💿🐜 Antkeeper source code
https://antkeeper.com
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135 lines
4.1 KiB
135 lines
4.1 KiB
/*
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* Copyright (C) 2023 Christopher J. Howard
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*
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* This file is part of Antkeeper source code.
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*
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* Antkeeper source code is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Antkeeper source code is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Antkeeper source code. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <engine/geom/brep/brep-operations.hpp>
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#include <engine/math/vector.hpp>
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#include <engine/debug/log.hpp>
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#include <algorithm>
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#include <cmath>
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namespace geom {
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void generate_face_normals(brep_mesh& mesh)
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{
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const auto& vertex_positions = mesh.vertices().attributes().at<math::fvec3>("position");
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auto& face_normals = static_cast<brep_attribute<math::fvec3>&>(*mesh.faces().attributes().try_emplace<math::fvec3>("normal").first);
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for (brep_face* face: mesh.faces())
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{
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auto loop = face->loops().begin();
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const auto& a = vertex_positions[loop->vertex()->index()];
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const auto& b = vertex_positions[(++loop)->vertex()->index()];
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const auto& c = vertex_positions[(++loop)->vertex()->index()];
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face_normals[face->index()] = math::normalize(math::cross(b - a, c - a));
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}
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}
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void generate_vertex_normals(brep_mesh& mesh)
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{
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// Generate face normals if they don't exist
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if (!mesh.faces().attributes().contains("normal"))
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{
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generate_face_normals(mesh);
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}
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const auto& vertex_positions = mesh.vertices().attributes().at<math::fvec3>("position");
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const auto& face_normals = mesh.faces().attributes().at<math::fvec3>("normal");
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auto& vertex_normals = static_cast<brep_attribute<math::fvec3>&>(*mesh.vertices().attributes().try_emplace<math::fvec3>("normal").first);
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for (brep_vertex* vertex: mesh.vertices())
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{
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// Zero vertex normal
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auto& vertex_normal = vertex_normals[vertex->index()];
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vertex_normal = {};
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// Skip vertices with no edges
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if (vertex->edges().empty())
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{
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continue;
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}
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// Get vertex position
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const auto& vertex_position = vertex_positions[vertex->index()];
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// For each edge bounded by this vertex
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for (brep_edge* edge: vertex->edges())
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{
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// Skip edges with no associated face
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if (edge->loops().empty())
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{
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continue;
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}
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// Calculate direction vector of current edge
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const auto direction0 = math::normalize
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(
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vertex_positions[edge->vertices()[edge->vertices().front() == vertex]->index()] -
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vertex_position
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);
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// For each edge loop
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for (brep_loop* loop: edge->loops())
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{
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// Skip loops not originating at vertex
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if (loop->vertex() != vertex)
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{
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continue;
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}
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// Calculate direction vector of previous edge
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const auto direction1 = math::normalize
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(
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vertex_positions[loop->previous()->vertex()->index()] -
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vertex_position
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);
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// Find angle between two edges
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const auto cos_edge_angle = math::dot(direction0, direction1);
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const auto edge_angle = std::acos(cos_edge_angle);
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// Weigh face normal by edge angle and add to vertex normal
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vertex_normal += face_normals[loop->face()->index()] * edge_angle;
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}
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}
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// Normalize vertex normal
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const auto sqr_length = math::sqr_length(vertex_normal);
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if (sqr_length)
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{
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vertex_normal /= std::sqrt(sqr_length);
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}
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}
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}
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void generate_loop_barycentric(brep_mesh& mesh)
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{
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const auto& vertex_positions = mesh.vertices().attributes().at<math::fvec3>("position");
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auto& loop_barycentric = static_cast<brep_attribute<math::fvec3>&>(*mesh.loops().attributes().try_emplace<math::fvec3>("barycentric").first);
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for (brep_face* face: mesh.faces())
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{
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auto loop = face->loops().begin();
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loop_barycentric[loop->index()] = {1.0f, 0.0f, 0.0f};
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loop_barycentric[(++loop)->index()] = {0.0f, 1.0f, 0.0f};
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loop_barycentric[(++loop)->index()] = {0.0f, 0.0f, 1.0f};
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}
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}
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} // namespace geom
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