ripple.c

在linux framebuffer上显示模拟的动态水波效果

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <math.h>

#include "fb.h"
#include "bmp.h"

#define SCREEN_WIDTH 320
#define SCREEN_HEIGHT 240
#define COLORBPP  16

#define DXPI  3.14159L
#define WAVE_LENGTH  64
#define PRECISION 1000

int disp_index; //wave center displacement index;
int disp[64];   //pixel displacement
int dist[240][320]; //distance to center

void Create_Ripple(int center_x, int center_y, int force, 
									int damp, int wave_length);
void Render_Ripple(FRAMEBUFFER *fb);

//ripple function
inline void Build_Disp_Matrix()
{
	int i;
    for(i = 0; i < 64; ++i)
        disp[i] = sin(i*30*DXPI/360.0) * PRECISION;
}

void Create_Ripple(int center_x, int center_y, int force, int damp, int wave_length)
{
	int i, j;
    int dist_x, dist_y;

    for(i = 0 ; i < wave_length; ++i)
    {
        disp[i] = force * disp[i] / PRECISION;
    }

    for(i = 0; i < SCREEN_HEIGHT; ++i)
    {
        for(j = 0; j< SCREEN_WIDTH; ++j)
        {
            dist_y = i - center_y;
            dist_x = j - center_x;
            dist[i][j] = (int)(sqrt(dist_x*dist_x +
                dist_y*dist_y) + 0.5) % wave_length;
        }
    }

}

void Render_Ripple(FRAMEBUFFER *fb)
{

	int left,right,bottom,top;
	int index_x,index_y;
	int x_off,y_off;
	int pos1,pos2;
	int i,j;

	if(disp_index < 0)
	{
    	Create_Ripple(rand()%320, rand()%240, rand()%15, 0, rand()%10);
		disp_index = 64;
	}

	--disp_index;
	fb->snap();
	for(i = 1; i < SCREEN_HEIGHT - 2; ++i) {
		for( j = 1; j < SCREEN_WIDTH - 2; ++j)
		{
			left = right = bottom = top = disp_index;

			left += dist[i][j -1];
			if(left > 12) left -= 12;
			right += dist[i][j+1];
			if(right >12) right -= 12;
			bottom+=dist[i+1][j];
			if(bottom > 12) bottom -= 12;
			top += dist[i-1][j];
			if(top >12 ) top -= 12;

			x_off = disp[left] - disp[right];
			y_off = disp[top] - disp[bottom];

			index_x = j + x_off;
			index_y = i + y_off;

			pos1 = i*320 +j;
			pos2 = index_y * SCREEN_WIDTH + index_x;
			if(pos2 < 0 || pos2 > SCREEN_WIDTH*SCREEN_HEIGHT) break;

			fb->fbclone[pos1*2] = fb->fbmem[pos2*2];
			fb->fbclone[pos1*2+1] = fb->fbmem[pos2*2+1];
		}
	}
	fb->refresh();	
	usleep(8000);
}

void simulate()
{
	while(1){
	 Render_Ripple(fb);
	}
}

int drawbmp(int x, int y, char *name)
{
    int sx, sy;
    unsigned char *buf, *buf2;

    if (0 == fh_bmp_id(name)) {
        fprintf(stderr, "file is not a BMP.\n");
        return -1;
    }
    if (fh_bmp_getsize(name, &sx, &sy) < 0)
        return -1;
    if (!(buf = (unsigned char *) malloc(sx * sy * 3)))
        return -1;
    if (fh_bmp_load(name, buf, sx, sy) < 0)
        return -1;
    if (!(buf2 = (unsigned char *) malloc(sx * sy * 2)))
        return -1;
    buf2 = fb->convert(buf, sx * sy, fb->fbinfo.bits_per_pixel);
	fb->blit(buf2, 0, 0, sx, sy);
    free(buf);
    free(buf2);
    return 0;
}

int main(int argc, char **argv)
{
	fb_init();
	disp_index = 64;
	drawbmp(0,0, argv[1]);
	printf("background loaded\n");
    Build_Disp_Matrix();
    Create_Ripple( 60, 120, 15, 0, 20);
	printf("start simulation\n\n");
	simulate();
	fb->release();
	return 0;	
}