a424fec9a9
they don't get stuck in the following frames, it works very well and Carza is happy :))))))
259 lines
7.7 KiB
C++
259 lines
7.7 KiB
C++
#include "collisions.h"
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#include "game.h"
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#include <algorithm>
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#include <cassert>
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#include <iostream>
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#include <vector>
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struct vertex {
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vec2d v, p1, p2;
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};
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typedef std::pair<vec2d, vec2d> segment;
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enum Orientation {
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COLINEAR,
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CLOCKWISE,
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COUNTER_CLOCKWISE,
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};
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static std::vector<vertex> vertices_of(polygon& p) {
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std::vector<vertex> vertices;
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vertices.reserve(p.global_points.size());
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// i = 1 and <= points.size() cuz { -1 % n = -1 } et c'est chiant
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// so start from 1, "overflow" with i = points.size() and gg
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for (uint i = 1; i <= p.global_points.size(); ++i)
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vertices.push_back({
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p.global_points[i % p.points.size()],
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p.global_points[(i + 1) % p.points.size()],
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p.global_points[(i - 1) % p.points.size()],
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});
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return vertices;
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}
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// Given three collinear points p, q, r, the function checks if
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// point q lies on line segment 'pr'
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static bool on_segment(vec2d& q, segment& pr) {
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return q.x <= std::max(pr.first.x, pr.second.x) &&
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q.x >= std::min(pr.first.x, pr.second.x) &&
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q.y <= std::max(pr.first.y, pr.second.y) &&
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q.y >= std::min(pr.first.y, pr.second.y);
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}
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static Orientation orientation(vec2d& p, vec2d& q, vec2d& r) {
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int v = (q.y - p.y) * (r.x - q.x) - (q.x - p.x) * (r.y - q.y);
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if (v == 0)
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return COLINEAR;
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return v > 0 ? CLOCKWISE : COUNTER_CLOCKWISE;
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}
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static bool do_intersect(segment s1, segment s2) {
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// Find the four orientations needed for general and
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// special cases
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Orientation o1 = orientation(s1.first, s1.second, s2.first);
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Orientation o2 = orientation(s1.first, s1.second, s2.second);
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Orientation o3 = orientation(s2.first, s2.second, s1.first);
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Orientation o4 = orientation(s2.first, s2.second, s1.second);
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// General case
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if (o1 != o2 && o3 != o4)
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return true;
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// Special Cases
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// p1, q1 and p2 are collinear and p2 lies on segment p1q1
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if (o1 == COLINEAR && on_segment(s2.first, s1))
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return true;
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// p1, q1 and q2 are collinear and q2 lies on segment p1q1
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if (o2 == COLINEAR && on_segment(s2.second, s1))
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return true;
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// p2, q2 and p1 are collinear and p1 lies on segment p2q2
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if (o3 == COLINEAR && on_segment(s1.first, s2))
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return true;
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// p2, q2 and q1 are collinear and q1 lies on segment p2q2
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if (o4 == COLINEAR && on_segment(s1.second, s2))
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return true;
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return false;
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}
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static std::vector<segment> edges_of(polygon& p) {
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std::vector<segment> ret;
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ret.reserve(p.points.size());
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for (uint i = 0; i < p.points.size(); ++i)
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ret.push_back(
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{p.global_points[i], p.global_points[(i + 1) % p.points.size()]});
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return ret;
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}
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static collision penetration(segment& edge, vertex& vertex, vec2d& d) {
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collision ret{true};
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ret.impact_point = vertex.v;
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vec2d n = (edge.second - edge.first).orthogonal();
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ret.n = vec2d::normalize(n);
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if (vec2d::dot(n, d) > 0)
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ret.n *= -1;
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vec2d temp = vertex.v - edge.first;
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ret.overlap = vec2d::dot(temp, ret.n) * -ret.n;
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ret.overlap += .1 * delta * -ret.n;
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// std::cout << "-------------- Impact: penetration --------------"
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// << std::endl;
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return ret;
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}
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static collision parallel(segment edge_p, segment edge_q, vec2d d) {
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collision ret{true};
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vec2d line_start = edge_p.first;
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vec2d base = vec2d::normalize(edge_p.second - line_start);
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std::pair<double, vec2d> proj_p1, proj_p2, proj_q1, proj_q2;
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proj_p1 = {0, edge_p.first};
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proj_p2 = {vec2d::dot(edge_p.second - line_start, base), edge_p.second};
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proj_q1 = {vec2d::dot(edge_q.first - line_start, base), edge_q.first};
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proj_q2 = {vec2d::dot(edge_q.second - line_start, base), edge_q.second};
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std::pair<double, vec2d>*p_min, *q_min, *p_max, *q_max;
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if (proj_p1.first < proj_p2.first) {
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p_min = &proj_p1;
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p_max = &proj_p2;
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} else {
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p_min = &proj_p2;
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p_max = &proj_p1;
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}
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if (proj_q1.first < proj_q2.first) {
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q_min = &proj_q1;
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q_max = &proj_q2;
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} else {
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q_min = &proj_q2;
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q_max = &proj_q1;
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}
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vec2d min = p_min->first < q_min->first ? q_min->second : p_min->second;
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vec2d max = p_max->first < q_max->first ? p_max->second : q_max->second;
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ret.impact_point = (min + max) / 2;
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ret.n = base.orthogonal();
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if (vec2d::dot(ret.n, d) > 0)
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ret.n *= -1;
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vec2d temp = ret.impact_point - edge_p.first;
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ret.overlap = vec2d::dot(temp, ret.n) * -ret.n;
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ret.overlap += .1 * delta * -ret.n;
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// std::cout << "-------------- Impact: parallel --------------" <<
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// std::endl;
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return ret;
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}
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static bool are_vecs_parallel(vec2d s1, vec2d s2) {
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return std::abs(vec2d::dot(vec2d::normalize(s1), vec2d::normalize(s2))) >
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.99;
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}
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static double distance_between_parallel_segments(segment s1, segment s2) {
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double area = vec2d::cross(s1.first - s2.first, s2.second - s2.first);
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double base = vec2d::norm(s2.second - s2.first);
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return std::abs(area / base);
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}
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#define SMALLEST_DIST 3
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static bool are_edges_colinear(segment& e1, segment& e2) {
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vec2d e1_vec = e1.second - e1.first;
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vec2d e2_vec = e2.second - e2.first;
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return are_vecs_parallel(e1_vec, e2_vec) &&
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distance_between_parallel_segments(e1, e2) < SMALLEST_DIST;
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}
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static collision vertex_edge_collision(polygon& p, polygon& q) {
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std::vector<vertex> vertices_p = vertices_of(p);
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std::vector<segment> edges_q = edges_of(q);
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vec2d d = q.centroid() - p.centroid();
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segment edge_p1, edge_p2;
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bool col1, col2;
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for (auto& vertex : vertices_p)
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for (auto& edge_q : edges_q) {
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edge_p1 = {vertex.v, vertex.p1};
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edge_p2 = {vertex.v, vertex.p2};
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col1 = do_intersect(edge_q, edge_p1);
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col2 = do_intersect(edge_q, edge_p2);
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if (col1 || col2) {
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if (are_edges_colinear(edge_q, edge_p1))
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return parallel(edge_q, edge_p1, d);
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if (are_edges_colinear(edge_q, edge_p2))
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return parallel(edge_q, edge_p2, d);
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if (col1 && col2)
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return penetration(edge_q, vertex, d);
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}
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}
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return {false};
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}
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static collision vertex_vertex_collision(polygon& p, polygon& q) {
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std::vector<vertex> vertices_p = vertices_of(p);
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std::vector<segment> edges_q = edges_of(q);
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vec2d d = q.centroid() - p.centroid();
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for (auto& vertex : vertices_p)
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for (auto& edge_q : edges_q) {
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if (do_intersect(edge_q, {vertex.v, vertex.p1})) {
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vec2d edge_q_vec = edge_q.second - edge_q.first;
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vec2d n = vec2d::normalize(edge_q_vec.orthogonal());
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if (vec2d::dot(n, d) > 0)
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n *= -1;
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vec2d temp = vertex.v - edge_q.first;
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vec2d overlap = vec2d::dot(temp, n) * -n;
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overlap += .1 * delta * -n;
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// std::cout
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// << "-------------- Impact: angle in angle --------------"
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// << std::endl;
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return {true, n, vertex.v, overlap};
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}
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}
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return {false};
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}
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static collision convex_collides(polygon& p, polygon& q) {
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collision ret;
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if ((ret = vertex_edge_collision(p, q)).collides)
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return ret;
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if ((ret = vertex_edge_collision(q, p)).collides) {
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ret.n *= -1;
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ret.overlap *= -1;
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return ret;
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}
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if ((ret = vertex_vertex_collision(p, q)).collides)
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return ret;
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if ((ret = vertex_vertex_collision(q, p)).collides) {
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ret.n *= -1;
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ret.overlap *= -1;
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}
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return ret;
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}
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collision collides(polygon& p, polygon& q) {
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return convex_collides(p, q);
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}
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