Need some help with Matrix4.lookAt in combination with makeScale

Questions
1

I have three scale values for x , y, and z axis…
I want to rotate and combine these into one vector, but I’m not getting the results I expect.

at first I tried to add each vector and their scale together into one vector, but it didn’t produce the correct results.

var vectorX = tilt.right.clone().multiplyScalar(x);
var vectorY = tilt.up.clone().multiplyScalar(y);
var vectorZ = tilt.backward.clone().multiplyScalar(z);
vector.copy(vectorX).add(vectorY).add(vectorZ);

So then I decided I would try to use a matrix4…

var mt = new THREE.Matrix4();
mt.makeScale( x, y, z );
			
var mt2 = new THREE.Matrix4();
mt2.lookAt( new THREE.Vector3(0,0,0), tilt.backward, tilt.up );
			
mt.multiply(mt2);
			
vector.setFromMatrixScale(mt);

but it still doesn’t produce the correct results…
I’m trying to basically scale/resize along a rotated axis.
Can anyone give me some clues as to what I am doing wrong?

2

Does this answer your question?

3

no… I’m not trying to change the scale. I’m cycling through vertices and adjusting their position (I need to do it this way).
I found a way to accomplish it, but if anyone knows how to simplify it, I’d like to know…
Here is what I have:

projectedVert.copy(vertPos);
projectedVert.sub( resizeOrigin.position);
projectedVert.projectOnVector( tilt.right );
projectedVert2.copy(projectedVert);
projectedVert.multiplyScalar( x );
projectedVert.sub(projectedVert2);
vertPos.add( projectedVert );
						
projectedVert.copy(vertPos);
projectedVert.sub( resizeOrigin.position);
projectedVert.projectOnVector( tilt.up );
projectedVert2.copy(projectedVert);
projectedVert.multiplyScalar( y );
projectedVert.sub(projectedVert2);
vertPos.add( projectedVert );
						
projectedVert.copy(vertPos);
projectedVert.sub( resizeOrigin.position);
projectedVert.projectOnVector( tilt.backward );
projectedVert2.copy(projectedVert);
projectedVert.multiplyScalar( z );
projectedVert.sub(projectedVert2);
vertPos.add( projectedVert );

This basically takes a vertex and resizes its position relative to the resizeOrigin, which could be located anywhere. The tilt.right, tilt.up stuff are normalized vectors that represent an axis from the resizeOrigin, and they can be angled at any direction. So the x, y, and z values are the amount to scale the vert positions along those axis…

If anyone knows of a simpler way to accomplish this, I’d be interested, because it seems like it doesn’t work if I try to resize everything all at once- I have to split each axis up and resize them separately like this for it to work.