Is there a way to achieve uv coordinate animation/morphing for vertices in a manner similar to morphTargets which works for position attribute?
Yes there is. There is no difference between the position attribute and the uv mapping attribute from a webgl viewpoint. Anything that you want to do or can do to one, you can do to the other.
Related
I have a problem with mapping a texture in THREE.js which is possibly related to creating custom UV-Coordinates as extensive search indicates.
The following picture shows a geometry which was created from THREE.BoxGeometry by manipulating the lower vertices of the box. The texture on the side looks stretched (although this is correct I guess).
picture1
Is there a way of "projecting" the texture onto the side, e.g. by creating custom uv-coordinates to look like in the second (photoshopped) picture?
picture2
Thanks for you help!
You will need to remap your vertices manually to perform what is called a "box mapping" or a "triplanar mapping".
Here is an example I threw together: https://codesandbox.io/s/qxk8xvnrvj
It creates a cube with some subdivisions.. perturbs those vertices if they are on top... and then does the iterations through the faces uvs and vertices to remap each faces UVs with a box mapping, by finding the dominant axis the face normal points along... and then using the other 2 axis' as the U and V axis for unwrapping.
After modifying my main camera's projection matrix, the ScreenPointToRay method that use ray casting begin to fail, so the method which detect touched object use raycast fail too. Is there any way to use ScreenPointToRay method with a custom camera projection matrix?
If you made a custom camera projection matrix, then you probably know where is the user pointing to, how about casting a ray yourself and not using the helper?
If you have a problem with translation of the cursor to world position, there is a good approximation - take four angles on approxiamtely the edges of your camera's viewpoint (top of the viewport horizontal center, left of the viewport vertical center etc.) and interpolate between them.
I was wondering if there is a way to copy the rotational information of a sprite into a plane. It seems that for the sprite the rotation is set within the material and it is just one value. I tried copying the matrix of the sprite into that of the plane but had no luck.
Sprite rotation is defined in WebGL as you can read in SpritePlugin.js. Thus, if you wish to copy the rotation of an existing sprite in your scene, the easiest way may be to use quaternion. They allow better defining than x/y/z-angle defined ones (Euler rotations) as they ask for the rotation axis and the angle value. In your context, at each camera movement you modify a quaternion. You set it with quaternion.setFromAxisAngle(axis,angle). Then apply it to the plane with plane.setRotationFromQuaternion(quaternion).
Math side :
The axis would be the cross product between the vectors lastCameraPosition-sprite.position and actualCameraPosition-sprite.position,
the angle, the one between those vectors, got with the acos of their dot product divided by the product of their lengths.
For more about those maths, functions getMouseProjectionOnBall and rotateCamera in TrackBallControls are of great interest.
Hope it helped !
What I'm trying to do is to "drape" some points on a PlaneGeometry. I have the planar coordinates of the points in the same coordinate system of my plane geometry, what I need i sto get the "height" from the plane to position the points on top of it.
What's the best way to achieve it? Querying the planar mesh in Javascript would be to heavy. Should it be done (and could it be done) using the vertex shader?
EDIT
Probably using a ray caster is the right solution, something like shown in this example: http://threejs.org/examples/#webgl_geometry_terrain_raycast
EDIT2
Raycasting does the job, but it's quite slow for a lot of objects. I suppose there are more efficient ways to do that...
https://dl.dropboxusercontent.com/u/13861666/2014-01-17%2011_27_15-firenze.png
Is it possible to apply texture to mesh without specifying UV's in geometry in three.js ?
There are classes such as THREE.CubeGeometry, THREE.SphereGeometry, etc. that automatically generate the UV coordinates for you. However, if you are creating your own geometry from scratch (i.e., specifying vertex locations, creating faces, etc.) then the answer is no. Either you need to set the UV coordinates manually when creating the geometry, or you need to write a custom shader which determines the UV coordinates for any given point. Think about it this way: if you don't specify UV coordinates, the points on your geometry have no idea which point on your texture they should display.