a424fec9a9
they don't get stuck in the following frames, it works very well and Carza is happy :))))))
268 lines
8.1 KiB
C++
268 lines
8.1 KiB
C++
#include "polygons.h"
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#include "balls.h" // just for the restitution_coefficient_get() function,
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// prolly should be placed in another header file
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#include "cairo.h"
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#include "collisions.h"
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#include "game.h"
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#include "gravity.h"
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#include "matrix.h"
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#include "polygon_generator.h"
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#include <algorithm>
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#include <iostream>
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#include <utility>
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polygon* polygons = nullptr;
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uint n_polygons = 0;
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void polygons_init_state() {
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n_polygons = 20;
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polygons = new polygon[n_polygons];
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int wall_thickness = 50;
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uint n = 0;
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// north wall
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polygons[n++] = poly_generate::rectangle(width, wall_thickness, INFINITY)
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.set_center({width / 2., -wall_thickness / 2.});
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// south wall
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polygons[n++] = poly_generate::rectangle(width, wall_thickness, INFINITY)
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.set_center({width / 2., height + wall_thickness / 2.});
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// west wall
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polygons[n++] = poly_generate::rectangle(wall_thickness, height, INFINITY)
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.set_center({-wall_thickness / 2., height / 2.});
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// east wall
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polygons[n++] = poly_generate::rectangle(wall_thickness, height, INFINITY)
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.set_center({width + wall_thickness / 2., height / 2.});
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// middle wall
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polygons[n++] = poly_generate::rectangle(50, height / 2., INFINITY)
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.set_center({25 + width * 1. / 2, height / 2.})
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.set_angle(0);
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polygons[n++] = poly_generate::regular(100, 3)
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.set_center({100, 400})
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.set_angle(0)
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.set_speed({200, -10});
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polygons[n++] = poly_generate::square(100)
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.set_center({600, 400})
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.set_angle(45)
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.set_speed({-200, -10});
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polygons[n++] = poly_generate::general(
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{{0, 0}, {100, 0}, {100, 100}, {50, 150}, {0, 100}},
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3
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)
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.set_center({200, 600})
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.set_angle(45)
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.set_speed({10, 0});
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polygons[n++] = poly_generate::rectangle(100, 150).set_center({600, 200});
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polygons[n++] = poly_generate::regular(50, 5).set_center({150, 150});
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polygons[n++] =
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poly_generate::general({{0, 0}, {50, 80}, {0, 160}, {-50, 80}})
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.set_center({700, 700})
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.set_speed({0, -100});
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assert(n <= n_polygons);
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n_polygons = n;
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}
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static double to_rad(double angle_in_deg) {
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static double PI_180 = M_PI / 180.;
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return angle_in_deg * PI_180;
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}
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static double to_deg(double angle_in_rad) {
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static double PI_180 = 180. / M_PI;
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return angle_in_rad * PI_180;
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}
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static bool is_point_inside_rect(rect rect, vec2d point) {
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vec2d tl = rect.first, br = rect.second;
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return point.x > tl.x && point.x < br.x && point.y > tl.y && point.y < br.y;
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}
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static bool bounding_rects_collide(rect cur_bound, rect other_bound) {
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vec2d other_tl = other_bound.first, other_br = other_bound.second;
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return is_point_inside_rect(cur_bound, other_tl)
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|| is_point_inside_rect(cur_bound, {other_tl.x, other_br.y})
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|| is_point_inside_rect(cur_bound, {other_br.x, other_tl.y})
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|| is_point_inside_rect(cur_bound, other_br);
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}
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static double impulse_parameter(
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vec2d v_ab1,
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vec2d n,
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double m_a,
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double m_b,
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vec2d r_ap,
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vec2d r_bp,
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double I_a,
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double I_b,
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double e
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) {
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double nominator = -(1 + e) * vec2d::dot(v_ab1, n);
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double r_ap_cross_n = vec2d::cross(r_ap, n);
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double r_bp_cross_n = vec2d::cross(r_bp, n);
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double denominator = 1 / m_a + 1 / m_b + r_ap_cross_n * r_ap_cross_n / I_a
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+ r_bp_cross_n * r_bp_cross_n / I_b;
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return nominator / denominator;
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}
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static void handle_collision(collision& c, polygon* a, polygon* b) {
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// see https://www.myphysicslab.com/engine2D/collision-en.html for the
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// formulas
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double omega_a1 = to_rad(a->angular_speed);
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double omega_b1 = to_rad(b->angular_speed);
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vec2d r_ap = c.impact_point - a->centroid();
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vec2d v_ap1 = a->speed + vec2d::cross(omega_a1, r_ap);
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vec2d r_bp = c.impact_point - b->centroid();
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vec2d v_bp1 = b->speed + vec2d::cross(omega_b1, r_bp);
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vec2d v_ab1 = v_ap1 - v_bp1;
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if (vec2d::norm(c.overlap) > 10)
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c.overlap = -.1 * vec2d::normalize(c.overlap);
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// std::cout << c.overlap << std::endl;
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if (b->mass == INFINITY)
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a->translate(c.overlap);
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else {
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double ma = a->mass;
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double mb = b->mass;
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double m_total = ma + mb;
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// If b is wall, then mb / m_total = INFINITY / INFINITY = -nan,
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// so we need the if statement above
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a->translate(c.overlap * mb / m_total);
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b->translate(-c.overlap * ma / m_total);
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}
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double I_a = a->inertia, I_b = b->inertia;
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double j = impulse_parameter(
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v_ab1,
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c.n,
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a->mass,
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b->mass,
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r_ap,
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r_bp,
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I_a,
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I_b,
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restitution_coefficient_get()
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);
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vec2d v_a2 = a->speed + j * c.n / a->mass;
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vec2d v_b2 = b->speed - j * c.n / b->mass;
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double omega_a2 = omega_a1 + vec2d::cross(r_ap, j * c.n) / I_a;
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double omega_b2 = omega_b1 - vec2d::cross(r_bp, j * c.n) / I_b;
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a->speed = v_a2;
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a->angular_speed = to_deg(omega_a2);
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b->speed = v_b2;
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b->angular_speed = to_deg(omega_b2);
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}
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static void check_collisions(polygon* current_p) {
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rect cur_bound = current_p->get_bounding_box();
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collision c;
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polygon* other_p;
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for (other_p = polygons; other_p != polygons + n_polygons; ++other_p) {
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if (other_p == current_p) // polygons don't collide with themselves
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continue;
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rect other_bound = other_p->get_bounding_box();
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if ((bounding_rects_collide(cur_bound, other_bound)
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|| bounding_rects_collide(other_bound, cur_bound))
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&& (c = collides(*current_p, *other_p)).collides) {
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handle_collision(c, current_p, other_p);
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}
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}
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}
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void polygons_update_state() {
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for (polygon* p = polygons; p != polygons + n_polygons; ++p) {
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if (p->mass == INFINITY) // immovable objects don't need to be updated
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continue;
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check_collisions(p);
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p->rotate(delta * p->angular_speed);
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p->angle = std::fmod(p->angle, 360);
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p->translate(delta * p->speed);
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vec2d g = gravity_vector(p);
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p->translate(.5 * delta * delta * g);
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p->speed += delta * g;
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}
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}
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void polygon::update_global_points() {
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double cos_theta = std::cos(to_rad(this->angle));
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double sin_theta = std::sin(to_rad(this->angle));
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matrix rotation = matrix{{cos_theta, sin_theta}, {-sin_theta, cos_theta}};
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for (uint i = 0; i < this->points.size(); ++i)
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this->global_points[i] = rotation * this->points[i] + this->center;
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}
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void polygon::draw_bounding_rect(cairo_t* cr) const {
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cairo_set_source_rgb(cr, .7, .7, .7);
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double dashes[] = {5, 10};
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cairo_set_dash(cr, dashes, 2, 0);
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auto bb = this->get_bounding_box();
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vec2d tl = bb.first, br = bb.second;
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cairo_line_to(cr, tl.x, tl.y);
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cairo_line_to(cr, tl.x, br.y);
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cairo_line_to(cr, br.x, br.y);
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cairo_line_to(cr, br.x, tl.y);
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cairo_line_to(cr, tl.x, tl.y);
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cairo_stroke(cr);
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cairo_set_dash(cr, 0, 0, 0); // disable dashes
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}
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static void draw_circle(cairo_t* cr, vec2d p, double radius) {
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cairo_translate(cr, p.x, p.y);
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cairo_arc(cr, 0, 0, radius, 0, 2 * M_PI);
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cairo_fill(cr);
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cairo_translate(cr, -p.x, -p.y);
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}
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void polygon::draw(cairo_t* cr) const {
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// this->draw_bounding_rect(cr);
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cairo_set_source_rgb(cr, 1, 1, 1);
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for (auto& point : this->global_points)
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cairo_line_to(cr, point.x, point.y);
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cairo_line_to(cr, this->global_points[0].x, this->global_points[0].y);
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cairo_stroke(cr);
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// draw centroid
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vec2d centroid = this->centroid();
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draw_circle(cr, centroid, 1);
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// draw speed
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(delta * this->speed).draw(cr, centroid);
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}
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void polygons_draw(cairo_t* cr) {
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for (const polygon* p = polygons; p != polygons + n_polygons; ++p)
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p->draw(cr);
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}
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void polygons_destroy() {
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delete[] (polygons);
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}
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