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helpers.js
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helpers.js
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defaultControls = [
{label: 'Inverted', type:'checkbox'},
{label: 'Brightness', value: 0, min: -100, max: 100},
{label: 'Contrast', value: 0, min: -100, max: 100},
{label: 'Min brightness', value: 0, min: 0, max: 255},
{label: 'Max brightness', value: 255, min: 0, max: 255},
]
// Apply brightness / contrast and flatten to monochrome
// taken from squigglecam
function pixelProcessor(config, imagePixels){
const width = parseInt(config.width);
const contrast = parseInt(config.Contrast);
const brightness = parseInt(config.Brightness);
const minBrightness = parseInt(config['Min brightness']);
const maxBrightness = parseInt(config['Max brightness']);
const black = config.Inverted;
let contrastFactor = (259 * (contrast + 255)) / (255 * (259 - contrast));
return function(x, y) {
let b;
let pixIndex = Math.floor(x) + Math.floor(y) * width;
let a = imagePixels.data[4 * (pixIndex + 2)];
if (contrast !== 0) {
b = (0.2125 * ((contrastFactor * (imagePixels.data[4 * pixIndex] - 128) + 128) + brightness))
+ (0.7154 * ((contrastFactor * (imagePixels.data[4 * (pixIndex + 1)] - 128) + 128) + brightness))
+ (0.0721 * ((contrastFactor * (imagePixels.data[4 * (pixIndex + 2)] - 128) + 128) + brightness));
} else {
b = (0.2125 * (imagePixels.data[4*pixIndex] + brightness))
+ (0.7154 * (imagePixels.data[4*(pixIndex + 1)] + brightness))
+ (0.0721 * (imagePixels.data[4*(pixIndex + 2)] + brightness));
}
if (a < 128)
b=0;
if (black) {
b = Math.min(255-minBrightness,255-b);
} else {
b = Math.max(minBrightness,b);
}
return Math.max(maxBrightness-b,0);
}
}
// autocontrast, my implementation
function autocontrast(pixData, cutoff){
function luma(x,y) {
let i = 4*(x+width*y)
return pixData.data[i]*0.299 + pixData.data[i+1]*0.587 + pixData.data[i]*0.114 // ITU-R 601-2
// return pixData.data[i]*0.2125 + pixData.data[i+1]*0.7154 + pixData.data[i]*0.0721 // ITU-R 709
}
let hist = []
for (let i=0;i<256;i++) hist[i]=0;
for (let x=0;x<width;x++) {
for (let y=0;y<height;y++) {
let b = Math.round(luma(x,y))
hist[b]++
}
}
let total=0, low=0, high=255
for (let i=0;i<256;i++){
total += hist[i];
}
cutoff*=total;
for (let i=0;i<255;i++) {
low+=hist[i]
if (low>cutoff) {low=i; break}
}
for (let i=255;i>1;i--) {
high+=hist[i]
if (high>=cutoff) {high=i; break}
}
let scale = (255/(high-low)) || 1
const pixelCache=[]
for (let x=0;x<width;x++) {
pixelCache[x]=[]
for (let y=0;y<height;y++) {
pixelCache[x][y] = Math.min(255,Math.max(0,(luma(x,y)-low)*scale ))
}
}
return (x,y)=>{
return (x>=0 && y>=0 && x<width &&y<height)
? pixelCache[x][y]
: 0
}
}
// perlin noise
// ported from lingdong's linedraw.py
(function(){
var PERLIN_YWRAPB = 4
var PERLIN_YWRAP = 1<<PERLIN_YWRAPB
var PERLIN_ZWRAPB = 8
var PERLIN_ZWRAP = 1<<PERLIN_ZWRAPB
var PERLIN_SIZE = 4095
var perlin_octaves = 4
var perlin_amp_falloff = 0.5
function scaled_cosine(i) {
return 0.5*(1.0-Math.cos(i*Math.PI))
}
var perlin = null
perlinNoise = function(x,y=0,z=0) {
if (perlin == null) {
perlin = []
for (let i =0;i<PERLIN_SIZE+1;i++) {
perlin.push(Math.random())
}
}
if (x<0) x=-x
if (y<0) y=-y
if (z<0) z=-z
let [ xi,yi,zi ] = [ ~~x, ~~y, ~~z ]
let xf = x-xi
let yf = y-yi
let zf = z-zi
let rxf, ryf
let r = 0
let ampl = 0.5
let n1, n2, n3
for (let o=0; o<perlin_octaves; o++) {
let of=xi+(yi<<PERLIN_YWRAPB)+(zi<<PERLIN_ZWRAPB)
rxf = scaled_cosine(xf)
ryf = scaled_cosine(yf)
n1 = perlin[of&PERLIN_SIZE]
n1 += rxf*(perlin[(of+1)&PERLIN_SIZE]-n1)
n2 = perlin[(of+PERLIN_YWRAP)&PERLIN_SIZE]
n2 += rxf*(perlin[(of+PERLIN_YWRAP+1)&PERLIN_SIZE]-n2)
n1 += ryf*(n2-n1)
of += PERLIN_ZWRAP
n2 = perlin[of&PERLIN_SIZE]
n2 += rxf*(perlin[(of+1)&PERLIN_SIZE]-n2)
n3 = perlin[(of+PERLIN_YWRAP)&PERLIN_SIZE]
n3 += rxf*(perlin[(of+PERLIN_YWRAP+1)&PERLIN_SIZE]-n3)
n2 += ryf*(n3-n2)
n1 += scaled_cosine(zf)*(n2-n1)
r += n1*ampl
ampl *= perlin_amp_falloff
xi<<=1
xf*=2
yi<<=1
yf*=2
zi<<=1
zf*=2
if (xf>=1.0) xi+=1, xf-=1
if (yf>=1.0) yi+=1, yf-=1
if (zf>=1.0) zi+=1, zf-=1
}
return r
}
})();
// Nearest-neighbour TSP solution, good enough for simple plotting
function sortlines(clines){
let slines = [clines.pop()]
let last = slines[0][slines[0].length-1]
function distance(a,b) {
return (a[0]-b[0])*(a[0]-b[0])+(a[1]-b[1])*(a[1]-b[1])
}
while (clines.length) {
let closest, min = 1e9, backwards=false
for (let j in clines) {
let d1 = distance( clines[j][0], last )
let d2 = distance( clines[j][ clines[j].length-1 ], last )
if (d1<min) {
min=d1, closest=j, backwards=false
}
if (d2<min) {
min=d2, closest=j, backwards=true
}
}
let l = clines.splice(closest,1)[0]
if (backwards) {
l.reverse()
}
slines=slines.concat([l])
last = l[l.length-1]
}
return slines
}
// slowly draw the points list - useful for debugging
function animatePointList(output, speed){
let out=[],i=0,j=0;
speed = speed || 1;
(function f(){
for (let q=0;q<speed;q++) {
if (!out[i]) out[i]=[]
out[i][j] = output[i][j]
if (++j>=output[i].length) j=0,i++
}
postLines(out)
if (i<output.length) setTimeout(f,20)
})();
}
function postLines(data){
let pathstring="";
// either a list of points, or a list of lists of points
if (typeof data[0][0] !== "object") data = [data]
if (data[0][0].x) {
for (let p in data) {
for (let i=1;i<data[p].length;i++)
pathstring+=data[p][i-1].x.toFixed(2)+";"+data[p][i-1].y.toFixed(2)+";"+data[p][i].x.toFixed(2)+";"+data[p][i].y.toFixed(2)+";"+data[p][i].z.toFixed(2);
postMessage(['svg-line',pathstring])
}
} else {
for (let p in data) {
for (let i=1;i<data[p].length;i++)
{ pathstring = data[p][i-1][0].toFixed(2)+";"+data[p][i-1][1].toFixed(2)+";"+data[p][i][0].toFixed(2)+";"+data[p][i][1].toFixed(2)+";"+data[p][i][2].toFixed(2);
postMessage(['svg-line',pathstring])
}
}
}
//postMessage(['svg-line',pathstring])
}
function postCircles(data){
let pathstring = ""
if (data[0].x) {
for (let p in data) {
let {x,y,r}=data[p];
pathstring += 'M'+x.toFixed(2)+','+(y-r).toFixed(2) +' a '+r.toFixed(3)+' '+r.toFixed(3)+' 0 1 0 0.001 0Z ';
}
} else {
for (let p in data) {
let [x,y,r]=data[p];
pathstring += 'M'+x.toFixed(2)+','+(y-r).toFixed(2) +' a '+r.toFixed(3)+' '+r.toFixed(3)+' 0 1 0 0.001 0Z ';
}
}
postMessage(['svg-path',pathstring])
}