The Tor Browser: comparison browser/devtools/tilt/TiltWorkerPicker.js

comparison: browser/devtools/tilt/TiltWorkerPicker.js

browser/devtools/tilt/TiltWorkerPicker.js

changeset 0: 6474c204b198

equal deleted inserted replaced

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+:ffbb672d0d9d
+/* -*- 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;
+};
+}());