frustum_render.java

	protected FloatBuffer Mvi = FloatBuffer.allocate(16);
	protected FloatBuffer Pi = FloatBuffer.allocate(16);
	protected ProjectFloat projectFloat = new ProjectFloat(true);

	public void renderFrustum() {
		GL2 gl = GLContext.getCurrentGL().getGL2();
		gl2 = gl;
		gl.glDisable(GL2.GL_CULL_FACE);
		gl.glDisable(GL2.GL_DEPTH_TEST);
		gl.glDisable(GL2.GL_TEXTURE_2D);
		gl.glDisable(GL2.GL_ALPHA_TEST);
		gl.glEnable(GL2.GL_BLEND);
		gl.glBlendFunc(GL2.GL_SRC_ALPHA, GL2.GL_ONE);
		gl.glColor4f(0.2f, 0.2f, 0.7f, 0.3f);
		gl.glBegin(GL2.GL_QUADS);
		flb.v();
		flt.v();
		frt.v();
		frb.v();
		gl.glEnd();
		gl.glBegin(GL2.GL_QUADS);
		nlb.v();
		nlt.v();
		nrt.v();
		nrb.v();
		gl.glEnd();
		gl.glBegin(GL2.GL_LINES);
		gl.glColor4f(1f, 1f, 1f, 0.4f);
		nearc.v();
		farc.v();
		gl.glColor3f(1.0f, 0.0f, 1.0f);
		nlb.v();
		flb.v();
		nlt.v();
		flt.v();
		nrt.v();
		frt.v();
		nrb.v();
		frb.v();
		gl.glEnd();
	}

	public void updateFrustum() {
		frustum.updateByPlanes(pmvMatrix.glGetFrustum().getPlanes()); 
		projectFloat.gluInvertMatrixf(pmvMatrix.glGetMvMatrixf(), Mvi);
		projectFloat.gluInvertMatrixf(pmvMatrix.glGetPMatrixf(), Pi);
		final float tang = (float) Math.tan((Math.PI * fov / 180) / 2.0f);
		final float near = 1f;
		final float far = 100f;
		final float nh = near * tang;
		final float nw = nh * aspect;
		final float fh = far * tang;
		final float fw = fh * aspect;
		eye.set(position.x, position.y, position.z);
		nearc.set(eye);
		nearc.translate(look, -near);
		farc.set(eye);
		farc.translate(look, -far);
		flb.set(farc);
		flb.translate(right, -fw / 2);
		flb.translate(up, -fh / 2);
		flt.set(farc);
		flt.translate(right, -fw / 2);
		flt.translate(up, fh / 2);
		frb.set(farc);
		frb.translate(right, fw / 2);
		frb.translate(up, -fh / 2);
		frt.set(farc);
		frt.translate(right, fw / 2);
		frt.translate(up, fh / 2);
		
		nlb.set(nearc);
		nlb.translate(right, -nw / 2);
		nlb.translate(up, -nh / 2);
		nlt.set(nearc);
		nlt.translate(right, -nw / 2);
		nlt.translate(up, nh / 2);
		nrb.set(nearc);
		nrb.translate(right, nw / 2);
		nrb.translate(up, -nh / 2);
		nrt.set(nearc);
		nrt.translate(right, nw / 2);
		nrt.translate(up, nh / 2);

	}

	private vec eye = new vec();
	private vec nearc = new vec();
	private vec flb = new vec();
	private vec flt = new vec();
	private vec frb = new vec();
	private vec frt = new vec();
	private vec nlb = new vec();
	private vec nlt = new vec();
	private vec nrb = new vec();
	private vec nrt = new vec();
	private vec farc = new vec();
	private GL2 gl2;

	private class vec {
		public float x;
		public float y;
		public float z;

		public void v() {
			gl2.glVertex3f(x, y, z);
		}

		public void set(vec v) {
			set(v.x, v.y, v.z);
		}

		public void set(float x, float y, float z) {
			this.x = x;
			this.y = y;
			this.z = z;
		}

		public void translate(Vector3f dir, float d) {
			translate(dir.x * d, dir.y * d, dir.z * d);
		}

		public void translate(float x, float y, float z) {
			this.x += x;
			this.y += y;
			this.z += z;
		}
	}