/*

 *	happy.c

 *	written by Holmes Futrell

 *	use however you want

 */

#include "SDL.h"

#include "common.h"

#define NUM_HAPPY_FACES 100     /* number of faces to draw */

#define MILLESECONDS_PER_FRAME 16       /* about 60 frames per second */

#define HAPPY_FACE_SIZE 32      /* width and height of happyface (pixels) */

static SDL_Texture *texture = 0;    /* reference to texture holding happyface */

static struct

{

    float x, y;                 /* position of happyface */

    float xvel, yvel;           /* velocity of happyface */

} faces[NUM_HAPPY_FACES];

/*

	Sets initial positions and velocities of happyfaces

	units of velocity are pixels per millesecond

*/

void

initializeHappyFaces()

{

    int i;

    for (i = 0; i < NUM_HAPPY_FACES; i++) {

        faces[i].x = randomFloat(0.0f, SCREEN_WIDTH - HAPPY_FACE_SIZE);

        faces[i].y = randomFloat(0.0f, SCREEN_HEIGHT - HAPPY_FACE_SIZE);

        faces[i].xvel = randomFloat(-0.1f, 0.1f);

        faces[i].yvel = randomFloat(-0.1f, 0.1f);

    }

}

void

render(SDL_Renderer *renderer)

{

    int i;

    SDL_Rect srcRect;

    SDL_Rect dstRect;

    /* setup boundaries for happyface bouncing */

    Uint16 maxx = SCREEN_WIDTH - HAPPY_FACE_SIZE;

    Uint16 maxy = SCREEN_HEIGHT - HAPPY_FACE_SIZE;

    Uint16 minx = 0;

    Uint16 miny = 0;

    /* setup rects for drawing */

    srcRect.x = 0;

    srcRect.y = 0;

    srcRect.w = HAPPY_FACE_SIZE;

    srcRect.h = HAPPY_FACE_SIZE;

    dstRect.w = HAPPY_FACE_SIZE;

    dstRect.h = HAPPY_FACE_SIZE;

    /* fill background in with black */

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);

    SDL_RenderClear(renderer);

    /*

       loop through all the happy faces:

       - update position

       - update velocity (if boundary is hit)

       - draw

     */

    for (i = 0; i < NUM_HAPPY_FACES; i++) {

        faces[i].x += faces[i].xvel * MILLESECONDS_PER_FRAME;

        faces[i].y += faces[i].yvel * MILLESECONDS_PER_FRAME;

        if (faces[i].x > maxx) {

            faces[i].x = maxx;

            faces[i].xvel = -faces[i].xvel;

        } else if (faces[i].y > maxy) {

            faces[i].y = maxy;

            faces[i].yvel = -faces[i].yvel;

        }

        if (faces[i].x < minx) {

            faces[i].x = minx;

            faces[i].xvel = -faces[i].xvel;

        } else if (faces[i].y < miny) {

            faces[i].y = miny;

            faces[i].yvel = -faces[i].yvel;

        }

        dstRect.x = faces[i].x;

        dstRect.y = faces[i].y;

        SDL_RenderCopy(renderer, texture, &srcRect, &dstRect);

    }

    /* update screen */

    SDL_RenderPresent(renderer);

}

/*

	loads the happyface graphic into a texture

*/

void

initializeTexture(SDL_Renderer *renderer)

{

    SDL_Surface *bmp_surface;

    /* load the bmp */

    bmp_surface = SDL_LoadBMP("icon.bmp");

    if (bmp_surface == NULL) {

        fatalError("could not load bmp");

    }

    /* set white to transparent on the happyface */

    SDL_SetColorKey(bmp_surface, 1,

                    SDL_MapRGB(bmp_surface->format, 255, 255, 255));

    /* convert RGBA surface to texture */

    texture = SDL_CreateTextureFromSurface(renderer, bmp_surface);

    if (texture == 0) {

        fatalError("could not create texture");

    }

    SDL_SetTextureBlendMode(texture, SDL_BLENDMODE_BLEND);

    /* free up allocated memory */

    SDL_FreeSurface(bmp_surface);

}

int

main(int argc, char *argv[])

{

    SDL_Window *window;

	SDL_Renderer *renderer;

    Uint32 startFrame;

    Uint32 endFrame;

    Uint32 delay;

    int done;

    /* initialize SDL */

    if (SDL_Init(SDL_INIT_VIDEO) < 0) {

        fatalError("Could not initialize SDL");

    }

    window = SDL_CreateWindow(NULL, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT,

                                SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN |

                                SDL_WINDOW_BORDERLESS);

    renderer = SDL_CreateRenderer(window, -1, 0);

    initializeTexture(renderer);

    initializeHappyFaces();

    /* main loop */

    done = 0;

    while (!done) {

        startFrame = SDL_GetTicks();

        SDL_Event event;

        while (SDL_PollEvent(&event)) {

            if (event.type == SDL_QUIT) {

                done = 1;

            }

        }

        render(renderer);

        endFrame = SDL_GetTicks();

        /* figure out how much time we have left, and then sleep */

        delay = MILLESECONDS_PER_FRAME - (endFrame - startFrame);

        if (delay < 0) {

            delay = 0;

        } else if (delay > MILLESECONDS_PER_FRAME) {

            delay = MILLESECONDS_PER_FRAME;

        }

    }

    /* cleanup */

    SDL_DestroyTexture(texture);

    /* shutdown SDL */

    SDL_Quit();

    return 0;

}