circular gradient module (#1496)

* circular gradient module

* circular gradient option inside gradient module

* Added test for gradient module

* final shadow module with module test

Co-authored-by: Jeffrey Warren <jeff@unterbahn.com>

src/modules/Gradient/Module.js

@@ -3,6 +3,9 @@ const pixelSetter = require('../../util/pixelSetter.js'),
 
 module.exports = function Gradient(options, UI) {
 
+  var defaults = require('./../../util/getDefaults.js')(require('./info.json'));
+  options.gradientType = options.gradientType || defaults.gradientType;
+
   var output;
 
   // The function which is called on every draw.
@@ -15,6 +18,7 @@ module.exports = function Gradient(options, UI) {
 
     function extraManipulation(pixels) {
       const [w, h] = pixels.shape;
+      if (options.gradientType === 'linear') {
         for (var i = 0; i < w; i++) {
           for (var j = 0; j < h; j++) {
             let val = (i / w) * 255;
@@ -22,6 +26,18 @@ module.exports = function Gradient(options, UI) {
             pixelSetter(i, j, [val, val, val, 255], pixels);
           }
         }
+      }
+      else {
+        for (var i = 0; i < w; i++) {
+          for (var j = 0; j < h; j++) {
+            var distX = Math.abs(w / 2 - i);
+            var distY = Math.abs(h / 2 - j);
+            var distance = Math.sqrt(Math.pow(distX, 2) + Math.pow(distY, 2));
+            val = 255 * (distance / pixels.shape[0]);
+            pixelSetter(i, j, [val, val, val, 255], pixels);
+          }
+        }
+      }
 
       return pixels;
     }

src/modules/Gradient/info.json

@@ -1,6 +1,13 @@
 {
     "name": "gradient",
     "description": "Gives a gradient of the image",
-    "inputs": {},
+    "inputs": {
+      "gradientType": {
+        "type": "select",
+        "desc": "Choose between linear or circular gradient",
+        "default": "linear",
+        "values": ["linear", "circular"]
+      }
+    },
     "docs-link":"https://github.com/publiclab/image-sequencer/blob/main/docs/MODULES.md#gradient-module"
 }