389 lines
12 KiB
C++
389 lines
12 KiB
C++
// spheremesh.cpp
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//
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// Copyright (C) 2001-2009, the Celestia Development Team
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// Original version by Chris Laurel <claurel@gmail.com>
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation; either version 2
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// of the License, or (at your option) any later version.
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// IMPORTANT: This file is a relic from the early days of Celestia.
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// It's sole function now is to handle the now-deprecated .cms mesh files;
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// it will eventually be removed from Celestia.
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#include <cmath>
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#include <cstdint>
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#include <cstring>
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#include <utility>
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#include <vector>
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#include <celmodel/mesh.h>
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#include "spheremesh.h"
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SphereMesh::SphereMesh(float radius, int _nRings, int _nSlices)
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{
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createSphere(radius, _nRings, _nSlices);
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}
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SphereMesh::SphereMesh(const Eigen::Vector3f& size, int _nRings, int _nSlices)
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{
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createSphere(1.0f, _nRings, _nSlices);
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scale(size);
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}
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SphereMesh::SphereMesh(const Eigen::Vector3f& size,
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const DisplacementMap& dispmap,
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float height)
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{
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createSphere(1.0f, dispmap.getHeight(), dispmap.getWidth());
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scale(size);
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displace(dispmap, height);
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generateNormals();
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fixNormals();
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}
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SphereMesh::SphereMesh(const Eigen::Vector3f& size,
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int _nRings, int _nSlices,
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DisplacementMapFunc func,
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void* info)
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{
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createSphere(1.0f, _nRings, _nSlices);
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scale(size);
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displace(func, info);
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generateNormals();
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fixNormals();
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}
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SphereMesh::~SphereMesh()
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{
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delete[] vertices;
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delete[] normals;
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delete[] texCoords;
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delete[] indices;
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delete[] tangents;
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}
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void SphereMesh::createSphere(float radius, int _nRings, int _nSlices)
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{
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nRings = _nRings;
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nSlices = _nSlices;
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nVertices = nRings * (nSlices + 1);
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vertices = new float[nVertices * 3];
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normals = new float[nVertices * 3];
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texCoords = new float[nVertices * 2];
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nIndices = (nRings - 1) * (nSlices + 1) * 2;
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indices = new unsigned short[nIndices];
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tangents = new float[nVertices * 3];
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int i;
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for (i = 0; i < nRings; i++)
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{
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float phi = (static_cast<float>(i) / static_cast<float>(nRings - 1) - 0.5f) * static_cast<float>(PI);
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for (int j = 0; j <= nSlices; j++)
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{
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float theta = static_cast<float>(j) / static_cast<float>(nSlices) * static_cast<float>(PI * 2.0);
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int n = i * (nSlices + 1) + j;
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auto x = std::cos(phi) * std::cos(theta);
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auto y = std::sin(phi);
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auto z = std::cos(phi) * std::sin(theta);
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vertices[n * 3] = x * radius;
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vertices[n * 3 + 1] = y * radius;
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vertices[n * 3 + 2] = z * radius;
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normals[n * 3] = x;
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normals[n * 3 + 1] = y;
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normals[n * 3 + 2] = z;
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texCoords[n * 2] = 1.0f - static_cast<float>(j) / static_cast<float>(nSlices);
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texCoords[n * 2 + 1] = 1.0f - static_cast<float>(i) / static_cast<float>(nRings - 1);
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// Compute the tangent--required for bump mapping
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auto tx = std::sin(phi) * std::sin(theta);
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auto ty = -std::cos(phi);
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auto tz = std::sin(phi) * std::cos(theta);
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tangents[n * 3] = tx;
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tangents[n * 3 + 1] = ty;
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tangents[n * 3 + 2] = tz;
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}
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}
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for (i = 0; i < nRings - 1; i++)
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{
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for (int j = 0; j <= nSlices; j++)
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{
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int n = i * (nSlices + 1) + j;
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indices[n * 2 + 0] = i * (nSlices + 1) + j;
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indices[n * 2 + 1] = (i + 1) * (nSlices + 1) + j;
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}
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}
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}
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// Generate vertex normals for a quad mesh by averaging face normals
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void SphereMesh::generateNormals()
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{
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int nQuads = nSlices * (nRings - 1);
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Eigen::Vector3f* faceNormals = new Eigen::Vector3f[nQuads];
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int i;
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// Compute face normals for the mesh
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for (i = 0; i < nRings - 1; i++)
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{
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for (int j = 0; j < nSlices; j++)
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{
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float* p0 = vertices + (i * (nSlices + 1) + j) * 3;
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float* p1 = vertices + ((i + 1) * (nSlices + 1) + j) * 3;
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float* p2 = vertices + ((i + 1) * (nSlices + 1) + j + 1) * 3;
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float* p3 = vertices + (i * (nSlices + 1) + j + 1) * 3;
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// Compute the face normal. Watch out for degenerate (zero-length)
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// edges. If there are two degenerate edges, the entire face must
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// be degenerate and we'll handle that later
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Eigen::Vector3f v0 = Eigen::Map<Eigen::Vector3f>(p1) - Eigen::Map<Eigen::Vector3f>(p0);
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Eigen::Vector3f v1 = Eigen::Map<Eigen::Vector3f>(p2) - Eigen::Map<Eigen::Vector3f>(p1);
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if (v0.norm() < 1e-6f)
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{
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v0 = Eigen::Map<Eigen::Vector3f>(p2) - Eigen::Map<Eigen::Vector3f>(p1);
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v1 = Eigen::Map<Eigen::Vector3f>(p3) - Eigen::Map<Eigen::Vector3f>(p2);
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}
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else if (v1.norm() < 1e-6f)
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{
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v0 = Eigen::Map<Eigen::Vector3f>(p3) - Eigen::Map<Eigen::Vector3f>(p2);
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v1 = Eigen::Map<Eigen::Vector3f>(p0) - Eigen::Map<Eigen::Vector3f>(p3);
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}
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Eigen::Vector3f faceNormal = v0.cross(v1);
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float length = faceNormal.norm();
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if (length != 0)
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faceNormal *= (1 / length);
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faceNormals[i * nSlices + j] = faceNormal;
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}
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}
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auto* faceCounts = new int[nVertices];
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for (i = 0; i < nVertices; i++)
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{
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faceCounts[i] = 0;
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normals[i * 3] = 0;
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normals[i * 3 + 1] = 0;
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normals[i * 3 + 2] = 0;
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}
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for (i = 1; i < nRings - 1; i++)
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{
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for (int j = 0; j <= nSlices; j++)
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{
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int vertex = i * (nSlices + 1) + j;
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faceCounts[vertex] = 4;
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int face = (i - 1) * nSlices + j % nSlices;
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normals[vertex * 3] += faceNormals[face].x();
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normals[vertex * 3 + 1] += faceNormals[face].y();
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normals[vertex * 3 + 2] += faceNormals[face].z();
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face = (i - 1) * nSlices + (j + nSlices - 1) % nSlices;
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normals[vertex * 3] += faceNormals[face].x();
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normals[vertex * 3 + 1] += faceNormals[face].y();
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normals[vertex * 3 + 2] += faceNormals[face].z();
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face = i * nSlices + (j + nSlices - 1) % nSlices;
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normals[vertex * 3] += faceNormals[face].x();
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normals[vertex * 3 + 1] += faceNormals[face].y();
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normals[vertex * 3 + 2] += faceNormals[face].z();
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face = i * nSlices + j % nSlices;
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normals[vertex * 3] += faceNormals[face].x();
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normals[vertex * 3 + 1] += faceNormals[face].y();
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normals[vertex * 3 + 2] += faceNormals[face].z();
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}
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}
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// Compute normals at the poles
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for (i = 0; i <= nSlices; i++)
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{
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int vertex = i;
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int j;
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faceCounts[vertex] = nSlices;
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for (j = 0; j < nSlices; j++)
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{
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int face = j;
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normals[vertex * 3] += faceNormals[face].x();
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normals[vertex * 3 + 1] += faceNormals[face].y();
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normals[vertex * 3 + 2] += faceNormals[face].z();
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}
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vertex = (nRings - 1) * (nSlices + 1) + i;
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faceCounts[vertex] = nSlices;
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for (j = 0; j < nSlices; j++)
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{
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int face = nQuads - j - 1;
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normals[vertex * 3] += faceNormals[face].x();
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normals[vertex * 3 + 1] += faceNormals[face].y();
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normals[vertex * 3 + 2] += faceNormals[face].z();
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}
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}
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for (i = 0; i < nVertices; i++)
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{
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if (faceCounts[i] > 0)
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{
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float s = 1.0f / static_cast<float>(faceCounts[i]);
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float nx = normals[i * 3] * s;
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float ny = normals[i * 3 + 1] * s;
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float nz = normals[i * 3 + 2] * s;
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auto length = std::sqrt(nx * nx + ny * ny + nz * nz);
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if (length > 0)
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{
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length = 1 / length;
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normals[i * 3] = nx * length;
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normals[i * 3 + 1] = ny * length;
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normals[i * 3 + 2] = nz * length;
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}
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}
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}
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delete[] faceCounts;
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delete[] faceNormals;
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}
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// Fix up the normals along the seam at longitude zero
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void SphereMesh::fixNormals()
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{
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for (int i = 0; i < nRings; i++)
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{
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float* v0 = normals + (i * (nSlices + 1)) * 3;
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float* v1 = normals + ((i + 1) * (nSlices + 1) - 1) * 3;
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Eigen::Map<Eigen::Vector3f> n0(v0);
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Eigen::Map<Eigen::Vector3f> n1(v1);
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Eigen::Vector3f normal = n0 + n1;
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normal.normalize();
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v0[0] = normal.x();
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v0[1] = normal.y();
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v0[2] = normal.z();
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v1[0] = normal.x();
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v1[1] = normal.y();
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v1[2] = normal.z();
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}
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}
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void SphereMesh::scale(const Eigen::Vector3f& s)
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{
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int i;
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for (i = 0; i < nVertices; i++)
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{
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vertices[i * 3] *= s.x();
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vertices[i * 3 + 1] *= s.y();
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vertices[i * 3 + 2] *= s.z();
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}
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// Modify the normals
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if (normals != nullptr)
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{
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// TODO: Make a fast special case for uniform scale factors, where
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// renormalization is not required.
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Eigen::Vector3f is = s.cwiseInverse();
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for (i = 0; i < nVertices; i++)
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{
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int n = i * 3;
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Eigen::Vector3f normal = Eigen::Map<Eigen::Vector3f>(normals).cwiseProduct(is);
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normal.normalize();
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normals[n] = normal.x();
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normals[n + 1] = normal.y();
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normals[n + 2] = normal.z();
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}
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}
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}
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void SphereMesh::displace(const DisplacementMap& dispmap,
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float height)
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{
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for (int i = 0; i < nRings; i++)
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{
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for (int j = 0; j <= nSlices; j++)
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{
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int n = (i * (nSlices + 1) + j) * 3;
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Eigen::Map<Eigen::Vector3f> normal(normals);
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int k = (j == nSlices) ? 0 : j;
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Eigen::Vector3f v = normal * dispmap.getDisplacement(k, i) * height;
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vertices[n] += v.x();
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vertices[n + 1] += v.y();
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vertices[n + 2] += v.z();
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}
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}
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}
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void SphereMesh::displace(DisplacementMapFunc func, void* info)
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{
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for (int i = 0; i < nRings; i++)
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{
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float v = (float) i / (float) (nRings - 1);
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for (int j = 0; j <= nSlices; j++)
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{
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float u = (float) j / (float) nSlices;
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int n = (i * (nSlices + 1) + j) * 3;
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Eigen::Map<Eigen::Vector3f> normal(normals);
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Eigen::Vector3f vert = normal * func(u, v, info);
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vertices[n] += vert.x();
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vertices[n + 1] += vert.y();
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vertices[n + 2] += vert.z();
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}
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}
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}
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cmod::Mesh SphereMesh::convertToMesh() const
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{
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static_assert(sizeof(float) == sizeof(cmod::VWord), "Float size mismatch with vertex data word size");
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constexpr std::uint32_t stride = 8;
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std::vector<cmod::VertexAttribute> attributes{
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cmod::VertexAttribute(cmod::VertexAttributeSemantic::Position,
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cmod::VertexAttributeFormat::Float3,
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0),
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cmod::VertexAttribute(cmod::VertexAttributeSemantic::Normal,
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cmod::VertexAttributeFormat::Float3,
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3),
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cmod::VertexAttribute(cmod::VertexAttributeSemantic::Texture0,
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cmod::VertexAttributeFormat::Float2,
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6),
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};
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cmod::Mesh mesh;
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mesh.setVertexDescription(cmod::VertexDescription(std::move(attributes)));
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// Copy the vertex data from the separate position, normal, and texture coordinate
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// arrays into a single array.
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std::vector<cmod::VWord> vertexData(stride * nVertices);
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for (int i = 0; i < nVertices; i++)
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{
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cmod::VWord* vertex = vertexData.data() + stride * i;
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std::memcpy(vertex, vertices + (i * 3), sizeof(float) * 3);
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std::memcpy(vertex + 3, normals + (i * 3), sizeof(float) * 3);
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std::memcpy(vertex + 6, texCoords + (i * 2), sizeof(float) * 2);
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}
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mesh.setVertices(nVertices, std::move(vertexData));
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for (int i = 0; i < nRings - 1; i++)
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{
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std::vector<cmod::Index32> indexData;
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indexData.reserve((nSlices + 1) * 2);
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for (int j = 0; j <= nSlices; j++)
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{
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indexData.push_back(i * (nSlices + 1) + j);
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indexData.push_back((i + 1) * (nSlices + 1) + j);
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}
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mesh.addGroup(cmod::PrimitiveGroupType::TriStrip, ~0u, std::move(indexData));
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}
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return mesh;
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}
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