How to find wall thickness of 3d models (STL) files?

Questions
40

Hi,
i have read all discussion going on, and i am also facing such kind of problem.
below is my current code:
var minDist = 0.6;
var raycaster = new THREE.Raycaster();
var intersects = [];
var pos = threejsobject.position; //positions of geometry
var ori = new THREE.Vector3();
var dir = new THREE.Vector3();
var trc = new THREE.Vector3();
var a = new THREE.Vector3(),
b = new THREE.Vector3(),
c = new THREE.Vector3(),
midPoint = new THREE.Vector3(),
tri = new THREE.Triangle();
var closest = new THREE.Vector3();
var faces = threejsobject.positioncount; // faces of geometry
console.log(“Faces:”+faces);
for (let i = 0; i < faces; i++) {
a.fromBufferAttribute(pos, i * 3 + 0);
b.fromBufferAttribute(pos, i * 3 + 1);
c.fromBufferAttribute(pos, i * 3 + 2);
tri.set(a, b, c);
console.log(tri);
// tri.getMidpoint(ori);
// get some random point on face
let r0 = 0.33 * Math.random();
let r1 = 0.33 * Math.random();
let r2 = 1.0 - r0 - r1;

		    let ori = new THREE.Vector3(
		        r0*a.x + r1*b.x + r2*c.x,
		        r0*a.y + r1*b.y + r2*c.y,
		        r0*a.z + r1*b.z + r2*c.z
		    );
		    tri.getNormal(dir);
		    raycaster.set(ori, dir.negate());
		    intersects = raycaster.intersectObject(mesh);
		
		    //minDist = Math.min(minDist, intersects[intersects.length > 1 ? 1 : 0].distance);
		    minDist = intersects[intersects.length > 1 ? 1 : 0].distance;  
	  }
  	console.log("printable:", minDist >= 0.6);

i got correct number of faces of geometry, but sometimes in For Loop “tri.set(a, b, c);” function set/show only one triangle(and not give any result) how ever in some cases it set/show all triangle which finally gives expected result.
Also i gone through the link
https://stackoverflow.com/questions/55126766/improving-raycasting-precision-in-three-js/55159041#55159041

Can anyone suggest where i am going wrong?

Thanks