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pcsx2/3rdparty/SDL-1.3.0-5387/test/testalpha.c

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/* Simple program: Fill a colormap with gray and stripe it down the screen,
Then move an alpha valued sprite around the screen.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include "SDL.h"
#define FRAME_TICKS (1000/30) /* 30 frames/second */
/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
static void
quit(int rc)
{
SDL_Quit();
exit(rc);
}
/* Fill the screen with a gradient */
static void
FillBackground(SDL_Surface * screen)
{
Uint8 *buffer;
Uint8 gradient;
int i, k;
/* Set the surface pixels and refresh! */
if (SDL_LockSurface(screen) < 0) {
fprintf(stderr, "Couldn't lock the display surface: %s\n",
SDL_GetError());
quit(2);
}
buffer = (Uint8 *) screen->pixels;
switch (screen->format->BytesPerPixel) {
case 1:
case 3:
for (i = 0; i < screen->h; ++i) {
memset(buffer, (i * 255) / screen->h,
screen->w * screen->format->BytesPerPixel);
buffer += screen->pitch;
}
break;
case 2:
for (i = 0; i < screen->h; ++i) {
Uint16 *buffer16;
Uint16 color;
gradient = ((i * 255) / screen->h);
color = (Uint16) SDL_MapRGB(screen->format,
gradient, gradient, gradient);
buffer16 = (Uint16 *) buffer;
for (k = 0; k < screen->w; k++) {
*buffer16++ = color;
}
buffer += screen->pitch;
}
break;
case 4:
for (i = 0; i < screen->h; ++i) {
Uint32 *buffer32;
Uint32 color;
gradient = ((i * 255) / screen->h);
color = SDL_MapRGB(screen->format, gradient, gradient, gradient);
buffer32 = (Uint32 *) buffer;
for (k = 0; k < screen->w; k++) {
*buffer32++ = color;
}
buffer += screen->pitch;
}
break;
}
SDL_UnlockSurface(screen);
SDL_UpdateRect(screen, 0, 0, 0, 0);
}
/* Create a "light" -- a yellowish surface with variable alpha */
SDL_Surface *
CreateLight(int radius)
{
Uint8 trans, alphamask;
int range, addition;
int xdist, ydist;
Uint16 x, y;
Uint16 skip;
Uint32 pixel;
SDL_Surface *light;
#ifdef LIGHT_16BIT
Uint16 *buf;
/* Create a 16 (4/4/4/4) bpp square with a full 4-bit alpha channel */
/* Note: this isn't any faster than a 32 bit alpha surface */
alphamask = 0x0000000F;
light = SDL_CreateRGBSurface(SDL_SWSURFACE, 2 * radius, 2 * radius, 16,
0x0000F000, 0x00000F00, 0x000000F0,
alphamask);
#else
Uint32 *buf;
/* Create a 32 (8/8/8/8) bpp square with a full 8-bit alpha channel */
alphamask = 0x000000FF;
light = SDL_CreateRGBSurface(SDL_SWSURFACE, 2 * radius, 2 * radius, 32,
0xFF000000, 0x00FF0000, 0x0000FF00,
alphamask);
if (light == NULL) {
fprintf(stderr, "Couldn't create light: %s\n", SDL_GetError());
return (NULL);
}
#endif
/* Fill with a light yellow-orange color */
skip = light->pitch - (light->w * light->format->BytesPerPixel);
#ifdef LIGHT_16BIT
buf = (Uint16 *) light->pixels;
#else
buf = (Uint32 *) light->pixels;
#endif
/* Get a tranparent pixel value - we'll add alpha later */
pixel = SDL_MapRGBA(light->format, 0xFF, 0xDD, 0x88, 0);
for (y = 0; y < light->h; ++y) {
for (x = 0; x < light->w; ++x) {
*buf++ = pixel;
}
buf += skip; /* Almost always 0, but just in case... */
}
/* Calculate alpha values for the surface. */
#ifdef LIGHT_16BIT
buf = (Uint16 *) light->pixels;
#else
buf = (Uint32 *) light->pixels;
#endif
for (y = 0; y < light->h; ++y) {
for (x = 0; x < light->w; ++x) {
/* Slow distance formula (from center of light) */
xdist = x - (light->w / 2);
ydist = y - (light->h / 2);
range = (int) sqrt(xdist * xdist + ydist * ydist);
/* Scale distance to range of transparency (0-255) */
if (range > radius) {
trans = alphamask;
} else {
/* Increasing transparency with distance */
trans = (Uint8) ((range * alphamask) / radius);
/* Lights are very transparent */
addition = (alphamask + 1) / 8;
if ((int) trans + addition > alphamask) {
trans = alphamask;
} else {
trans += addition;
}
}
/* We set the alpha component as the right N bits */
*buf++ |= (255 - trans);
}
buf += skip; /* Almost always 0, but just in case... */
}
/* Enable RLE acceleration of this alpha surface */
SDL_SetAlpha(light, SDL_SRCALPHA | SDL_RLEACCEL, 0);
/* We're done! */
return (light);
}
static Uint32 flashes = 0;
static Uint32 flashtime = 0;
void
FlashLight(SDL_Surface * screen, SDL_Surface * light, int x, int y)
{
SDL_Rect position;
Uint32 ticks1;
Uint32 ticks2;
/* Easy, center light */
position.x = x - (light->w / 2);
position.y = y - (light->h / 2);
position.w = light->w;
position.h = light->h;
ticks1 = SDL_GetTicks();
SDL_BlitSurface(light, NULL, screen, &position);
ticks2 = SDL_GetTicks();
SDL_UpdateRects(screen, 1, &position);
++flashes;
/* Update time spend doing alpha blitting */
flashtime += (ticks2 - ticks1);
}
static int sprite_visible = 0;
static SDL_Surface *sprite;
static SDL_Surface *backing;
static SDL_Rect position;
static int x_vel, y_vel;
static int alpha_vel;
int
LoadSprite(SDL_Surface * screen, char *file)
{
SDL_Surface *converted;
/* Load the sprite image */
sprite = SDL_LoadBMP(file);
if (sprite == NULL) {
fprintf(stderr, "Couldn't load %s: %s", file, SDL_GetError());
return (-1);
}
/* Set transparent pixel as the pixel at (0,0) */
if (sprite->format->palette) {
SDL_SetColorKey(sprite, SDL_SRCCOLORKEY, *(Uint8 *) sprite->pixels);
}
/* Convert sprite to video format */
converted = SDL_DisplayFormat(sprite);
SDL_FreeSurface(sprite);
if (converted == NULL) {
fprintf(stderr, "Couldn't convert background: %s\n", SDL_GetError());
return (-1);
}
sprite = converted;
/* Create the background */
backing = SDL_CreateRGBSurface(SDL_SWSURFACE, sprite->w, sprite->h, 8,
0, 0, 0, 0);
if (backing == NULL) {
fprintf(stderr, "Couldn't create background: %s\n", SDL_GetError());
SDL_FreeSurface(sprite);
return (-1);
}
/* Convert background to video format */
converted = SDL_DisplayFormat(backing);
SDL_FreeSurface(backing);
if (converted == NULL) {
fprintf(stderr, "Couldn't convert background: %s\n", SDL_GetError());
SDL_FreeSurface(sprite);
return (-1);
}
backing = converted;
/* Set the initial position of the sprite */
position.x = (screen->w - sprite->w) / 2;
position.y = (screen->h - sprite->h) / 2;
position.w = sprite->w;
position.h = sprite->h;
x_vel = 0;
y_vel = 0;
alpha_vel = 1;
/* We're ready to roll. :) */
return (0);
}
void
AttractSprite(Uint16 x, Uint16 y)
{
x_vel = ((int) x - position.x) / 10;
y_vel = ((int) y - position.y) / 10;
}
void
MoveSprite(SDL_Surface * screen, SDL_Surface * light)
{
SDL_Rect updates[2];
Uint8 alpha;
/* Erase the sprite if it was visible */
if (sprite_visible) {
updates[0] = position;
SDL_BlitSurface(backing, NULL, screen, &updates[0]);
} else {
updates[0].x = 0;
updates[0].y = 0;
updates[0].w = 0;
updates[0].h = 0;
sprite_visible = 1;
}
/* Since the sprite is off the screen, we can do other drawing
without being overwritten by the saved area behind the sprite.
*/
if (light != NULL) {
int x, y;
SDL_GetMouseState(&x, &y);
FlashLight(screen, light, x, y);
}
/* Move the sprite, bounce at the wall */
position.x += x_vel;
if ((position.x < 0) || (position.x >= screen->w)) {
x_vel = -x_vel;
position.x += x_vel;
}
position.y += y_vel;
if ((position.y < 0) || (position.y >= screen->h)) {
y_vel = -y_vel;
position.y += y_vel;
}
/* Update transparency (fade in and out) */
SDL_GetSurfaceAlphaMod(sprite, &alpha);
if (((int) alpha + alpha_vel) < 0) {
alpha_vel = -alpha_vel;
} else if (((int) alpha + alpha_vel) > 255) {
alpha_vel = -alpha_vel;
}
SDL_SetAlpha(sprite, SDL_SRCALPHA, (Uint8) (alpha + alpha_vel));
/* Save the area behind the sprite */
updates[1] = position;
SDL_BlitSurface(screen, &updates[1], backing, NULL);
/* Blit the sprite onto the screen */
updates[1] = position;
SDL_BlitSurface(sprite, NULL, screen, &updates[1]);
/* Make it so! */
SDL_UpdateRects(screen, 2, updates);
}
int
main(int argc, char *argv[])
{
const SDL_VideoInfo *info;
SDL_Surface *screen;
int w, h;
Uint8 video_bpp;
Uint32 videoflags;
int i, done;
SDL_Event event;
SDL_Surface *light;
int mouse_pressed;
Uint32 ticks, lastticks;
/* Initialize SDL */
if (SDL_Init(SDL_INIT_VIDEO) < 0) {
fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());
return (1);
}
/* Alpha blending doesn't work well at 8-bit color */
#ifdef _WIN32_WCE
/* Pocket PC */
w = 240;
h = 320;
#else
w = 640;
h = 480;
#endif
info = SDL_GetVideoInfo();
if (info->vfmt->BitsPerPixel > 8) {
video_bpp = info->vfmt->BitsPerPixel;
} else {
video_bpp = 16;
fprintf(stderr, "forced 16 bpp mode\n");
}
videoflags = SDL_SWSURFACE;
for (i = 1; argv[i]; ++i) {
if (strcmp(argv[i], "-bpp") == 0) {
video_bpp = atoi(argv[++i]);
if (video_bpp <= 8) {
video_bpp = 16;
fprintf(stderr, "forced 16 bpp mode\n");
}
} else if (strcmp(argv[i], "-hw") == 0) {
videoflags |= SDL_HWSURFACE;
} else if (strcmp(argv[i], "-warp") == 0) {
videoflags |= SDL_HWPALETTE;
} else if (strcmp(argv[i], "-width") == 0 && argv[i + 1]) {
w = atoi(argv[++i]);
} else if (strcmp(argv[i], "-height") == 0 && argv[i + 1]) {
h = atoi(argv[++i]);
} else if (strcmp(argv[i], "-resize") == 0) {
videoflags |= SDL_RESIZABLE;
} else if (strcmp(argv[i], "-noframe") == 0) {
videoflags |= SDL_NOFRAME;
} else if (strcmp(argv[i], "-fullscreen") == 0) {
videoflags |= SDL_FULLSCREEN;
} else {
fprintf(stderr,
"Usage: %s [-width N] [-height N] [-bpp N] [-warp] [-hw] [-fullscreen]\n",
argv[0]);
quit(1);
}
}
/* Set video mode */
if ((screen = SDL_SetVideoMode(w, h, video_bpp, videoflags)) == NULL) {
fprintf(stderr, "Couldn't set %dx%dx%d video mode: %s\n",
w, h, video_bpp, SDL_GetError());
quit(2);
}
FillBackground(screen);
/* Create the light */
light = CreateLight(82);
if (light == NULL) {
quit(1);
}
/* Load the sprite */
if (LoadSprite(screen, "icon.bmp") < 0) {
SDL_FreeSurface(light);
quit(1);
}
/* Print out information about our surfaces */
printf("Screen is at %d bits per pixel\n", screen->format->BitsPerPixel);
if ((screen->flags & SDL_HWSURFACE) == SDL_HWSURFACE) {
printf("Screen is in video memory\n");
} else {
printf("Screen is in system memory\n");
}
if ((screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF) {
printf("Screen has double-buffering enabled\n");
}
if ((sprite->flags & SDL_HWSURFACE) == SDL_HWSURFACE) {
printf("Sprite is in video memory\n");
} else {
printf("Sprite is in system memory\n");
}
/* Run a sample blit to trigger blit acceleration */
MoveSprite(screen, NULL);
if ((sprite->flags & SDL_HWACCEL) == SDL_HWACCEL) {
printf("Sprite blit uses hardware alpha acceleration\n");
} else {
printf("Sprite blit dosn't uses hardware alpha acceleration\n");
}
/* Set a clipping rectangle to clip the outside edge of the screen */
{
SDL_Rect clip;
clip.x = 32;
clip.y = 32;
clip.w = screen->w - (2 * 32);
clip.h = screen->h - (2 * 32);
SDL_SetClipRect(screen, &clip);
}
/* Wait for a keystroke */
lastticks = SDL_GetTicks();
done = 0;
mouse_pressed = 0;
while (!done) {
/* Update the frame -- move the sprite */
if (mouse_pressed) {
MoveSprite(screen, light);
mouse_pressed = 0;
} else {
MoveSprite(screen, NULL);
}
/* Slow down the loop to 30 frames/second */
ticks = SDL_GetTicks();
if ((ticks - lastticks) < FRAME_TICKS) {
#ifdef CHECK_SLEEP_GRANULARITY
fprintf(stderr, "Sleeping %d ticks\n",
FRAME_TICKS - (ticks - lastticks));
#endif
SDL_Delay(FRAME_TICKS - (ticks - lastticks));
#ifdef CHECK_SLEEP_GRANULARITY
fprintf(stderr, "Slept %d ticks\n", (SDL_GetTicks() - ticks));
#endif
}
lastticks = ticks;
/* Check for events */
while (SDL_PollEvent(&event)) {
switch (event.type) {
case SDL_VIDEORESIZE:
screen =
SDL_SetVideoMode(event.resize.w, event.resize.h,
video_bpp, videoflags);
if (screen) {
FillBackground(screen);
}
break;
/* Attract sprite while mouse is held down */
case SDL_MOUSEMOTION:
if (event.motion.state != 0) {
AttractSprite(event.motion.x, event.motion.y);
mouse_pressed = 1;
}
break;
case SDL_MOUSEBUTTONDOWN:
if (event.button.button == 1) {
AttractSprite(event.button.x, event.button.y);
mouse_pressed = 1;
} else {
SDL_Rect area;
area.x = event.button.x - 16;
area.y = event.button.y - 16;
area.w = 32;
area.h = 32;
SDL_FillRect(screen, &area,
SDL_MapRGB(screen->format, 0, 0, 0));
SDL_UpdateRects(screen, 1, &area);
}
break;
case SDL_KEYDOWN:
if (event.key.keysym.sym == SDLK_ESCAPE) {
done = 1;
}
if (event.key.keysym.sym == SDLK_RETURN) {
SDL_WM_ToggleFullScreen(screen);
}
break;
case SDL_QUIT:
done = 1;
break;
default:
break;
}
}
}
SDL_FreeSurface(light);
SDL_FreeSurface(sprite);
SDL_FreeSurface(backing);
/* Print out some timing information */
if (flashes > 0) {
printf("%d alpha blits, ~%4.4f ms per blit\n",
flashes, (float) flashtime / flashes);
}
SDL_Quit();
return (0);
}
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