added some helper methods to VectorFloat

src/main/java/de/neemann/digital/draw/graphics/Polygon.java

@@ -84,7 +84,7 @@ public class Polygon implements Iterable<VectorInterface> {
      * @param p  the end point to add
      * @return this for chained calls
      */
-    public Polygon add(Vector c1, Vector c2, Vector p) {
+    public Polygon add(VectorInterface c1, VectorInterface c2, VectorInterface p) {
         isBezierStart.add(points.size());
         points.add(c1);
         points.add(c2);

src/main/java/de/neemann/digital/draw/graphics/VectorFloat.java

@@ -51,6 +51,16 @@ public class VectorFloat implements VectorInterface {
         return tr.transform(this);
     }
 
+    /**
+     * Creates a new vector which has the value this+a
+     *
+     * @param a a
+     * @return this+a
+     */
+    public VectorFloat add(VectorInterface a) {
+        return new VectorFloat(x + a.getXFloat(), y + a.getYFloat());
+    }
+
     /**
      * Subtracts the given vector
      *
@@ -61,6 +71,26 @@ public class VectorFloat implements VectorInterface {
         return new VectorFloat(x - sub.getXFloat(), y - sub.getYFloat());
     }
 
+    /**
+     * Creates a new vector which has the value this*a
+     *
+     * @param a a
+     * @return this*a
+     */
+    public VectorFloat mul(int a) {
+        return new VectorFloat(x * a, y * a);
+    }
+
+    /**
+     * Creates a new vector which has the value this/d
+     *
+     * @param d a
+     * @return this/d
+     */
+    public VectorFloat div(int d) {
+        return new VectorFloat(x / d, y / d);
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;