From 9ef76536ca78b47beaed4b5bedd9d99df4d6a1cd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Matt=C3=A9o=20Delabre?= <spam@delab.re>
Date: Sat, 9 May 2020 14:29:54 +0200
Subject: [PATCH] Integrate obstacles in repel force

---
 boids.mjs    | 34 ++++++++++++++++------------------
 geometry.mjs | 20 +++++++++-----------
 2 files changed, 25 insertions(+), 29 deletions(-)

diff --git a/boids.mjs b/boids.mjs
index 9aed1a8..e9a2ebc 100644
--- a/boids.mjs
+++ b/boids.mjs
@@ -79,11 +79,9 @@ class Boids
 
         // List of active simulated boids
         this.boids = [];
-        this.boidsLength = 0;
 
         // List of obstacles
         this.obstacles = obstacles;
-        this.obstaclesLength = this.obstacles.length;
 
         // Vector registers used for holding temporary values
         this.registers = [
@@ -122,7 +120,6 @@ class Boids
     add(center)
     {
         this.boids.push(new Boid(this.params, center));
-        this.boidsLength += 1;
     }
 
     /** Start the simulation. */
@@ -174,7 +171,8 @@ class Boids
      */
     _update(delta)
     {
-        const boidsLength = this.boidsLength;
+        const boidsLength = this.boids.length;
+        const obstaclesLength = this.obstacles.length;
 
         for (let i = 0; i < boidsLength; ++i)
         {
@@ -187,7 +185,7 @@ class Boids
             let visibles = 0;
 
             // Compute mean flock position and velocity and compute
-            // the repel force
+            // the repel force from other boids
             for (let j = 0; j < boidsLength; ++j)
             {
                 if (i != j)
@@ -211,6 +209,17 @@ class Boids
                 }
             }
 
+            // Compute the repel force from obstacles
+            for (let j = 0; j < obstaclesLength; ++j)
+            {
+                const obstacle = this.obstacles[j];
+
+                if (obstacle.distance(me.pos) < this.params.closeDist)
+                {
+                    me.vel.add(me.pos).sub(obstacle.center);
+                }
+            }
+
             // Attract towards center of visible flock
             if (visibles >= 1)
             {
@@ -239,17 +248,6 @@ class Boids
                                   .mul(this.params.matchAccel));
             }
 
-            // Avoid obstacles
-            for (let j = 0; j < this.obstaclesLength; ++j)
-            {
-                const obstacle = this.obstacles[j];
-
-                if (obstacle.intersect(me.pos, this.params.radius))
-                {
-                    me.vel.sub(obstacle.center).add(me.pos);
-                }
-            }
-
             // Do not surpass maximum speed
             const speed = me.vel.normSquared();
 
@@ -269,8 +267,8 @@ class Boids
      */
     _draw()
     {
-        const boidsLength = this.boidsLength;
-        const obstaclesLength = this.obstaclesLength;
+        const boidsLength = this.boids.length;
+        const obstaclesLength = this.obstacles.length;
 
         this.ctx.clearRect(
             -this.width / 2, -this.height / 2,
diff --git a/geometry.mjs b/geometry.mjs
index d1dcda5..fa8bf57 100644
--- a/geometry.mjs
+++ b/geometry.mjs
@@ -93,13 +93,11 @@ export class Rectangle
         this.center = new Vector(x + w / 2, y + h / 2);
     }
 
-    intersect(point, radius)
+    distance(point)
     {
-        return (
-            point.x >= this.x - radius
-            && point.x < this.x + this.w + radius
-            && point.y >= this.y - radius
-            && point.y < this.y + this.h + radius
+        return Math.hypot(
+            Math.max(point.x - this.x - this.w, 0, this.x - point.x),
+            Math.max(point.y - this.y - this.h, 0, this.y - point.y),
         );
     }
 
@@ -117,12 +115,12 @@ export class Circle
         this.center = new Vector(x, y);
     }
 
-    intersect(point, radius)
+    distance(point)
     {
-        return (
-            Vector.distSquared(this.center, point)
-            <= (this.r + radius) * (this.r + radius)
-        );
+        return Math.hypot(
+            this.center.x - point.x,
+            this.center.y - point.y,
+        ) - this.r;
     }
 
     draw(ctx)