CODEWITHSUNDEEP
three.js
Jason Perreault
Jason Perreault

Reputation: 51

Rotating Object Around an Axis

I have a geometry object, and I'm trying to add a Torus mesh that goes around that geometry. What I'm trying to do is have the original geometry, and then when the geometry is clicked, it adds a Torus shape on the line around the location that was clicked. However, I'm having trouble getting it to rotate correctly.

I get the torus to show up at the correct place, but I can't orient it around the line. I'm using a raycaster to get the point clicked, so I have the face and the faceindex of the point clicked. On every implementation I try using rotation (using setEulerFromRotationMatrix), it simply moves the location of the torus mesh, not actually rotate it to allow the line to go through the torus.

This seems like it would be trivial, but it's giving me a lot of trouble. What am I doing wrong? Two methods I tried, both unsucessful and exhibiting the behavior above:

var rotationMatrix = new THREE.Matrix4();
    rotationMatrix.makeRotationAxis(geometry.faces[fIndex].centroid.normalize(), Math.PI/2);
    torusLoop.matrix.multiply(rotationMatrix);
    torusLoop.rotation.setEulerFromRotationMatrix(torusLoop.matrix);

//attempt two, similar results to above attempt
tangent = geometry.tangents[segments/radiusSegments].normalize();
    axis.crossVectors( up, tangent ).normalize();
    var radians = Math.acos( up.dot( tangent ) );
    matrix.makeRotationAxis( axis, radians );
    torusLoop.rotation.setEulerFromRotationMatrix( matrix );

I need the torus knot to follow the curve of the spline, but it will only stay flat, and rotations simply cause it to move around, not change angles.

Upvotes: 3

Views: 857

Answers (1)

Jason Perreault
Jason Perreault

Reputation: 51

Never mind, I figured it out. For those wondering, I translated before rotating, which caused my figure to be rotating around a different axis. My solution was to rotate first, and then translate, and then after creating the mesh, moving that to the position I needed it to be.

Upvotes: 2

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