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Diffstat (limited to 'dep/src/g3dlite/MeshAlg.cpp')
| -rw-r--r-- | dep/src/g3dlite/MeshAlg.cpp | 637 |
1 files changed, 637 insertions, 0 deletions
diff --git a/dep/src/g3dlite/MeshAlg.cpp b/dep/src/g3dlite/MeshAlg.cpp new file mode 100644 index 00000000000..626fed92920 --- /dev/null +++ b/dep/src/g3dlite/MeshAlg.cpp @@ -0,0 +1,637 @@ +/** + @file MeshAlg.cpp + + @maintainer Morgan McGuire, http://graphics.cs.williams.edu + @created 2003-09-14 + @edited 2008-09-03 + + Copyright 2000-2009, Morgan McGuire. + All rights reserved. + + */ + +#include "G3D/MeshAlg.h" +#include "G3D/Table.h" +#include "G3D/Set.h" +#include "G3D/Box.h" +#include "G3D/Sphere.h" +#include "G3D/vectorMath.h" +#include "G3D/AABox.h" +#include "G3D/Image1.h" + +#include <climits> + +namespace G3D { + +const int MeshAlg::Face::NONE = INT_MIN; + +void MeshAlg::generateGrid( + Array<Vector3>& vertex, + Array<Vector2>& texCoord, + Array<int>& index, + int wCells, + int hCells, + const Vector2& textureScale, + bool spaceCentered, + bool twoSided, + const CoordinateFrame& xform, + const Image1::Ref& height) { + + vertex.fastClear(); + texCoord.fastClear(); + index.fastClear(); + + // Generate vertices + for (int z = 0; z <= hCells; ++z) { + for (int x = 0; x <= wCells; ++x) { + Vector3 v(x / (float)wCells, 0, z / (float)hCells); + + Vector2 t = v.xz() * textureScale; + + texCoord.append(t); + + if (height.notNull()) { + v.y = height->nearest(v.x * (height->width() - 1), v.z * (height->height() - 1)).value; + } + if (spaceCentered) { + v -= Vector3(0.5f, 0, 0.5f); + } + v = xform.pointToWorldSpace(v); + vertex.append(v); + } + } + + // Generate indices + for (int z = 0; z < hCells; ++z) { + for (int x = 0; x < wCells; ++x) { + int A = x + z * (wCells + 1); + int B = A + 1; + int C = A + (wCells + 1); + int D = C + 1; + + // A B + // *-----* + // | \ | + // | \ | + // *-----* + // C D + + index.append(A, D, B); + index.append(A, C, D); + } + } + + if (twoSided) { + // The index array needs to have reversed winding for the bottom + // and offset by the original number of vertices + Array<int> ti = index; + ti.reverse(); + for (int i = 0; i < ti.size(); ++i) { + ti[i] += vertex.size(); + } + index.append(ti); + + // Duplicate the arrays + vertex.append(Array<Vector3>(vertex)); + texCoord.append(Array<Vector2>(texCoord)); + } +} + +MeshAlg::Face::Face() { + for (int i = 0; i < 3; ++i) { + edgeIndex[i] = 0; + vertexIndex[i] = 0; + } +} + + +MeshAlg::Edge::Edge() { + for (int i = 0; i < 2; ++i) { + vertexIndex[i] = 0; + // Negative face indices are faces that don't exist + faceIndex[i] = -1; + } +} + + +MeshAlg::Geometry& MeshAlg::Geometry::operator=(const MeshAlg::Geometry& src) { + vertexArray.resize(src.vertexArray.size()); + normalArray.resize(src.vertexArray.size()); + + System::memcpy(vertexArray.getCArray(), src.vertexArray.getCArray(), sizeof(Vector3)*vertexArray.size()); + System::memcpy(normalArray.getCArray(), src.normalArray.getCArray(), sizeof(Vector3)*normalArray.size()); + + return *this; +} + + +void MeshAlg::computeNormals( + Geometry& geometry, + const Array<int>& indexArray) { + + Array<Face> faceArray; + Array<Vertex> vertexArray; + Array<Edge> edgeArray; + Array<Vector3> faceNormalArray; + + computeAdjacency(geometry.vertexArray, indexArray, faceArray, edgeArray, vertexArray); + + computeNormals(geometry.vertexArray, faceArray, vertexArray, + geometry.normalArray, faceNormalArray); +} + + +void MeshAlg::computeNormals( + const Array<Vector3>& vertexGeometry, + const Array<Face>& faceArray, + const Array< Array<int> >& adjacentFaceArray, + Array<Vector3>& vertexNormalArray, + Array<Vector3>& faceNormalArray) { + + // Construct a fake vertex array for backwards compatibility + Array<Vertex> fakeVertexArray; + fakeVertexArray.resize(adjacentFaceArray.size()); + + for (int v = 0; v < adjacentFaceArray.size(); ++v) { + fakeVertexArray[v].faceIndex.resize(adjacentFaceArray[v].size()); + for (int i = 0; i < fakeVertexArray[v].faceIndex.size(); ++i) { + fakeVertexArray[v].faceIndex[i] = adjacentFaceArray[v][i]; + } + // We leave out the edges because they aren't used to compute normals + } + + computeNormals(vertexGeometry, faceArray, fakeVertexArray, + vertexNormalArray, faceNormalArray); +} + + +void MeshAlg::computeNormals( + const Array<Vector3>& vertexGeometry, + const Array<Face>& faceArray, + const Array<Vertex>& vertexArray, + Array<Vector3>& vertexNormalArray, + Array<Vector3>& faceNormalArray) { + + // Face normals (not unit length) + faceNormalArray.resize(faceArray.size()); + for (int f = 0; f < faceArray.size(); ++f) { + const Face& face = faceArray[f]; + + Vector3 vertex[3]; + for (int j = 0; j < 3; ++j) { + vertex[j] = vertexGeometry[face.vertexIndex[j]]; + debugAssert(vertex[j].isFinite()); + } + + faceNormalArray[f] = (vertex[1] - vertex[0]).cross(vertex[2] - vertex[0]); +# ifdef G3D_DEBUG + const Vector3& N = faceNormalArray[f]; + debugAssert(N.isFinite()); +# endif + } + + // Per-vertex normals, computed by averaging + vertexNormalArray.resize(vertexGeometry.size()); + for (int v = 0; v < vertexNormalArray.size(); ++v) { + Vector3 sum = Vector3::zero(); + for (int k = 0; k < vertexArray[v].faceIndex.size(); ++k) { + const int f = vertexArray[v].faceIndex[k]; + sum += faceNormalArray[f]; + } + vertexNormalArray[v] = sum.directionOrZero(); +# ifdef G3D_DEBUG + const Vector3& N = vertexNormalArray[v]; + debugAssert(N.isUnit() || N.isZero()); +# endif + } + + + for (int f = 0; f < faceArray.size(); ++f) { + faceNormalArray[f] = faceNormalArray[f].directionOrZero(); +# ifdef G3D_DEBUG + const Vector3& N = faceNormalArray[f]; + debugAssert(N.isUnit() || N.isZero()); +# endif + } + +} + + +void MeshAlg::computeFaceNormals( + const Array<Vector3>& vertexArray, + const Array<MeshAlg::Face>& faceArray, + Array<Vector3>& faceNormals, + bool normalize) { + + faceNormals.resize(faceArray.size()); + + for (int f = 0; f < faceArray.size(); ++f) { + const MeshAlg::Face& face = faceArray[f]; + + const Vector3& v0 = vertexArray[face.vertexIndex[0]]; + const Vector3& v1 = vertexArray[face.vertexIndex[1]]; + const Vector3& v2 = vertexArray[face.vertexIndex[2]]; + + faceNormals[f] = (v1 - v0).cross(v2 - v0); + } + + if (normalize) { + for (int f = 0; f < faceArray.size(); ++f) { + faceNormals[f] = faceNormals[f].direction(); + } + } +} + + +void MeshAlg::identifyBackfaces( + const Array<Vector3>& vertexArray, + const Array<MeshAlg::Face>& faceArray, + const Vector4& HP, + Array<bool>& backface) { + + Vector3 P = HP.xyz(); + + backface.resize(faceArray.size()); + + if (fuzzyEq(HP.w, 0.0)) { + // Infinite case + for (int f = faceArray.size() - 1; f >= 0; --f) { + const MeshAlg::Face& face = faceArray[f]; + + const Vector3& v0 = vertexArray[face.vertexIndex[0]]; + const Vector3& v1 = vertexArray[face.vertexIndex[1]]; + const Vector3& v2 = vertexArray[face.vertexIndex[2]]; + + const Vector3 N = (v1 - v0).cross(v2 - v0); + + backface[f] = N.dot(P) < 0; + } + } else { + // Finite case + for (int f = faceArray.size() - 1; f >= 0; --f) { + const MeshAlg::Face& face = faceArray[f]; + + const Vector3& v0 = vertexArray[face.vertexIndex[0]]; + const Vector3& v1 = vertexArray[face.vertexIndex[1]]; + const Vector3& v2 = vertexArray[face.vertexIndex[2]]; + + const Vector3 N = (v1 - v0).cross(v2 - v0); + + backface[f] = N.dot(P - v0) < 0; + } + } +} + + +void MeshAlg::identifyBackfaces( + const Array<Vector3>& vertexArray, + const Array<MeshAlg::Face>& faceArray, + const Vector4& HP, + Array<bool>& backface, + const Array<Vector3>& faceNormals) { + + Vector3 P = HP.xyz(); + + backface.resize(faceArray.size()); + + if (fuzzyEq(HP.w, 0.0)) { + // Infinite case + for (int f = faceArray.size() - 1; f >= 0; --f) { + const Vector3& N = faceNormals[f]; + backface[f] = N.dot(P) < 0; + } + } else { + // Finite case + for (int f = faceArray.size() - 1; f >= 0; --f) { + const MeshAlg::Face& face = faceArray[f]; + const Vector3& v0 = vertexArray[face.vertexIndex[0]]; + const Vector3& N = faceNormals[f]; + + backface[f] = N.dot(P - v0) < 0; + } + } +} + + +void MeshAlg::createIndexArray(int n, Array<int>& array, int start, int run, int skip) { + debugAssert(skip >= 0); + debugAssert(run >= 0); + + array.resize(n); + if (skip == 0) { + for (int i = 0; i < n; ++i) { + array[i] = start + i; + } + } else { + int rcount = 0; + int j = start; + for (int i = 0; i < n; ++i) { + array[i] = j; + + ++j; + ++rcount; + + if (rcount == run) { + rcount = 0; + j += skip; + } + } + } +} + + +void MeshAlg::computeAreaStatistics( + const Array<Vector3>& vertexArray, + const Array<int>& indexArray, + double& minEdgeLength, + double& meanEdgeLength, + double& medianEdgeLength, + double& maxEdgeLength, + double& minFaceArea, + double& meanFaceArea, + double& medianFaceArea, + double& maxFaceArea) { + + debugAssert(indexArray.size() % 3 == 0); + + Array<double> area; + area.resize(indexArray.size() / 3); + Array<double> magnitude; + magnitude.resize(indexArray.size()); + + for (int i = 0; i < indexArray.size(); i += 3) { + const Vector3& v0 = vertexArray[indexArray[i]]; + const Vector3& v1 = vertexArray[indexArray[i + 1]]; + const Vector3& v2 = vertexArray[indexArray[i + 2]]; + + area[i / 3] = (v1 - v0).cross(v2 - v0).magnitude() / 2.0; + magnitude[i] = (v1 - v0).magnitude(); + magnitude[i + 1] = (v2 - v1).magnitude(); + magnitude[i + 2] = (v0 - v2).magnitude(); + } + + area.sort(); + magnitude.sort(); + + minEdgeLength = max(0.0, magnitude[0]); + maxEdgeLength = max(0.0, magnitude.last()); + medianEdgeLength = max(0.0, magnitude[magnitude.size() / 2]); + meanEdgeLength = 0; + for (int i = 0; i < magnitude.size(); ++i) { + meanEdgeLength += magnitude[i]; + } + meanEdgeLength /= magnitude.size(); + + minFaceArea = max(0.0, area[0]); + maxFaceArea = max(0.0, area.last()); + medianFaceArea = max(0.0, area[area.size() / 2]); + meanFaceArea = 0; + for (int i = 0; i < area.size(); ++i) { + meanFaceArea += area[i]; + } + meanFaceArea /= area.size(); + + + // Make sure round-off hasn't pushed values less than zero + meanFaceArea = max(0.0, meanFaceArea); + meanEdgeLength = max(0.0, meanEdgeLength); +} + + +int MeshAlg::countBoundaryEdges(const Array<MeshAlg::Edge>& edgeArray) { + int b = 0; + + for (int i = 0; i < edgeArray.size(); ++i) { + if ((edgeArray[i].faceIndex[0] == MeshAlg::Face::NONE) != + (edgeArray[i].faceIndex[1] == MeshAlg::Face::NONE)) { + ++b; + } + } + + return b; +} + +void MeshAlg::computeBounds( + const Array<Vector3>& vertexArray, + const Array<int>& indexArray, + AABox& box, + Sphere& sphere) { + + Array<Vector3> newArray; + newArray.resize(indexArray.size()); + for (int i = 0; i < indexArray.size(); ++i) { + newArray[i] = vertexArray[indexArray[i]]; + } + computeBounds(newArray, box, sphere); +} + + +void MeshAlg::computeBounds( + const Array<Vector3>& vertexArray, + AABox& box, + Sphere& sphere) { + + Vector3 xmin, xmax, ymin, ymax, zmin, zmax; + + // FIRST PASS: find 6 minima/maxima points + xmin.x = ymin.y = zmin.z = finf(); + xmax.x = ymax.y = zmax.z = -finf(); + + for (int v = 0; v < vertexArray.size(); ++v) { + const Vector3& vertex = vertexArray[v]; + + if (vertex.x < xmin.x) { + xmin = vertex; + } + + if (vertex.x > xmax.x) { + xmax = vertex; + } + + if (vertex.y < ymin.y) { + ymin = vertex; + } + + if (vertex.y > ymax.y) { + ymax = vertex; + } + + if (vertex.z < zmin.z) { + zmin = vertex; + } + + if (vertex.z > zmax.z) { + zmax = vertex; + } + } + + // Set points dia1 & dia2 to the maximally separated pair + Vector3 dia1 = xmin; + Vector3 dia2 = xmax; + { + // Set xspan = distance between the 2 points xmin & xmax (squared) + double xspan = (xmax - xmin).squaredMagnitude(); + + // Same for y & z spans + double yspan = (ymax - ymin).squaredMagnitude(); + double zspan = (zmax - zmin).squaredMagnitude(); + + double maxspan = xspan; + + if (yspan > maxspan) { + maxspan = yspan; + dia1 = ymin; + dia2 = ymax; + } + + if (zspan > maxspan) { + maxspan = zspan; + dia1 = zmin; + dia2 = zmax; + } + } + + + // dia1, dia2 is a diameter of initial sphere + + // calc initial center + Vector3 center = (dia1 + dia2) / 2.0; + + // calculate initial radius^2 and radius + Vector3 d = dia2 - sphere.center; + + double radSq = d.squaredMagnitude(); + double rad = sqrt(radSq); + + // SECOND PASS: increment current sphere + double old_to_p, old_to_new; + + for (int v = 0; v < vertexArray.size(); ++v) { + const Vector3& vertex = vertexArray[v]; + + d = vertex - center; + + double old_to_p_sq = d.squaredMagnitude(); + + // do r^2 test first + if (old_to_p_sq > radSq) { + // this point is outside of current sphere + old_to_p = sqrt(old_to_p_sq); + + // calc radius of new sphere + rad = (rad + old_to_p) / 2.0; + + // for next r^2 compare + radSq = rad * rad; + old_to_new = old_to_p - rad; + + // calc center of new sphere + center = (rad * center + old_to_new * vertex) / old_to_p; + } + } + + const Vector3 min(xmin.x, ymin.y, zmin.z); + const Vector3 max(xmax.x, ymax.y, zmax.z); + + box = AABox(min, max); + + const float boxRadSq = (max - min).squaredMagnitude() * 0.25f; + + if (boxRadSq >= radSq){ + if (isNaN(center.x) || ! isFinite(rad)) { + sphere = Sphere(Vector3::zero(), finf()); + } else { + sphere = Sphere(center, rad); + } + } else { + sphere = Sphere((max + min) * 0.5f, sqrt(boxRadSq)); + } +} + +void MeshAlg::computeTangentSpaceBasis( + const Array<Vector3>& vertexArray, + const Array<Vector2>& texCoordArray, + const Array<Vector3>& vertexNormalArray, + const Array<Face>& faceArray, + Array<Vector3>& tangent, + Array<Vector3>& binormal) { + + debugAssertM(faceArray.size() != 0, "Unable to calculate valid tangent space without faces."); + + tangent.resize(vertexArray.size()); + binormal.resize(vertexArray.size()); + + // Zero the output arrays. + System::memset(tangent.getCArray(), 0, sizeof(Vector3) * tangent.size()); + System::memset(binormal.getCArray(), 0, sizeof(Vector3) * binormal.size()); + + // Iterate over faces, computing the tangent vectors for each + // vertex. Accumulate those into the tangent and binormal arrays + // and then orthonormalize at the end. + + for (int f = 0; f < faceArray.size(); ++f) { + const Face& face = faceArray[f]; + + const int i0 = face.vertexIndex[0]; + const int i1 = face.vertexIndex[1]; + const int i2 = face.vertexIndex[2]; + + const Vector3& v0 = vertexArray[i0]; + const Vector3& v1 = vertexArray[i1]; + const Vector3& v2 = vertexArray[i2]; + + const Vector2& t0 = texCoordArray[i0]; + const Vector2& t1 = texCoordArray[i1]; + const Vector2& t2 = texCoordArray[i2]; + + // See http://www.terathon.com/code/tangent.html for a derivation of the following code + + // vertex edges + Vector3 ve1 = v1 - v0; + Vector3 ve2 = v2 - v0; + + // texture edges + Vector2 te1 = t1 - t0; + Vector2 te2 = t2 - t0; + + Vector3 n(ve1.cross(ve2).direction()); + Vector3 t, b; + + float r = te1.x * te2.y - te1.y * te2.x; + if (r == 0.0) { + // degenerate case + Vector3::generateOrthonormalBasis(t, b, n, true); + } else { + r = 1.0f / r; + t = (te2.y * ve1 - te1.y * ve2) * r; + b = (te2.x * ve1 - te1.x * ve2) * r; + } + + for (int v = 0; v < 3; ++v) { + int i = face.vertexIndex[v]; + tangent[i] += t; + binormal[i] += b; + } + } + + // Normalize the basis vectors + for (int v = 0; v < vertexArray.size(); ++v) { + // Remove the component parallel to the normal + const Vector3& N = vertexNormalArray[v]; + Vector3& T = tangent[v]; + Vector3& B = binormal[v]; + + debugAssertM(N.isUnit() || N.isZero(), "Input normals must have unit length"); + + T -= T.dot(N) * N; + B -= B.dot(N) * N; + + // Normalize + T = T.directionOrZero(); + B = B.directionOrZero(); + } +} + + + +} // G3D namespace |