The Tor Browser: browser/devtools/tilt/TiltWorkerPicker.js@6474c204b198 (annotated)

browser/devtools/tilt/TiltWorkerPicker.js@6474c204b198 (annotated)

browser/devtools/tilt/TiltWorkerPicker.js

Wed, 31 Dec 2014 06:09:35 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Wed, 31 Dec 2014 06:09:35 +0100
changeset 0: 6474c204b198
permissions: -rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

 /* -*- Mode: javascript; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
 /* vim: set ts=2 et sw=2 tw=80: */
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 "use strict";
 /**
  * This worker handles picking, given a set of vertices and a ray (calculates
  * the intersection points and offers back information about the closest hit).
  *
  * Used in the TiltVisualization.Presenter object.
  */
 self.onmessage = function TWP_onMessage(event)
 {
   let data = event.data;
   let vertices = data.vertices;
   let ray = data.ray;
   let intersection = null;
   let hit = [];
   // calculates the squared distance between two points
   function dsq(p1, p2) {
     let xd = p2[0] - p1[0];
     let yd = p2[1] - p1[1];
     let zd = p2[2] - p1[2];
     return xd * xd + yd * yd + zd * zd;
   }
   // check each stack face in the visualization mesh for intersections with
   // the mouse ray (using a ray picking algorithm)
   for (let i = 0, len = vertices.length; i < len; i += 36) {
     // the front quad
     let v0f = [vertices[i],      vertices[i + 1],  vertices[i + 2]];
     let v1f = [vertices[i + 3],  vertices[i + 4],  vertices[i + 5]];
     let v2f = [vertices[i + 6],  vertices[i + 7],  vertices[i + 8]];
     let v3f = [vertices[i + 9],  vertices[i + 10], vertices[i + 11]];
     // the back quad
     let v0b = [vertices[i + 24], vertices[i + 25], vertices[i + 26]];
     let v1b = [vertices[i + 27], vertices[i + 28], vertices[i + 29]];
     let v2b = [vertices[i + 30], vertices[i + 31], vertices[i + 32]];
     let v3b = [vertices[i + 33], vertices[i + 34], vertices[i + 35]];
     // don't do anything with degenerate quads
     if (!v0f[0] && !v1f[0] && !v2f[0] && !v3f[0]) {
       continue;
     }
     // for each triangle in the stack box, check for the intersections
     if (self.intersect(v0f, v1f, v2f, ray, hit) || // front left
         self.intersect(v0f, v2f, v3f, ray, hit) || // front right
         self.intersect(v0b, v1b, v1f, ray, hit) || // left back
         self.intersect(v0b, v1f, v0f, ray, hit) || // left front
         self.intersect(v3f, v2b, v3b, ray, hit) || // right back
         self.intersect(v3f, v2f, v2b, ray, hit) || // right front
         self.intersect(v0b, v0f, v3f, ray, hit) || // top left
         self.intersect(v0b, v3f, v3b, ray, hit) || // top right
         self.intersect(v1f, v1b, v2b, ray, hit) || // bottom left
         self.intersect(v1f, v2b, v2f, ray, hit)) { // bottom right
       // calculate the distance between the intersection hit point and camera
       let d = dsq(hit, ray.origin);
       // we're picking the closest stack in the mesh from the camera
       if (intersection === null || d < intersection.distance) {
         intersection = {
           // each mesh stack is composed of 12 vertices, so there's information
           // about a node once in 12 * 3 = 36 iterations (to avoid duplication)
           index: i / 36,
           distance: d
         };
       }
     }
   }
   self.postMessage(intersection);
   close();
 };
 /**
  * Utility function for finding intersections between a ray and a triangle.
  */
 self.intersect = (function() {
   // creates a new instance of a vector
   function create() {
     return new Float32Array(3);
   }
   // performs a vector addition
   function add(aVec, aVec2, aDest) {
     aDest[0] = aVec[0] + aVec2[0];
     aDest[1] = aVec[1] + aVec2[1];
     aDest[2] = aVec[2] + aVec2[2];
     return aDest;
   }
   // performs a vector subtraction
   function subtract(aVec, aVec2, aDest) {
     aDest[0] = aVec[0] - aVec2[0];
     aDest[1] = aVec[1] - aVec2[1];
     aDest[2] = aVec[2] - aVec2[2];
     return aDest;
   }
   // performs a vector scaling
   function scale(aVec, aVal, aDest) {
     aDest[0] = aVec[0] * aVal;
     aDest[1] = aVec[1] * aVal;
     aDest[2] = aVec[2] * aVal;
     return aDest;
   }
   // generates the cross product of two vectors
   function cross(aVec, aVec2, aDest) {
     let x = aVec[0];
     let y = aVec[1];
     let z = aVec[2];
     let x2 = aVec2[0];
     let y2 = aVec2[1];
     let z2 = aVec2[2];
     aDest[0] = y * z2 - z * y2;
     aDest[1] = z * x2 - x * z2;
     aDest[2] = x * y2 - y * x2;
     return aDest;
   }
   // calculates the dot product of two vectors
   function dot(aVec, aVec2) {
     return aVec[0] * aVec2[0] + aVec[1] * aVec2[1] + aVec[2] * aVec2[2];
   }
   let edge1 = create();
   let edge2 = create();
   let pvec = create();
   let tvec = create();
   let qvec = create();
   let lvec = create();
   // checks for ray-triangle intersections using the Fast Minimum-Storage
   // (simplified) algorithm by Tomas Moller and Ben Trumbore
   return function intersect(aVert0, aVert1, aVert2, aRay, aDest) {
     let dir = aRay.direction;
     let orig = aRay.origin;
     // find vectors for two edges sharing vert0
     subtract(aVert1, aVert0, edge1);
     subtract(aVert2, aVert0, edge2);
     // begin calculating determinant - also used to calculate the U parameter
     cross(dir, edge2, pvec);
     // if determinant is near zero, ray lines in plane of triangle
     let inv_det = 1 / dot(edge1, pvec);
     // calculate distance from vert0 to ray origin
     subtract(orig, aVert0, tvec);
     // calculate U parameter and test bounds
     let u = dot(tvec, pvec) * inv_det;
     if (u < 0 || u > 1) {
       return false;
     }
     // prepare to test V parameter
     cross(tvec, edge1, qvec);
     // calculate V parameter and test bounds
     let v = dot(dir, qvec) * inv_det;
     if (v < 0 || u + v > 1) {
       return false;
     }
     // calculate T, ray intersects triangle
     let t = dot(edge2, qvec) * inv_det;
     scale(dir, t, lvec);
     add(orig, lvec, aDest);
     return true;
   };
 }());