From fdb337df28b987dea280ba674e7952c3c64dafc9 Mon Sep 17 00:00:00 2001
From: Stewart Allen <stewart.allen@gmail.com>
Date: Wed, 12 Jan 2022 23:19:24 -0500
Subject: [PATCH] document vertex/line/face selection algorithm

---
 src/mesh/model.js |  5 +++--
 src/mesh/work.js  | 13 ++++++++++---
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/src/mesh/model.js b/src/mesh/model.js
index 0ca8d637..233fa149 100644
--- a/src/mesh/model.js
+++ b/src/mesh/model.js
@@ -259,10 +259,11 @@ mesh.model = class MeshModel extends mesh.object {
         let material = new MeshPhongMaterial( { color: 0x777777, transparent: true, opacity: 0.25 } );
         let sphere = new Mesh( geometry, material );
         let { x, y, z } = point;
+        let { a, b, c } = face;
         sphere.position.set(x,y,z);
         space.scene.add(sphere);
-        worker.model_locate({
-            id: this.id, x, y:-z, z:y, matrix: this.matrix
+        worker.model_select({
+            id: this.id, x, y:-z, z:y, a, b, c, matrix: this.matrix
         }).then(data => {
             console.log('located', data);
         });
diff --git a/src/mesh/work.js b/src/mesh/work.js
index 759ce8b1..3bff726d 100644
--- a/src/mesh/work.js
+++ b/src/mesh/work.js
@@ -101,11 +101,13 @@ let model = {
     },
 
     // given model and point, locate matching vertices, lines, and faces
-    locate(data) {
-        let { id, x, y, z, matrix } = data;
+    select(data) {
+        let { id, x, y, z, a, b, c, matrix } = data;
         let arr = translate_encode(id, matrix);
         let eps = 2;
         for (let i=0, l=arr.length; i<l; ) {
+            // matches here are within radius of a vertex
+            // select all faces that share a matched vertex
             let face = (i/9) | 0;
             let ax = arr[i++];
             let ay = arr[i++];
@@ -114,9 +116,14 @@ let model = {
             let dy = Math.abs(ay - y);
             let dz = Math.abs(az - z);
             if (dz < eps && dy < eps && dz < eps) {
-                console.log(`match @ ${face}`, ax, ay, az);
+                console.log(`match @ ${i-3} = ${face}`, ax, ay, az);
             }
         }
+        // no matches and we look at the line segments from the provided face
+        // to see if x,y,z point was on or near that line. then select the
+        // two faces shared by that line
+        // ---
+        // if no lines match, select the provided face only
         return {};
     }
 };