324 lines
9 KiB
C++
324 lines
9 KiB
C++
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// Copyright NVIDIA Corporation 2008 -- Ignacio Castano <icastano@nvidia.com>
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#include "nvmesh.h" // pch
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#include "ParameterizationQuality.h"
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#include "nvmesh/halfedge/Mesh.h"
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#include "nvmesh/halfedge/Face.h"
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#include "nvmesh/halfedge/Vertex.h"
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#include "nvmesh/halfedge/Edge.h"
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#include "nvmath/Vector.inl"
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#include "nvcore/Debug.h"
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#include <float.h>
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using namespace nv;
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#if 0
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/*
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float triangleConformalEnergy(Vector3 q[3], Vector2 p[3])
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{
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const Vector3 v1 = q[0];
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const Vector3 v2 = q[1];
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const Vector3 v3 = q[2];
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const Vector2 w1 = p[0];
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const Vector2 w2 = p[1];
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const Vector2 w3 = p[2];
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float x1 = v2.x() - v1.x();
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float x2 = v3.x() - v1.x();
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float y1 = v2.y() - v1.y();
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float y2 = v3.y() - v1.y();
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float z1 = v2.z() - v1.z();
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float z2 = v3.z() - v1.z();
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float s1 = w2.x() - w1.x();
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float s2 = w3.x() - w1.x();
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float t1 = w2.y() - w1.y();
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float t2 = w3.y() - w1.y();
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float r = 1.0f / (s1 * t2 - s2 * t1);
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Vector3 sdir((t2 * x1 - t1 * x2) * r, (t2 * y1 - t1 * y2) * r, (t2 * z1 - t1 * z2) * r);
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Vector3 tdir((s1 * x2 - s2 * x1) * r, (s1 * y2 - s2 * y1) * r, (s1 * z2 - s2 * z1) * r);
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Vector3 N = cross(v3-v1, v2-v1);
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// Rotate 90 around N.
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}
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*/
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static float triangleConformalEnergy(Vector3 q[3], Vector2 p[3])
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{
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// Using Denis formulas:
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Vector3 c0 = q[1] - q[2];
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Vector3 c1 = q[2] - q[0];
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Vector3 c2 = q[0] - q[1];
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Vector3 N = cross(-c0, c1);
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float T = length(N); // 2T
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N = normalize(N, 0);
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float cot_alpha0 = dot(-c1, c2) / length(cross(-c1, c2));
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float cot_alpha1 = dot(-c2, c0) / length(cross(-c2, c0));
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float cot_alpha2 = dot(-c0, c1) / length(cross(-c0, c1));
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Vector3 t0 = -cot_alpha1 * c1 + cot_alpha2 * c2;
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Vector3 t1 = -cot_alpha2 * c2 + cot_alpha0 * c0;
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Vector3 t2 = -cot_alpha0 * c0 + cot_alpha1 * c1;
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nvCheck(equal(length(t0), length(c0)));
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nvCheck(equal(length(t1), length(c1)));
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nvCheck(equal(length(t2), length(c2)));
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nvCheck(equal(dot(t0, c0), 0));
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nvCheck(equal(dot(t1, c1), 0));
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nvCheck(equal(dot(t2, c2), 0));
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// Gradients
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Vector3 grad_u = 1.0f / T * (p[0].x * t0 + p[1].x * t1 + p[2].x * t2);
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Vector3 grad_v = 1.0f / T * (p[0].y * t0 + p[1].y * t1 + p[2].y * t2);
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// Rotated gradients
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Vector3 Jgrad_u = 1.0f / T * (p[0].x * c0 + p[1].x * c1 + p[2].x * c2);
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Vector3 Jgrad_v = 1.0f / T * (p[0].y * c0 + p[1].y * c1 + p[2].y * c2);
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// Using Lengyel's formulas:
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{
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const Vector3 v1 = q[0];
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const Vector3 v2 = q[1];
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const Vector3 v3 = q[2];
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const Vector2 w1 = p[0];
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const Vector2 w2 = p[1];
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const Vector2 w3 = p[2];
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float x1 = v2.x - v1.x;
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float x2 = v3.x - v1.x;
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float y1 = v2.y - v1.y;
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float y2 = v3.y - v1.y;
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float z1 = v2.z - v1.z;
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float z2 = v3.z - v1.z;
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float s1 = w2.x - w1.x;
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float s2 = w3.x - w1.x;
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float t1 = w2.y - w1.y;
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float t2 = w3.y - w1.y;
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float r = 1.0f / (s1 * t2 - s2 * t1);
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Vector3 sdir((t2 * x1 - t1 * x2) * r, (t2 * y1 - t1 * y2) * r, (t2 * z1 - t1 * z2) * r);
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Vector3 tdir((s1 * x2 - s2 * x1) * r, (s1 * y2 - s2 * y1) * r, (s1 * z2 - s2 * z1) * r);
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Vector3 Jsdir = cross(N, sdir);
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Vector3 Jtdir = cross(N, tdir);
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float x = 3;
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}
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// check: sdir == grad_u
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// check: tdir == grad_v
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return length(grad_u - Jgrad_v);
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}
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#endif // 0
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ParameterizationQuality::ParameterizationQuality()
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{
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m_totalTriangleCount = 0;
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m_flippedTriangleCount = 0;
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m_zeroAreaTriangleCount = 0;
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m_parametricArea = 0.0f;
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m_geometricArea = 0.0f;
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m_stretchMetric = 0.0f;
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m_maxStretchMetric = 0.0f;
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m_conformalMetric = 0.0f;
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m_authalicMetric = 0.0f;
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}
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ParameterizationQuality::ParameterizationQuality(const HalfEdge::Mesh * mesh)
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{
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nvDebugCheck(mesh != NULL);
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m_totalTriangleCount = 0;
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m_flippedTriangleCount = 0;
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m_zeroAreaTriangleCount = 0;
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m_parametricArea = 0.0f;
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m_geometricArea = 0.0f;
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m_stretchMetric = 0.0f;
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m_maxStretchMetric = 0.0f;
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m_conformalMetric = 0.0f;
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m_authalicMetric = 0.0f;
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const uint faceCount = mesh->faceCount();
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for (uint f = 0; f < faceCount; f++)
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{
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const HalfEdge::Face * face = mesh->faceAt(f);
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const HalfEdge::Vertex * vertex0 = NULL;
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Vector3 p[3];
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Vector2 t[3];
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for (HalfEdge::Face::ConstEdgeIterator it(face->edges()); !it.isDone(); it.advance())
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{
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const HalfEdge::Edge * edge = it.current();
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if (vertex0 == NULL)
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{
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vertex0 = edge->vertex;
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p[0] = vertex0->pos;
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t[0] = vertex0->tex;
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}
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else if (edge->to() != vertex0)
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{
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p[1] = edge->from()->pos;
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p[2] = edge->to()->pos;
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t[1] = edge->from()->tex;
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t[2] = edge->to()->tex;
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processTriangle(p, t);
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}
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}
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}
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if (m_flippedTriangleCount + m_zeroAreaTriangleCount == faceCount)
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{
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// If all triangles are flipped, then none is.
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m_flippedTriangleCount = 0;
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}
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nvDebugCheck(isFinite(m_parametricArea) && m_parametricArea >= 0);
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nvDebugCheck(isFinite(m_geometricArea) && m_geometricArea >= 0);
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nvDebugCheck(isFinite(m_stretchMetric));
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nvDebugCheck(isFinite(m_maxStretchMetric));
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nvDebugCheck(isFinite(m_conformalMetric));
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nvDebugCheck(isFinite(m_authalicMetric));
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}
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bool ParameterizationQuality::isValid() const
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{
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return m_flippedTriangleCount == 0; // @@ Does not test for self-overlaps.
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}
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float ParameterizationQuality::rmsStretchMetric() const
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{
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if (m_geometricArea == 0) return 0.0f;
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float normFactor = sqrtf(m_parametricArea / m_geometricArea);
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return sqrtf(m_stretchMetric / m_geometricArea) * normFactor;
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}
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float ParameterizationQuality::maxStretchMetric() const
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{
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if (m_geometricArea == 0) return 0.0f;
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float normFactor = sqrtf(m_parametricArea / m_geometricArea);
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return m_maxStretchMetric * normFactor;
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}
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float ParameterizationQuality::rmsConformalMetric() const
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{
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if (m_geometricArea == 0) return 0.0f;
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return sqrtf(m_conformalMetric / m_geometricArea);
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}
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float ParameterizationQuality::maxAuthalicMetric() const
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{
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if (m_geometricArea == 0) return 0.0f;
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return sqrtf(m_authalicMetric / m_geometricArea);
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}
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void ParameterizationQuality::operator += (const ParameterizationQuality & pq)
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{
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m_totalTriangleCount += pq.m_totalTriangleCount;
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m_flippedTriangleCount += pq.m_flippedTriangleCount;
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m_zeroAreaTriangleCount += pq.m_zeroAreaTriangleCount;
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m_parametricArea += pq.m_parametricArea;
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m_geometricArea += pq.m_geometricArea;
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m_stretchMetric += pq.m_stretchMetric;
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m_maxStretchMetric = max(m_maxStretchMetric, pq.m_maxStretchMetric);
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m_conformalMetric += pq.m_conformalMetric;
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m_authalicMetric += pq.m_authalicMetric;
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}
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void ParameterizationQuality::processTriangle(Vector3 q[3], Vector2 p[3])
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{
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m_totalTriangleCount++;
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// Evaluate texture stretch metric. See:
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// - "Texture Mapping Progressive Meshes", Sander, Snyder, Gortler & Hoppe
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// - "Mesh Parameterization: Theory and Practice", Siggraph'07 Course Notes, Hormann, Levy & Sheffer.
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float t1 = p[0].x;
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float s1 = p[0].y;
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float t2 = p[1].x;
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float s2 = p[1].y;
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float t3 = p[2].x;
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float s3 = p[2].y;
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float geometricArea = length(cross(q[1] - q[0], q[2] - q[0])) / 2;
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float parametricArea = ((s2 - s1)*(t3 - t1) - (s3 - s1)*(t2 - t1)) / 2;
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if (isZero(parametricArea))
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{
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m_zeroAreaTriangleCount++;
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return;
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}
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Vector3 Ss = (q[0] * (t2- t3) + q[1] * (t3 - t1) + q[2] * (t1 - t2)) / (2 * parametricArea);
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Vector3 St = (q[0] * (s3- s2) + q[1] * (s1 - s3) + q[2] * (s2 - s1)) / (2 * parametricArea);
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float a = dot(Ss, Ss); // E
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float b = dot(Ss, St); // F
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float c = dot(St, St); // G
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// Compute eigen-values of the first fundamental form:
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float sigma1 = sqrtf(0.5f * max(0.0f, a + c - sqrtf(square(a - c) + 4 * square(b)))); // gamma uppercase, min eigenvalue.
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float sigma2 = sqrtf(0.5f * max(0.0f, a + c + sqrtf(square(a - c) + 4 * square(b)))); // gamma lowercase, max eigenvalue.
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nvCheck(sigma2 >= sigma1);
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// isometric: sigma1 = sigma2 = 1
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// conformal: sigma1 / sigma2 = 1
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// authalic: sigma1 * sigma2 = 1
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float rmsStretch = sqrtf((a + c) * 0.5f);
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float rmsStretch2 = sqrtf((square(sigma1) + square(sigma2)) * 0.5f);
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nvDebugCheck(equal(rmsStretch, rmsStretch2, 0.01f));
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if (parametricArea < 0.0f)
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{
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// Count flipped triangles.
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m_flippedTriangleCount++;
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parametricArea = fabsf(parametricArea);
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}
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m_stretchMetric += square(rmsStretch) * geometricArea;
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m_maxStretchMetric = max(m_maxStretchMetric, sigma2);
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if (!isZero(sigma1, 0.000001f)) {
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// sigma1 is zero when geometricArea is zero.
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m_conformalMetric += (sigma2 / sigma1) * geometricArea;
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}
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m_authalicMetric += (sigma1 * sigma2) * geometricArea;
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// Accumulate total areas.
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m_geometricArea += geometricArea;
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m_parametricArea += parametricArea;
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//triangleConformalEnergy(q, p);
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}
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