Conics (#900)

* sketch out ellipse endpoints

* change center to 2d

* added conic endpoint

* don't need Ellipseto

* Update modeling-cmds/src/shared.rs

Co-authored-by: Jonathan Tran <jonnytran@gmail.com>

---------

Co-authored-by: Jonathan Tran <jonnytran@gmail.com>

Author: benjamaan476

modeling-cmds/src/shared.rs

@@ -340,6 +340,33 @@ pub enum PathSegment {
         ///from the end of the involute, otherwise it will start from that start.
         reverse: bool,
     },
+    ///Adds an elliptical arc segment.
+    Ellipse {
+        /// The center point of the ellipse.
+        center: Point2d<LengthUnit>,
+        /// Major radius of the ellipse (along the x axis).
+        major_radius: LengthUnit,
+        /// Minor radius of the ellipse (along the y axis).
+        minor_radius: LengthUnit,
+        /// Start of the path along the perimeter of the ellipse.
+        start_angle: Angle,
+        /// End of the path along the perimeter of the ellipse.
+        end_angle: Angle,
+    },
+    ///Adds a generic conic section specified by the end point, interior point and tangents at the
+    ///start and end of the section.
+    ConicTo {
+        /// Interior point that lies on the conic.
+        interior: Point2d<LengthUnit>,
+        /// End point of the conic.
+        end: Point2d<LengthUnit>,
+        /// Tangent at the start of the conic.
+        start_tangent: Point2d<LengthUnit>,
+        /// Tangent at the end of the conic.
+        end_tangent: Point2d<LengthUnit>,
+        /// Whether or not the interior and end points are relative to the previous path position.
+        relative: bool,
+    },
 }
 
 /// An angle, with a specific unit.