I use sprite create sprite in three.js.
And it works. But i want to change the canvas texture dynamic.
Maybe i can use fillText to change the text.But it works nor very well.
I just want it looks like electronic watch.
let canvas = document.createElement('canvas');
canvas.width = w;
canvas.height = h;
let ctx = canvas.getContext('2d');
drawBg(ctx, bg);
drawText(ctx, data);
let texture = new THREE.CanvasTexture(canvas);
texture.needsUpdate = true;
let material = new THREE.SpriteMaterial({map: texture});
let spriteOject = new THREE.Sprite(material);
spriteOject.scale.set(scale * w / h, scale)
spriteOject.position.set(positions[0], positions[1], positions[2]);
Related
after gone through three.js docs, I found it is quite hard to draw line with stroke width, and text.
For the line with stroke width I have to draw an rectange and adjust it to look likes a thick line
For the text, there only two option, one is using font loader, which I found it very hard to handle the promise of font loader, and it become slower if I have so many text.
But if I use canvas to draw the text then use sprite to add that canvas, then I got my texts keep rotates whenever I rotate my camera
so it is 2018, is there any way to make life more easier with three js.
Thanks all
my code to create a thick curve line
function curveLine(start, mid, end, width) {
var curveLine = new THREE.Shape();
curveLine.moveTo(start.x, start.y + width);
curveLine.quadraticCurveTo(mid.x, mid.y + width, end.x, end.y + width);
curveLine.lineTo(end.x, end.y);
curveLine.quadraticCurveTo(mid.x, mid.y, start.x, start.y);
curveLine.lineTo(start.x, start.y);
return curveLine;
}
var line = curveLine({x:0,y:0}, {x:120,y:80}, {x:240,y:0}, 20);
var lineGeo = new THREE.ExtrudeGeometry(line, extrudeSettings);
var lineMesh = new THREE.Mesh(lineGeo, new THREE.MeshBasicMaterial({color: 'red'}));
scene.add(lineMesh);
And this my code to draw text, current using canvas to draws
function text2D(text, params) {
var canvas = document.createElement('canvas');
canvas.width = params.radius * 4;
canvas.height = params.radius * 2;
var context = canvas.getContext('2d');
context.font = '20px Verdana';
var metrics = context.measureText(text);
var textWidth = metrics.width;
context.fillStyle = params.color;
context.fillText(text, (canvas.width - textWidth) / 2, params.radius);
var texture = new THREE.Texture(canvas);
texture.needsUpdate = true;
var spriteMaterial = new THREE.SpriteMaterial({map: texture});
var sprite = new THREE.Sprite(spriteMaterial);
sprite.scale.set(canvas.width, canvas.height, 1);
return sprite;
}
and then whenever i rotate the camera, the text keep face the camera. is there any way to prevent that
Cheers all
I have some code at https://jsfiddle.net/72mnd2yt/1/ that doesn't display the sprite I'm trying to draw. I tried to follow the code over at https://stemkoski.github.io/Three.js/Sprite-Text-Labels.html and read it line by line, but I'm not sure where I went wrong. would someone mind taking a look at it?
Here is some relevant code:
// picture
var getPicture = function(message){
var canvas = document.createElement('canvas');
canvas.width = "100%";
canvas.height = "100%";
var context = canvas.getContext('2d');
context.font = "10px";
context.fillText(message, 0, 10);
var picture = canvas.toDataURL();
// return picture;
return canvas;
};
// let there be light and so forth...
var getScene = function(){
var scene = new THREE.Scene();
var camera = new THREE.PerspectiveCamera(
70,
$('body').width(),
$('body').height(),
1,
1000
);
var light = new THREE.PointLight(0xeeeeee);
scene.add(camera);
scene.add(light);
var renderer = new THREE.WebGLRenderer();
renderer.setClearColor(0xefefef);
renderer.setSize($('body').width(), $('body').height());
camera.position.z = -10;
camera.lookAt(new THREE.Vector3(0, 0, 0));
return [scene, renderer, camera];
};
// now for the meat
var getLabel = function(message){
var texture = new THREE.Texture(getPicture(message));
var spriteMaterial = new THREE.SpriteMaterial(
{map: texture }
);
var sprite = new THREE.Sprite(spriteMaterial);
//sprite.scale.set(100, 50, 1.0);
return sprite
};
var setup = function(){
var scene;
var renderer;
var camera;
[scene, renderer, camera] = getScene();
$('body').append(renderer.domElement);
var label = getLabel("Hello, World!");
scene.add(label);
var animate = function(){
requestAnimationFrame(animate);
renderer.render(scene, camera);
};
animate();
};
setup();
A few points:
1) canvas.width = "100%" should be canvas.width = "100" (canvas sizes are assumed to be px). Same with canvas.height.
2) $('body').height() is 0, so the renderer canvas is not visible (you can check this out in dev tools, it's in the element tree but squashed to 0px high). I know nothing about jQuery, so not sure why this is, but I would recommend using window.innerHeight and window.innerWidth instead anyways. So renderer.setSize(window.innerWidth, window.innerHeight). You'll also want to make this change in the camera initialization.
3) Speaking of the camera initialization, you are passing in width and height as separate arguments, when there should only be an aspect ratio argument. See the docs. So
var camera = new THREE.PerspectiveCamera(70, window.innerWidth, window.innerHeight, 1, 1000)
becomes
var camera = new THREE.PerspectiveCamera(70, window.innerWidth/window.innerHeight, 1, 1000)
4) Because textures are assumed to be static, you need to add something to this part:
var texture = new THREE.Texture(getPicture(message))
texture.needsUpdate = true // this signals that the texture has changed
That's a one-time flag, so you need to set it every time the canvas changes if you want a dynamic texture. You don't have to make a new THREE.Texture each time, just add texture.needsUpdate in the render loop (or in an event that only fires when you want the texture to change, if you're going for efficiency). See the docs, under .needsUpdate.
At this point, it should work. Here are some further things to consider:
5) Instead of using Texture you could use CanvasTexture, which sets .needsUpdate for you. The fiddle you posted is using Three.js r71, which doesn't have it, but newer versions do. That would look like this:
var texture = new THREE.CanvasTexture(getPicture(message));
// no needsUpdate necessary
6) It looks like you were on this path already based on the commented out return picture, but you can use either canvas element, or a data url generated from the canvas for a texture. If getPicture now returns a data url, try this:
var texture = new THREE.TextureLoader().load(getPicture(message))
You can also indirectly use a data url with Texture:
var img = document.createElement('img')
var img = new Image()
img.src = getPicture(message)
var texture = new THREE.Texture(img);
texture.needsUpdate = true
If not, just stick with Texture or CanvasTexture, both will take a canvas element. Texture can indirectly take a url by passing in an image element whose src is set to the data url.
Fiddle with the outlined fixes:
https://jsfiddle.net/jbjw/x0uL1kbh/
I'm fairly new to Three.js, but I'm trying to use a Texture map to control pixel colors in a THREE.Points mesh. My desired outcome is that vertex 0 will be colored as image pixel x=0, y=0. Vertex 1 will be colored as image x=1, y=0, and so on.
All attempts I have make result is each vertex point being rendered with the whole image (not use one color according to the coordinates.)
Here is a snippet of my code.
... Define Geometry ...
var texture = new THREE.TextureLoader().load("img/MyImage.jpg");
var mat = new THREE.PointsMaterial({ size: 2.5, vertexColors: THREE.VertexColors, map: texture });
var points = new THREE.Points(geo, mat);
If you don't feel like you have to use a texure (maybe that is possible with a similar approach) you could just read the pixeldata of the image and use that to set colors similar to WestLangleys suggestion.
I'm not sure if the difference between colors size and number of vertices are going to be a problem, but it's working fine for me. Good luck!
var img = new Image();
img.src = "Image1.png";
img.onload = function(){
// apply image to canvas
var canvas = document.createElement("canvas");
canvas.width = img.width;
canvas.height = img.height;
canvas.getContext('2d').drawImage(img,0,0,img.width,img.height);
var colors = [];
// geometry of choice
var geo = new THREE.SphereGeometry(50,50);
for(var i = 0; i < img.width; i++){
for(var j = 0; j < img.height; j++){
// pd - pixeldata array in the format of rgba. example: [53, 53, 130, 255]
var pd = canvas.getContext('2d').getImageData(i,j,1,1).data;
// not pretty, but works
colors.push(new THREE.Color("rgb("+pd[0]+","+pd[1]+","+pd[2]+")"));
}
}
geo.colors = colors;
var material = new THREE.PointsMaterial( {size: 10, vertexColors: THREE.VertexColors });
var point = new THREE.Points(geo, material);
scene.add(point);
};
I need to get the color of an image texture on a mesh at a given xyz point (mouse click + ray cast). How can I achieve it in THREE.js?
I know I could use gl.readPixels from plain webgl, but it's not a valid option for me.
Thanks!
So I ended using a separate canvas, in which I load the image texture, translate the three.js coordinates into canvas one and read the pixel. Something like this:
// point is a THREE.Vector3
var getColor = function(point, callback) {
var img = new Image();
img.src = 'assets/img/myImage.png';
img.onload = function() {
// get the xy coords from the point
var xyCoords = convertVector3ToXY(point);
// create a canvas to manipulate the image
var canvas = document.createElement('canvas');
canvas.width = img.width;
canvas.height = img.height;
canvas.getContext('2d').drawImage(img, 0, 0, img.width, img.height);
// get the pixel data and callback
var pixelData = canvas.getContext('2d').getImageData(x, y, 1, 1).data;
callback(pixelData);
}
};
Thanks
I have a set of plane geometries, each having a their own texture from a url. At any point during navigation(zoom/pan) the container (THREE.Object3D) contains 26 plane geometries. How will i merge them to a single big plane so that i could apply a heighmap for all tiles in the merge geometry.
Or How could I get all the texture from the 36 images.(currently as a map property for MeshPhongMaterial) in to a single geometry?
EDIT:
Currently I create a Big geometry as suggested by Dainel. and put a texture to the geometry which is a combined texture of a set of images via canvas.
context = canvas.getContext( '2d' );
var img = Image();
img.src = url //url of the texture tile
context.drawImage(img,xpos, ypos);
This is done or every images. Each image have a url, xpos, ypos. Images are preloaded and after loading every images a callback is called which creates the geometry(plane) and add texture from the canvas.
var texture = new THREE.Texture(canvas);
texture.needsUpdate = true;
var material = new THREE.MeshPhongMaterial({ map : texture });
var geom = new THREE.PlaneGeometry(canvas.width, canvas.height, 57, 40);
var mesh = new THREE.Mesh(geom, material);
scene.add( mesh );
also i update the z vertex of geometry with the height values.
u may create one "big" plane and apply a merged texture to it
or u could manually set the vertex Y-values of each plane to match the corresponding part of the height map. so u have a set of separate planes that all share the same "base" height map.
regards,
daniel
Using terrainLoader class for threejs and canvas texture I was able to acheive
scene = new THREE.Scene();
camera = new THREE.PerspectiveCamera(45, mywidth / myheight, 0.01, 10000);
camera.position.set(0, 0, 240);
scene.add(new THREE.AmbientLight(0xeeeeee));
renderer = new THREE.WebGLRenderer();
renderer.setSize(mywidth, myheight);
var group = new THREE.Object3D();
var canvas = document.createElement( 'canvas' );
canvas.width = mywidth;
canvas.height = myheight;
var ctx = canvas.getContext('2d');
/* adjust width, height, segments based on height data;*/
/* create a plane geometry */
var geom = new THREE.PlaneGeometry(800, 692, 40, 55);
/*
read height values from .bin file uing terrainLoader
and update the Z values of the plane
*/
heightdata = 'assets/heightmap.bin';
terrainLoader.load(heightdata, function(data) {
/* bin file generated from USGS SRTM tile */
for (var i = 0, l = geom.vertices.length ; i < l; i++) {
geom.vertices[i].z = data[i] / 200; /*simple scale */
}
geom.verticesNeedUpdate = true;
});
/*
create a texture from canvas created above with width and height
of the of the scene. This is to be careful as the size of texture
image may not be the same but as same ratio as height map.
Atleast for my case it was the situation. But geometry width and
texture width are in same ratio. So that i need a small array of
heightmap from bin but a much bigger texture
*/
var texture = new THREE.Texture(canvas);
var material = new THREE.MeshPhongMaterial({ map : texture });
var mesh = new THREE.Mesh(geom, material);
group.add( mesh );
scene.add(group);
Now to draw multiple images to canvas check this page
I will just duplicate the code from HTML5 Canvas Image Loader Tutorial
function loadImages(sources, callback) {
var images = {};
var loadedImages = 0;
var numImages = 0;
// get num of sources
for(var src in sources) {
numImages++;
}
for(var src in sources) {
images[src] = new Image();
images[src].onload = function() {
if(++loadedImages >= numImages) {
callback(images);
}
};
images[src].src = sources[src];
}
}
var sources = {
darthVader: 'http://www.html5canvastutorials.com/demos/assets/darth-vader.jpg',
yoda: 'http://www.html5canvastutorials.com/demos/assets/yoda.jpg'
};
You can call the loadImages function after updating the Plane geometry from heightmap in above code.
loadImages(sources, function(images) {
//context = context of the texture put in threejs texture
context.drawImage(images.darthVader, 100, 30, 200, 137);
context.drawImage(images.yoda, 350, 55, 93, 104);
});