This repository has been archived by the owner on Feb 11, 2021. It is now read-only.
happy.c
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/*
* 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_TextureID texture_id = 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(void)
{
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_RenderFill(0, 0, 0, 255, NULL);
/*
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(texture_id, &srcRect, &dstRect);
}
/* update screen */
SDL_RenderPresent();
}
/*
loads the happyface graphic into a texture
*/
void
initializeTexture()
{
SDL_Surface *bmp_surface;
SDL_Surface *bmp_surface_rgba;
int format = SDL_PIXELFORMAT_ABGR8888; /* desired texture format */
Uint32 Rmask, Gmask, Bmask, Amask; /* masks for desired format */
int bpp; /* bits per pixel for desired format */
/* 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));
SDL_PixelFormatEnumToMasks(format, &bpp, &Rmask, &Gmask, &Bmask, &Amask);
/*
create a new RGBA surface and blit the bmp to it
this is an extra step, but it seems to be necessary
is this a bug?
*/
bmp_surface_rgba =
SDL_CreateRGBSurface(0, bmp_surface->w, bmp_surface->h, bpp, Rmask,
Gmask, Bmask, Amask);
SDL_BlitSurface(bmp_surface, NULL, bmp_surface_rgba, NULL);
/* convert RGBA surface to texture */
texture_id = SDL_CreateTextureFromSurface(format, bmp_surface_rgba);
if (texture_id == 0) {
fatalError("could not create texture");
}
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SDL_SetTextureBlendMode(texture_id, SDL_BLENDMODE_BLEND);
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/* free up allocated memory */
SDL_FreeSurface(bmp_surface_rgba);
SDL_FreeSurface(bmp_surface);
}
int
main(int argc, char *argv[])
{
SDL_WindowID windowID;
Uint32 startFrame;
Uint32 endFrame;
Uint32 delay;
int done;
/* initialize SDL */
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
fatalError("Could not initialize SDL");
}
windowID = SDL_CreateWindow(NULL, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT,
SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN |
SDL_WINDOW_BORDERLESS);
SDL_CreateRenderer(windowID, -1, 0);
initializeTexture();
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();
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;
}
SDL_Delay(delay);
}
/* cleanup */
SDL_DestroyTexture(texture_id);
/* shutdown SDL */
SDL_Quit();
return 0;
}