The First Oni Program

The first Oni program is OpenWindow.java, which draws a white triangle on the screen as show below. Press the 'q' key to terminate.

Below is the step-by-step guide to this source code.

Execute the OpenWindow Class

Here are the steps to execute the OpenWindow class under Windows OS. First of all, the following are required:

Java 2 SDK has been installed.

Oni's Java runtime, oni.jar, is ready to be read by -classpass, etc. upon execution.

Oni's DLLs (gl.dll, grt.dll) are ready to be read by setting PATH to a directory where these DLLs exist or by other ways.

To run OpenWindow, a Oni program, after compilation, execute the following command.
> java oni.runtime.OniRuntime OpenWindow
Unlike execution of common Java programs, the program activates the oni.runtime.OniRuntime class and then passes a class to be executed to its argument.

Import Statement

import oni.runtime.OniRuntime;
import oni.runtime.Application;
import oni.gfx.GLGraphics;
import oni.gfx.GLConstants;
import oni.gfx.PixelFormat;
import oni.runtime.event.KeyListener;
import oni.runtime.event.KeyEvent;
First, the classes that control the screen with Oni are imported. The Oni packages used here are:

oni.runtime

oni.gfx

oni.runtime.event

Implement the Application Interface

public class OpenWindow implements Application {
    private int width = 640;
    private int height = 480;

    public void oniMain(OniRuntime oniRuntime, String[] args) {
        ...
    }
    
    public void initGraphics(GLGraphics glGraphics) {
        ...
    }
    
    public void update(GLGraphics glGraphics) {
        ...
    }
}
The class activated by Oni must implement the oni.runtime.Application nterface. This class must be able to be renewed by no-argument constructor. There are three methods that must be implemented by oni.runtime.Application;

oniMain(OniRuntime oniRuntime, String[] args): is called only once when activated.

initGraphics(GLGraphics glGraphics): is called when the initialization of GLGraphics is required (when the window is first displayed, or is changed to full-screen, etc.)

update(GLGraphics glGraphics): is called when drawing on the screen.

Implement the oniMain Method

 
 
  public void oniMain(OniRuntime oniRuntime, String[] args) {

    oniRuntime.addKeyListener(new DemoKeyListener(oniRuntime));
    oniRuntime.createWindow("your first KEEL program", width, height);
    oniRuntime.createGraphicsWithDefaultPixelFormat();

    oniRuntime.run();

    System.out.println("Never called.");
}

   This program does the following.
  
    Specifies oni.runtime.event.KeyListener 
      objects that handle key input events.
    Specifies a window title and screen size. 
    3. Defines the default display setting, oni.gfx.PixelFormat.
  
   When the Application class is activated, this method is called first. The 
    argument, oni.runtime.OniRuntime 
    is a class that controls the screen. To create an actual screen, an instance 
    of OniRuntime must be retrieved and handled. After completing the settings 
    to the OniRuntime instance, the screen is displayed by calling the
    run 
 	method. Once the run method is called, the program will not proceed 
    further than that statement.
  

Define the initGraphics 
  and update Methods
 
  public void initGraphics(GLGraphics glGraphics) {
    glGraphics.glOrtho(0, width, 0, height, -1, 1);
    glGraphics.glScalef(1.0f, -1.0f, 1.0f);
    glGraphics.glTranslatef(0, -height, 0);
}

public void update(GLGraphics glGraphics) {
    glGraphics.glClear(GLConstants.GL_COLOR_BUFFER_BIT);
    drawTriangle(glGraphics);
    glGraphics.glFlush();
}

public void quitRequested() {

}

private void drawTriangle(GLGraphics glGraphics) {
    int topY = height / 3;
    int bottomY = (height / 3) * 2;
    int centerX = width / 2;
    int leftX = width / 3;
    int rightX = (width / 3) * 2;
    
    glGraphics.glBegin(GLConstants.GL_TRIANGLES);
    
    glGraphics.glColor3f(1.0f, 1.0f, 1.0f);
    
    glGraphics.glVertex2i(leftX, bottomY);
    glGraphics.glVertex2i(rightX, bottomY);
    glGraphics.glVertex2i(centerX, topY);
    
    glGraphics.glEnd();
}

   In this program, the initGraphics method sets the graphics coordinates to 
    upper-left (0,0), lower-right (width, height). The update method clears the 
    screen and then draws a white triangle polygon. 
   In the initGraphics and update methods, oni.gfx.GLGraphics 
    objects are passed. With GLGraphics objects, you can write the program in 
    the same manner as OpenGL programming.
  The quitRequested method is a method to be called for termination. It does 
    not do anything here. 

Define the KeyListener Interface 

 
  class DemoKeyListener implements KeyListener {
    public DemoKeyListener(OniRuntime aOniRuntime) {
        oniRuntime = aOniRuntime;
    }
    
    public void keyTyped(KeyEvent event) {
        System.out.println(event);
    }
    
    public void keyPressed(KeyEvent event) {
        System.out.println(event);
        if (event.getKeyCode() == KeyEvent.VK_Q) {
            oniRuntime.disposeDisplay();
            System.exit(0);
        }
    }
    
    public void keyReleased(KeyEvent event) {
        System.out.println(event);
    }
    
    private OniRuntime oniRuntime;
}

  The oni.runtime.event.KeyListener 
    interface can receive keyboard events that are input by registering to the 
    OniRuntime instance. In the above program, a oni.runtime.event.KeyEvent 
    object passed by each keyboard event is written to standard output. When the 
    'q' key is pressed, the screen is closed and the program is terminated. 



   
   
     Copyright © 2001-2002 CyberStep, Inc. All 
      Rights Reserved.

    
     

      Oni Software

The First Oni Program

Execute the OpenWindow Class

Import Statement

Implement the Application Interface

Implement the oniMain Method

Define the initGraphics and update Methods

Define the KeyListener Interface

`Define the KeyListener Interface`