The ‘way it’s done’ is to use homogenous transformations and coordinates. You take a point in space and: Position it relative to the camera using the model matrix. Project it either orthographically or in perspective using the projection matrix. Apply the viewport trnasformation to place it on the screen. This gets pretty vague, but I’ll … Read more
Use ‘real’ physics for that. ball have parameters acceleration a(ax,ay,az) [m/s^2]… this is sum of all forces driving ball divided by its mass velocity v(vx,vy,vz) [m/s]… actual speed = integration of acceleration v += a * dt position p(x,y,z) [m]… actual position = integration of velocity p += v * dt radius r [m] mass … Read more
The easiest way to do this is “clearing” the rotational part of the transform matrix. Your typical homogenous transformation looks like this | xx xy xz xw | | yx yy yz yw | | zx zy zz zw | | wx wy wz ww | with wx = wy = wz = 0, ww … Read more
EDIT: You can use the built-in method Object3D.attach(): // add object as a child of parent, while maintaining the object’s world transform parent.attach( object ); three.js r.109
You want to render a clipped surface as if it were a solid — i.e., not hollow. You can achieve that effect with MeshPhongMaterial — or any three.js material for that matter — with a simple hack to the material shader. material.onBeforeCompile = function( shader ) { shader.fragmentShader = shader.fragmentShader.replace( ‘#include <output_fragment>’, ` vec3 backfaceColor … Read more
Maybe you can use the projectPoint function of the SCNSceneRenderer. extension ARFaceAnchor{ // struct to store the 3d vertex and the 2d projection point struct VerticesAndProjection { var vertex: SIMD3<Float> var projected: CGPoint } // return a struct with vertices and projection func verticeAndProjection(to view: ARSCNView) -> [VerticesAndProjection]{ let points = geometry.vertices.compactMap({ (vertex) -> VerticesAndProjection? … Read more
I don’t think any of these answers is correct. Andres is correct that quaternions don’t have handedness (*). Handedness (or what I’ll call “axis conventions”) is a property that humans apply; it’s how we map our concepts of “forward, right, up” to the X, Y, Z axes. These things are true: Pure-rotation matrices (orthogonal, determinant … Read more
IE doesn’t support transform-style: preserve-3d yet. You have to remove the transform from #header-cube and apply it to each of the figure children. Unfortunately IE already uses the non-prefixed properties, so you either can’t use transform-3d at all or have to define the prefixed properties last. From the IE transforms documentation: At this time, Internet … Read more
You don’t need to use invisible geometry — Scene Kit can do all the coordinate conversions you need without having to hit test invisible objects. Basically you need to do the same thing you would in a 2D drawing app for moving an object: find the offset between the mouseDown: location and the object position, … Read more
A rotated vector can be described as a product of a rotation matrix with that vector. The German Wikipedia page on pitch, roll and yaw describes the rotation matrix for given Euler rotation angles. With that information, the rotation of all points with the same angles can be written as JavaScript function, where the points … Read more