From 69da5dcd16903683532c923c403c5fdfe99c0c8e Mon Sep 17 00:00:00 2001
From: Val Erastov <xibyte@gmail.com>
Date: Tue, 6 Dec 2016 23:42:38 -0800
Subject: [PATCH] ellipse tangent constraint math / 'Grater Than' constraint
 math

---
 web/app/sketcher/constr/constraints.js | 92 ++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/web/app/sketcher/constr/constraints.js b/web/app/sketcher/constr/constraints.js
index edfda92b..6b75b473 100644
--- a/web/app/sketcher/constr/constraints.js
+++ b/web/app/sketcher/constr/constraints.js
@@ -25,6 +25,8 @@ function createByConstraintName(name, params, values) {
       return new P2PDistanceV(params);
     case "PointOnEllipse":
       return new PointOnEllipse(params);
+    case "EllipseTangent":
+      return new EllipseTangent(params);
     case "angle":
       return new Angle(params);
     case "angleConst":
@@ -33,6 +35,9 @@ function createByConstraintName(name, params, values) {
       return new ConstantWrapper(new Angle(params), [x,x,x,x,x,x,x,x,_]);
     case 'LockConvex':
       return new LockConvex(params);
+    case 'GreaterThan':
+      return new GreaterThan(params, values[0]);
+    
   }
 }
 
@@ -540,6 +545,93 @@ function PointOnEllipse(params) {
   this.gradient = NumericGradient;
 }
 
+/** @constructor */
+function EllipseTangent(params) {
+
+  this.params = params;
+
+  const P1X = 0;
+  const P1Y = 1;
+  const P2X = 2;
+  const P2Y = 3;
+  const EP1X = 4;
+  const EP1Y = 5;
+  const EP2X = 6;
+  const EP2Y = 7;
+  const R = 8;
+
+  this.error = function(gr) {
+    let p1x = params[P1X].get();
+    let p1y = params[P1Y].get();
+    let p2x = params[P2X].get();
+    let p2y = params[P2Y].get();
+
+    let ep1x = params[EP1X].get();
+    let ep1y = params[EP1Y].get();
+    let ep2x = params[EP2X].get();
+    let ep2y = params[EP2Y].get();
+    
+    const radiusY = params[R].get();
+
+    let axisX = ep2x - ep1x;
+    let axisY = ep2y - ep1y;
+    const radiusX = Math.sqrt(sq(axisX) + sq(axisY)) * 0.5;
+    const scaleToCircleSpace = radiusY / radiusX;
+    const rotation = - Math.atan2(axisY, axisX);
+    function tr(x, y) {
+      let xx =  x * Math.cos(rotation) - y * Math.sin(rotation)
+      let yy =  x * Math.sin(rotation) + y * Math.cos(rotation);
+      xx *= scaleToCircleSpace;
+      return {x: xx, y: yy};
+    }
+    
+    const axis = tr(axisX, axisY);
+    const p1 = tr(p1x, p1y);
+    const p2 = tr(p2x, p2y);
+    const ep1 = tr(ep1x, ep1y);
+
+    const centerX = ep1.x + axis.x * 0.5;
+    const centerY = ep1.y + axis.y * 0.5;
+    
+    
+    let normalX = -(p2.y - p1.y);
+    let normalY =   p2.x - p1.x;
+    
+    const normalD = Math.sqrt(sq(normalX) + sq(normalY));
+    normalX /= normalD;
+    normalY /= normalD;
+      
+      //this length of normal of line to center 
+    let perpendicularLength = (centerX - p1.x) * normalX + (centerY - p1.y) * normalY;
+
+    if (perpendicularLength < 0) {
+      perpendicularLength *= -1;
+    } else {
+    }
+    
+    return (radiusY - perpendicularLength); //*1000;
+  };
+
+  this.gradient = NumericGradient;
+}
+
+function GreaterThan(params, limit) {
+
+  this.params = params;
+  
+  this.error = function() {
+    let value = this.params[0].get();
+    var error = value <= limit ? limit - value : 0;
+    console.log("GreaterThan: " + error + ", value: " +value);
+    return error;
+  };
+
+  this.gradient = function(out) {
+    out[0] = -1;
+  }
+}
+
+
 function NumericGradient(out) {
   const h = 1;
   const approx = (param) => {