Clip Plane help please

OpenGL Development JOGL Development
#1

I am using an ortho projection and trying to use clip plans for regular 2D clip boxing. I can clip to left/upper edge of a box with a call like:

gl.glClipPlane(GL.GL_CLIP_PLANE0, new double[] {1.0, 0.0, 0.0, bounds.getMinX()});

I am trying to get the left/bottom edge with:

gl.glClipPlane(GL.GL_CLIP_PLANE0, new double[] {-1.0, 0.0, 0.0, -bounds.getMaxX()});

But, that clips all shapes! Any pointers would help. I have only been able to find the first case in examples on the net.

Michael