From 357db9a248183e70c02423564ef8df0b2c920147 Mon Sep 17 00:00:00 2001
From: Eryn Wells <eryn@erynwells.me>
Date: Sun, 6 Aug 2017 08:24:50 -0700
Subject: [PATCH] [all] Add a ball on click; regenerate the field on right
 click

---
 Metaballs/ViewController.swift | 23 +++++++++++++++++++++--
 MetaballsKit/Metaballs.swift   |  4 ++++
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/Metaballs/ViewController.swift b/Metaballs/ViewController.swift
index 1d1febf..35521da 100644
--- a/Metaballs/ViewController.swift
+++ b/Metaballs/ViewController.swift
@@ -41,17 +41,36 @@ class ViewController: NSViewController, RendererDelegate {
         super.viewWillAppear()
         renderer.mtkView(metalView, drawableSizeWillChange: metalView.drawableSize)
         for _ in 1...10 {
-            let r = Float(20 + arc4random_uniform(50))
-            field.add(ballWithRadius: r)
+            addBallWithRandomRadius()
         }
     }
 
+    override func mouseDown(with event: NSEvent) {
+        addBallWithRandomRadius()
+    }
+
+    override func rightMouseDown(with event: NSEvent) {
+        field.clear()
+        for _ in 1...10 {
+            addBallWithRandomRadius()
+        }
+    }
+
+    // MARK: - Private
+
     private func newErrorView() -> NSView {
         let view = NSView()
         view.layer?.backgroundColor = NSColor.red.cgColor
         return view
     }
 
+    private func addBallWithRandomRadius() {
+        let base = UInt32(view.bounds.width * 0.05)
+        let variance = UInt32(base * 2)
+        let r = Float(base + arc4random_uniform(variance))
+        field.add(ballWithRadius: r)
+    }
+
     // MARK: - RendererDelegate
 
     var renderSize: CGSize {
diff --git a/MetaballsKit/Metaballs.swift b/MetaballsKit/Metaballs.swift
index f229ec8..a4e201d 100644
--- a/MetaballsKit/Metaballs.swift
+++ b/MetaballsKit/Metaballs.swift
@@ -110,6 +110,10 @@ public class Field {
         populateBallBuffer()
     }
 
+    public func clear() {
+        balls.removeAll(keepingCapacity: true)
+    }
+
     // MARK: - Metal Configuration
 
     private var device: MTLDevice?