From 36be938d2a1c5eb44ad88c7181ad82ba47694eb0 Mon Sep 17 00:00:00 2001
From: Stewart Allen <sa@grid.space>
Date: Mon, 6 Sep 2021 18:10:34 -0400
Subject: [PATCH] add geo/mesh class to contain repair utilities

---
 app.js             |   2 +
 src/geo/mesh.js    | 182 +++++++++++++++++++++++++++++++++++++++++++++
 src/kiri/slicer.js |   3 +-
 src/kiri/widget.js |   5 ++
 4 files changed, 190 insertions(+), 2 deletions(-)
 create mode 100644 src/geo/mesh.js

diff --git a/app.js b/app.js
index 23851022..3710c608 100644
--- a/app.js
+++ b/app.js
@@ -240,6 +240,7 @@ const script = {
         "geo/polygon",
         "geo/polygons",
         // "geo/gyroid",
+        "geo/mesh",
         "moto/kv",
         "moto/ajax",
         "moto/ctrl",
@@ -300,6 +301,7 @@ const script = {
         "geo/polygon",
         "geo/polygons",
         "geo/gyroid",
+        "geo/mesh",
         "moto/pack",
         "kiri/slice",
         "kiri/slicer",
diff --git a/src/geo/mesh.js b/src/geo/mesh.js
new file mode 100644
index 00000000..56b6e610
--- /dev/null
+++ b/src/geo/mesh.js
@@ -0,0 +1,182 @@
+/** Copyright Stewart Allen <sa@grid.space> -- All Rights Reserved */
+
+"use strict";
+
+(function() {
+
+    const BASE = self.base = self.base || {};
+
+    if (BASE.Mesh) {
+        return;
+    }
+
+    BASE.Mesh = class Mesh {
+        constructor(params = {}) {
+            this.precision = params.precision || 6;
+            if (params.vertices) {
+                this.setData(params.vertices, params.faces);
+            }
+        }
+
+        /**
+         * set vertices and faces of the mesh. if only vertices are provided
+         * then the data is assumed to be un-indexed and will be indexed into
+         * faces. if faces are provided, they are assumed to be index references
+         * into the vertex data.
+         * 
+         * the end result is face data mapped to an indexed set of unique vertices.
+         * 
+         * @param {number[]} vertices 
+         * @param {number[]} faces 
+         */
+        setData(vertices, faces) {
+            if (!vertices) {
+                throw "missing vertices";
+            }
+            if (vertices.length % 3 !== 0) {
+                throw "invalid vertices";
+            }
+            // when face/index data is missing, vertices need to be normalized
+            if (!faces) {
+                faces = [];
+                let nuvt = []; // new vertex list
+                let hash = {}; // find vertex matches
+                let prec = this.precision;
+                for (let i=0, l=vertices.length; i<l; i += 3) {
+                    let x = vertices[i];
+                    let y = vertices[i+1];
+                    let z = vertices[i+2];
+                    let key = [
+                        x.toFixed(prec),
+                        y.toFixed(prec),
+                        z.toFixed(prec)
+                    ].join(',');
+                    let vpos = hash[key];
+                    if (vpos === undefined) {
+                        hash[key] = vpos = nuvt.length;
+                        nuvt.push(x);
+                        nuvt.push(y);
+                        nuvt.push(z);
+                    }
+                    faces.push(vpos);
+                }
+                vertices = nuvt;
+            }
+            this.vertices = vertices;
+            this.faces = faces;
+            return this;
+        }
+
+        heal() {
+            // construct ordered line map with array of connected lines
+            // for each point pair, create ordered line
+            // for each face triple, add lines to connect line array
+            let vertices = this.vertices;
+            let faces = this.faces;
+            let hash = {}; // key to line map
+            let vmap = {}; // vertext to line map
+            let lines = [];
+
+            class Line {
+                constructor(v1, v2) {
+                    this.v1 = v1;
+                    this.v2 = v2;
+                    this.peers = [];
+                    this.faces = [];
+                }
+
+                addPeers(lines, face) {
+                    this.peers.appendAll(lines);
+                    if (this.faces.indexOf(face) < 0) {
+                        this.faces.push(face);
+                    }
+                }
+            }
+
+            function getLine(v1, v2) {
+                let s1 = vertices[v1] + vertices[v1+1]*1000 + vertices[v1+2]*100000;
+                let s2 = vertices[v2] + vertices[v2+1]*1000 + vertices[v2+2]*100000;
+                let key = s1 <= s2 ? [v1,v2].join('-') : [v2,v1].join('-');
+                let line = hash[key];
+                if (!line) {
+                    // point order will be swapped for reconstructed faces
+                    // to preserve chirality (assuming face normals are correct)
+                    line = hash[key] = new Line(v1, v2);
+                    lines.push(line);
+                    let lm1 = vmap[v1] = vmap[v1] || [];
+                    let lm2 = vmap[v2] = vmap[v2] || [];
+                    lm1.push(line);
+                    lm2.push(line);
+                }
+                return line;
+            }
+
+            for (let i=0, l=this.faces.length; i<l; i += 3) {
+                let v1 = faces[i];
+                let v2 = faces[i+1];
+                let v3 = faces[i+2];
+                let l1 = getLine(v1, v2);
+                let l2 = getLine(v2, v3);
+                let l3 = getLine(v3, v1);
+                l1.addPeers([l2, l3], i);
+                l2.addPeers([l3, l1], i);
+                l3.addPeers([l1, l2], i);
+            }
+
+            this.lines = lines;
+
+            // lines belonging to only one face or with only 2 peers
+            // are on the edge of a hole
+            let edges = lines.filter(l => l.faces.length === 1);
+            console.log({edges});
+
+            let loops = [];
+
+            // connect edge lines into closed loops
+            for (let i=0, l=edges.length; i<l; i++) {
+                let line = edges[i];
+                if (line.used) {
+                    continue;
+                }
+                line.used = true;
+                let loop = [ line ];
+                // build line through adjacent lines
+                while (true) {
+                    let adjacent = vmap[line.v1].concat(vmap[line.v2]).filter(l => l !== line && !l.used && l.faces.length === 1);
+                    if (adjacent.length === 0) {
+                        break;
+                    }
+                    if (adjacent.length > 2) {
+                        console.log('error adjacent', adjacent);
+                        break;
+                    }
+                    line = adjacent[0];
+                    loop.push(line);
+                    line.used = true;
+                }
+                console.log({loop});
+                // drop co-linear points because they can't be connected into valid faces
+                // fixup remaining line by dropping common point and using dropped line's point
+                for (let j=0, jl=loop.length; j<jl-1; j++) {
+                    let l1 = loop[j];
+                    if (l1.del) {
+                        continue;
+                    }
+                    for (let k=j+1; k<jl; k++) {
+                        let l2 = loop[k];
+                        if (l2.del) {
+                            continue;
+                        }
+                        // todo
+                    }
+                }
+                loops.push(loop);
+            }
+
+            console.log({loops});
+
+            return this;
+        }
+    };
+
+})();
diff --git a/src/kiri/slicer.js b/src/kiri/slicer.js
index 7bb0317e..f5f30096 100644
--- a/src/kiri/slicer.js
+++ b/src/kiri/slicer.js
@@ -26,8 +26,7 @@
         tracker = UTIL.pwait,
         newSlice = KIRI.newSlice,
         newOrderedLine = BASE.newOrderedLine,
-        beltfact = Math.cos(Math.PI/4),
-        ibeltfact = 1/beltfact;
+        beltfact = Math.cos(Math.PI/4);
 
     /**
      * Convenience method. Gets a Widget's points and calls slice()
diff --git a/src/kiri/widget.js b/src/kiri/widget.js
index b11967cd..d3fb29bd 100644
--- a/src/kiri/widget.js
+++ b/src/kiri/widget.js
@@ -303,6 +303,11 @@ console.log/** Copyright Stewart Allen <sa@grid.space> -- All Rights Reserved */
         }
     };
 
+    PRO.debugMesh = function(precision) {
+        let mesh = new base.Mesh({precision, vertices: this.getVertices().array});
+        return mesh;
+    };
+
     PRO.getVertices = function() {
         return this.mesh.geometry.attributes.position;
     };