mirror of
https://github.com/joel16/SDL2.git
synced 2024-12-15 15:29:46 +00:00
9648484187
--HG-- extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%403283
539 lines
15 KiB
C
539 lines
15 KiB
C
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/* Simple program: Fill a colormap with gray and stripe it down the screen,
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Then move an alpha valued sprite around the screen.
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include "SDL.h"
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#define FRAME_TICKS (1000/30) /* 30 frames/second */
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/* Call this instead of exit(), so we can clean up SDL: atexit() is evil. */
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static void
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quit(int rc)
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{
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SDL_Quit();
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exit(rc);
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}
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/* Fill the screen with a gradient */
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static void
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FillBackground(SDL_Surface * screen)
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{
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Uint8 *buffer;
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Uint8 gradient;
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int i, k;
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/* Set the surface pixels and refresh! */
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if (SDL_LockSurface(screen) < 0) {
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fprintf(stderr, "Couldn't lock the display surface: %s\n",
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SDL_GetError());
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quit(2);
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}
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buffer = (Uint8 *) screen->pixels;
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switch (screen->format->BytesPerPixel) {
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case 1:
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case 3:
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for (i = 0; i < screen->h; ++i) {
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memset(buffer, (i * 255) / screen->h,
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screen->w * screen->format->BytesPerPixel);
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buffer += screen->pitch;
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}
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break;
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case 2:
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for (i = 0; i < screen->h; ++i) {
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Uint16 *buffer16;
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Uint16 color;
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gradient = ((i * 255) / screen->h);
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color = (Uint16) SDL_MapRGB(screen->format,
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gradient, gradient, gradient);
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buffer16 = (Uint16 *) buffer;
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for (k = 0; k < screen->w; k++) {
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*buffer16++ = color;
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}
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buffer += screen->pitch;
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}
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break;
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case 4:
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for (i = 0; i < screen->h; ++i) {
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Uint32 *buffer32;
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Uint32 color;
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gradient = ((i * 255) / screen->h);
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color = SDL_MapRGB(screen->format, gradient, gradient, gradient);
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buffer32 = (Uint32 *) buffer;
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for (k = 0; k < screen->w; k++) {
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*buffer32++ = color;
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}
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buffer += screen->pitch;
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}
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break;
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}
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SDL_UnlockSurface(screen);
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SDL_UpdateRect(screen, 0, 0, 0, 0);
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}
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/* Create a "light" -- a yellowish surface with variable alpha */
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SDL_Surface *
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CreateLight(int radius)
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{
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Uint8 trans, alphamask;
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int range, addition;
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int xdist, ydist;
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Uint16 x, y;
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Uint16 skip;
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Uint32 pixel;
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SDL_Surface *light;
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#ifdef LIGHT_16BIT
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Uint16 *buf;
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/* Create a 16 (4/4/4/4) bpp square with a full 4-bit alpha channel */
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/* Note: this isn't any faster than a 32 bit alpha surface */
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alphamask = 0x0000000F;
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light = SDL_CreateRGBSurface(SDL_SWSURFACE, 2 * radius, 2 * radius, 16,
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0x0000F000, 0x00000F00, 0x000000F0,
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alphamask);
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#else
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Uint32 *buf;
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/* Create a 32 (8/8/8/8) bpp square with a full 8-bit alpha channel */
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alphamask = 0x000000FF;
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light = SDL_CreateRGBSurface(SDL_SWSURFACE, 2 * radius, 2 * radius, 32,
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0xFF000000, 0x00FF0000, 0x0000FF00,
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alphamask);
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if (light == NULL) {
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fprintf(stderr, "Couldn't create light: %s\n", SDL_GetError());
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return (NULL);
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}
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#endif
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/* Fill with a light yellow-orange color */
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skip = light->pitch - (light->w * light->format->BytesPerPixel);
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#ifdef LIGHT_16BIT
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buf = (Uint16 *) light->pixels;
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#else
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buf = (Uint32 *) light->pixels;
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#endif
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/* Get a tranparent pixel value - we'll add alpha later */
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pixel = SDL_MapRGBA(light->format, 0xFF, 0xDD, 0x88, 0);
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for (y = 0; y < light->h; ++y) {
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for (x = 0; x < light->w; ++x) {
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*buf++ = pixel;
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}
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buf += skip; /* Almost always 0, but just in case... */
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}
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/* Calculate alpha values for the surface. */
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#ifdef LIGHT_16BIT
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buf = (Uint16 *) light->pixels;
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#else
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buf = (Uint32 *) light->pixels;
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#endif
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for (y = 0; y < light->h; ++y) {
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for (x = 0; x < light->w; ++x) {
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/* Slow distance formula (from center of light) */
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xdist = x - (light->w / 2);
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ydist = y - (light->h / 2);
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range = (int) sqrt(xdist * xdist + ydist * ydist);
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/* Scale distance to range of transparency (0-255) */
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if (range > radius) {
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trans = alphamask;
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} else {
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/* Increasing transparency with distance */
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trans = (Uint8) ((range * alphamask) / radius);
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/* Lights are very transparent */
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addition = (alphamask + 1) / 8;
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if ((int) trans + addition > alphamask) {
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trans = alphamask;
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} else {
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trans += addition;
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}
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}
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/* We set the alpha component as the right N bits */
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*buf++ |= (255 - trans);
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}
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buf += skip; /* Almost always 0, but just in case... */
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}
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/* Enable RLE acceleration of this alpha surface */
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SDL_SetAlpha(light, SDL_SRCALPHA | SDL_RLEACCEL, 0);
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/* We're done! */
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return (light);
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}
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static Uint32 flashes = 0;
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static Uint32 flashtime = 0;
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void
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FlashLight(SDL_Surface * screen, SDL_Surface * light, int x, int y)
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{
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SDL_Rect position;
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Uint32 ticks1;
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Uint32 ticks2;
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/* Easy, center light */
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position.x = x - (light->w / 2);
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position.y = y - (light->h / 2);
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position.w = light->w;
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position.h = light->h;
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ticks1 = SDL_GetTicks();
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SDL_BlitSurface(light, NULL, screen, &position);
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ticks2 = SDL_GetTicks();
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SDL_UpdateRects(screen, 1, &position);
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++flashes;
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/* Update time spend doing alpha blitting */
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flashtime += (ticks2 - ticks1);
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}
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static int sprite_visible = 0;
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static SDL_Surface *sprite;
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static SDL_Surface *backing;
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static SDL_Rect position;
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static int x_vel, y_vel;
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static int alpha_vel;
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int
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LoadSprite(SDL_Surface * screen, char *file)
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{
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SDL_Surface *converted;
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/* Load the sprite image */
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sprite = SDL_LoadBMP(file);
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if (sprite == NULL) {
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fprintf(stderr, "Couldn't load %s: %s", file, SDL_GetError());
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return (-1);
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}
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/* Set transparent pixel as the pixel at (0,0) */
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if (sprite->format->palette) {
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SDL_SetColorKey(sprite, SDL_SRCCOLORKEY, *(Uint8 *) sprite->pixels);
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}
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/* Convert sprite to video format */
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converted = SDL_DisplayFormat(sprite);
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SDL_FreeSurface(sprite);
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if (converted == NULL) {
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fprintf(stderr, "Couldn't convert background: %s\n", SDL_GetError());
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return (-1);
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}
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sprite = converted;
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/* Create the background */
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backing = SDL_CreateRGBSurface(SDL_SWSURFACE, sprite->w, sprite->h, 8,
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0, 0, 0, 0);
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if (backing == NULL) {
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fprintf(stderr, "Couldn't create background: %s\n", SDL_GetError());
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SDL_FreeSurface(sprite);
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return (-1);
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}
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/* Convert background to video format */
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converted = SDL_DisplayFormat(backing);
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SDL_FreeSurface(backing);
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if (converted == NULL) {
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fprintf(stderr, "Couldn't convert background: %s\n", SDL_GetError());
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SDL_FreeSurface(sprite);
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return (-1);
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}
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backing = converted;
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/* Set the initial position of the sprite */
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position.x = (screen->w - sprite->w) / 2;
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position.y = (screen->h - sprite->h) / 2;
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position.w = sprite->w;
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position.h = sprite->h;
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x_vel = 0;
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y_vel = 0;
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alpha_vel = 1;
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/* We're ready to roll. :) */
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return (0);
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}
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void
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AttractSprite(Uint16 x, Uint16 y)
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{
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x_vel = ((int) x - position.x) / 10;
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y_vel = ((int) y - position.y) / 10;
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}
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void
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MoveSprite(SDL_Surface * screen, SDL_Surface * light)
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{
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SDL_Rect updates[2];
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Uint8 alpha;
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/* Erase the sprite if it was visible */
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if (sprite_visible) {
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updates[0] = position;
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SDL_BlitSurface(backing, NULL, screen, &updates[0]);
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} else {
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updates[0].x = 0;
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updates[0].y = 0;
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updates[0].w = 0;
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updates[0].h = 0;
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sprite_visible = 1;
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}
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/* Since the sprite is off the screen, we can do other drawing
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without being overwritten by the saved area behind the sprite.
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*/
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if (light != NULL) {
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int x, y;
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SDL_GetMouseState(0, &x, &y);
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FlashLight(screen, light, x, y);
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}
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/* Move the sprite, bounce at the wall */
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position.x += x_vel;
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if ((position.x < 0) || (position.x >= screen->w)) {
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x_vel = -x_vel;
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position.x += x_vel;
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}
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position.y += y_vel;
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if ((position.y < 0) || (position.y >= screen->h)) {
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y_vel = -y_vel;
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position.y += y_vel;
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}
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/* Update transparency (fade in and out) */
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SDL_GetSurfaceAlphaMod(sprite, &alpha);
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if (((int) alpha + alpha_vel) < 0) {
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alpha_vel = -alpha_vel;
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} else if (((int) alpha + alpha_vel) > 255) {
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alpha_vel = -alpha_vel;
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}
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SDL_SetAlpha(sprite, SDL_SRCALPHA, (Uint8) (alpha + alpha_vel));
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/* Save the area behind the sprite */
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updates[1] = position;
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SDL_BlitSurface(screen, &updates[1], backing, NULL);
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/* Blit the sprite onto the screen */
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updates[1] = position;
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SDL_BlitSurface(sprite, NULL, screen, &updates[1]);
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/* Make it so! */
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SDL_UpdateRects(screen, 2, updates);
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}
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int
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main(int argc, char *argv[])
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{
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const SDL_VideoInfo *info;
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SDL_Surface *screen;
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int w, h;
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Uint8 video_bpp;
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Uint32 videoflags;
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int i, done;
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SDL_Event event;
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SDL_Surface *light;
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int mouse_pressed;
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Uint32 ticks, lastticks;
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/* Initialize SDL */
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if (SDL_Init(SDL_INIT_VIDEO) < 0) {
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fprintf(stderr, "Couldn't initialize SDL: %s\n", SDL_GetError());
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return (1);
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}
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/* Alpha blending doesn't work well at 8-bit color */
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#ifdef _WIN32_WCE
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/* Pocket PC */
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w = 240;
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h = 320;
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#else
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w = 640;
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h = 480;
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#endif
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info = SDL_GetVideoInfo();
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if (info->vfmt->BitsPerPixel > 8) {
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video_bpp = info->vfmt->BitsPerPixel;
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} else {
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video_bpp = 16;
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fprintf(stderr, "forced 16 bpp mode\n");
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}
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videoflags = SDL_SWSURFACE;
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for (i = 1; argv[i]; ++i) {
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if (strcmp(argv[i], "-bpp") == 0) {
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video_bpp = atoi(argv[++i]);
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if (video_bpp <= 8) {
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video_bpp = 16;
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fprintf(stderr, "forced 16 bpp mode\n");
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}
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} else if (strcmp(argv[i], "-hw") == 0) {
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videoflags |= SDL_HWSURFACE;
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} else if (strcmp(argv[i], "-warp") == 0) {
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videoflags |= SDL_HWPALETTE;
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} else if (strcmp(argv[i], "-width") == 0 && argv[i + 1]) {
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w = atoi(argv[++i]);
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} else if (strcmp(argv[i], "-height") == 0 && argv[i + 1]) {
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h = atoi(argv[++i]);
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} else if (strcmp(argv[i], "-resize") == 0) {
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videoflags |= SDL_RESIZABLE;
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} else if (strcmp(argv[i], "-noframe") == 0) {
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videoflags |= SDL_NOFRAME;
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} else if (strcmp(argv[i], "-fullscreen") == 0) {
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videoflags |= SDL_FULLSCREEN;
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} else {
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fprintf(stderr,
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"Usage: %s [-width N] [-height N] [-bpp N] [-warp] [-hw] [-fullscreen]\n",
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argv[0]);
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quit(1);
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}
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}
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/* Set video mode */
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if ((screen = SDL_SetVideoMode(w, h, video_bpp, videoflags)) == NULL) {
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fprintf(stderr, "Couldn't set %dx%dx%d video mode: %s\n",
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w, h, video_bpp, SDL_GetError());
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quit(2);
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}
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FillBackground(screen);
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/* Create the light */
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light = CreateLight(82);
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if (light == NULL) {
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quit(1);
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}
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/* Load the sprite */
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if (LoadSprite(screen, "icon.bmp") < 0) {
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SDL_FreeSurface(light);
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quit(1);
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}
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/* Print out information about our surfaces */
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printf("Screen is at %d bits per pixel\n", screen->format->BitsPerPixel);
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if ((screen->flags & SDL_HWSURFACE) == SDL_HWSURFACE) {
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printf("Screen is in video memory\n");
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} else {
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printf("Screen is in system memory\n");
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}
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if ((screen->flags & SDL_DOUBLEBUF) == SDL_DOUBLEBUF) {
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printf("Screen has double-buffering enabled\n");
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}
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if ((sprite->flags & SDL_HWSURFACE) == SDL_HWSURFACE) {
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printf("Sprite is in video memory\n");
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} else {
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printf("Sprite is in system memory\n");
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}
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/* Run a sample blit to trigger blit acceleration */
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MoveSprite(screen, NULL);
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if ((sprite->flags & SDL_HWACCEL) == SDL_HWACCEL) {
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printf("Sprite blit uses hardware alpha acceleration\n");
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} else {
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printf("Sprite blit dosn't uses hardware alpha acceleration\n");
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}
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/* Set a clipping rectangle to clip the outside edge of the screen */
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{
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SDL_Rect clip;
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clip.x = 32;
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clip.y = 32;
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clip.w = screen->w - (2 * 32);
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clip.h = screen->h - (2 * 32);
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SDL_SetClipRect(screen, &clip);
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}
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/* Wait for a keystroke */
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lastticks = SDL_GetTicks();
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done = 0;
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mouse_pressed = 0;
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while (!done) {
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/* Update the frame -- move the sprite */
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if (mouse_pressed) {
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MoveSprite(screen, light);
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mouse_pressed = 0;
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} else {
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MoveSprite(screen, NULL);
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}
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/* Slow down the loop to 30 frames/second */
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ticks = SDL_GetTicks();
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if ((ticks - lastticks) < FRAME_TICKS) {
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#ifdef CHECK_SLEEP_GRANULARITY
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fprintf(stderr, "Sleeping %d ticks\n",
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FRAME_TICKS - (ticks - lastticks));
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#endif
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SDL_Delay(FRAME_TICKS - (ticks - lastticks));
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#ifdef CHECK_SLEEP_GRANULARITY
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fprintf(stderr, "Slept %d ticks\n", (SDL_GetTicks() - ticks));
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#endif
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}
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lastticks = ticks;
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/* Check for events */
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while (SDL_PollEvent(&event)) {
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switch (event.type) {
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case SDL_VIDEORESIZE:
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screen =
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SDL_SetVideoMode(event.resize.w, event.resize.h,
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video_bpp, videoflags);
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if (screen) {
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FillBackground(screen);
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}
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break;
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/* Attract sprite while mouse is held down */
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case SDL_MOUSEMOTION:
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if (event.motion.state != 0) {
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AttractSprite(event.motion.x, event.motion.y);
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mouse_pressed = 1;
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}
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break;
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case SDL_MOUSEBUTTONDOWN:
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if (event.button.button == 1) {
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AttractSprite(event.button.x, event.button.y);
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mouse_pressed = 1;
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} else {
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SDL_Rect area;
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area.x = event.button.x - 16;
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area.y = event.button.y - 16;
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area.w = 32;
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area.h = 32;
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SDL_FillRect(screen, &area,
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SDL_MapRGB(screen->format, 0, 0, 0));
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SDL_UpdateRects(screen, 1, &area);
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}
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break;
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case SDL_KEYDOWN:
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if (event.key.keysym.sym == SDLK_ESCAPE) {
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done = 1;
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}
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break;
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case SDL_QUIT:
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done = 1;
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break;
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default:
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break;
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|
}
|
|
}
|
|
}
|
|
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);
|
|
}
|