80 lines
2.0 KiB
C
80 lines
2.0 KiB
C
#include <stdlib.h>
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#include <time.h>
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#include <math.h>
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#include "gimpressionist.h"
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#include "ppmtool.h"
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int pfix(int n)
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{
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if(n<1) return 1;
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if(n>255) return 255;
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return n;
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}
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#define PIXEL(y,x,z) p->col[(y)*rowstride+(x)*3+z]
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void mkplasma_sub(struct ppm *p, int x1, int x2, int y1, int y2, float turb)
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{
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int rowstride = p->width * 3;
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int r=0;
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int xr, yr, nx, ny;
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xr = abs(x1-x2);
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yr = abs(y1-y2);
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if((xr==0) && (yr==0)) return;
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nx = (x1+x2)/2;
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ny = (y1+y2)/2;
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if(!PIXEL(y1,nx,r))
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PIXEL(y1,nx,r) = pfix((PIXEL(y1,x1,r)+PIXEL(y1,x2,r))/2.0+
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turb*(RAND_FUNC()%xr-xr/2.0));
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if(!PIXEL(y2,nx,r))
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PIXEL(y2,nx,r) = pfix((PIXEL(y2,x1,r)+PIXEL(y2,x2,r))/2.0+
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turb*(RAND_FUNC()%xr-xr/2.0));
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if(!PIXEL(ny,x1,r))
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PIXEL(ny,x1,r) = pfix((PIXEL(y1,x1,r)+PIXEL(y2,x1,r))/2.0+
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turb*(RAND_FUNC()%yr-yr/2.0));
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if(!PIXEL(ny,x2,r))
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PIXEL(ny,x2,r) = pfix((PIXEL(y1,x2,r)+PIXEL(y2,x2,r))/2.0+
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turb*(RAND_FUNC()%yr-yr/2.0));
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if(!PIXEL(ny,nx,r))
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PIXEL(ny,nx,r) =
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pfix((PIXEL(y1,x1,r)+PIXEL(y1,x2,r)+PIXEL(y2,x1,r)+
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PIXEL(y2,x2,r))/4.0+turb*(RAND_FUNC()%(xr+yr)/2.0-(xr+yr)/4.0));
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if(xr>1) {
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mkplasma_sub(p,x1,nx,y1,ny, turb);
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mkplasma_sub(p,nx,x2,y1,ny, turb);
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}
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if(yr>1) {
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mkplasma_sub(p,x1,nx,ny,y2, turb);
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mkplasma_sub(p,nx,x2,ny,y2, turb);
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}
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}
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void mkplasma_red(struct ppm *p, float turb)
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{
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int x=0, y=0;
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int rowstride = p->width * 3;
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for(x = 0; x < p->width; x++)
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for(y = 0; y < p->height; y++)
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PIXEL(y,x,0) = 0;
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x--; y--;
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PIXEL(0,0,0) = 1+RAND_FUNC()%255;
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PIXEL(y,0,0) = 1+RAND_FUNC()%255;
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PIXEL(0,x,0) = 1+RAND_FUNC()%255;
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PIXEL(y,x,0) = 1+RAND_FUNC()%255;
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mkplasma_sub(p, 0, x, 0, y, turb);
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}
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void mkgrayplasma(struct ppm *p, float turb)
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{
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int y,l;
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mkplasma_red(p, turb);
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l = p->width * 3 * p->height;
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for(y = 0; y < l; y += 3)
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p->col[y+1] = p->col[y+2] = p->col[y];
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}
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