From fbb6d63e0338f681bd624e49f28bd10535ca72c8 Mon Sep 17 00:00:00 2001
From: Florrie <towerofnix@gmail.com>
Date: Fri, 28 Dec 2018 10:39:42 -0400
Subject: [PATCH] Clamp ghost effect

Cherry-picked from 35c88904253f7f8ef494a32c2644157fbe4d45cb (#1887)
---
 src/blocks/scratch3_looks.js | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/src/blocks/scratch3_looks.js b/src/blocks/scratch3_looks.js
index ebf40e555..94d70ea5b 100644
--- a/src/blocks/scratch3_looks.js
+++ b/src/blocks/scratch3_looks.js
@@ -4,6 +4,7 @@ const RenderedTarget = require('../sprites/rendered-target');
 const uid = require('../util/uid');
 const StageLayering = require('../engine/stage-layering');
 const getMonitorIdForBlockWithArgs = require('../util/get-monitor-id');
+const MathUtil = require('../util/math-util');
 
 /**
  * @typedef {object} BubbleState - the bubble state associated with a particular target.
@@ -67,6 +68,14 @@ class Scratch3LooksBlocks {
         return 330;
     }
 
+    /**
+     * Limit for ghost effect
+     * @const {object}
+     */
+    static get EFFECT_GHOST_LIMIT (){
+        return {min: 0, max: 100};
+    }
+
     /**
      * @param {Target} target - collect bubble state for this target. Probably, but not necessarily, a RenderedTarget.
      * @returns {BubbleState} the mutable bubble state associated with that target. This will be created if necessary.
@@ -479,13 +488,23 @@ class Scratch3LooksBlocks {
         const effect = Cast.toString(args.EFFECT).toLowerCase();
         const change = Cast.toNumber(args.CHANGE);
         if (!util.target.effects.hasOwnProperty(effect)) return;
-        const newValue = change + util.target.effects[effect];
+        let newValue = change + util.target.effects[effect];
+        if (effect === 'ghost') {
+            newValue = MathUtil.clamp(newValue,
+                Scratch3LooksBlocks.EFFECT_GHOST_LIMIT.min,
+                Scratch3LooksBlocks.EFFECT_GHOST_LIMIT.max);
+        }
         util.target.setEffect(effect, newValue);
     }
 
     setEffect (args, util) {
         const effect = Cast.toString(args.EFFECT).toLowerCase();
-        const value = Cast.toNumber(args.VALUE);
+        let value = Cast.toNumber(args.VALUE);
+        if (effect === 'ghost') {
+            value = MathUtil.clamp(value,
+                Scratch3LooksBlocks.EFFECT_GHOST_LIMIT.min,
+                Scratch3LooksBlocks.EFFECT_GHOST_LIMIT.max);
+        }
         util.target.setEffect(effect, value);
     }