Can someone help find the bug here?

OpenGL Development JOGL Development
#1

This original from my c++ code was an inclass quiz…the java version I’m doing just for the heck of it. Not for a grade. Can someone point out what I need to do to
get display draw Triangle in a loop - should print the # of triangles specified by the variable “num”

thanks…Bernie

import javax.media.opengl.;
import javax.swing.;

public class Quiz1{

public static void main (String []args){
final int num = 1;
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame jframe = new JFrame(Quiz1.class.getSimpleName());
jframe.setSize(500,500);
jframe.setLocationRelativeTo(null);//center of screen

  GLCanvas canvas = new GLCanvas();
  
  canvas.addGLEventListener(new GLEventListener(){
      public void init(GLAutoDrawable drawable){}
      
      public void display(GLAutoDrawable drawable){
          GL gl = drawable.getGL();
          
          for (int i = 0; i< num; i++){
              gl.glPushMatrix();
              gl.glScalef(1/num,1/num,1);
              gl.glTranslatef((1/num*i), 0, 0);
              
              drawTriangle();
              gl.glPopMatrix();
              
            }
        }
        public void drawTriangle(){
            gl.glClearColor(0.0f,0.0f,0.0f,0.0f);
            gl.glClear(GL.GL_COLOR_BUFFER_BIT);
            gl.glColor3f(1.0f,1.0f,0.0f);
            gl.glMatrixMode(GL.GL_PROJECTION);
            gl.glLoadIsentity();
            gl.glOrtho2D(0,1,0,1);
            gl.glBegin(GL.GL_POLYGON);
            gl.glVertex2f(0.0,0.0);
            gl.glVertex2f(.5,1.0);
            gl.glVertex2f(1.0,0.0);
            gl.glEnd();
            gl.glFlush();
        }
    
    
    public void reshape(GLAutoDrawable drawable, int x, int y, int width, int height) {}
    
    public void displayChanged(GLAutoDrawable drawable, boolean modeChanged, boolean deviceChanged){}
    
});
jframe.add(canvas);
jframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jframe.setVisible(true);

}
}

#2 
    I attach the original quiz with graphic output sample for your perusal.

thanks very much

bernie

–eager noob

#3

This doesn’t really have anything to do with OpenGL or jogl. Maybe this should be moved to the newless clubies forum…

public static void main(String[] args) {
    int num = 0;
    
    BufferedReader r = new BufferedReader(new InputStreamReader(System.in));
    boolean done = false;
    while (!done) {
      try {
        System.out.println("How many?");
        String input = r.readLine();
        num = Integer.parseInt(input);
        done = true;
      } catch (NumberFormatException e) {
        System.out.println("Invalid number entered; Please try again");
      } catch (IOException e) {
        System.out.println("Error reading from stdin: " + e.getMessage());
        return;
      }
    }

    System.out.println(num + " triangles...");
}