LWJGL (Light-weight Java Game Library) is a game library that is the basis for many graphics libraries including jMonkeyEngine. You might be wondering why I'm covering LWJGL in a separate post when it is used in jMonkeyEngine which I covered several weeks ago. Though there is some overlap, each fits a specific need.

I'd describe the relationship like this: OpenGL/JOGL is a bicycle, LWJGL is a Vespa, and jME is a Harley. OpenGL is great if you want to touch the bare metal, LWJGL if you want to tweak and customize, jME if you singular goal is to make a game.

Getting started

• Download LWJGL and drop the lwjgl.jar in your lib directory.
• Find the native files for your operating system and extract them into lib/native
• Download jME 2.0 Distribution. We aren't doing that much advanced stuff so we only need jme.jar, jinput.jar, and jme-awt.jar. Drop these into your lib directory.
• Modify your Config.groovy file to contain the following:
  

   
  griffon {
     app {
      javaOpts = ["-Djava.library.path=${basedir}/lib/native"]
     }
  }
  

Linking our model and view

Our model and view are going to be fairly basic and initiate a model property called canvas that is added to the view. We don't need to do anything in our controller.

SimpleLWJGLModel.groovy

 
import groovy.beans.Bindable
 
class SimpleLWJGLModel {
   @Bindable canvas = new SimpleCanvas()
}

SimpleLWJGLView.groovy

 
application(title:'SimpleLWJGL',
  size:[300,300],
  resizable:false,
  locationByPlatform:true,
  iconImage: imageIcon('/griffon-icon-48x48.png').image,
  iconImages: [imageIcon('/griffon-icon-48x48.png').image,
               imageIcon('/griffon-icon-32x32.png').image,
               imageIcon('/griffon-icon-16x16.png').image]
) {
    widget(model.canvas)
}

Drawing on our canvas

Here we draw a rotating quad.

 
import org.lwjgl.LWJGLException
import org.lwjgl.opengl.AWTGLCanvas
import org.lwjgl.opengl.Display
import org.lwjgl.opengl.GL11

public class SimpleCanvas extends AWTGLCanvas {
 
    float angle = 0
 
    public SimpleCanvas() throws LWJGLException {
      // Launch a thread to repaint the canvas 60 fps
      Thread.start{
          while (true) {
            if (isVisible()) {
              repaint()
            }
            Display.sync(60)
          }
      }
    }
 
    public void paintGL() {
	  GL11.with {
		  glClear(GL_COLOR_BUFFER_BIT)
		  glMatrixMode(GL_PROJECTION_MATRIX)
		  glLoadIdentity()
		  glOrtho(0, 640, 0, 480, 1, -1)
		  glMatrixMode(GL_MODELVIEW_MATRIX)
	 
		  glPushMatrix()
		  glTranslatef(320, 240, 0.0f)
		  glRotatef(angle, 0, 0, 1.0f)
		  glBegin(GL_QUADS)
		  glVertex2i(-50, -50)
		  glVertex2i(50, -50)
		  glVertex2i(50, 50)
		  glVertex2i(-50, 50)
		  glEnd()
		  glPopMatrix()
	  }
      angle += 1
 
      try {
        swapBuffers()
      } catch (Exception e) { }
    }   
}

One thing you might notice is that LWJGL requires a lot less setup than jME. Download the source here.

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