code: public void setFrustum(double left, double right, double bottom, double top,
  			double near, double far) {
  		matrixMode(MatrixMode.PROJECTION);
  		resetMatrix();
  		gl.glFrustum(left, right, bottom, top, near, far);
  		matrixMode(MatrixMode.MODELVIEW);
  		resetMatrix();
  	}
docs: Sets a perspective matrix defined through the parameters. Works like
  glFrustum, except it wipes out the current perspective matrix rather
  than multiplying itself with it.
  
  @param left
  left coordinate of the clipping plane
  @param right
  right coordinate of the clipping plane
  @param bottom
  bottom coordinate of the clipping plane
  @param top
  top coordinate of the clipping plane
  @param near
  near component of the clipping plane
  @param far
  far component of the clipping plane