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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <SDL.h>
#include <SDL_image.h>
#include <SDL_framerate.h>
//#define EFFECT_FIRE_COLORKEYED
#define NARRAY(ARRAY) \
(sizeof(ARRAY) / sizeof((ARRAY)[0]))
#define SDL_MAYBE_LOCK(SURFACE) do { \
if (SDL_MUSTLOCK(SURFACE)) \
SDL_LockSurface(SURFACE); \
} while (0)
#define SDL_MAYBE_UNLOCK(SURFACE) do { \
if (SDL_MUSTLOCK(SURFACE)) \
SDL_UnlockSurface(SURFACE); \
} while (0)
#define SDL_ERROR(FMT, ...) do { \
fprintf(stderr, "%s(%d): " FMT ": %s\n", \
__FILE__, __LINE__, ##__VA_ARGS__, SDL_GetError()); \
} while (0)
#define SDL_IMAGE_ERROR(FMT, ...) do { \
fprintf(stderr, "%s(%d): " FMT ": %s\n", \
__FILE__, __LINE__, ##__VA_ARGS__, IMG_GetError()); \
} while (0)
#define SCREEN_WIDTH 640
#define SCREEN_HEIGHT 480
#define FRAMERATE 20 /* Hz */
static SDL_Surface *screen;
static SDL_Color colors[256];
#define FIRE_DECAY(C) \
((C) > 0 ? (C) - 1 : 0)
static inline SDL_Surface *
effect_fire_init(void)
{
Uint32 flags = SDL_HWSURFACE;
SDL_Surface *surface;
#ifdef EFFECT_FIRE_COLORKEYED
surface = SDL_CreateRGBSurface(flags, screen->w, screen->h, 8,
0, 0, 0, 0);
#else
flags |= SDL_SRCALPHA;
surface = SDL_CreateRGBSurface(flags, screen->w, screen->h, 32,
0x000000FF, 0x0000FF00,
0x00FF0000, 0xFF000000);
#endif
if (surface == NULL) {
SDL_ERROR("SDL_CreateRGBSurface");
exit(EXIT_FAILURE);
}
#ifdef EFFECT_FIRE_COLORKEYED
if (SDL_SetColorKey(surface, SDL_SRCCOLORKEY, 0)) {
SDL_ERROR("SDL_SetColorKey");
SDL_FreeSurface(surface);
exit(EXIT_FAILURE);
}
#endif
memset(colors, 0, sizeof(colors));
for (int i = 0; i < 32; i++) {
#ifdef EFFECT_FIRE_COLORKEYED
/* black to blue, 32 values */
colors[i].b = i << 1;
#else
/* transparent to blue, 32 values */
colors[i].b = 255;
colors[i].unused = i << 3;
#endif
/* blue to red, 32 values */
colors[i + 32].r = i << 3;
colors[i + 32].b = 64 - (i << 1);
colors[i + 32].unused = SDL_ALPHA_OPAQUE;
/*red to yellow, 32 values */
colors[i + 64].r = 255;
colors[i + 64].g = i << 3;
colors[i + 64].unused = SDL_ALPHA_OPAQUE;
/* yellow to white, 162 */
colors[i + 96].r = 255;
colors[i + 96].g = 255;
colors[i + 96].b = i << 2;
colors[i + 96].unused = SDL_ALPHA_OPAQUE;
colors[i + 128].r = 255;
colors[i + 128].g = 255;
colors[i + 128].b = 64 + (i << 2);
colors[i + 128].unused = SDL_ALPHA_OPAQUE;
colors[i + 160].r = 255;
colors[i + 160].g = 255;
colors[i + 160].b = 128 + (i << 2);
colors[i + 160].unused = SDL_ALPHA_OPAQUE;
colors[i + 192].r = 255;
colors[i + 192].g = 255;
colors[i + 192].b = 192 + i;
colors[i + 192].unused = SDL_ALPHA_OPAQUE;
colors[i + 224].r = 255;
colors[i + 224].g = 255;
colors[i + 224].b = 224 + i;
colors[i + 224].unused = SDL_ALPHA_OPAQUE;
}
#ifdef EFFECT_FIRE_COLORKEYED
SDL_SetPalette(surface, SDL_LOGPAL | SDL_PHYSPAL, colors,
0, NARRAY(colors));
#else
SDL_FillRect(surface, NULL,
SDL_MapRGBA(surface->format,
colors[0].r, colors[0].g,
colors[0].b, colors[0].unused));
#endif
return surface;
}
#ifdef EFFECT_FIRE_COLORKEYED
static inline Uint8
effect_fire_get_color(SDL_Surface *surface, int x, int y)
{
return ((Uint8 *)surface->pixels)[surface->w*y + x];
}
static inline void
effect_fire_set_color(SDL_Surface *surface, int x, int y, Uint8 color)
{
((Uint8 *)surface->pixels)[surface->w*y + x] = color;
}
#else
static inline Uint8
effect_fire_get_color(SDL_Surface *surface, int x, int y)
{
SDL_Color color;
/* alpha-channel surface */
SDL_GetRGBA(((Uint32 *)surface->pixels)[surface->w*y + x],
surface->format, &color.r, &color.g, &color.b, &color.unused);
for (Uint8 i = 0; i < NARRAY(colors); i++)
if (!memcmp(colors + i, &color, sizeof(color)))
return i;
/* shouldn't be reached */
return 0;
}
static inline void
effect_fire_set_color(SDL_Surface *surface, int x, int y, Uint8 color)
{
((Uint32 *)surface->pixels)[surface->w*y + x] =
SDL_MapRGBA(surface->format,
colors[color].r, colors[color].g,
colors[color].b, colors[color].unused);
}
#endif
static inline void
effect_fire_update(SDL_Surface *surface)
{
int mouse_x, mouse_y;
SDL_MAYBE_LOCK(surface);
if (SDL_GetMouseState(&mouse_x, &mouse_y) & SDL_BUTTON(1))
effect_fire_set_color(surface, mouse_x, mouse_y,
(float)rand()/RAND_MAX > .3 ? 255 : 0);
for (int y = surface->h - 1; y > 0; y--) {
Uint16 acc;
Uint8 color;
/* right edge */
acc = (Uint16)effect_fire_get_color(surface, surface->w - 2, y)
+ effect_fire_get_color(surface, surface->w - 1, y);
color = effect_fire_get_color(surface, surface->w - 1, y - 1);
if (acc/2 > color)
color = (Uint8)((acc + color)/3);
effect_fire_set_color(surface, surface->w - 1, y - 1,
FIRE_DECAY(color));
/* center */
for (int x = surface->w - 2; x > 0; x--) {
acc = (Uint16)effect_fire_get_color(surface, x - 1, y)
+ effect_fire_get_color(surface, x, y)
+ effect_fire_get_color(surface, x + 1, y);
color = effect_fire_get_color(surface, x, y - 1);
if (acc/3 > color)
color = (Uint8)((acc + color)/4);
effect_fire_set_color(surface, x, y - 1, FIRE_DECAY(color));
}
/* left edge */
acc = (Uint16)effect_fire_get_color(surface, 0, y)
+ effect_fire_get_color(surface, 1, y);
color = effect_fire_get_color(surface, 0, y - 1);
if (acc/2 > color)
color = (Uint8)((acc + color)/3);
effect_fire_set_color(surface, 0, y - 1, FIRE_DECAY(color));
}
SDL_MAYBE_UNLOCK(surface);
}
static inline void
process_events(void)
{
SDL_Event event;
while (SDL_PollEvent(&event)) {
switch (event.type) {
case SDL_KEYDOWN:
switch (event.key.keysym.sym) {
case SDLK_f:
if (!SDL_WM_ToggleFullScreen(screen)) {
SDL_ERROR("SDL_WM_ToggleFullScreen");
exit(EXIT_FAILURE);
}
break;
case SDLK_m:
SDL_ShowCursor(!SDL_ShowCursor(SDL_QUERY));
break;
case SDLK_ESCAPE:
exit(EXIT_SUCCESS);
default:
break;
}
break;
case SDL_QUIT:
exit(EXIT_SUCCESS);
default:
break;
}
}
}
int
main(int argc, char **argv)
{
FPSmanager fpsm;
SDL_Surface *fire_surface;
SDL_Surface *image_surface;
if (SDL_Init(SDL_INIT_VIDEO)) {
SDL_ERROR("SDL_Init");
return EXIT_FAILURE;
}
atexit(SDL_Quit);
SDL_WM_SetCaption("Effect Pad", NULL);
screen = SDL_SetVideoMode(SCREEN_WIDTH, SCREEN_HEIGHT, 32,
SDL_HWSURFACE | SDL_DOUBLEBUF);
if (screen == NULL) {
SDL_ERROR("SDL_SetVideoMode");
return EXIT_FAILURE;
}
SDL_initFramerate(&fpsm);
SDL_setFramerate(&fpsm, FRAMERATE);
image_surface = IMG_Load("image_1.jpg");
if (image_surface == NULL) {
SDL_IMAGE_ERROR("IMG_Load");
return EXIT_FAILURE;
}
assert(image_surface->w == screen->w && image_surface->h == screen->h);
fire_surface = effect_fire_init();
for (;;) {
process_events();
SDL_FillRect(screen, NULL,
SDL_MapRGB(screen->format, 0, 0, 0));
SDL_BlitSurface(image_surface, NULL, screen, NULL);
effect_fire_update(fire_surface);
SDL_BlitSurface(fire_surface, NULL, screen, NULL);
SDL_Flip(screen);
SDL_framerateDelay(&fpsm);
}
/* never reached */
return EXIT_FAILURE;
}
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