In three.js How can I render a cube with no fill but only the edges?
For example:
If you need to control the thickness of the lines you can use the LineGeometry class that's implemented in the THREE.js examples folder that creates triangle strips instead of GL.Lines to render.
See the following examples:
https://threejs.org/examples/?q=line#webgl_lines_fat
https://threejs.org/examples/?q=line#webgl_lines_fat_wireframe
Let me know if you need clarification and I can try to give a bit more detail.
Edit
I've taken your example comment and modified it a bit here: https://jsfiddle.net/L21ozkdq/2/.
Here are the big things to keep in mind (they are called out in comments, as well):
- Import the LineGeometry example files.
Create a LineGeometry object instead of BufferGeometry.
Create a LineMaterial instead of LineBasicMaterial.
Create a Line2 Object from the geometry and material.
Create a positions array instead of an attribute for the LineGeometry.
Create a box from a single line instead of many line segments in the position array.
Related
I'm using three.js library to work with 3d models (mostly .glb but it shouldn't matter)
The idea is to import a 3d model that contains groups and meshes. I want to be able to move meshes between already existing groups within a model without changing the visual representation of the model.
Piece of my code is below. movedInternal is
movedMesh.matrixWorldNeedsUpdate = true; // not sure if it's needed
let meshPosition = new THREE.Vector3();
movedMesh.getWorldPosition(meshPosition);
oldParent.remove(movedMesh);
newParent.add(movedMesh);
movedMesh.worldToLocal(meshPosition);
movedMesh.position.set(meshPosition.x, meshPosition.y, meshPosition.z);
And this is not working. Mesh changes its global position because new parent’s position is not the same as previous parent position, but I expect it to stay where it was but change its local position considering new parent’s position.
What do I do wrong?
I think you need to update the movedMesh's world matrix after you change its parents. When you .remove() then .add(), it doesn't know that its parents have been updated (Three.js usually does it when you're rendering, but this is happening before the next frame render).
let meshPosition = new THREE.Vector3();
movedMesh.getWorldPosition(meshPosition);
oldParent.remove(movedMesh);
newParent.add(movedMesh);
// Here it needs to re-learn its new coordinates
movedMesh.updateMatrixWorld(true);
movedMesh.worldToLocal(meshPosition);
movedMesh.position.set(meshPosition.x, meshPosition.y, meshPosition.z);
I've been searching for this solution since a week and haven't been able to tackle the exact problem. Though my question is diferent but has same scenario, I would like to give a solution for those, looking for it.
I have a 3D object with different child meshes, and i want to replace one of my child mesh with another 3D model.
Below code snippet:
replacementMesh is a new 3D object, meshToReplace is the child mesh that needs to be replaced.
// Copy the transformation matrix from obj1 to obj2
replacementMesh.matrix.copy(meshToReplace.matrix);
// Update obj2's position, rotation, and scale to match the transformation matrix
replacementMesh.position.setFromMatrixPosition(replacementMesh.matrix);
replacementMesh.rotation.setFromRotationMatrix(replacementMesh.matrix);
replacementMesh.scale.setFromMatrixScale(replacementMesh.matrix);
meshToReplace.parent.add(replacementMesh);
meshToReplace.parent.remove(meshToReplace);
I've an object in Blender. Because I want to do some UV-unwrapping using ThreeJS (see here) I determined that I need merge two of the sides to correctly unwrap.
So before exporting the .blend as a .obj object I selected the Tris to Quads face option to create a square face for the two sides as opposed to it being made up of two triangles. Here's what it looked like in Blender:
But when I import the .obj and .mtl file into ThreeJs I get this:
Is this a problem to do with me not updating the material being added to the new object?
The handles appearing white makes me think this is the case. If so how can I go about fixing it?
When I see something like this, the first thing I usually do is to set the material to side: THREE.DoubleSide. If that helps, the problem has to do with the normal-directions (so the face is actually there but isn't rendered because it is facing away from you).
To fix this, you should try the following:
In blender you can enable displaying of normal-directions in the right-hand menu (select "Face normals in section "Mesh Display").
You should now see if any of the normals are pointing inwards/in the wrong direction.
There is an automatic fix that works well for properly constructed meshes:
select object and switch into edit-mode (<Tab>)
select all vertices (shortcut <A>)
via menu "Mesh" > "Normals" > "Recalculate Outside" (shortcut <Ctrl>+<N>).
I want to have two overlapping objects in a scene but I want to define which object should be drawn first. I have a sample of the code here: http://jsfiddle.net/sg02e5sm/1/
I'm using renderOrder = 1 for the second object to make it appear always on top of the first object (as long as they have the same Z value), but it's not working.
renderOrder does not make something appear "on top". It controls the order in which objects are rendered.
If you want your 2nd plane to be "on top", you can add
mesh.material.depthTest = false;
for the 2nd plane.
Alternatively, you can implement two render passes, as described in this SO answer.
three.js r.142
i need some help in my webGL code.
I created a TextGeometry and i included it in a mesh, i didn't have any problem about that. However, i would like updating this text without creating another TextGeometry.
Indeed, my main goal is to translate a text (from right to left) and to make it disappear when he reaches to the left side, but only character by character (like a fade effect).
I tried some attempts : for example, according to text position, deleting it with a :
scene.remove(text)
and creating another text which is the same as previously minus the first character. I don't know if i was clear... But this solution makes my application very slow : that's why i don't want creating an Object every time, but just updating his text property.
I didn't find many help in three.js documentation, may you give me a hand about that ?
Cheers
You could try this:
Create a PlaneGeometry and texture it using the image from a hidden canvas object that contains your text, then apply image transforms to the canvas itself (fading as necessary) and continually update the texture in Three.js as it moves across the scene.
For an example of how to use a canvas object as an image (of text), I have an example posted at: http://stemkoski.github.com/Three.js/Texture-From-Canvas.html
I am trying to create a cube using three.js for a project. I need to add text to vertices and at different points inside the cube. Any idea how this can be done?
For some basic code examples of using Sprite objects in Three.js, check out:
http://stemkoski.github.com/Three.js/Sprites.html
And for an easy way to create images that contain text to use as your sprite textures, check out the sample code at:
http://stemkoski.github.com/Three.js/Texture-From-Canvas.html
I think a combination of these two ideas will achieve what you are looking to do.
If you want to have label-style texts, so that the text begins at a specific point, but is always oriented with the camera and easily readable no matter the camera position, you can use sprites. (example of canvas-created text label sprites: http://i.imgur.com/e9I68xD.jpg - here they are rendered on a separate pass to that they are never obscured by the scene but you can do it on the same pass)
If that's what you are looking for, I'd suggest first checking the Sprites examples, and learn to attach some static image as a sprite to correct position in the scene. After you get that working, you modify the code so that you generate the text to an image canvas using standard Javascript Canvas functions, and using that image as the sprite.