test/testalpha.c
author Sam Lantinga <slouken@libsdl.org>
Thu, 06 May 2004 15:55:06 +0000
changeset 886 05c551e5bc64
parent 691 609543e2b3a1
child 1151 be9c9c8f6d53
permissions -rw-r--r--
Date: Sat, 24 Apr 2004 15:13:32 +0300 From: "Mike Gorchak" Subject: SDL updates for the QNX6 1. Updated the README.QNX 2. Updated libtool scripts, which are shipped with SDL for QNX6 support. 3. Added some code to support the new QNX 6.3.0, which is in beta now. 4. Added code to detect the hw features, which driver supports. 5. Added hw alpha blits code. 6. Fixed bug when application switches to fullscreen more the 2 times. (afte\ r that window becames always stay on top). 7. Updated a bit README for the tests. 8. Added information about acceleration show in the testalpha.c test. 9. Added small fixes to the testoverlay2.c test. 10. Added alpha and cc+alpha blits benchmarks to the testvidinfo.c test.


/* 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 */

/* Create a "light" -- a yellowish surface with variable alpha */
SDL_Surface *CreateLight(SDL_Surface *screen, 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];
	int 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) */
	alpha = sprite->format->alpha;
	if ( (alpha+alpha_vel) < 0 ) {
		alpha_vel = -alpha_vel;
	} else
	if ( (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);
}

void WarpSprite(SDL_Surface *screen, int x, int y)
{
	SDL_Rect updates[2];

	/* Erase, move, Draw, update */
	updates[0] = position;
	SDL_BlitSurface(backing, NULL, screen, &updates[0]);
	position.x = x-sprite->w/2;	/* Center about X */
	position.y = y-sprite->h/2;	/* Center about Y */
	updates[1] = position;
	SDL_BlitSurface(screen, &updates[1], backing, NULL);
	updates[1] = position;
	SDL_BlitSurface(sprite, NULL, screen, &updates[1]);
	SDL_UpdateRects(screen, 2, updates);
}

int main(int argc, char *argv[])
{
	const SDL_VideoInfo *info;
	SDL_Surface *screen;
	Uint8  video_bpp;
	Uint32 videoflags;
	Uint8 *buffer;
	int    i, k, done;
	SDL_Event event;
	SDL_Surface *light;
	int mouse_pressed;
	Uint32 ticks, lastticks;
	Uint16 *buffer16;
        Uint16 color;
        Uint8  gradient;


	/* Initialize SDL */
	if ( SDL_Init(SDL_INIT_VIDEO) < 0 ) {
		fprintf(stderr, "Couldn't initialize SDL: %s\n",SDL_GetError());
		exit(1);
	}
	atexit(SDL_Quit);

	/* Alpha blending doesn't work well at 8-bit color */
	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;
	while ( argc > 1 ) {
		--argc;
		if ( strcmp(argv[argc-1], "-bpp") == 0 ) {
			video_bpp = atoi(argv[argc]);
                        if (video_bpp<=8) {
                            video_bpp=16;
                            fprintf(stderr, "forced 16 bpp mode\n");
                        }
			--argc;
		} else
		if ( strcmp(argv[argc], "-hw") == 0 ) {
			videoflags |= SDL_HWSURFACE;
		} else
		if ( strcmp(argv[argc], "-warp") == 0 ) {
			videoflags |= SDL_HWPALETTE;
		} else
		if ( strcmp(argv[argc], "-fullscreen") == 0 ) {
			videoflags |= SDL_FULLSCREEN;
		} else {
			fprintf(stderr, 
			"Usage: %s [-bpp N] [-warp] [-hw] [-fullscreen]\n",
								argv[0]);
			exit(1);
		}
	}

	/* Set 640x480 video mode */
	if ( (screen=SDL_SetVideoMode(640,480,video_bpp,videoflags)) == NULL ) {
		fprintf(stderr, "Couldn't set 640x480x%d video mode: %s\n",
						video_bpp, SDL_GetError());
		exit(2);
	}

	/* Set the surface pixels and refresh! */
	if ( SDL_LockSurface(screen) < 0 ) {
		fprintf(stderr, "Couldn't lock the display surface: %s\n",
							SDL_GetError());
		exit(2);
	}
	buffer=(Uint8 *)screen->pixels;
	if (screen->format->BytesPerPixel!=2) {
		for ( i=0; i<screen->h; ++i ) {
			memset(buffer,(i*255)/screen->h, screen->pitch);
			buffer += screen->pitch;
		}
	}
        else
        {
		for ( i=0; i<screen->h; ++i ) {
			gradient=((i*255)/screen->h);
                        color = SDL_MapRGB(screen->format, gradient, gradient, gradient);
                        buffer16=(Uint16*)buffer;
                        for (k=0; k<screen->w; k++)
                        {
                            *(buffer16+k)=color;
                        }
			buffer += screen->pitch;
		}
        }

	SDL_UnlockSurface(screen);
	SDL_UpdateRect(screen, 0, 0, 0, 0);

	/* Create the light */
	light = CreateLight(screen, 82);
	if ( light == NULL ) {
		exit(1);
	}

	/* Load the sprite */
	if ( LoadSprite(screen, "icon.bmp") < 0 ) {
		SDL_FreeSurface(light);
		exit(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 */
	{ SDL_Rect dst;
		dst.x = 0;
		dst.y = 0;
		dst.w = sprite->w;
		dst.h = sprite->h;
		SDL_BlitSurface(sprite, NULL, screen, &dst);
		SDL_FillRect(screen, &dst, 0);
	}
	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) {
				/* 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, 0);
						SDL_UpdateRects(screen,1,&area);
					}
					break;
				case SDL_KEYDOWN:
					/* Any keypress quits the app... */
				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);
	}
	return(0);
}