
|
|
|
// Get the input components
|
|
float vx = normal.getX();
|
|
float vy = normal.getY();
|
|
float vz = normal.getZ();
|
|
|
|
// Project the sphere onto the octahedron, and then onto the xy plane
|
|
float px = vx * (1.0f / (std::abs(vx) + std::abs(vy) + std::abs(vz)));
|
|
float py = vy * (1.0f / (std::abs(vx) + std::abs(vy) + std::abs(vz)));
|
|
|
|
// Reflect the folds of the lower hemisphere over the diagonals.
|
|
if (vz <= 0.0f)
|
|
{
|
|
float refx = ((1.0f - std::abs(py)) * (px >= 0.0f ? +1.0f : -1.0f));
|
|
float refy = ((1.0f - std::abs(px)) * (py >= 0.0f ? +1.0f : -1.0f));
|
|
px = refx;
|
|
py = refy;
|
|
}
|
|
|
|
// The next part was not given in the paper. We map our two
|
|
// floats into two bytes and store them in a single uint16_t
|
|
|
|
// Move from range [-1.0f, 1.0f] to [0.0f, 255.0f]
|
|
px = (px + 1.0f) * 127.5f;
|
|
py = (py + 1.0f) * 127.5f;
|
|
|
|
// Convert to uints
|
|
uint16_t resultX = static_cast<uint16_t>(px + 0.5f);
|
|
uint16_t resultY = static_cast<uint16_t>(py + 0.5f);
|
|
|
|
// Make sure only the lower bits are set. Probably
|
|
// not necessary but we're just being careful really.
|
|
resultX &= 0xFF;
|
|
resultY &= 0xFF;
|
|
|
|
// Contatenate the bytes and return the result.
|
|
return (resultX << 8) | resultY;
|
|
}
|
|
|
|
inline Vector3DFloat decodeNormal(const uint16_t& encodedNormal)
|
|
{
|
|
// Extract the two bytes from the uint16_t.
|
|
uint16_t ux = (encodedNormal >> 8) & 0xFF;
|
|
uint16_t uy = (encodedNormal ) & 0xFF;
|
|
|
|
// Convert to floats in the range [-1.0f, +1.0f].
|
|
float ex = ux / 127.5f - 1.0f;
|
|
float ey = uy / 127.5f - 1.0f;
|
|
|
|
// Reconstruct the origninal vector. This is a C++ implementation
|
|
// of Listing 2 of http://jcgt.org/published/0003/02/01/
|
|
float vx = ex;
|
|
float vy = ey;
|
|
float vz = 1.0f - std::abs(ex) - std::abs(ey);
|
|
|
|
if (vz < 0.0f)
|
|
{
|
|
float refX = ((1.0f - std::abs(vy)) * (vx >= 0.0f ? +1.0f : -1.0f));
|
|
float refY = ((1.0f - std::abs(vx)) * (vy >= 0.0f ? +1.0f : -1.0f));
|
|
vx = refX;
|
|
vy = refY;
|
|
}
|
|
|
|
// Normalise and return the result.
|
|
Vector3DFloat v(vx, vy, vz);
|
|
v.normalise();
|
|
return v;
|
|
}
|
|
|
|
/// Decodes a MarchingCubesVertex by converting it into a regular Vertex which can then be directly used for rendering.
|
|
template<typename DataType>
|
|
Vertex<DataType> decodeVertex(const MarchingCubesVertex<DataType>& marchingCubesVertex)
|
|
{
|
|
Vertex<DataType> result;
|
|
result.position = decodePosition(marchingCubesVertex.encodedPosition);
|
|
result.normal = decodeNormal(marchingCubesVertex.encodedNormal);
|
|
result.data = marchingCubesVertex.data; // Data is not encoded
|
|
return result;
|
|
}
|
|
|
|
/// Do not use this class directly. Use the 'extractMarchingCubesSurface' function instead (see examples).
|
|
template< typename VolumeType, typename MeshType, typename ControllerType>
|
|
class MarchingCubesSurfaceExtractor
|
|
{
|
|
public:
|
|
MarchingCubesSurfaceExtractor(VolumeType* volData, Region region, MeshType* result, ControllerType controller);
|
|
|
|
void execute();
|
|
|
|
private:
|
|
//Compute the cell bitmask for a particular slice in z.
|
|
template<bool isPrevZAvail>
|
|
uint32_t computeBitmaskForSlice(const Array2DUint8& pPreviousBitmask, Array2DUint8& pCurrentBitmask);
|
|
|
|
//Compute the cell bitmask for a given cell.
|
|
template<bool isPrevXAvail, bool isPrevYAvail, bool isPrevZAvail>
|
|
void computeBitmaskForCell(const Array2DUint8& pPreviousBitmask, Array2DUint8& pCurrentBitmask, uint32_t uXRegSpace, uint32_t uYRegSpace);
|
|
|
|
//Use the cell bitmasks to generate all the vertices needed for that slice
|
|
void generateVerticesForSlice(const Array2DUint8& pCurrentBitmask,
|
|
Array2DInt32& m_pCurrentVertexIndicesX,
|
|
Array2DInt32& m_pCurrentVertexIndicesY,
|
|
Array2DInt32& m_pCurrentVertexIndicesZ);
|
|
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// NOTE: These two functions are in the .h file rather than the .inl due to an apparent bug in VC2010.
|
|
//See http://stackoverflow.com/questions/1484885/strange-vc-compile-error-c2244 for details.
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
Vector3DFloat computeCentralDifferenceGradient(const typename VolumeType::Sampler& volIter)
|
|
{
|
|
//FIXME - Should actually use DensityType here, both in principle and because the maths may be
|
|
//faster (and to reduce casts). So it would be good to add a way to get DensityType from a voxel.
|
|
//But watch out for when the DensityType is unsigned and the difference could be negative.
|
|
float voxel1nx = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx0py0pz()));
|
|
float voxel1px = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px0py0pz()));
|
|
|
|
float voxel1ny = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px1ny0pz()));
|
|
float voxel1py = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px1py0pz()));
|
|
|
|
float voxel1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px0py1nz()));
|
|
float voxel1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px0py1pz()));
|
|
|
|
return Vector3DFloat
|
|
(
|
|
voxel1nx - voxel1px,
|
|
voxel1ny - voxel1py,
|
|
voxel1nz - voxel1pz
|
|
);
|
|
}
|
|
|
|
Vector3DFloat computeSobelGradient(const typename VolumeType::Sampler& volIter)
|
|
{
|
|
static const int weights[3][3][3] = { { {2,3,2}, {3,6,3}, {2,3,2} }, {
|
|
{3,6,3}, {6,0,6}, {3,6,3} }, { {2,3,2}, {3,6,3}, {2,3,2} } };
|
|
|
|
//FIXME - Should actually use DensityType here, both in principle and because the maths may be
|
|
//faster (and to reduce casts). So it would be good to add a way to get DensityType from a voxel.
|
|
//But watch out for when the DensityType is unsigned and the difference could be negative.
|
|
const float pVoxel1nx1ny1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx1ny1nz()));
|
|
const float pVoxel1nx1ny0pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx1ny0pz()));
|
|
const float pVoxel1nx1ny1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx1ny1pz()));
|
|
const float pVoxel1nx0py1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx0py1nz()));
|
|
const float pVoxel1nx0py0pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx0py0pz()));
|
|
const float pVoxel1nx0py1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx0py1pz()));
|
|
const float pVoxel1nx1py1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx1py1nz()));
|
|
const float pVoxel1nx1py0pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx1py0pz()));
|
|
const float pVoxel1nx1py1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1nx1py1pz()));
|
|
|
|
const float pVoxel0px1ny1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px1ny1nz()));
|
|
const float pVoxel0px1ny0pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px1ny0pz()));
|
|
const float pVoxel0px1ny1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px1ny1pz()));
|
|
const float pVoxel0px0py1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px0py1nz()));
|
|
//const float pVoxel0px0py0pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px0py0pz()));
|
|
const float pVoxel0px0py1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px0py1pz()));
|
|
const float pVoxel0px1py1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px1py1nz()));
|
|
const float pVoxel0px1py0pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px1py0pz()));
|
|
const float pVoxel0px1py1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel0px1py1pz()));
|
|
|
|
const float pVoxel1px1ny1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px1ny1nz()));
|
|
const float pVoxel1px1ny0pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px1ny0pz()));
|
|
const float pVoxel1px1ny1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px1ny1pz()));
|
|
const float pVoxel1px0py1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px0py1nz()));
|
|
const float pVoxel1px0py0pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px0py0pz()));
|
|
const float pVoxel1px0py1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px0py1pz()));
|
|
const float pVoxel1px1py1nz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px1py1nz()));
|
|
const float pVoxel1px1py0pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px1py0pz()));
|
|
const float pVoxel1px1py1pz = static_cast<float>(m_controller.convertToDensity(volIter.peekVoxel1px1py1pz()));
|
|
|
|
const float xGrad(- weights[0][0][0] * pVoxel1nx1ny1nz -
|
|
weights[1][0][0] * pVoxel1nx1ny0pz - weights[2][0][0] *
|
|
pVoxel1nx1ny1pz - weights[0][1][0] * pVoxel1nx0py1nz -
|
|
weights[1][1][0] * pVoxel1nx0py0pz - weights[2][1][0] *
|
|
pVoxel1nx0py1pz - weights[0][2][0] * pVoxel1nx1py1nz -
|
|
weights[1][2][0] * pVoxel1nx1py0pz - weights[2][2][0] *
|
|
pVoxel1nx1py1pz + weights[0][0][2] * pVoxel1px1ny1nz +
|
|
weights[1][0][2] * pVoxel1px1ny0pz + weights[2][0][2] *
|
|
pVoxel1px1ny1pz + weights[0][1][2] * pVoxel1px0py1nz +
|
|
weights[1][1][2] * pVoxel1px0py0pz + weights[2][1][2] *
|
|
pVoxel1px0py1pz + weights[0][2][2] * pVoxel1px1py1nz +
|
|
weights[1][2][2] * pVoxel1px1py0pz + weights[2][2][2] *
|
|
pVoxel1px1py1pz);
|
|
|
|
const float yGrad(- weights[0][0][0] * pVoxel1nx1ny1nz -
|
|
weights[1][0][0] * pVoxel1nx1ny0pz - weights[2][0][0] *
|
|
pVoxel1nx1ny1pz + weights[0][2][0] * pVoxel1nx1py1nz +
|
|
weights[1][2][0] * pVoxel1nx1py0pz + weights[2][2][0] *
|
|
pVoxel1nx1py1pz - weights[0][0][1] * pVoxel0px1ny1nz -
|
|
weights[1][0][1] * pVoxel0px1ny0pz - weights[2][0][1] *
|
|
pVoxel0px1ny1pz + weights[0][2][1] * pVoxel0px1py1nz +
|
|
weights[1][2][1] * pVoxel0px1py0pz + weights[2][2][1] *
|
|
pVoxel0px1py1pz - weights[0][0][2] * pVoxel1px1ny1nz -
|
|
weights[1][0][2] * pVoxel1px1ny0pz - weights[2][0][2] *
|
|
pVoxel1px1ny1pz + weights[0][2][2] * pVoxel1px1py1nz +
|
|
weights[1][2][2] * pVoxel1px1py0pz + weights[2][2][2] *
|
|
pVoxel1px1py1pz);
|
|
|
|
const float zGrad(- weights[0][0][0] * pVoxel1nx1ny1nz +
|
|
weights[2][0][0] * pVoxel1nx1ny1pz - weights[0][1][0] *
|
|
pVoxel1nx0py1nz + weights[2][1][0] * pVoxel1nx0py1pz -
|
|
weights[0][2][0] * pVoxel1nx1py1nz + weights[2][2][0] *
|
|
pVoxel1nx1py1pz - weights[0][0][1] * pVoxel0px1ny1nz +
|
|
weights[2][0][1] * pVoxel0px1ny1pz - weights[0][1][1] *
|
|
pVoxel0px0py1nz + weights[2][1][1] * pVoxel0px0py1pz -
|
|
weights[0][2][1] * pVoxel0px1py1nz + weights[2][2][1] *
|
|
pVoxel0px1py1pz - weights[0][0][2] * pVoxel1px1ny1nz +
|
|
weights[2][0][2] * pVoxel1px1ny1pz - weights[0][1][2] *
|
|
pVoxel1px0py1nz + weights[2][1][2] * pVoxel1px0py1pz -
|
|
weights[0][2][2] * pVoxel1px1py1nz + weights[2][2][2] *
|
|
pVoxel1px1py1pz);
|
|
|
|
//Note: The above actually give gradients going from low density to high density.
|
|
//For our normals we want the the other way around, so we switch the components as we return them.
|
|
return Vector3DFloat(-xGrad,-yGrad,-zGrad);
|
|
}
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
// End of compiler bug workaroumd.
|
|
////////////////////////////////////////////////////////////////////////////////
|
|
|
|
//Use the cell bitmasks to generate all the indices needed for that slice
|
|
void generateIndicesForSlice(const Array2DUint8& pPreviousBitmask,
|
|
const Array2DInt32& m_pPreviousVertexIndicesX,
|
|
const Array2DInt32& m_pPreviousVertexIndicesY,
|
|
const Array2DInt32& m_pPreviousVertexIndicesZ,
|
|
const Array2DInt32& m_pCurrentVertexIndicesX,
|
|
const Array2DInt32& m_pCurrentVertexIndicesY);
|
|
|
|
//The volume data and a sampler to access it.
|
|
VolumeType* m_volData;
|
|
typename VolumeType::Sampler m_sampVolume;
|
|
|
|
//Used to return the number of cells in a slice which contain triangles.
|
|
uint32_t m_uNoOfOccupiedCells;
|
|
|
|
//The surface patch we are currently filling.
|
|
MeshType* m_meshCurrent;
|
|
|
|
//Information about the region we are currently processing
|
|
Region m_regSizeInVoxels;
|
|
Region m_regSizeInCells;
|
|
/*Region m_regSizeInVoxelsCropped;
|
|
Region m_regSizeInVoxelsUncropped;
|
|
Region m_regVolumeCropped;*/
|
|
Region m_regSlicePrevious;
|
|
Region m_regSliceCurrent;
|
|
|
|
//Used to convert arbitrary voxel types in densities and materials.
|
|
ControllerType m_controller;
|
|
|
|
//Our threshold value
|
|
typename ControllerType::DensityType m_tThreshold;
|
|
};
|
|
|
|
// This version of the function performs the extraction into a user-provided mesh rather than allocating a mesh automatically.
|
|
// There are a few reasons why this might be useful to more advanced users:
|
|
//
|
|
// 1. It leaves the user in control of memory allocation and would allow them to implement e.g. a mesh pooling system.
|
|
// 2. The user-provided mesh could have a different index type (e.g. 16-bit indices) to reduce memory usage.
|
|
// 3. The user could provide a custom mesh class, e.g a thin wrapper around an openGL VBO to allow direct writing into this structure.
|
|
//
|
|
// We don't provide a default MeshType here. If the user doesn't want to provide a MeshType then it probably makes
|
|
// more sense to use the other variant of this function where the mesh is a return value rather than a parameter.
|
|
//
|
|
// Note: This function is called 'extractMarchingCubesMeshCustom' rather than 'extractMarchingCubesMesh' to avoid ambiguity when only three parameters
|
|
// are provided (would the third parameter be a controller or a mesh?). It seems this can be fixed by using enable_if/static_assert to emulate concepts,
|
|
// but this is relatively complex and I haven't done it yet. Could always add it later as another overload.
|
|
template< typename VolumeType, typename MeshType, typename ControllerType = DefaultMarchingCubesController<typename VolumeType::VoxelType> >
|
|
void extractMarchingCubesMeshCustom(VolumeType* volData, Region region, MeshType* result, ControllerType controller = ControllerType())
|
|
{
|
|
MarchingCubesSurfaceExtractor<VolumeType, MeshType, ControllerType> extractor(volData, region, result, controller);
|
|
extractor.execute();
|
|
}
|
|
|
|
template< typename VolumeType, typename ControllerType = DefaultMarchingCubesController<typename VolumeType::VoxelType> >
|
|
Mesh<MarchingCubesVertex<typename VolumeType::VoxelType> > extractMarchingCubesMesh(VolumeType* volData, Region region, ControllerType controller = ControllerType())
|
|
{
|
|
Mesh<MarchingCubesVertex<typename VolumeType::VoxelType> > result;
|
|
extractMarchingCubesMeshCustom<VolumeType, Mesh<MarchingCubesVertex<typename VolumeType::VoxelType>, DefaultIndexType > >(volData, region, &result, controller);
|
|
return result;
|
|
}
|
|
}
|
|
|
|
#include "PolyVox/MarchingCubesSurfaceExtractor.inl"
|
|
|
|
#endif
|