100 lines
2.5 KiB
C++
100 lines
2.5 KiB
C++
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// This code is in the public domain -- castano@gmail.com
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#include "nvmesh.h" // pch
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#include "OrthogonalProjectionMap.h"
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#include "nvcore/Array.inl"
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#include "nvmath/Fitting.h"
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#include "nvmath/Vector.inl"
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#include "nvmath/Box.inl"
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#include "nvmath/Plane.inl"
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#include "nvmesh/halfedge/Mesh.h"
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#include "nvmesh/halfedge/Vertex.h"
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#include "nvmesh/halfedge/Face.h"
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#include "nvmesh/geometry/Bounds.h"
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using namespace nv;
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bool nv::computeOrthogonalProjectionMap(HalfEdge::Mesh * mesh)
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{
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Vector3 axis[2];
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#if 1
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uint vertexCount = mesh->vertexCount();
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Array<Vector3> points(vertexCount);
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points.resize(vertexCount);
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for (uint i = 0; i < vertexCount; i++)
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{
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points[i] = mesh->vertexAt(i)->pos;
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}
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#if 0
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axis[0] = Fit::computePrincipalComponent_EigenSolver(vertexCount, points.buffer());
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axis[0] = normalize(axis[0]);
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Plane plane = Fit::bestPlane(vertexCount, points.buffer());
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Vector3 n = plane.vector();
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axis[1] = cross(axis[0], n);
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axis[1] = normalize(axis[1]);
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#else
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// Avoid redundant computations.
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float matrix[6];
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Fit::computeCovariance(vertexCount, points.buffer(), matrix);
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if (matrix[0] == 0 && matrix[3] == 0 && matrix[5] == 0) {
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return false;
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}
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float eigenValues[3];
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Vector3 eigenVectors[3];
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if (!nv::Fit::eigenSolveSymmetric3(matrix, eigenValues, eigenVectors)) {
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return false;
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}
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axis[0] = normalize(eigenVectors[0]);
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axis[1] = normalize(eigenVectors[1]);
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#endif
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#else
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// IC: I thought this was generally more robust, but turns out it's not even guaranteed to return a valid projection. Imagine a narrow quad perpendicular to one plane, but rotated so that the shortest axis of
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// the bounding box is in the direction of that plane.
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// Use the shortest box axis
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Box box = MeshBounds::box(mesh);
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Vector3 dir = box.extents();
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if (fabs(dir.x) <= fabs(dir.y) && fabs(dir.x) <= fabs(dir.z)) {
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axis[0] = Vector3(0, 1, 0);
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axis[1] = Vector3(0, 0, 1);
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}
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else if (fabs(dir.y) <= fabs(dir.z)) {
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axis[0] = Vector3(1, 0, 0);
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axis[1] = Vector3(0, 0, 1);
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}
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else {
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axis[0] = Vector3(1, 0, 0);
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axis[1] = Vector3(0, 1, 0);
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}
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#endif
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// Project vertices to plane.
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for (HalfEdge::Mesh::VertexIterator it(mesh->vertices()); !it.isDone(); it.advance())
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{
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HalfEdge::Vertex * vertex = it.current();
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vertex->tex.x = dot(axis[0], vertex->pos);
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vertex->tex.y = dot(axis[1], vertex->pos);
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}
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return true;
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}
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