Initial revision
--HG-- extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%401
This commit is contained in:
Sam Lantinga
commit
2f110628a7
892 changed files with 170313 additions and 0 deletions
440
test/testalpha.c
Normal file
440
test/testalpha.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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/* Create a "light" -- a yellowish surface with variable alpha */
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SDL_Surface *CreateLight(SDL_Surface *screen, 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, 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, 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 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 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,
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*(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",
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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",
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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",
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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; 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 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 MoveSprite(SDL_Surface *screen, SDL_Surface *light)
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{
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SDL_Rect updates[2];
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int 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; updates[0].y = 0;
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updates[0].w = 0; 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(&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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alpha = sprite->format->alpha;
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if ( (alpha+alpha_vel) < 0 ) {
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alpha_vel = -alpha_vel;
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} else
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if ( (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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void WarpSprite(SDL_Surface *screen, int x, int y)
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{
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SDL_Rect updates[2];
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/* Erase, move, Draw, update */
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updates[0] = position;
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SDL_BlitSurface(backing, NULL, screen, &updates[0]);
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position.x = x-sprite->w/2; /* Center about X */
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position.y = y-sprite->h/2; /* Center about Y */
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updates[1] = position;
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SDL_BlitSurface(screen, &updates[1], backing, NULL);
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updates[1] = position;
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SDL_BlitSurface(sprite, NULL, screen, &updates[1]);
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SDL_UpdateRects(screen, 2, updates);
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}
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int 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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Uint8 video_bpp;
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Uint32 videoflags;
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Uint8 *buffer;
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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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exit(1);
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}
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atexit(SDL_Quit);
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/* Alpha blending doesn't work well at 8-bit color */
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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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}
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videoflags = SDL_SWSURFACE;
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while ( argc > 1 ) {
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--argc;
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if ( strcmp(argv[argc-1], "-bpp") == 0 ) {
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video_bpp = atoi(argv[argc]);
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--argc;
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} else
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if ( strcmp(argv[argc], "-hw") == 0 ) {
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videoflags |= SDL_HWSURFACE;
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} else
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if ( strcmp(argv[argc], "-warp") == 0 ) {
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videoflags |= SDL_HWPALETTE;
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} else
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if ( strcmp(argv[argc], "-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 [-bpp N] [-warp] [-hw] [-fullscreen]\n",
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argv[0]);
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exit(1);
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}
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}
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/* Set 640x480 video mode */
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if ( (screen=SDL_SetVideoMode(640,480,video_bpp,videoflags)) == NULL ) {
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fprintf(stderr, "Couldn't set 640x480x%d video mode: %s\n",
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video_bpp, SDL_GetError());
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exit(2);
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}
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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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exit(2);
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}
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buffer=(Uint8 *)screen->pixels;
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for ( i=0; i<screen->h; ++i ) {
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memset(buffer,(i*255)/screen->h, screen->pitch);
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buffer += screen->pitch;
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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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/* Create the light */
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light = CreateLight(screen, 82);
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if ( light == NULL ) {
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exit(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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exit(1);
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}
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/* Set a clipping rectangle to clip the outside edge of the screen */
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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", 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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/* 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,
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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,
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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, 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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/* Any keypress quits the app... */
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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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}
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}
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}
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SDL_FreeSurface(light);
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SDL_FreeSurface(sprite);
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SDL_FreeSurface(backing);
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/* Print out some timing information */
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if ( flashes > 0 ) {
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printf("%d alpha blits, ~%4.4f ms per blit\n",
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flashes, (float)flashtime/flashes);
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}
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return(0);
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}
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