374 lines
11 KiB
C++
374 lines
11 KiB
C++
//
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// Created by Иван Ильин on 05.02.2021.
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//
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#include <cmath>
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#include <utility>
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#include "RigidBody.h"
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#include "../utils/Log.h"
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#include "../utils/Time.h"
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#include "../Consts.h"
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RigidBody::RigidBody(ObjectNameTag nameTag, const std::string &filename, const Vec3D &scale) : Mesh(std::move(nameTag),
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filename, scale),
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_hitBox(*this) {
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}
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Vec3D RigidBody::_findFurthestPoint(const Vec3D &direction) {
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Vec3D maxPoint{0, 0, 0};
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double maxDistance = -std::numeric_limits<double>::max();
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Vec3D transformedDirection = (view() * direction).normalized();
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/*
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for (auto &tri : triangles()) {
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for (int i = 0; i < 3; i++) {
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Vec3D point = Vec3D(tri[i]);
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double distance = point.dot(transformedDirection);
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if (distance > maxDistance) {
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maxDistance = distance;
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maxPoint = point;
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}
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}
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}
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*/
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for(auto & it : _hitBox) {
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double distance = it.dot(transformedDirection);
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if (distance > maxDistance) {
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maxDistance = distance;
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maxPoint = it;
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}
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}
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return model() * maxPoint + position();
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}
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Vec3D RigidBody::_support(std::shared_ptr<RigidBody> obj, const Vec3D &direction) {
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Vec3D p1 = _findFurthestPoint(direction);
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Vec3D p2 = obj->_findFurthestPoint(-direction);
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Vec3D res = p1 - p2;
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return p1 - p2;
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}
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NextSimplex RigidBody::_nextSimplex(const Simplex &points) {
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switch (points.type()) {
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case SimplexType::Line:
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return _lineCase(points);
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case SimplexType::Triangle:
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return _triangleCase(points);
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case SimplexType::Tetrahedron:
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return _tetrahedronCase(points);
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default:
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throw std::logic_error{"RigidBody::_nextSimplex: simplex is not Line, Triangle or Tetrahedron"};
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}
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}
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NextSimplex RigidBody::_lineCase(const Simplex &points) {
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Simplex newPoints(points);
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Vec3D newDirection;
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Vec3D a = points[0];
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Vec3D b = points[1];
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Vec3D ab = b - a;
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Vec3D ao = -a;
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if (ab.dot(ao) > 0) {
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newDirection = ab.cross(ao).cross(ab);
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} else {
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newPoints = Simplex{a};
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newDirection = ao;
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}
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return NextSimplex{newPoints, newDirection, false};
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}
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NextSimplex RigidBody::_triangleCase(const Simplex &points) {
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Simplex newPoints(points);
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Vec3D newDirection;
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Vec3D a = points[0];
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Vec3D b = points[1];
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Vec3D c = points[2];
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Vec3D ab = b - a;
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Vec3D ac = c - a;
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Vec3D ao = -a;
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Vec3D abc = ab.cross(ac);
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if (abc.cross(ac).dot(ao) > 0) {
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if (ac.dot(ao) > 0) {
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newPoints = Simplex{a, c};
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newDirection = ac.cross(ao).cross(ac);
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} else {
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return _lineCase(Simplex{a, b});
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}
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} else {
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if (ab.cross(abc).dot(ao) > 0) {
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return _lineCase(Simplex{a, b});
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} else {
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if (abc.dot(ao) > 0) {
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newDirection = abc;
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} else {
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newPoints = Simplex{a, c, b};
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newDirection = -abc;
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}
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}
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}
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return NextSimplex{newPoints, newDirection, false};
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}
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NextSimplex RigidBody::_tetrahedronCase(const Simplex &points) {
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Vec3D a = points[0];
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Vec3D b = points[1];
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Vec3D c = points[2];
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Vec3D d = points[3];
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Vec3D ab = b - a;
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Vec3D ac = c - a;
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Vec3D ad = d - a;
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Vec3D ao = -a;
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Vec3D abc = ab.cross(ac);
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Vec3D acd = ac.cross(ad);
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Vec3D adb = ad.cross(ab);
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if (abc.dot(ao) > 0) {
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return _triangleCase(Simplex{a, b, c});
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}
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if (acd.dot(ao) > 0) {
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return _triangleCase(Simplex{a, c, d});
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}
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if (adb.dot(ao) > 0) {
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return _triangleCase(Simplex{a, d, b});
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}
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return NextSimplex{points, Vec3D(), true};
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}
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std::pair<bool, Simplex> RigidBody::checkGJKCollision(std::shared_ptr<RigidBody> obj) {
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// This is implementation of GJK algorithm for collision detection.
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// It builds a simplex (a simplest shape that can select point in space) around
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// zero for Minkowski Difference. Collision happend when zero point is inside.
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// See references:
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// https://www.youtube.com/watch?v=MDusDn8oTSE
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// https://blog.winter.dev/2020/gjk-algorithm/
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// Get initial support point in any direction
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Vec3D support = _support(obj, Vec3D{1, 0, 0});
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// Simplex is an array of points, max count is 4
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Simplex points{};
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points.push_front(support);
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// New direction is towards the origin
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Vec3D direction = -support;
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size_t iters = 0;
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while (iters++ < size() + obj->size()) {
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support = _support(obj, direction);
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if (support.dot(direction) <= 0) {
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return std::make_pair(false, points); // no collision
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}
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points.push_front(support);
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NextSimplex nextSimplex = _nextSimplex(points);
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direction = nextSimplex.newDirection;
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points = nextSimplex.newSimplex;
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if (nextSimplex.finishSearching) {
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if (obj->isCollider()) {
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_inCollision = true;
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}
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return std::make_pair(true, points);
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}
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}
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return std::make_pair(false, points);
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}
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CollisionPoint RigidBody::EPA(const Simplex &simplex, std::shared_ptr<RigidBody> obj) {
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// This is implementation of EPA algorithm for solving collision.
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// It uses a simplex from GJK around and expand it to the border.
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// The goal is to calculate the nearest normal and the intersection depth.
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// See references:
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// https://www.youtube.com/watch?v=0XQ2FSz3EK8
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// https://blog.winter.dev/2020/epa-algorithm/
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std::vector<Vec3D> polytope(simplex.begin(), simplex.end());
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std::vector<size_t> faces = {
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0, 1, 2,
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0, 3, 1,
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0, 2, 3,
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1, 3, 2
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};
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auto faceNormals = _getFaceNormals(polytope, faces);
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std::vector<FaceNormal> normals = faceNormals.first;
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size_t minFace = faceNormals.second;
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Vec3D minNormal = normals[minFace].normal;
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double minDistance = std::numeric_limits<double>::max();
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size_t iters = 0;
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while (minDistance == std::numeric_limits<double>::max() && iters++ < size() + obj->size()) {
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minNormal = normals[minFace].normal;
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minDistance = normals[minFace].distance;
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Vec3D support = _support(obj, minNormal);
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double sDistance = minNormal.dot(support);
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if (std::abs(sDistance - minDistance) > Consts::EPA_EPS) {
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minDistance = std::numeric_limits<double>::max();
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std::vector<std::pair<size_t, size_t>> uniqueEdges;
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size_t f = 0;
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for (auto &normal : normals) {
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if (normal.normal.dot(support) > 0) {
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uniqueEdges = _addIfUniqueEdge(uniqueEdges, faces, f + 0, f + 1);
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uniqueEdges = _addIfUniqueEdge(uniqueEdges, faces, f + 1, f + 2);
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uniqueEdges = _addIfUniqueEdge(uniqueEdges, faces, f + 2, f + 0);
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faces.erase(faces.begin() + f);
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faces.erase(faces.begin() + f);
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faces.erase(faces.begin() + f);
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} else {
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f += 3;
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}
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}
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std::vector<size_t> newFaces;
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newFaces.reserve(uniqueEdges.size() * 3);
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for (auto[edgeIndex1, edgeIndex2] : uniqueEdges) {
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newFaces.push_back(edgeIndex1);
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newFaces.push_back(edgeIndex2);
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newFaces.push_back(polytope.size());
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}
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polytope.push_back(support);
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faces.insert(faces.end(), newFaces.begin(), newFaces.end());
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auto newFaceNormals = _getFaceNormals(polytope, faces);
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normals = std::move(newFaceNormals.first);
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minFace = newFaceNormals.second;
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}
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}
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_collisionNormal = minNormal;
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if (std::abs(minDistance - std::numeric_limits<double>::max()) < Consts::EPS) {
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return CollisionPoint{minNormal, 0};
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}
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return CollisionPoint{minNormal, minDistance + Consts::EPA_EPS};
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}
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std::pair<std::vector<FaceNormal>, size_t>
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RigidBody::_getFaceNormals(const std::vector<Vec3D> &polytope, const std::vector<size_t> &faces) {
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std::vector<FaceNormal> normals;
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normals.reserve(faces.size() / 3);
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size_t nearestFaceIndex = 0;
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double minDistance = std::numeric_limits<double>::max();
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for (size_t i = 0; i < faces.size(); i += 3) {
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Vec3D a = polytope[faces[i + 0]];
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Vec3D b = polytope[faces[i + 1]];
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Vec3D c = polytope[faces[i + 2]];
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Vec3D normal = (b - a).cross(c - a).normalized();
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double distance = normal.dot(a);
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if (distance < -Consts::EPS) {
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normal = -normal;
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distance *= -1;
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}
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normals.emplace_back(FaceNormal{normal, distance});
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if (distance < minDistance) {
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nearestFaceIndex = i / 3;
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minDistance = distance;
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}
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}
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return {normals, nearestFaceIndex};
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}
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std::vector<std::pair<size_t, size_t>>
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RigidBody::_addIfUniqueEdge(const std::vector<std::pair<size_t, size_t>> &edges, const std::vector<size_t> &faces,
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size_t a, size_t b) {
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std::vector<std::pair<size_t, size_t>> newEdges = edges;
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// We are interested in reversed edge
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// 0--<--3
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// / \ B / A: 2-0
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// / A \ / B: 0-2
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// 1-->--2
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auto reverse = std::find(newEdges.begin(), newEdges.end(), std::make_pair(faces[b], faces[a]));
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if (reverse != newEdges.end()) {
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newEdges.erase(reverse);
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} else {
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newEdges.emplace_back(faces[a], faces[b]);
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}
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return newEdges;
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}
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void RigidBody::solveCollision(const CollisionPoint &collision) {
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Vec3D velocity_parallel = collision.normal * velocity().dot(collision.normal);
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Vec3D velocity_perpendicular = velocity() - velocity_parallel;
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if (velocity().dot(collision.normal) > 0) {
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setVelocity(velocity_perpendicular);
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}
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translate(-collision.normal * collision.depth);
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}
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void RigidBody::updatePhysicsState() {
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translate(_velocity * Time::deltaTime());
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_velocity = _velocity + _acceleration * Time::deltaTime();
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}
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void RigidBody::setVelocity(const Vec3D &velocity) {
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_velocity = velocity;
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}
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void RigidBody::addVelocity(const Vec3D &velocity) {
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_velocity = _velocity + velocity;
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}
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void RigidBody::setAcceleration(const Vec3D &acceleration) {
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_acceleration = acceleration;
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}
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RigidBody::RigidBody(const Mesh &mesh) : Mesh(mesh), _hitBox(mesh) {
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}
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void RigidBody::setSimpleHitBox(bool b) {
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_simpleHitBox = b;
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if (_simpleHitBox) {
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_hitBox = HitBox::Box(*this);
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} else {
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_hitBox = HitBox(*this);
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}
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}
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