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Category: "FM Tutorial"
Title: "Life"
Author: "Ilyich the Toad"

Dialog:color=lightgrey

ctl[0]:"Iterations",range=(0,500),val=5,pagesize=5,linesize=1, fontcolor=black
ctl[1]:"Threshold Position", range=(0,200),val=200,pagesize=5,linesize=1, fontcolor=black
ctl[2]:"Threshold Width", range=(0,128),val=100,pagesize=2,linesize=1, fontcolor=black
ctl[3]:CHECKBOX, "Animated Preview", val=1, pos=(200,100), size=(100,10), fontcolor=black
ctl[4]:"Radius",range=(1,scaleFactor*X/2),val=1,pagesize=3,linesize=1, fontcolor=black

Brief explanations for controls: both "Threshold" sliders control what total neighbours weight cause cell die and how close to that splitting threshold is. "Radius" control sets the size of the kernel at which the neighbours are counted.

ForEveryTile:
{

int iterations; int die; int grow;
int i;
int neigh;
int xstart; int ystart;
int xstop; int ystop;
int xrange=max((2*ctl(4)+scaleFactor)/(2*scaleFactor), 1);
int yrange=max((2*ctl(4)+scaleFactor)/(2*scaleFactor), 1);
int xlook; int ylook; int zlook;
int temp; int randx; int randy;
bool anim;
int kernelwidth=2*xrange+1; int kernelheight=2*yrange+1; int value;
int currentx; int currenty; int total;

setCtlRange(0,0,500); setCtlRange(1,0,255); setCtlRange(2,0,255);
iterations=ctl(0);

Variables definition and controls setting.

die = ctl(1)/3+ctl(2)/2; grow = ctl(1)/3-ctl(2)/2;

Threshold settings are converted to "die if neighbours >" and "split if neighbours >" parameters. Those might be set directly, simplyfying controls definition - but I find this way more logical; besides, it prevents user from setting cell die defore it can split and so on.

setCtlRange(4,1,5);

anim=ctl(3);

Finishing settings.

for (y=0; y for (x=0; x < X; x++) {
for (z= 0; z < Z; z++) {
tset(x,y,z,src(x,y,z));
t2set(x,y,z,src(x,y,z));
}
}
};

Copying source image into buffer.

for (i=0; i<iterations; i++) { if(updateProgress(i,iterations)) break;

Preparing outer loop. Image passes will be made inside this loop.

for (y=0; y < Y; y++) {
for (x=0; x < X; x++) {
xstart=x-xrange; xstop=x+xrange; ystart=y-yrange; ystop=y+yrange;
randx=rnd(-1,1); randy=rnd(-1,1);
for (z= 0; z < 3; z++) {
temp = tget(x,y,z);
if (temp>0) { //is there anybody in there?
neigh=0;
for (ylook=ystart; ylook < ystop; ylook++) {
for (xlook=xstart; xlook < xstop; xlook++) {
for (zlook=0; zlook < 3; zlook++) {
neigh+=tget(xlook,ylook,zlook); //sum a brightness
} //for zlook
} //for xlook
} //for ylook

neigh=neigh/((2*xrange+1)*(2*yrange+1));
neigh=neigh/3;

Calculating total neighbour pixel brightness (namely, sum of all three RGB channes). This way we make filter to work "hue-protected". Once the total brightness (weight) is calculated, we proceed to make a decision: should the cell die or split or continue living.

if (neigh>die) {
t2set(x,y,z,0);}

Die by too many neighbours.

else if (neigh>grow) {
t2set((x-randx+X)%X,(y-randy+Y)%Y,z,temp);
t2set((x+randx+X)%X,(y+randy+Y)%Y,z,temp);
t2set(x,y,z,0);}

Splitting a cell into two new, randomly placed nearby. Take notice, the filter wrap image edges!

else t2set(x,y,z,0) ;

Die of weakness...

} //if empty
} //for z
} //fox x
} //for y

for (y=0; y < Y; y++) {
for (x=0; x < X; x++) {
for (z= 0; z < Z; z++) {
tset(x,y,z,t2get(x,y,z));
}
}
};

During calculating new pixels generation, we had to place them into another array called "t2". Otherwise every new pixel placed below or right during cell splitting get overwritten while processing next pixels. After finishing calculating all the "t2" array is copied to "t" array.

if (doingProxy && anim > 0) {
for (y=0; y for (x=0; x for (z= 0; z pset(x,y,z,tget(x,y,z));
}
}
}
updatePreview(-99);
};


}//for i

If the preview was set by user to be updated as filter works (user-defined boolean variable "anim" set to "true") and filter is applied to preview image, not to final image (doingProxy=true), the "t" array is copied back to source image and preview updated. Then we close the outer loop.

if (doingProxy * anim == 0) {

for (y=0; y < Y; y++) {
for (x=0; x < X; x++) {
for (z= 0; z < Z; z++) {
pset(x,y,z,tget(x,y,z));
}
}
}
}

updateProgress(0, 100);
true;
}

Finished processing, just copy the "t" array back to the image, reset progress indicator and finish the filter.