Develop Reference

Extrude 2D Colored Image in Three.js

I've looked for resources online, but I have not seen a way to extrude a colored image in Three.js. I'm trying to create something like a Minecraft item where the image is used to then create an extruded geometry. An example would be: https://minecraft.gamepedia.com/File:BowSpinning3.gif
I've tried looking at this resource: https://muffinman.io/three-js-extrude-svg-path/ but this only extrudes uncolored SVGs.
loader.load('./textures/diamondbleu.svg', function (data) {
// Group we'll use for all SVG paths
const svgGroup = new THREE.Group();
// When importing SVGs paths are inverted on Y axis
// it happens in the process of mapping from 2d to 3d coordinate system
svgGroup.scale.y *= -1;
const material = new THREE.MeshLambertMaterial();
// Loop through all of the parsed paths
data.paths.forEach((path, i) => {
const shapes = path.toShapes(true);
// Each path has array of shapes
shapes.forEach((shape, j) => {
// Finally we can take each shape and extrude it
const geometry = new THREE.ExtrudeGeometry(shape, {
depth: 20,
bevelEnabled: false
});
// Create a mesh and add it to the group
const mesh = new THREE.Mesh(geometry, material);
svgGroup.add(mesh);
});
});
// Get group's size
const box = new THREE.Box3().setFromObject(svgGroup);
const size = new THREE.Vector3();
box.getSize(size);
const yOffset = size.y / -2;
const xOffset = size.x / -2;
// Offset all of group's elements, to center them
svgGroup.children.forEach(item => {
item.position.x = xOffset;
item.position.y = yOffset;
});
svgGroup.position.set(0, blockSize*75, 0);
// Finally we add svg group to the scene
scene.add(svgGroup);
})
Is there a way to modify the code to allow for colored SVGs? Thanks!

You can use the SVGLoader that's available in the "examples/jsm/loaders/" folder.
The docs have outlined how to generate SVGs in 3D space, it looks like your code sample is missing the part where the paths loop makes a new material and assigns a color for each path:
var material = new THREE.MeshBasicMaterial( {
color: path.color,
side: THREE.DoubleSide,
depthWrite: false
} );
Your code seems to create a single LambertMaterial with no colors assigned, and no lights. Lambert materials need lights to be illuminated, whereas BasicMaterial just shows the color without need of lights.
Look at the code in this demo for another example. Instead of using path.color, this demo finds the color by accessing path.userData.style.fill. I think you'll want the latter approach, depending on your SVG file.

Fading trailing stroke in p5.js

How to effectively create curveVertex with an array of p5.Vector points which fades (decreases opacity) the trail after the mouse position?
So far the following code removes the trailing points after a certain amount of time, creating the effect of trailing after the mouse, but it does not create a translucent trail. The trailing stroke just goes away.
const trail = sk => {
let points = [];
let fadeTime = 1000;
sk.setup = () => {
sk.createCanvas(300, 600);
sk.noFill();
};
sk.draw = () => {
sk.clear();
sk.beginShape();
for (let i = points.length - 1; i >= 0; i--) {
let p = points[i];
let timeAlive = sk.millis() - p.z;
if (timeAlive > fadeTime) {
// start removing last point
points.shift();
} else {
sk.strokeWeight(10);
sk.strokeJoin(sk.ROUND);
sk.strokeCap(sk.ROUND);
sk.stroke(255, 255, 255);
sk.curveVertex(p.x, p.y);
}
}
sk.endShape();
}
// Add more points forward when dragging mouse
sk.touchMoved = () => {
points.push(sk.createVector(sk.mouseX, sk.mouseY, sk.millis()));
return false;
}
};
let mySketch = new p5(trail, elementId);

The problem is that shapes created using the beginShape() and vertex functions (including curveVertex()) can only have a single stroke and fill color. So you can't color parts of the shape differently from the rest of the shape.
To prove this, try changing this line:
sk.stroke(255, 255, 255);
To this line:
sk.stroke(random(256));
To get around this, you could make each section of your curve its own shape with its own color. Start by just making each section a random color.
Then you need to base the color of each section off of the current index. I recommend drawing out a few examples. If a curve has 10 sections, what color should section 1 have? Section 2? Section 10? Repeat that process until you notice a pattern.
If you get stuck, please post an updated MCVE in a new question, and we'll go from there. Good luck.

Javascript canvas draw line strange behavior using algorithm

There are plenty of examples on how to draw lines on canvas, in js.
But for only educational purposes i want to draw line using algorithm. basically method gets two Vector2 points, from them it finds middle point, then it continues like that recursively until minimum distance of 2 pixels is reached.
I have DrawPoint method to basically draw 1 point on canvas, and DrawLine method that does all the job.
For now I have 2 problems:
1: points are not colored red, as they should be.
2:
It doesnt look like a line.
For Vector2 i used "Victor.js" plugin, and it seems to be working well.
this is code i have:
JS:
var point2 = new Victor(100, 100);
var point3 = new Victor(150, 150);
DrawLine(point2, point3);
function DrawLine(vec0, vec1)
{
var point0 = new Victor(vec0.x, vec0.y);
var point1 = new Victor(vec1.x, vec1.y);
var dist = point1.distance(point0);
if (dist < 2)
return;
//this is how it should look like in c# var middlePoint = point0 + (point1 - point0)/2; But looks like i cant just divide by 2 using victor js because i can only divide vector by vector.
var middlePoint = point0.add(point1.subtract(point0).divide(new Victor(2,2)));
DrawPoint(middlePoint);
DrawLine(point0, middlePoint);
DrawLine(middlePoint, point1);
}
function DrawPoint(point){
var c = document.getElementById("screen");
var ctx = c.getContext("2d");
ctx.fillStyle = "FF0000";
ctx.fillRect(point.x, point.y, 3,1);
}
I really appreciate any help you can provide.

The victor.js documentation shows that most functions of Victors do not return new Victors, but operate on the current instance. In a way, v1.add(v2) is semantically more like v1 += v2 and not v1 + v2.
The problem is with calculating the midpoint. You could use the mix() method, which blends two vectors with a weight. You must clone() the Victor first, otherwise point0will be midofied:
var middlePoint = point0.clone().mix(point1, 0.5);
If you don't change the original Vectors, you don't need to create new instances of Victors from the arguments, you can use the arguments directly:
function DrawLine(point0, point1)
{
var dist = point1.distance(point0);
if (dist < 2) return;
var middlePoint = point0.clone().mix(point1, 0.5);
DrawPoint(middlePoint);
DrawLine(point0, middlePoint);
DrawLine(middlePoint, point1);
}
Finally, as Sven the Surfer has already said in a comment, "FF0000" isn't a valid colour. Use "#FF0000", note the hash mark, or one of the named web colours such as "crimson".

pdf.js: Get the text colour

I have a simple pdf file, containing the words "Hello world", each in a different colour.
I'm loading the PDF, like this:
PDFJS.getDocument('test.pdf').then( onPDF );
function onPDF( pdf )
{
pdf.getPage( 1 ).then( onPage );
}
function onPage( page )
{
page.getTextContent().then( onText );
}
function onText( text )
{
console.log( JSON.stringify( text ) );
}
And I get a JSON output like this:
{
"items" : [{
"str" : "Hello ",
"dir" : "ltr",
"width" : 29.592,
"height" : 12,
"transform" : [12, 0, 0, 12, 56.8, 774.1],
"fontName" : "g_font_1"
}, {
"str" : "world",
"dir" : "ltr",
"width" : 27.983999999999998,
"height" : 12,
"transform" : [12, 0, 0, 12, 86.5, 774.1],
"fontName" : "g_font_1"
}
],
"styles" : {
"g_font_1" : {
"fontFamily" : "serif",
"ascent" : 0.891,
"descent" : 0.216
}
}
}
However, I've not been able to find a way to determine the colour of each word. When I render it, it renders properly, so I know the information is in there somewhere. Is there somewhere I can access this?

As Respawned alluded to, there is no easy answer that will work in all cases. That being said, here are two approaches which seem to work fairly well. Both having upsides and downsides.
Approach 1
Internally, the getTextContent method uses whats called an EvaluatorPreprocessor to parse the PDF operators, and maintain the graphic state. So what we can do is, implement a custom EvaluatorPreprocessor, overwrite the preprocessCommand method, and use it to add the current text color to the graphic state. Once this is in place, anytime a new text chunk is created, we can add a color attribute, and set it to the current color state.
The downsides to this approach are:
Requires modifying the PDFJS source code. It also depends heavily on
the current implementation of PDFJS, and could break if this is
changed.
It will fail in cases where the text is used as a path to be filled with an image. In some PDF creators (such as Photoshop), the way it creates colored text is, it first creates a clipping path from all the given text characters, and then paints a solid image over the path. So the only way to deduce the fill-color is by reading the pixel values from the image, which would require painting it to a canvas. Even hooking into paintChar wont be of much help here, since the fill color will only emerge at a later time.
The upside is, its fairly robust and works irrespective of the page background. It also does not require rendering anything to canvas, so it can be done entirely in the background thread.
Code
All the modifications are made in the core/evaluator.js file.
First you must define the custom evaluator, after the EvaluatorPreprocessor definition.
var CustomEvaluatorPreprocessor = (function() {
function CustomEvaluatorPreprocessor(stream, xref, stateManager, resources) {
EvaluatorPreprocessor.call(this, stream, xref, stateManager);
this.resources = resources;
this.xref = xref;
// set initial color state
var state = this.stateManager.state;
state.textRenderingMode = TextRenderingMode.FILL;
state.fillColorSpace = ColorSpace.singletons.gray;
state.fillColor = [0,0,0];
}
CustomEvaluatorPreprocessor.prototype = Object.create(EvaluatorPreprocessor.prototype);
CustomEvaluatorPreprocessor.prototype.preprocessCommand = function(fn, args) {
EvaluatorPreprocessor.prototype.preprocessCommand.call(this, fn, args);
var state = this.stateManager.state;
switch(fn) {
case OPS.setFillColorSpace:
state.fillColorSpace = ColorSpace.parse(args[0], this.xref, this.resources);
break;
case OPS.setFillColor:
var cs = state.fillColorSpace;
state.fillColor = cs.getRgb(args, 0);
break;
case OPS.setFillGray:
state.fillColorSpace = ColorSpace.singletons.gray;
state.fillColor = ColorSpace.singletons.gray.getRgb(args, 0);
break;
case OPS.setFillCMYKColor:
state.fillColorSpace = ColorSpace.singletons.cmyk;
state.fillColor = ColorSpace.singletons.cmyk.getRgb(args, 0);
break;
case OPS.setFillRGBColor:
state.fillColorSpace = ColorSpace.singletons.rgb;
state.fillColor = ColorSpace.singletons.rgb.getRgb(args, 0);
break;
}
};
return CustomEvaluatorPreprocessor;
})();
Next, you need to modify the getTextContent method to use the new evaluator:
var preprocessor = new CustomEvaluatorPreprocessor(stream, xref, stateManager, resources);
And lastly, in the newTextChunk method, add a color attribute:
color: stateManager.state.fillColor
Approach 2
Another approach would be to extract the text bounding boxes via getTextContent, render the page, and for each text, get the pixel values which reside within its bounds, and take that to be the fill color.
The downsides to this approach are:
The computed text bounding boxes are not always correct, and in some cases may even be off completely (eg: rotated text). If the bounding box does not cover at least partially the actual text on canvas, then this method will fail. We can recover from complete failures, by checking that the text pixels have a color variance greater than a threshold. The rationale being, if bounding box is completely background, it will have little variance, in which case we can fallback to a default text color (or maybe even the color of k nearest-neighbors).
The method assumes the text is darker than the background. Otherwise, the background could be mistaken as the fill color. This wont be a problem is most cases, as most docs have white backgrounds.
The upside is, its simple, and does not require messing with the PDFJS source-code. Also, it will work in cases where the text is used as a clipping path, and filled with an image. Though this can become hazy when you have complex image fills, in which case, the choice of text color becomes ambiguous.
Demo
http://jsfiddle.net/x2rajt5g/
Sample PDF's to test:
https://www.dropbox.com/s/0t5vtu6qqsdm1d4/color-test.pdf?dl=1
https://www.dropbox.com/s/cq0067u80o79o7x/testTextColour.pdf?dl=1
Code
function parseColors(canvasImgData, texts) {
var data = canvasImgData.data,
width = canvasImgData.width,
height = canvasImgData.height,
defaultColor = [0, 0, 0],
minVariance = 20;
texts.forEach(function (t) {
var left = Math.floor(t.transform[4]),
w = Math.round(t.width),
h = Math.round(t.height),
bottom = Math.round(height - t.transform[5]),
top = bottom - h,
start = (left + (top * width)) * 4,
color = [],
best = Infinity,
stat = new ImageStats();
for (var i, v, row = 0; row < h; row++) {
i = start + (row * width * 4);
for (var col = 0; col < w; col++) {
if ((v = data[i] + data[i + 1] + data[i + 2]) < best) { // the darker the "better"
best = v;
color[0] = data[i];
color[1] = data[i + 1];
color[2] = data[i + 2];
}
stat.addPixel(data[i], data[i+1], data[i+2]);
i += 4;
}
}
var stdDev = stat.getStdDev();
t.color = stdDev < minVariance ? defaultColor : color;
});
}
function ImageStats() {
this.pixelCount = 0;
this.pixels = [];
this.rgb = [];
this.mean = 0;
this.stdDev = 0;
}
ImageStats.prototype = {
addPixel: function (r, g, b) {
if (!this.rgb.length) {
this.rgb[0] = r;
this.rgb[1] = g;
this.rgb[2] = b;
} else {
this.rgb[0] += r;
this.rgb[1] += g;
this.rgb[2] += b;
}
this.pixelCount++;
this.pixels.push([r,g,b]);
},
getStdDev: function() {
var mean = [
this.rgb[0] / this.pixelCount,
this.rgb[1] / this.pixelCount,
this.rgb[2] / this.pixelCount
];
var diff = [0,0,0];
this.pixels.forEach(function(p) {
diff[0] += Math.pow(mean[0] - p[0], 2);
diff[1] += Math.pow(mean[1] - p[1], 2);
diff[2] += Math.pow(mean[2] - p[2], 2);
});
diff[0] = Math.sqrt(diff[0] / this.pixelCount);
diff[1] = Math.sqrt(diff[1] / this.pixelCount);
diff[2] = Math.sqrt(diff[2] / this.pixelCount);
return diff[0] + diff[1] + diff[2];
}
};

This question is actually extremely hard if you want to do it to perfection... or it can be relatively easy if you can live with solutions that work only some of the time.
First of all, realize that getTextContent is intended for searchable text extraction and that's all it's intended to do.
It's been suggested in the comments above that you use page.getOperatorList(), but that's basically re-implementing the whole PDF drawing model in your code... which is basically silly because the largest chunk of PDFJS does exactly that... except not for the purpose of text extraction but for the purpose of rendering to canvas. So what you want to do is to hack canvas.js so that instead of just setting its internal knobs it also does some callbacks to your code. Alas, if you go this way, you won't be able to use stock PDFJS, and I rather doubt that your goal of color extraction will be seen as very useful for PDFJS' main purpose, so your changes are likely not going to get accepted upstream, so you'll likely have to maintain your own fork of PDFJS.
After this dire warning, what you'd need to minimally change are the functions where PDFJS has parsed the PDF color operators and sets its own canvas painting color. That happens around line 1566 (of canvas.js) in function setFillColorN. You'll also need to hook the text render... which is rather a character renderer at canvas.js level, namely CanvasGraphics_paintChar around line 1270. With these two hooked, you'll get a stream of callbacks for color changes interspersed between character drawing sequences. So you can reconstruct the color of character sequences reasonably easy from this.. in the simple color cases.
And now I'm getting to the really ugly part: the fact that PDF has an extremely complex color model. First there are two colors for drawing anything, including text: a fill color and stroke (outline) color. So far not too scary, but the color is an index in a ColorSpace... of which there are several, RGB being only one possibility. Then there's also alpha and compositing modes, so the layers (of various alphas) can result in a different final color depending on the compositing mode. And the PDFJS has not a single place where it accumulates color from layers.. it simply [over]paints them as they come. So if you only extract the fill color changes and ignore alpha, compositing etc.. it will work but not for complex documents.
Hope this helps.

There's no need to patch pdfjs, the transform property gives the x and y, so you can go through the operator list and find the setFillColor op that precedes the text op at that point.

three.js - canvas texture on tube geometry for ipad

I've a 3d model of a tube geometry. There are 18000 co-ordinates on production side. I am taking every 9th co-ordinate so that actually plotting 9000 co-ordinates to build a tube geometry. I've to use CanvasRenderer only.
Now when I use vertexColors: THREE.VertexColors in WebGLRenderer, the model displays different color on each face. When I change it to CanvasRenderer, the model turns into white color only. Even I change vertexColors: THREE.FaceColors, the result is same.
Please find below the link of jsfiddle and link of my previous where mrdoob added support for material.vertexColors = THREE.FaceColors to CanvasRenderer.
support for vertex color in canvas rendering
tube in canvas rendering
Please find below the image to apply colors based on values.
As shown in the image there are 12 values at 12 different degrees for every co-ordinate. So I've created a tube with radius segment of 12. Then I've stored these values into JSON file but as there 18000 points, the file becomes to heavy. Even though I am plotting 2000 points it takes too much time. For 2000 segments and each segment has 12 faces, there are 24000 faces on a tube.
Please find below the programming logic to apply color based on value of a parameter.
// get res values & apply color
var lblSeg=0; var pntId; var d=0; var faceLength=tube.faces.length;
var degrees = [ '30', '60', '90', '120', '150', '180', '210', '240', '270', '300', '330' ];
var faces = tube.faces; var degreeCntr=0; var degreeProp;
//console.log(faces);
var res30=0,res60=0,res90=0,res120=0,res150=0,res180=0,res210=0,res240=0,res270=0,res300=0,res330=0;
var res; var resDegree; var pnt=0;
// fetching json data of resistivity values at different degree as //shown in the image
var result = getResValue();
for(var k=0; k<faceLength; k++){
resDegree = degrees[degreeCntr];
degreeProp = "r"+resDegree;
res = result.resistivity[pnt][degreeProp];
objects.push(result.resistivity[pnt]);
f = faces[k];
color = new THREE.Color( 0xffffff );
if(res<5){
color.setRGB( 197/255, 217/255, 241/255);
}
else if(res>=5 && res<50){
color.setRGB( 141/255, 180/255, 226/255);
}
else if(res>=50 && res<100){
color.setRGB( 83/255, 141/255, 213/255);
}
else if(res>=100 && res<200){
color.setRGB( 22, 54, 92);
}
else if(res>=200 && res<300){
color.setRGB( 15/255,36/255,62/255);
}
else if(res>=300 && res<400){
color.setRGB( 220/255, 230/255, 241/255);
}
else if(res>=400 && res<700){
color.setRGB( 184/255, 204/255, 228/255);
}
else if(res>=700 && res<1200){
color.setRGB( 149/255, 179/255, 215/255);
}
else if(res>=1200 && res<1500){
color.setRGB( 54/255, 96/255, 146/255);
}
else if(res>=1700 && res<1800){
color.setRGB( 36/255, 84/255, 98/255);
}
else if(res>1900){
color.setRGB( 128/255, 128/255, 128/255);
}
for(var j=0;j<4;j++)
{
tube.vertices.push(f.centroid);
vertexIndex = f[ faceIndices[ j ] ];
p = tube.vertices[ vertexIndex ];
f.vertexColors[ j ] = color;
}
degreeCntr++;
if(degreeCntr==10){
degreeCntr=0;
}
if(k%12==0 && k!=0){
pnt++;
}
}
This logic takes too much time to render the model and the model becomes too heavy and we can't perform other operations. The FPS on android drops at 2-3 FPS. Actually I've to render this model on iPad so have to use canvas renderer only.
So, how do I make this model lighter to load and works smoothly on iPad ? and is there any other way to apply colors on every face ? If canvas map as texture can be applied to make the model lighter, how do I build that map with all the colors based on value ?
Update:
After changing library version to r53, vertexColors: THREE.FaceColors and face.color.setRGB( Math.random(), Math.random(), Math.random()), the model displays random color for each face on canvas rendering.
So now the issue is applying colors as per requirements (either by canvas map or any feasible solution) and to make the model lighter to load it smoothly on iPad.

I believe this will give you a little bit better performance + if you could come up with some automated method of calculating colors for each angle offset, that you could set hex color directly:
for ( var i = 0; i < tube.faces.length; i ++ ) {
tube.faces[ i ].color.setHex( Math.random() * 0xffffff );
}
As I explained to you in the previous message - three.js - text next to line, using canvas textures will only increase load to you fps if you'll attempt to render so many faces.
If you really want to render 24,000 faces on canvas renderer and still hope that it gonna show up good on an iPad – you are out of your mind!))
Here is the only solution that I can think of for now:
1) Set your tube to only 1 segment.
2) Create 12 canvas elements (for every radius segment) with Width equal to your tube length (see my link above).
3) Now imagine that your 2000 segments you are going to create inside of each canvas. So, you divide your canvas length by 2000 and for every one of the portion of this division you set your calculated color!!! (Just like the Stats() FPS bar shows it’s bar, but you are going to have each bar different color).
4) Then you just apply your colored-bars-canvas-texture to each one of your 12 radius segments and you are good to go!!
This way you’ll only get initial page load (calculating 'em 24,000 colored-bars) and YOUR WHOLE TUBE ONLY GONNA BE 12 FACES!!!
Now, I know your next question is going to be: How I'll pick my faces to show my lines with tag text?
Well, very simple! Just take current face (1 of 12) pick position coordinates and translate them back to your JSON, just the same way you would do with 24,000 faces;)
Hope that helps!