Fixed curvePoint and curveTangent ignoring curveTightness

.all-contributorsrc

@@ -3018,6 +3018,15 @@
         "bug"
       ]
     },
+    {
+      "login": "sparshg",
+      "name": "sparshg",
+      "avatar_url": "https://avatars.githubusercontent.com/u/43041139?v=4",
+      "profile": "https://sparshg.github.io",
+      "contributions": [
+        "bug"
+      ]
+    },
     {
       "login": "liz-peng",
       "name": "Liz Peng",

src/core/shape/curves.js

@@ -481,13 +481,13 @@ p5.prototype.curveTightness = function(t) {
  */
 p5.prototype.curvePoint = function(a, b, c, d, t) {
   p5._validateParameters('curvePoint', arguments);
-
-  const t3 = t * t * t,
+  const s = this._renderer._curveTightness,
+    t3 = t * t * t,
     t2 = t * t,
-    f1 = -0.5 * t3 + t2 - 0.5 * t,
-    f2 = 1.5 * t3 - 2.5 * t2 + 1.0,
-    f3 = -1.5 * t3 + 2.0 * t2 + 0.5 * t,
-    f4 = 0.5 * t3 - 0.5 * t2;
+    f1 = (s - 1) / 2 * t3 + (1 - s) * t2 + (s - 1) / 2 * t,
+    f2 = (s + 3) / 2 * t3 + (-5 - s) / 2 * t2 + 1.0,
+    f3 = (-3 - s) / 2 * t3 + (s + 2) * t2 + (1 - s) / 2 * t,
+    f4 = (1 - s) / 2 * t3 + (s - 1) / 2 * t2;
   return a * f1 + b * f2 + c * f3 + d * f4;
 };
 
@@ -529,11 +529,13 @@ p5.prototype.curvePoint = function(a, b, c, d, t) {
 p5.prototype.curveTangent = function(a, b, c, d, t) {
   p5._validateParameters('curveTangent', arguments);
 
-  const t2 = t * t,
-    f1 = -3 * t2 / 2 + 2 * t - 0.5,
-    f2 = 9 * t2 / 2 - 5 * t,
-    f3 = -9 * t2 / 2 + 4 * t + 0.5,
-    f4 = 3 * t2 / 2 - t;
+  const s = this._renderer._curveTightness,
+    tt3 = t * t * 3,
+    t2 = t * 2,
+    f1 = (s - 1) / 2 * tt3 + (1 - s) * t2 + (s - 1) / 2,
+    f2 = (s + 3) / 2 * tt3 + (-5 - s) / 2 * t2,
+    f3 = (-3 - s) / 2 * tt3 + (s + 2) * t2 + (1 - s) / 2,
+    f4 = (1 - s) / 2 * tt3 + (s - 1) / 2 * t2;
   return a * f1 + b * f2 + c * f3 + d * f4;
 };