232 lines
8.3 KiB
C++
232 lines
8.3 KiB
C++
/*******************************************************************************
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* The MIT License (MIT)
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*
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* Copyright (c) 2015 David Williams and Matthew Williams
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*******************************************************************************/
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#ifndef __PolyVox_CubicSurfaceExtractor_H__
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#define __PolyVox_CubicSurfaceExtractor_H__
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#include "Impl/PlatformDefinitions.h"
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#include "Array.h"
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#include "BaseVolume.h" //For wrap modes... should move these?
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#include "DefaultIsQuadNeeded.h"
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#include "Mesh.h"
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#include "Vertex.h"
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namespace PolyVox
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{
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template<typename _DataType>
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struct CubicVertex
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{
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typedef _DataType DataType;
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// Each component of the position is stored as a single unsigned byte.
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// The true position is found by offseting each component by 0.5f.
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Vector3DUint8 encodedPosition;
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// User data
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DataType data;
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};
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// Convienient shorthand for declaring a mesh of 'cubic' vertices
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// Currently disabled because it requires GCC 4.7
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//template <typename VertexDataType, typename IndexType = DefaultIndexType>
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//using CubicMesh = Mesh< CubicVertex<VertexDataType>, IndexType >;
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/// Decodes a position from a CubicVertex
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inline Vector3DFloat decodePosition(const Vector3DUint8& encodedPosition)
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{
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Vector3DFloat result(encodedPosition.getX(), encodedPosition.getY(), encodedPosition.getZ());
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result -= 0.5f; // Apply the required offset
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return result;
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}
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/// Decodes a MarchingCubesVertex by converting it into a regular Vertex which can then be directly used for rendering.
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template<typename DataType>
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Vertex<DataType> decodeVertex(const CubicVertex<DataType>& cubicVertex)
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{
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Vertex<DataType> result;
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result.position = decodePosition(cubicVertex.encodedPosition);
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result.normal.setElements(0.0f, 0.0f, 0.0f); // Currently not calculated
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result.data = cubicVertex.data; // Data is not encoded
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return result;
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}
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struct Quad
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{
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Quad(uint32_t v0, uint32_t v1, uint32_t v2, uint32_t v3)
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{
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vertices[0] = v0;
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vertices[1] = v1;
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vertices[2] = v2;
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vertices[3] = v3;
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}
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uint32_t vertices[4];
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};
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// This constant defines the maximum number of quads which can share a vertex in a cubic style mesh.
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//
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// We try to avoid duplicate vertices by checking whether a vertex has already been added at a given position.
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// However, it is possible that vertices have the same position but different materials. In this case, the
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// vertices are not true duplicates and both must be added to the mesh. As far as I can tell, it is possible to have
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// at most eight vertices with the same position but different materials. For example, this worst-case scenario
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// happens when we have a 2x2x2 group of voxels, all with different materials and some/all partially transparent.
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// The vertex position at the center of this group is then going to be used by all eight voxels all with different
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// materials.
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const uint32_t MaxVerticesPerPosition = 8;
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template<typename VolumeType>
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struct IndexAndMaterial
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{
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int32_t iIndex;
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typename VolumeType::VoxelType uMaterial;
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};
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enum FaceNames
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{
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PositiveX,
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PositiveY,
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PositiveZ,
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NegativeX,
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NegativeY,
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NegativeZ,
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NoOfFaces
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};
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template<typename MeshType>
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bool mergeQuads(Quad& q1, Quad& q2, MeshType* m_meshCurrent)
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{
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//All four vertices of a given quad have the same data,
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//so just check that the first pair of vertices match.
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if (m_meshCurrent->getVertex(q1.vertices[0]).data == m_meshCurrent->getVertex(q2.vertices[0]).data)
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{
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//Now check whether quad 2 is adjacent to quad one by comparing vertices.
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//Adjacent quads must share two vertices, and the second quad could be to the
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//top, bottom, left, of right of the first one. This gives four combinations to test.
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if ((q1.vertices[0] == q2.vertices[1]) && ((q1.vertices[3] == q2.vertices[2])))
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{
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q1.vertices[0] = q2.vertices[0];
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q1.vertices[3] = q2.vertices[3];
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return true;
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}
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else if ((q1.vertices[3] == q2.vertices[0]) && ((q1.vertices[2] == q2.vertices[1])))
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{
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q1.vertices[3] = q2.vertices[3];
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q1.vertices[2] = q2.vertices[2];
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return true;
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}
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else if ((q1.vertices[1] == q2.vertices[0]) && ((q1.vertices[2] == q2.vertices[3])))
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{
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q1.vertices[1] = q2.vertices[1];
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q1.vertices[2] = q2.vertices[2];
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return true;
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}
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else if ((q1.vertices[0] == q2.vertices[3]) && ((q1.vertices[1] == q2.vertices[2])))
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{
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q1.vertices[0] = q2.vertices[0];
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q1.vertices[1] = q2.vertices[1];
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return true;
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}
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}
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//Quads cannot be merged.
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return false;
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}
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template<typename MeshType>
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bool performQuadMerging(std::list<Quad>& quads, MeshType* m_meshCurrent)
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{
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bool bDidMerge = false;
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for (typename std::list<Quad>::iterator outerIter = quads.begin(); outerIter != quads.end(); outerIter++)
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{
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typename std::list<Quad>::iterator innerIter = outerIter;
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innerIter++;
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while (innerIter != quads.end())
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{
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Quad& q1 = *outerIter;
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Quad& q2 = *innerIter;
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bool result = mergeQuads(q1, q2, m_meshCurrent);
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if (result)
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{
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bDidMerge = true;
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innerIter = quads.erase(innerIter);
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}
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else
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{
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innerIter++;
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}
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}
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}
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return bDidMerge;
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}
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template<typename VolumeType, typename MeshType>
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int32_t addVertex(uint32_t uX, uint32_t uY, uint32_t uZ, typename VolumeType::VoxelType uMaterialIn, Array<3, IndexAndMaterial<VolumeType> >& existingVertices, MeshType* m_meshCurrent)
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{
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for (uint32_t ct = 0; ct < MaxVerticesPerPosition; ct++)
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{
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IndexAndMaterial<VolumeType>& rEntry = existingVertices(uX, uY, ct);
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if (rEntry.iIndex == -1)
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{
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//No vertices matched and we've now hit an empty space. Fill it by creating a vertex. The 0.5f offset is because vertices set between voxels in order to build cubes around them.
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CubicVertex<typename VolumeType::VoxelType> cubicVertex;
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cubicVertex.encodedPosition.setElements(static_cast<uint8_t>(uX), static_cast<uint8_t>(uY), static_cast<uint8_t>(uZ));
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cubicVertex.data = uMaterialIn;
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rEntry.iIndex = m_meshCurrent->addVertex(cubicVertex);
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rEntry.uMaterial = uMaterialIn;
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return rEntry.iIndex;
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}
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//If we have an existing vertex and the material matches then we can return it.
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if (rEntry.uMaterial == uMaterialIn)
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{
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return rEntry.iIndex;
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}
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}
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// If we exit the loop here then apparently all the slots were full but none of them matched.
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// This shouldn't ever happen, so if it does it is probably a bug in PolyVox. Please report it to us!
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POLYVOX_THROW(std::runtime_error, "All slots full but no matches during cubic surface extraction. This is probably a bug in PolyVox");
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return -1; //Should never happen.
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}
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// Generates a cubic-style mesh from the voxel data.
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template<typename VolumeType, typename MeshType, typename IsQuadNeeded = DefaultIsQuadNeeded<typename VolumeType::VoxelType> >
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void extractCubicMeshCustom(VolumeType* volData, Region region, MeshType* result, IsQuadNeeded isQuadNeeded = IsQuadNeeded(), bool bMergeQuads = true);
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// Generates a cubic-style mesh from the voxel data, placing the result into a user-provided Mesh.
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template<typename VolumeType, typename IsQuadNeeded = DefaultIsQuadNeeded<typename VolumeType::VoxelType> >
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Mesh<CubicVertex<typename VolumeType::VoxelType> > extractCubicMesh(VolumeType* volData, Region region, IsQuadNeeded isQuadNeeded = IsQuadNeeded(), bool bMergeQuads = true);
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}
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#include "CubicSurfaceExtractor.inl"
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#endif
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