public void start( Stage primaryStage )
  {
    final double width = 200.0, height = 200.0;
    double centerX = width/2, centerY=height/2;   // center of ellipse and arc
    double radiusX = width*0.4, radiusY=width*0.4;   // radii of ellipse and arc
    double startAngle = 20.0;  // angle to start drawing the arc
    double length = 360.0 - 2*startAngle;     // number of degrees to draw
    
    Arc arc = new Arc( centerX,  centerY,  radiusX,  radiusY, startAngle, length );
    arc.setFill(  Color.YELLOW );
    arc.setType( ArcType.ROUND );  
 
    Pane pane = new Pane( arc );
    Scene scene = new Scene( pane, width, height, Color.BLACK );
    
    primaryStage.setTitle("Pac Man");
    primaryStage.setScene( scene );
    primaryStage.show();
  }

Polygon

JavaFX class Polygon is used for polygons of any number of sides. Here is a program that draws a triangle. Of course, a triangle is a polygon with three sides.

import javafx.stage.*;
import javafx.scene.Scene;  
import javafx.scene.shape.*;
import javafx.scene.paint.*;
import javafx.scene.layout.*; 

public class TriangleSimple extends Application
{
  public void start( Stage primaryStage )
  {
    double sceneWidth = 400.0, sceneHeight = 300.0;
 
    Polygon triangle = new Polygon( 0, 300.0, 400.0, 300.0, 200.0, 0 );
    triangle.setFill( new Color( 0.8, 0.2, 0.1, 1.0) );
     
    Pane pane = new Pane( triangle );
    Scene scene = new Scene( pane, sceneWidth, sceneHeight, Color.FLORALWHITE );
    
    primaryStage.setTitle("Simple Triangle Demo");
    primaryStage.setScene( scene );
    primaryStage.show();
  }
}

The constructor for Polygon looks like this:

public Polygon(double... points)

The parameters are the vertices of the polygon as a comma-separated list, each vertex as two X Y values, with the vertices in clockwise or counter-clockwise order. The number of sides of the polygon is the number of vertices.

Polygon triangle = new Polygon( 0, 300.0, 400.0, 300.0, 200.0, 0 );

1. lower left vertex: 0, 300
2. lower right vertex: 400, 300
3. top vertex: 200, 0

It does not matter which vertex you begin with, but the vertices should be in order. For a triangle, a list of three vertices will always be in order, but with more sides than 3 the order matters. The last point on the list will automatically be connected to the first to close the polygon.

Polygon triangle = new Polygon( 0, 300.0, 400.0, 300.0, 200.0, 0 );

double sceneWidth = 400.0, sceneHeight = 300.0;
...

Polygon triangle = new Polygon( 0, , , , , 0);