flying-balls/main.cc

#include <assert.h>
#include <gdk/gdkkeysyms.h>
#include <gtk/gtk.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define DEFAULT_WIDTH 800
#define DEFAULT_HEIGHT 800

#include "balls.h"
#include "c_index.h"
#include "game.h"
#include "gravity.h"
#include "polygons.h"
#include "spaceship.h"

/* Trivial collision check
 */
void check_collisions_simple() {
    for (unsigned int i = 0; i < n_balls; ++i)
        for (unsigned int j = i + 1; j < n_balls; ++j)
            ball_ball_collision(balls + i, balls + j);
    for (unsigned int j = 0; j < n_balls; ++j)
        ball_ball_collision(&spaceship, balls + j);
    gravity_collisions(balls, balls + n_balls);
    gravity_collisions(&spaceship, &spaceship + 1);
}

void check_collisions_with_index() {
    c_index_build();
    c_index_check_collisions(ball_ball_collision);
    for (unsigned int j = 0; j < n_balls; ++j)
        ball_ball_collision(&spaceship, balls + j);
    gravity_collisions(balls, balls + n_balls);
    gravity_collisions(&spaceship, &spaceship + 1);
}

void (*check_collisions)() = check_collisions_simple;

unsigned int polys = 0;

void update_state() {
    if (check_collisions)
        check_collisions();
    for (unsigned int i = 0; i < n_balls; ++i)
        ball_update_state(balls + i);
    spaceship_update_state();
    polygons_update_state();
}

/* Graphics System
 */

void game_init() {
    srand(time(NULL));
    balls_init();
    assert(c_index_init());

    if (polys)
        polygons_init_state();
    else
        spaceship_init_state();
}

void game_destroy() {
    c_index_destroy();
    balls_destroy();
}

static guint animation_timeout_id = 0;
gboolean animation_timeout(gpointer user_data);

static bool game_paused() {
    return animation_timeout_id == 0;
}

void game_animation_on_off() {
    if (animation_timeout_id == 0) {
        animation_timeout_id =
            g_timeout_add(delta * 1000, animation_timeout, canvas);
    } else {
        g_source_remove(animation_timeout_id);
        animation_timeout_id = 0;
    }
}

struct param_controls {
    void (*draw)(cairo_t* cr);
    gint (*keyboard_input)(GdkEventKey* event);
    gboolean (*mouse_scroll)(
        GtkWidget* widget, GdkEvent* event, gpointer user_data);
};

gint gravity_controls_keyboard_input(GdkEventKey* event) {
    switch (event->keyval) {
    case GDK_KEY_Up:
        gravity_change(0, -10);
        return TRUE;
    case GDK_KEY_Down:
        gravity_change(0, 10);
        return TRUE;
    case GDK_KEY_Left:
        gravity_change(-10, 0);
        return TRUE;
    case GDK_KEY_Right:
        gravity_change(10, 0);
        return TRUE;
    }
    return FALSE;
}

param_controls gravity_control = {
    .draw = gravity_draw,
    .keyboard_input = gravity_controls_keyboard_input,
};

gint restitution_coefficient_controls_keyboard_input(GdkEventKey* event) {
    switch (event->keyval) {
    case GDK_KEY_Up:
        restitution_coefficient_change(0.01);
        return TRUE;
    case GDK_KEY_Down:
        restitution_coefficient_change(-0.01);
        return TRUE;
    case GDK_KEY_Left:
        restitution_coefficient_change(-0.01);
        return TRUE;
    case GDK_KEY_Right:
        restitution_coefficient_change(0.01);
        return TRUE;
    }
    return FALSE;
}

param_controls restitution_coefficient_control = {
    .draw = restitution_coefficient_draw,
    .keyboard_input = restitution_coefficient_controls_keyboard_input,
};


static param_controls* param_control = nullptr;
static guint param_control_timeout_id = 0;
static const guint param_control_active_ms = 3000;

gboolean param_control_timeout(gpointer user_data) {
    param_control = nullptr;
    param_control_timeout_id = 0;
    gtk_widget_queue_draw(canvas);
    return FALSE;
}

void param_control_activate(struct param_controls* ctrl) {
    if (param_control)
        g_source_remove(param_control_timeout_id);
    param_control = ctrl;
    param_control_timeout_id =
        g_timeout_add(param_control_active_ms, param_control_timeout, canvas);
    gtk_widget_queue_draw(canvas);
}

gboolean draw_frame(GtkWidget* widget, cairo_t* cr, gpointer data) {
    cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0);
    cairo_paint(cr);
    if (param_control)
        param_control->draw(cr);
    gravity_draw_visible_field(cr);
    balls_draw(cr);
    spaceship_draw(cr);
    polygons_draw(cr);
    return FALSE;
}

gint configure_event(GtkWidget* widget, GdkEventConfigure* event) {
    if (width == event->width && height == event->height)
        return FALSE;

    width = gtk_widget_get_allocated_width(widget);
    height = gtk_widget_get_allocated_height(widget);

    for (ball* b = balls; b != balls + n_balls; ++b)
        ball_reposition(b);
    ball_reposition(&spaceship);
    return TRUE;
}

gint keyboard_input(GtkWidget* widget, GdkEventKey* event) {
    if (event->type != GDK_KEY_PRESS)
        return FALSE;
    if (param_control && param_control->keyboard_input(event)) {
        gtk_widget_queue_draw(canvas);
        g_source_remove(param_control_timeout_id);
        param_control_timeout_id = g_timeout_add(
            param_control_active_ms, param_control_timeout, canvas);
        return TRUE;
    }
    switch (event->keyval) {
    case GDK_KEY_R:
    case GDK_KEY_r:
        param_control_activate(&restitution_coefficient_control);
        return TRUE;
    case GDK_KEY_G:
    case GDK_KEY_g:
        param_control_activate(&gravity_control);
        return TRUE;
    case GDK_KEY_period: // evaluate and draw single frame
        update_state();
        gtk_widget_queue_draw(canvas);
        return TRUE;
    case GDK_KEY_P:
    case GDK_KEY_p:
        game_animation_on_off();
        return TRUE;
    case GDK_KEY_Q:
    case GDK_KEY_q:
        gtk_main_quit();
        return TRUE;
    }
    return FALSE;
}

gboolean mouse_scroll(GtkWidget* widget, GdkEvent* event, gpointer user_data) {
    if (event->type == GDK_SCROLL && !game_paused()) {
        GdkEventScroll* e = (GdkEventScroll*) event;
        switch (e->direction) {
        case GDK_SCROLL_SMOOTH: {
            double dx, dy;
            gdk_event_get_scroll_deltas(event, &dx, &dy);
            spaceship_control(dx, dy);
            break;
        }
        default:
            break;
        }
    }
    return TRUE;
}

void destroy_window(void) {
    gtk_main_quit();
}

void print_usage(const char* progname) {
    fprintf(stderr,
        "usage: %s [options...]\n"
        "options:\n"
        "\t<width>x<height>\n"
        "\tpolygons=<0 | 1> :: boolean\n"
        "\tn=<number of balls>\n"
        "\tfconst=<x-force>,<y-force> :: constant force field\n"
        "\tfnewt=<radius>,<g> :: radial, Newtonian force field\n"
        "\tfy=<y-force>\n"
        "\tradius=<min-radius>-<max-radius>\n"
        "\tv=<min-velocity>-<max-velocity>\n"
        "\tdelta=<frame-delta-time> (in seconds)\n"
        "\tface=<filename>\n"
        "\tstats=<sample-count> :: rendering timing statitstics (0=disabled, "
        "default)\n"
        "\tcollisions=<C> :: n=no collisions, s=simple, i=index\n"
        "\trestitution=<C_r> :: restitution coefficient C_r\n"
        "\t-r :: activate face rotation\n",
        progname);
}

static unsigned int stats_sampling = 0;
static guint64 stats_update_usec = 0;
static unsigned int stats_update_samples = 0;
static guint64 stats_draw_usec = 0;
static unsigned int stats_draw_samples = 0;

gboolean draw_event(GtkWidget* widget, cairo_t* cr, gpointer data) {
    if (stats_sampling > 0) {
        guint64 start = g_get_monotonic_time();
        draw_frame(widget, cr, data);
        stats_draw_usec += g_get_monotonic_time() - start;
        ++stats_draw_samples;
    } else
        draw_frame(widget, cr, data);
    return FALSE;
}

gboolean animation_timeout(gpointer user_data) {
    if (stats_sampling > 0) {
        guint64 start = g_get_monotonic_time();
        update_state();
        stats_update_usec += g_get_monotonic_time() - start;
        if (++stats_update_samples == stats_sampling) {
            float uavg = 1.0 * stats_update_usec / stats_update_samples;
            float davg = 1.0 * stats_draw_usec / stats_draw_samples;
            printf("\rupdate = %.0f us, draw = %.0f us, load = %.0f%% (%u "
                   "update, %u draw)  ",
                uavg,
                davg,
                (uavg + davg) / (10000.0 * delta),
                stats_update_samples,
                stats_draw_samples);
            fflush(stdout);
            stats_update_usec = 0;
            stats_update_samples = 0;
            stats_draw_usec = 0;
            stats_draw_samples = 0;
        }
    } else {
        update_state();
    }
    gtk_widget_queue_draw(canvas);
    return TRUE;
}

int main(int argc, const char* argv[]) {
    int w = DEFAULT_WIDTH;
    int h = DEFAULT_HEIGHT;
    double fa, fb;

    for (int i = 1; i < argc; ++i) {
        if (sscanf(argv[i], "%dx%d", &w, &h) == 2)
            continue;
        if (sscanf(argv[i], "polygons=%u", &polys) == 1) {
            if (polys)
                n_balls = 0;
            continue;
        }
        if (sscanf(argv[i], "n=%u", &n_balls) == 1)
            continue;
        if (sscanf(argv[i], "fconst=%lf,%lf", &fa, &fb) == 2) {
            gravity_constant_field(fa, fb);
            continue;
        }
        if (sscanf(argv[i], "fnewt=%lf,%lf", &fa, &fb) == 2) {
            gravity_newton_field(fa, fb);
            continue;
        }
        if (sscanf(argv[i], "radius=%u-%u", &radius_min, &radius_max) == 2)
            continue;
        if (sscanf(argv[i], "v=%u-%u", &v_min, &v_max) == 2)
            continue;
        if (sscanf(argv[i], "delta=%lf", &delta) == 1)
            continue;
        if (strncmp(argv[i], "face=", 5) == 0) {
            face_filename = argv[i] + 5;
            continue;
        }
        if (sscanf(argv[i], "stats=%u", &stats_sampling) == 1)
            continue;
        char collisions;
        if (sscanf(argv[i], "collisions=%c", &collisions) == 1) {
            switch (collisions) {
            case 'i':
            case 'I':
                check_collisions = check_collisions_with_index;
                continue;
            case '0':
            case 'N':
            case 'n':
                check_collisions = 0;
                continue;
            case 's':
            case 'S':
                check_collisions = check_collisions_simple;
                continue;
            }
        }
        if (strcmp(argv[i], "-r") == 0) {
            face_rotation = 1;
            continue;
        }
        double c_r;
        if (sscanf(argv[i], "restitution=%lf", &c_r) == 1) {
            restitution_coefficient_set(c_r);
            continue;
        }
        print_usage(argv[0]);
        return 1;
    }

    gtk_init(0, 0);

    GtkWidget* window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
    gtk_window_set_default_size(GTK_WINDOW(window), width, height);
    gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
    gtk_window_set_title(GTK_WINDOW(window), "Game");

    g_signal_connect(window, "destroy", G_CALLBACK(destroy_window), NULL);
    g_signal_connect(
        G_OBJECT(window), "delete-event", G_CALLBACK(destroy_window), NULL);
    g_signal_connect(
        G_OBJECT(window), "key-press-event", G_CALLBACK(keyboard_input), NULL);
    gtk_widget_set_events(window,
        GDK_EXPOSURE_MASK | GDK_SCROLL_MASK | GDK_SMOOTH_SCROLL_MASK |
            GDK_KEY_PRESS_MASK);

    canvas = gtk_drawing_area_new();

    g_signal_connect(
        G_OBJECT(canvas), "configure-event", G_CALLBACK(configure_event), NULL);
    g_signal_connect(G_OBJECT(canvas), "draw", G_CALLBACK(draw_event), NULL);
    g_signal_connect(
        G_OBJECT(canvas), "scroll-event", G_CALLBACK(mouse_scroll), NULL);
    gtk_widget_set_events(canvas, GDK_SCROLL_MASK | GDK_SMOOTH_SCROLL_MASK);

    gtk_container_add(GTK_CONTAINER(window), canvas);

    game_animation_on_off();

    gtk_widget_show_all(window);

    game_init();

    gtk_main();

    if (stats_sampling > 0)
        printf("\n");

    game_destroy();

    return 0;
}