From c3f29258bea5a6d116d0f6cd4442381d6f359f0f Mon Sep 17 00:00:00 2001
From: Seth Trowbridge <seth111@gmail.com>
Date: Sun, 10 Apr 2022 15:43:43 -0400
Subject: [PATCH] normals trying to figure out whats going on with the random
 normal directions.

---
 app.js    | 13 +++++--------
 region.js | 45 +++++++++++++++++++++++++++++++--------------
 2 files changed, 36 insertions(+), 22 deletions(-)

diff --git a/app.js b/app.js
index 8e26df6..c7151ab 100644
--- a/app.js
+++ b/app.js
@@ -1,31 +1,29 @@
 // @ts-check
 
 import * as T from 'three';
+//import { FaceNormalsHelper } from 'three/examples/jsm/helpers/FaceNormalsHelper.js';
 import { Scene } from './scene.js';
 import Region from "./region.js";
 
 let voxels = [];
 voxels[Region.I(0, 0, 0)] = true;
-voxels[Region.I(1, 0, 0)] = true;
-voxels[Region.I(2, 0, 0)] = true;
-voxels[Region.I(0, 1, 0)] = true;
-voxels[Region.I(1, 1, 0)] = true;
-voxels[Region.I(0, 2, 0)] = true;
 
 
 let surfaceCubeGeometry = new T.BufferGeometry();
 let surfaceCubeObject = new T.Mesh(
     surfaceCubeGeometry,
-    new T.MeshPhongMaterial({color:0x666666, wireframe:false, flatShading:true, side:T.DoubleSide})
+    new T.MeshPhongMaterial({color:0x666666, wireframe:false, flatShading:true, side:T.BackSide})
 );
 
+//var vnh = new FaceNormalsHelper( surfaceCubeObject, 1, 0xff0000 );
+
 let rebuildSurface = inVoxels =>
 {
     let { pos, ind } = Region.Surface(inVoxels);
 
     surfaceCubeGeometry.setAttribute("position", new T.BufferAttribute(pos, 3));
     surfaceCubeGeometry.setIndex(ind);
-    surfaceCubeGeometry.computeVertexNormals(true);
+    //surfaceCubeGeometry.computeVertexNormals();
 };
 rebuildSurface(voxels);
 
@@ -38,7 +36,6 @@ Scene({
         light.position.set(5, 5, -5);
         inScene.add(light)
         inScene.add(surfaceCubeObject);
-
         inScene.add(new T.GridHelper(10, 10));
         inScene.add(new T.AxesHelper( 5 ));
     },
diff --git a/region.js b/region.js
index 2fcdd60..8e451ff 100644
--- a/region.js
+++ b/region.js
@@ -20,10 +20,27 @@ const Region =
     /** @type {Region.BufferBuilder} */
     Surface(inVoxels)
     {
-        var vertices = []; // array of surface vertices
-        var triPointVert = []; // triangle array, contains integer pointers to vertices
-        var vertPointNeighbors = []; // vertex array, contains arrays of integer pointers to vertices
+        var vertices = []; // output position buffer
+        var triPointVert = []; // output index buffer
 
+        var vertPointNeighbors = []; // vertex array, contains arrays of integer pointers to vertices
+        var voxPointVert = []; // for each inVoxel; integer pointer to vertices output buffer
+
+        /*  
+
+        inVoxels
+            |
+        [1 to 1]
+            |
+        voxPointVert---[optional pointers to]---> vertices <---- triPointVert
+                                                     |
+                                                 [1 to 1]
+                                                     |
+                                                 vertPointNeighbors
+                     
+        */
+
+        /** @type {(voxIndex:number)=>[number, boolean]} */
         function Vert(inVoxIndex)
         {
             /*
@@ -35,15 +52,15 @@ const Region =
 
                 Impure refs: voxPointVert, vertPointNeighbors, vertices
             */
-            var voxPointVert = []; // vox array, contains integer pointers to vertices
-            var vertPointer = voxPointVert[inVoxIndex]
-            if(vertPointer === undefined)
+            
+            var vertPointer = voxPointVert[inVoxIndex] 
+            if(vertPointer === undefined)// is there no vertex for this voxel?
             {
-                let vert = Region.XYZ(inVoxIndex);
                 vertPointer = vertices.length;
                 voxPointVert[inVoxIndex] = vertPointer;
+
                 vertPointNeighbors.push([]);
-                vertices.push(vert);
+                vertices.push(Region.XYZ(inVoxIndex));
 
                 return [vertPointer, false];
             }
@@ -119,13 +136,13 @@ const Region =
                 CD = Region.I(x,   y-1, z  );
                 CB = Region.I(x,   y,   z-1);
 
-                if(!inVoxels[BU]){ Face(BU, BC, TC, TU); }
-                if(!inVoxels[BR]){ Face(BC, BR, TR, TC); }
-                if(!inVoxels[TA]){ Face(TA, TU, TC, TR); }
+                if(!inVoxels[BU]){ Face(BU, BC, TC, TU); } // XZ (away from origin) | "top" (these labels assume y-up)
+                if(!inVoxels[BR]){ Face(BC, BR, TR, TC); } // YZ (away from origin) | "side"
+                if(!inVoxels[TA]){ Face(TA, TU, TC, TR); } // XY (away from origin) | "side"
 
-                if(!inVoxels[CL]){ Face(BA, BU, TU, TA); }
-                if(!inVoxels[CD]){ Face(BR, BA, TA, TR); }
-                if(!inVoxels[CB]){ Face(BA, BU, BC, BR); }
+                if(!inVoxels[CL]){ Face(BA, BU, TU, TA); } // YZ (touches the origin) | "side"
+                if(!inVoxels[CD]){ Face(BR, BA, TA, TR); } // XZ (touches the origin) | "bottom"
+                if(!inVoxels[CB]){ Face(BA, BU, BC, BR); } // XY (touches the origin) | "side" <-- this one needs normals flipped
             }
         }