I am creating one geometry at location (0,0,0) but projecting at some other location (for ex. #50,50,50). If the point (0,0,0) is going out of canvas, then geometry is hiding.
Is there any way to always render it on canvas?
How far off the edge does the origin need to be?
You could make the canvas larger than you need, than mask the areas on the edge such that only the center area shows. That way when the origin goes off the side, it will still technically be on the canvas, and the projected geometry will be in the visible area. I expect you will only need a buffer space equal to projection offset.
See here for an example of applying a mask: https://jsfiddle.net/shawnoakley/n1368qr0/2/
Example code:
var context = document.getElementById('canvas').getContext('2d');
// Mask color
context.fillStyle = '#000';
// Image proportions
context.fillRect(0,0,600,400);
var unmaskedImage = function(x, y, radius){
context.save();
context.globalCompositeOperation = 'destination-out';
context.beginPath();
context.arc(x, y, radius, 0, 2 * Math.PI, false);
context.fill();
context.restore();
};
unmaskedImage(300, 300, 300);
Related
I have a special control called SphericalControls. Its similar to OrbitControls, but it keeps camera at position 0,0,0 and instead rotates camera on x and y to look around a scene. It is placed in the middle of a SphereBufferGeometry which has a 360 equirectangular image projected upon it. The user can look around the 360 image, and as he does the camera x and y rotation values change.
When a user clicks a button, I need to take these x and y rotation values and rotate the sphere to the rotation of the camera. I then set camera back to x:0 and y:0.
The result is that the camera is reset and the 360 scene has now rotated to show the same rotation view that the camera was previously looking at. So to the user, the view stays basically static, just the values for camera.rotation and sphere rotation have swapped.
This works great if I offset the texture on the sphere:
sphereObj.material.map.wrapS = THREE.RepeatWrapping;
sphereObj.material.map.offset.x = ((camera.rotation.x) / (Math.PI * 2));
sphereObj.material.map.needsUpdate = true;
sphereObj.material.needsUpdate = true;
camera.rotation.set(0, 0);
// Success!
But what I need to do is not offset the texture, but rotate the entire geometry. I have tried:
var axis = new THREE.Vector3(0, 1, 0).normalize();;
var offsetRadian = ((camera.rotation.x) / (Math.PI * 2));
sphere.rotateOnAxis(axis, offsetRadian);
// Fail
But the result is that the sphere rotation is off by approx 30%. Any help is appreciated.
Every objects' rotational data is stored in their respective .quaternion object. Both camera and sphereObj have a quaternion, so what you could do is copy the camera's rotational data into the sphere:
// Get camera's rotation
targetRotation = camera.quaternion;
// Invert rotation
targetRotation.inverse();
// Set sphere's rotation
sphereObj.quaternion.copy(targetRotation);
camera.rotation.set(0, 0, 0);
I'm not entirely sure if you need the .inverse() line... if you're noticing the sphere is rotating in the opposite direction, just get rid of it to get the desired result.
I'd like to enable a user to rotate a texture on a rectangle while keeping the aspect ratio of the texture image intact. I'm doing the rotation of a 1:1 aspect ratio image on a surface that is rectangular (say width: 2 and length: 1)
Steps to reproduce:
In the below texture rotation example
https://threejs.org/examples/?q=rotation#webgl_materials_texture_rotation
If we change one of the faces of the geometry like below:
https://github.com/mrdoob/three.js/blob/master/examples/webgl_materials_texture_rotation.html#L57
var geometry = new THREE.BoxBufferGeometry( 20, 10, 10 );
Then you can see that as you play around with the rotation control, the image aspect ratio is distorted. (form a square to a weird shape)
At 0 degree:
At some angle between 0 and 90:
I understand that by changing the repeatX and repeatY factor I can control this. It's also easy to see what the values would be at 0 degree, 90 degree rotations.
But I'm struggling to come up with the formula for repeatX and repeatY that works for any texture rotation given length and width of the rectangular face.
Unfortunately when stretching geometry like that, you'll get a distortion in 3D space, not UV space. In this example, one UV.x unit occupies twice as much 3D space as one UV.y unit:
This is giving you those horizontally-skewed diamonds when in between rotations:
Sadly, there's no way to solve this with texture matrix transforms. The horizontal stretching will be applied after the texture transform, in 3D space, so texture.repeat won't help you avoid this. The only way to solve this is by modifying the UVs so the UV.x units take up as much 3D space as UV.y units:
With complex models, you'd do this kind of "equalizing" in a 3D editor, but since the geometry is simple enough, we can do it via code. See the example below. I'm using a width/height ratio variable to use in my UV.y remapping, that way the UV transformations will match up, regardless of how much wider it is.
//////// Boilerplate Three setup
const renderer = new THREE.WebGLRenderer({canvas: document.querySelector("canvas")});
const camera = new THREE.PerspectiveCamera(50, 1, 1, 100);
camera.position.z = 3;
const scene = new THREE.Scene();
/////////////////// CREATE GEOM & MATERIAL
const width = 2;
const height = 1;
const ratio= width / height; // <- magic number that will help with UV remapping
const geometry = new THREE.BoxBufferGeometry(width, height, width);
let uvY;
const uvArray = geometry.getAttribute("uv").array;
// Re-map UVs to avoid distortion
for (let i2 = 0; i2 < uvArray.length; i2 += 2){
uvY = uvArray[i2 + 1]; // Extract Y value,
uvY -= 0.5; // center around 0
uvY /= ratio; // divide by w/h ratio
uvY += 0.5; // remove center around 0
uvArray[i2 + 1] = uvY;
}
geometry.getAttribute("uv").needsUpdate = true;
const uvMap = new THREE.TextureLoader().load("https://raw.githubusercontent.com/mrdoob/three.js/dev/examples/textures/uv_grid_opengl.jpg");
// Now we can apply texture transformations as expected
uvMap.center.set(0.5, 0.5);
uvMap.repeat.set(0.25, 0.5);
uvMap.anisotropy = 16;
const material = new THREE.MeshBasicMaterial({map: uvMap});
const mesh = new THREE.Mesh(geometry, material);
scene.add(mesh);
window.addEventListener("mousemove", onMouseMove);
window.addEventListener("resize", resize);
// Add rotation on mousemove
function onMouseMove(ev) {
uvMap.rotation = (ev.clientX / window.innerWidth) * Math.PI * 2;
}
function resize() {
const width = window.innerWidth;
const height = window.innerHeight;
renderer.setSize(width, height);
camera.aspect = width / height;
camera.updateProjectionMatrix();
}
function animate(time) {
mesh.rotation.y = Math.cos(time/ 3000) * 2;
renderer.render(scene, camera);
requestAnimationFrame(animate);
}
resize();
requestAnimationFrame(animate);
body { margin: 0; }
canvas { width: 100vw; height: 100vh; display: block; }
<script src="https://threejs.org/build/three.js"></script>
<canvas></canvas>
First of all, I agree with the solution #Marquizzo provided to your problem. And setting UV explicitly to the geometry should be the easiest way to solve your problem.
But #Marquizzo did not answer why changing the matrix of the texture (set repeatX and repeatY) does not work.
We all know the 2D rotation matrix R
cos -sin
sin cos
UVs are calculated in the shader with a transform matrix T, which is the texture matrix from your question.
T * UV = new UV
To simplify the question, we only consider rotation. And assume we have another additional matrix X for calculating the new UV. Then we have
X * R * UV = new UV
The question now is whether we can find a solution ofX, so that with any rotation, new UV of any points in your question can be calculated correctly. If there is a solution of X, then we can simply use
var X = new Matrix3();
//X.set(x,y,z,...)
texture.matrix.premultiply(X);
Otherwise, we can't find the approach you expected.
Let's create several equations to figure out X.
In the pic below, ABCD is one face of your geometry, and the transparent green is the texture. The UV of point A is (0,1), point B is (0,0), and (1,0), (1,1) for C and D respectively.
The first equation comes from the consideration, without any rotation, the original UV should never be changed (UV for A is always (0,1)). So we should have
X * I * (0, 1) = (0, 1) // I is the identity matrix
From here we can see X should also be an identity matrix.
Then let's see whether the identity matrix X can satisfy the second equation. What's the second equation? Simplify again, let B be the rotation centre(origin) and rotate the texture 90 degrees(counterclockwise). We use -90 to calculate UV though we rotate 90 degrees.
The new UV for point A after rotating the texture 90 degrees should be the current value of E. The value of E is (a/b, 0). Then we have
From this equation we can see X should not be an identity matrix, which means, WE ARE NOT ABLE TO FIND A SOLUTION OF X TO SOLVE YOUR PROBLEM WITH
X * R * UV = new UV
Certainly, you can change the shader of calculating new UVs, but it's even harder than the way #Marquizzo provided.
I need to convert the position and rotation on a 3d object to screen position and rotation. I can convert the position easily but not the rotation. I've attempted to convert the rotation of the camera but it does not match up.
Attached is an example plunkr & conversion code.
The white facebook button should line up with the red plane.
https://plnkr.co/edit/0MOKrc1lc2Bqw1MMZnZV?p=preview
function toScreenPosition(position, camera, width, height) {
var p = new THREE.Vector3(position.x, position.y, position.z);
var vector = p.project(camera);
vector.x = (vector.x + 1) / 2 * width;
vector.y = -(vector.y - 1) / 2 * height;
return vector;
}
function updateScreenElements() {
var btn = document.querySelector('#btn-share')
var pos = plane.getWorldPosition();
var vec = toScreenPosition(pos, camera, canvas.width, canvas.height);
var translate = "translate3d("+vec.x+"px,"+vec.y+"px,"+vec.z+"px)";
var euler = camera.getWorldRotation();
var rotate = "rotateX("+euler.x+"rad)"+
" rotateY("+(euler.y)+"rad)"+
" rotateY("+(euler.z)+"rad)";
btn.style.transform= translate+ " "+rotate;
}
... And a screenshot of the issue.
I would highly recommend not trying to match this to the camera space, but instead to apply the image as a texture map to the red plane, and then use a raycast to see whether a click goes over the plane. You'll save yourself headache in translating and rotating and then hiding the symbol when it's behind the cube, etc
check out the THREEjs examples to see how to use the Raycaster. It's a lot more flexible and easier than trying to do rotations and matching. Then whatever the 'btn' onclick function is, you just call when you detect a raycast collision with the plane
I'm new to threejs
I need to draw a sphere connected with triangles. I use Icosahedron to construct the sphere in the following way
var material = new THREE.MeshPhongMaterial({
emissive : 0xffffff,
transparent: true,
opacity : 0.5,
wireframe : true
});
var icogeo = new THREE.IcosahedronGeometry(80,2);
var mesh = new THREE.Mesh(icogeo, material);
scean.add(mesh);
But i need the width of the line to be more but line width won't show up in windows so i taught of looping through the vertices and draw a cylinder/tube between the vertices. (I can't draw lines because the LineBasicMaterial was not responding to Light.)
for(i=0;i<icogeo.faces.length;i++){
var face = icogeo.faces[i];
//get vertices from face and draw cylinder/tube between the three vertices
}
Can some one please help on drawing the tube/cylinder between two vector3 vertices?
**the problem i'm facing with wireframe was it was not smooth and i can't increase width of it in windows.
If you really want to create a cylinder between two points one way to do is to create it in a unit space and then transform it to your line. But that is very mathy.
An intuitive way to create it is to think about how would you do it in a unit space? A circle around the z axis (in x,y) and another one a bit down z.
Creating a circle in 2d is easy: for ( angle(0,360,360/numsteps) ) (x,y)=(sin(angle),cos(angle))*radius. (see for example Calculating the position of points in a circle).
Now the two butt ends of your cylinder are not in x,y! But If you have two vectors dx,dy you can just multiply your x,y with them and get a 3d position!
So how to get dx, dy? One way is http://en.wikipedia.org/wiki/Gram%E2%80%93Schmidt_process
which reads way more scary than it is. You start with your forward direction, which is your line. forward = normalize(end-start). Then you just pick a direction "up". Usually (0,1,0). Unless forward is already close to up, then pick another one like (1,0,0). Take their cross product. This gives you "left". Then take the cross product between "left" and "forward" to get "right". Now "left" and "right" are you dx and dy!
That way you can make two circles at the two ends of your line. Add triangles in between and you have a cylinder!
Even though I do believe it is an overkill for what you are trying to achieve, here is code that draws a capsule (cylinder with spheres at the end) between two endpoints.
/**
* Returns a THREE.Object3D cylinder and spheres going from top to bottom positions
* #param radius - the radius of the capsule's cylinder
* #param top, bottom - THREE.Vector3, top and bottom positions of cone
* #param radiusSegments - tessellation around equator
* #param openTop, openBottom - whether the end is given a sphere; true means they are not
* #param material - THREE.Material
*/
function createCapsule (radius, top, bottom, radiusSegments, openTop, openBottom, material)
{
radiusSegments = (radiusSegments === undefined) ? 32 : radiusSegments;
openTop = (openTop === undefined) ? false : openTop;
openBottom = (openBottom === undefined) ? false : openBottom;
var capsule = new THREE.Object3D();
var cylinderAxis = new THREE.Vector3();
cylinderAxis.subVectors (top, bottom); // get cylinder height
var cylinderGeom = new THREE.CylinderGeometry (radius, radius, cylinderAxis.length(), radiusSegments, 1, true); // open-ended
var cylinderMesh = new THREE.Mesh (cylinderGeom, material);
// get cylinder center for translation
var center = new THREE.Vector3();
center.addVectors (top, bottom);
center.divideScalar (2.0);
// pass in the cylinder itself, its desired axis, and the place to move the center.
makeLengthAngleAxisTransform (cylinderMesh, cylinderAxis, center);
capsule.add (cylinderMesh);
if (! openTop || ! openBottom)
{
// instance geometry
var hemisphGeom = new THREE.SphereGeometry (radius, radiusSegments, radiusSegments/2, 0, 2*Math.PI, 0, Math.PI/2);
// make a cap instance of hemisphGeom around 'center', looking into some 'direction'
var makeHemiCapMesh = function (direction, center)
{
var cap = new THREE.Mesh (hemisphGeom, material);
makeLengthAngleAxisTransform (cap, direction, center);
return cap;
};
// ================================================================================
if (! openTop)
capsule.add (makeHemiCapMesh (cylinderAxis, top));
// reverse the axis so that the hemiCaps would look the other way
cylinderAxis.negate();
if (! openBottom)
capsule.add (makeHemiCapMesh (cylinderAxis, bottom));
}
return capsule;
}
// Transform object to align with given axis and then move to center
function makeLengthAngleAxisTransform (obj, align_axis, center)
{
obj.matrixAutoUpdate = false;
// From left to right using frames: translate, then rotate; TR.
// So translate is first.
obj.matrix.makeTranslation (center.x, center.y, center.z);
// take cross product of axis and up vector to get axis of rotation
var yAxis = new THREE.Vector3 (0, 1, 0);
// Needed later for dot product, just do it now;
var axis = new THREE.Vector3();
axis.copy (align_axis);
axis.normalize();
var rotationAxis = new THREE.Vector3();
rotationAxis.crossVectors (axis, yAxis);
if (rotationAxis.length() < 0.000001)
{
// Special case: if rotationAxis is just about zero, set to X axis,
// so that the angle can be given as 0 or PI. This works ONLY
// because we know one of the two axes is +Y.
rotationAxis.set (1, 0, 0);
}
rotationAxis.normalize();
// take dot product of axis and up vector to get cosine of angle of rotation
var theta = -Math.acos (axis.dot (yAxis));
// obj.matrix.makeRotationAxis (rotationAxis, theta);
var rotMatrix = new THREE.Matrix4();
rotMatrix.makeRotationAxis (rotationAxis, theta);
obj.matrix.multiply (rotMatrix);
}
I want to draw a closed shape(Using paths) & my stroke width is 10.
Now,i want to fill that shape,i can fill it using fill() function of context.
But,when i want to change alpha of my shape,then stroke & fill area overlap at border of shape.
I want only fill the area of shape that remains black after my stroke.
I have attached image of explaining my problem.
Click here to show shape with stork & fill bug.
As you can see in jsfiddle,
-- Color of overlapping area are composite color. That i don't want.
I want it to be exactly same as in border(or stroke color with alpha).
-- i am not enable to specify fill area of closed path.(there is no method of contexx.)
-- I can't use "glabalCompositeOperation",because i am drawing more than 1 shapes in 1 canvas in my application.
The effect you are getting seems to be a property of how canvas draws lines round a shape. Half the thickness of the line is drawn inside the shape and half outside the shape. One way round it is to draw the filled shape and the border as seperate paths. The changes to do this for your example are shown below. This will be more difficult with irregular shapes.
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext("2d");
var topLeftCornerX = 188;
var topLeftCornerY = 50;
var width = 200;
var height = 100;
var linewidth = 10;
context.globalAlpha = 0.5;
context.beginPath();
context.moveTo(topLeftCornerX, topLeftCornerY);
context.lineTo(topLeftCornerX+width,topLeftCornerY);
context.lineTo(topLeftCornerX+width,topLeftCornerY+height);
context.lineTo(topLeftCornerX,topLeftCornerY+height);
context.closePath();
context.fillStyle = "#FF0000";
context.fill();
context.beginPath();
context.moveTo(topLeftCornerX-linewidth/2, topLeftCornerY-linewidth/2);
context.lineTo(topLeftCornerX+width+linewidth/2,topLeftCornerY-linewidth/2);
context.lineTo(topLeftCornerX+width+linewidth/2,topLeftCornerY+height+linewidth/2);
context.lineTo(topLeftCornerX-linewidth/2,topLeftCornerY+height+linewidth/2);
context.closePath();
context.lineWidth = linewidth;
context.strokeStyle = "#00FF00";
context.stroke();