From a7ff77364d6b3d15eaf38fb09d3a6a10711b7b90 Mon Sep 17 00:00:00 2001
From: bach <bachir@figureslibres.io>
Date: Mon, 12 Jun 2023 23:37:02 +0200
Subject: [PATCH] implemented Gift wrapping algorithm

---
 src/components/ConcernementMapItem.vue | 54 +++++++++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)

diff --git a/src/components/ConcernementMapItem.vue b/src/components/ConcernementMapItem.vue
index 4142fc0..1536cd6 100644
--- a/src/components/ConcernementMapItem.vue
+++ b/src/components/ConcernementMapItem.vue
@@ -88,7 +88,8 @@ export default {
     // }
 
     this.parsePoints()
-    this.getSalientPoints()
+    // this.getSalientPoints()
+    this.getJarvisEnvelopeConvexe()
 
     if (this.salientPoints.length > 3) { // do not build item if it doesn't get enougth salient points
       if (this.canvasMap) {
@@ -229,6 +230,57 @@ export default {
       }
       // console.log(`this.salientPoints ${this.concernement.id}`, this.salientPoints);
     },
+    getJarvisEnvelopeConvexe(){
+      // https://www.geeksforgeeks.org/convex-hull-using-jarvis-algorithm-or-wrapping/
+      // the most left point
+      let l = 0, min_x = null;
+      for (let i = 1; i < this.entites.length; i++) {
+        let entite = this.entites[i];
+        let x = entite.display.ray * Math.cos(entite.display.alpha * (Math.PI/180));
+        if(!min_x || min_x > x){
+          l = i;
+          min_x = x;
+        }
+      }
+      let p = l, q;
+      do {
+        let entite = this.entites[p];
+        let farest = {
+          alpha: entite.display.alpha,
+          ray: entite.display.ray,
+          pos: {
+            x: (entite.display.ray) * Math.cos(entite.display.alpha * (Math.PI/180)),
+            y: (entite.display.ray) * Math.sin(entite.display.alpha * (Math.PI/180))
+          }
+        };
+        this.salientPoints.push(farest);
+
+        q = (p + 1) % this.entites.length;
+        for (let i = 0; i < this.entites.length; i++) {
+          let p_x = (this.entites[p].display.ray + 3) * Math.cos(this.entites[p].display.alpha * (Math.PI/180));
+          let p_y = (this.entites[p].display.ray + 3) * Math.sin(this.entites[p].display.alpha * (Math.PI/180));
+          let i_x = (this.entites[i].display.ray + 3) * Math.cos(this.entites[i].display.alpha * (Math.PI/180));
+          let i_y = (this.entites[i].display.ray + 3) * Math.sin(this.entites[i].display.alpha * (Math.PI/180));
+          let q_x = (this.entites[q].display.ray + 3) * Math.cos(this.entites[q].display.alpha * (Math.PI/180));
+          let q_y = (this.entites[q].display.ray + 3) * Math.sin(this.entites[q].display.alpha * (Math.PI/180));
+          
+          let val = (i_y - p_y) * (q_x - i_x) - (i_x - p_x) * (q_y - i_y);
+
+          if (val > 0){
+            q = i;
+          }
+
+        }
+
+        // Now q is the most counterclockwise with
+        // respect to p. Set p as q for next iteration, 
+        // so that q is added to result 'hull'
+        p = q;
+      } while (p != l) {
+        
+      }
+
+    },
     initCanvasMap (){
       // console.log(`ConcernementsMapItem ${this.concernement.id} initCanvasMap`);
       // record canvas and ctx for rendering (drawing)