Hi Richard,

I'm a little bit lost with the pull request, as I don't have Away3D GIT repo cloned here. The occlusion part is rather simple.

This is a ColorMaterial, der hides itself and all objects behind it by calling context.setColorMask(false, false, false, false);

The only thing, that the DefaultRenderer is missing in drawRenderables is a
_activeMaterial.cleanUp(_context); call (so the material itself could do the context.setColorMask(true, true, true, true);
Or the DefaultMaterialBase.updateMaterial() itself includes context.setColorMask(true, true, true, true);

I'm not sure, what fits your engine best as this is the first time I'm looking at its code today.

Anyway. Hope to see it implemented somehow


package away3d.materials {
    import away3d.arcane;

    import flash.display3D.Context3D;

    use namespace arcane;

    /**
     * OcclusionMaterial is a ColorMaterial for an object, that hides all other objects behind itself.
     */
    public class OcclusionMaterial extends ColorMaterial
    {
        private var _occlude : Boolean = true;

        /**
         * Creates a new OcclusionMaterial object.
         * @param occlude Whether or not to occlude other objects.
         * @param color The material's diffuse surface color.
         * @param alpha The material's surface alpha.
         */
        public function OcclusionMaterial(occlude : Boolean = true, color : uint = 0xcccccc, alpha : Number = 1)
        {
            super(color, alpha);
            this.occlude = occlude;
        }

        /**
         * Whether or not an object with this material applied hides other objects.
         */
        public function get occlude() : Boolean
        {
            return _occlude;
        }

        public function set occlude(value : Boolean) : void
        {
            _occlude = value;
        }

        /**
         * @inheritDoc
         */
        arcane override function updateMaterial(context : Context3D) : void
        {
            super.updateMaterial(context);
            if(occlude) {
                context.setColorMask(false, false, false, false);
            }
        }
    }
}