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Bricks

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Briks is a very simplistic imitation of the Atari Breakout video game, which will allow us to make an introduction to the world of Synchronous applications. Any real-time application must be constantly updating whether or not the user intervenes. The source code is in folder /src/demo/bricks of the SDK distribution.

  • Use osmain_sync to start a synchronous application, indicating an interval and update callback function. NAppGUI will periodically launch time events that will update the program.
  • Game capture bricks, imitation of the Atari Breakout.
    Figure 1: Bricks video game on Windows, macOS and Linux.

This application is managed by two events (Figure 2). On the one hand the slider movement, which can occur at any time (asynchronous event), and will update the player position. On the other a synchronous event produced by osmain_sync every 40 milliseconds and will be notified through i_update() to update the game state and graphic view.

Graph showing two events, one synchronous and one asynchronous.
Figure 2: Synchronous and asynchronous events.
Listing 1: demo/bricks/bricks.c
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/* Simplistic Breakout-like game */

#include "nappgui.h"

#define NUM_BRICKS 40

typedef struct _brick_t Brick;
typedef struct _app_t App;

struct _brick_t
{
    real32_t x;
    real32_t y;
    uint8_t color;
    bool_t is_visible;
};

struct _app_t
{
    bool_t is_running;
    Brick bricks[NUM_BRICKS];
    color_t color[4];
    real32_t brick_width;
    real32_t player_pos;
    real32_t ball_x;
    real32_t ball_y;
    V2Df ball_dir;
    real32_t ball_speed;
    Cell *button;
    Slider *slider;
    View *view;
    Window *window;
};

/*---------------------------------------------------------------------------*/

static const real32_t i_BALL_RADIUS = .03f;
static const real32_t i_BRICK_HEIGHT = .03f;
static const real32_t i_BRICK_SEPARATION = .005f;
static const uint32_t i_BRICKS_PER_ROW = 10;
static const uint32_t i_NUM_ROWS = 4;

/*---------------------------------------------------------------------------*/

static void i_OnDraw(App *app, Event *e)
{    
    const EvDraw *params = event_params(e, EvDraw);
    uint32_t i = 0;

    draw_clear(params->ctx, color_rgb(102, 153, 26));
    draw_line_color(params->ctx, kCOLOR_BLACK);

    for (i = 0; i < NUM_BRICKS; ++i)
    {
        if (app->bricks[i].is_visible == TRUE)
        {
            real32_t x = app->bricks[i].x * params->width;
            real32_t y = app->bricks[i].y * params->height;
            real32_t width = app->brick_width * params->width;
            real32_t height = i_BRICK_HEIGHT * params->height;
            draw_fill_color(params->ctx, app->color[app->bricks[i].color]);
            draw_rect(params->ctx, ekFILLSK, x, y, width, height);
        }
    }
    
    {
        real32_t x = (app->player_pos - app->brick_width) * params->width;
        real32_t y = (1 - i_BRICK_HEIGHT - i_BRICK_SEPARATION) * params->height;
        real32_t width = 2 * app->brick_width * params->width;
        real32_t height = i_BRICK_HEIGHT * params->height;
        draw_fill_color(params->ctx, kCOLOR_BLACK);
        draw_rect(params->ctx, ekFILL, x, y, width, height);
    }

    {
        real32_t x = app->ball_x * params->width;
        real32_t y = app->ball_y * params->height;
        real32_t rad = i_BALL_RADIUS * params->width;
        draw_fill_color(params->ctx, kCOLOR_WHITE);
        draw_circle(params->ctx, ekFILL, x, y, rad);
    }
}

/*---------------------------------------------------------------------------*/

static void i_OnSlider(App *app, Event *e)
{
    const EvSlider *params = event_params(e, EvSlider);
    app->player_pos = params->pos;
}

/*---------------------------------------------------------------------------*/

static void i_OnStart(App *app, Event *e)
{
    unref(e);
    app->is_running = TRUE;
    cell_enabled(app->button, FALSE);
}

/*---------------------------------------------------------------------------*/

 static Panel *i_panel(App *app)
 {
    Panel *panel = panel_create();
    Layout *layout = layout_create(1, 4);
    View *view = view_create();
    Slider *slider = slider_create();
    Label *label = label_create();
    Button *button = button_push();
    view_size(view, s2df(258, 344));
    view_OnDraw(view, listener(app, i_OnDraw, App)); 
    slider_OnMoved(slider, listener(app, i_OnSlider, App));
    label_text(label, "Use the slider!");
    button_text(button, "Start");
    button_OnClick(button, listener(app, i_OnStart, App));    
    layout_view(layout, view, 0, 0);
    layout_slider(layout, slider, 0, 1);
    layout_label(layout, label, 0, 2);
    layout_button(layout, button, 0, 3);
    layout_vexpand(layout, 0);
    layout_vmargin(layout, 0, 10);
    layout_vmargin(layout, 2, 10);
    layout_margin(layout, 10);
    panel_layout(panel, layout);
    app->view = view;
    app->slider = slider;
    app->button = layout_cell(layout, 0, 3);
    return panel;
}

/*---------------------------------------------------------------------------*/

static void i_init_game(App *app)
{
    real32_t hoffset;
    Brick *brick = NULL;
    uint32_t j, i;
    
    app->color[0] = color_rgb(255, 0, 0);
    app->color[1] = color_rgb(0, 255, 0);
    app->color[2] = color_rgb(0, 0, 255);
    app->color[3] = color_rgb(0, 255, 255);

    hoffset = i_BRICK_SEPARATION;
    brick = app->bricks;

    app->is_running = FALSE;
    app->brick_width = (1 - ((real32_t)i_BRICKS_PER_ROW + 1) * i_BRICK_SEPARATION) / (real32_t)i_BRICKS_PER_ROW;

    for (j = 0; j < i_NUM_ROWS; ++j)
    {
        real32_t woffset = i_BRICK_SEPARATION;
        
        for (i = 0; i < i_BRICKS_PER_ROW; ++i)
        {
            brick->x = woffset;
            brick->y = hoffset;
            brick->is_visible = TRUE;
            brick->color = (uint8_t)j;
            woffset += app->brick_width + i_BRICK_SEPARATION;
            brick++;
        }
        
        hoffset += i_BRICK_HEIGHT + i_BRICK_SEPARATION;
    }
    
    app->player_pos = slider_get_value(app->slider);
    app->ball_x = .5f;
    app->ball_y = .5f;
    app->ball_dir.x = .3f;
    app->ball_dir.y = -.1f;
    app->ball_speed = .6f;
    v2d_normf(&app->ball_dir);
}

/*---------------------------------------------------------------------------*/

static void i_OnClose(App *app, Event *e)
{
    osapp_finish();
    unref(app);
    unref(e);
}

/*---------------------------------------------------------------------------*/

static App *i_create(void)
{
    App *app = heap_new0(App);
    Panel *panel = i_panel(app);
    app->window = window_create(ekWNSRES, &panel);
    window_origin(app->window, v2df(200, 200));
    window_title(app->window, "Bricks - A 2D Game");
    window_OnClose(app->window, listener(app, i_OnClose, App));
    window_show(app->window);
    i_init_game(app);
    return app;
}

/*---------------------------------------------------------------------------*/

static void i_destroy(App **app)
{
    window_destroy(&(*app)->window);
    heap_delete(app, App);
}

/*---------------------------------------------------------------------------*/

static bool_t i_collision(Brick *brick, real32_t brick_width, real32_t ball_x, real32_t ball_y)
{
    if (ball_x + i_BALL_RADIUS < brick->x)
        return FALSE;
    if (ball_x - i_BALL_RADIUS > brick->x + brick_width)
        return FALSE;
    if (ball_y + i_BALL_RADIUS < brick->y)
        return FALSE;
    if (ball_y - i_BALL_RADIUS > brick->y + i_BRICK_HEIGHT)
        return FALSE;
    return TRUE;
}

/*---------------------------------------------------------------------------*/

static void i_update(App *app, const real64_t prtime, const real64_t ctime)
{
    if (app->is_running == TRUE)
    {
        real32_t step = (real32_t)(ctime - prtime);
        bool_t collide;
        uint32_t i;
    
        // Update ball position
        app->ball_x += step * app->ball_speed * app->ball_dir.x;
        app->ball_y += step * app->ball_speed * app->ball_dir.y;
    
        // Collision with limits
        if (app->ball_x + i_BALL_RADIUS >= 1.f && app->ball_dir.x >= 0.f)
            app->ball_dir.x = - app->ball_dir.x;
    
        if (app->ball_x - i_BALL_RADIUS <= 0.f && app->ball_dir.x <= 0.f)
            app->ball_dir.x = - app->ball_dir.x;

        if (app->ball_y - i_BALL_RADIUS <= 0.f && app->ball_dir.y <= 0.f)
            app->ball_dir.y = - app->ball_dir.y;
    
        // Collision with bricks
        collide = FALSE;
        for (i = 0; i < NUM_BRICKS; ++i)
        {
            if (app->bricks[i].is_visible == TRUE)
            {
                if (i_collision(&app->bricks[i], app->brick_width, app->ball_x, app->ball_y) == TRUE)
                {
                    app->bricks[i].is_visible = FALSE;
                    if (collide == FALSE)
                    {
                        real32_t brick_x = app->bricks[i].x + .5f * app->brick_width;
                        app->ball_dir.x = 5.f * (app->ball_x - brick_x);
                        app->ball_dir.y = - app->ball_dir.y;
                        v2d_normf(&app->ball_dir);
                        collide = TRUE;
                    }
                }
            }
        }

        // Collision with player
        {
            Brick player;
            player.x = app->player_pos - app->brick_width;
            player.y = 1.f - i_BRICK_HEIGHT - i_BRICK_SEPARATION;
            if (i_collision(&player, 2.f * app->brick_width, app->ball_x, app->ball_y) == TRUE)
            {
                app->ball_dir.x = 5.f * (app->ball_x - app->player_pos);
                app->ball_dir.y = - app->ball_dir.y;
                v2d_normf(&app->ball_dir);
            }
        }

        // Game Over
        if (app->ball_y + i_BALL_RADIUS >= 1.f)
        {
            i_init_game(app);
            cell_enabled(app->button, TRUE);
        }
    }

    view_update(app->view);
}

/*---------------------------------------------------------------------------*/

#include "osmain.h"
osmain_sync(.04, i_create, i_destroy, i_update, "", App)
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