// Cpw_01 [Cpw-OpenGL Triangle].nova



// Using namespace declarations.
using Library.CPW;
using Library.OpenGL;



// The application class.
class CpwTriangleApp
{
   // Static data members.
   private static CPW cpw;


   // Application class's "main" function.
   public static void main( String[] args )
   {
      // Create a new CPW context object.
      cpw = new CPW( );

      // Initialize the CPW context object.
      cpw.cpwInitContext( );

      // Create a window.
      cpw.cpwCreateWindowEx( "Cpw_01 [Cpw-OpenGL Triangle]",
                             100,
                             100,
                             640,
                             480 );

      // Register the event callbacks.
      cpw.cpwCreateCallback( createCallback );
      cpw.cpwDisplayCallback( displayCallback );
      cpw.cpwReshapeCallback( reshapeCallback );

      // Enter the main rendering loop.
      cpw.cpwMainLoop( );

      // Shutdown the CPW context.
      cpw.cpwFreeContext( );
   }


   // Window create / close event callback.
   private static void createCallback( CPW cpw, uint winID, bool flag )
   {
      Stream.writeLine( "createCallback - called" );

      if ( flag == false )
      {
         // Window close event.
         cpw.cpwDestroyWindow( winID );
      }
   }


   // Window draw event callback.
   private static void displayCallback( CPW cpw, uint winID )
   {
      Stream.writeLine( "displayCallback - called" );

      OpenGL.glClear( OpenGL.GL_COLOR_BUFFER_BIT | OpenGL.GL_DEPTH_BUFFER_BIT );

      // Draw a triangle.
      OpenGL.glBegin( OpenGL.GL_TRIANGLES );
         OpenGL.glColor3f(   0.0f,  0.0f, 1.0f );  // Blue.
         OpenGL.glVertex3f(  0.0f,  1.0f, 0.0f );  // Top
         OpenGL.glColor3f(   1.0f,  0.0f, 0.0f );  // Red.
         OpenGL.glVertex3f( -1.0f, -1.0f, 0.0f );  // Bottom left.
         OpenGL.glColor3f(   0.0f,  1.0f, 0.0f );  // Green.
         OpenGL.glVertex3f(  1.0f, -1.0f, 0.0f );  // Bottom right.
      OpenGL.glEnd( );

      cpw.cpwSwapWindowBuffers( winID );
   }


   // Window resize event callback.
   private static void reshapeCallback( CPW cpw, uint winID, uint w, uint h )
   {
      Stream.writeLine( "reshapeCallback - called" );

      // Prevent a divide by zero.
      if ( h == 0 )
      {
         h = 1;
      }

      // Set the viewport to be the entire window.
      OpenGL.glViewport( 0, 0, (int)w, (int)h );

      // Set the perspective.
      OpenGL.glMatrixMode( OpenGL.GL_PROJECTION );
      OpenGL.glLoadIdentity( );
      OpenGL.gluPerspective( 45.0,
                             (double)w / (double)h,
                             1.0,
                             150.0 );
      OpenGL.glMatrixMode( OpenGL.GL_MODELVIEW );

      // Set the view.
      OpenGL.glLoadIdentity( );
      OpenGL.gluLookAt( 0.0, 0.0,  4.0,
                        0.0, 0.0, -1.0,
                        0.0, 1.0,  0.0);
   }
}