// -*-c++-*-
// SPDX-License-Identifier: LGPL-2.1-only
// Copyright (C) 2022 James Hogan <james@albanarts.com>

#ifndef OSGXR_CompositionLayer
#define OSGXR_CompositionLayer 1

#include <osgXR/Export>

#include <osg/Referenced>

#include <memory>

namespace osgXR {

/**
 * Represents an OpenXR composition layer.
 */
class OSGXR_EXPORT CompositionLayer : public osg::Referenced
{
    public:

        class Private;

    protected:

        /// Constructor (internal).
        CompositionLayer(Private *priv);

    public:

        /// Destructor.
        ~CompositionLayer();

        // Accessors

        /// Set whether the layer should be submitted to OpenXR.
        void setVisible(bool visible);
        /// Get whether the layer should be submitted to OpenXR (default: true).
        bool getVisible() const;

        /**
         * Set ordering index.
         * The default projection layer will have an order of 0, so layers with
         * positive order indices will be composited in front, and negative
         * behind.
         */
        void setOrder(int order);
        /// Get ordering index (default 1).
        int getOrder() const;

        typedef enum {
            /// No blending, alpha treated as 1.
            BLEND_NONE,
            /// Per pixel alpha, with color values premultiplied by alpha.
            BLEND_ALPHA_PREMULT,
            /// Per pixel alpha, with color values unassociated with alpha.
            BLEND_ALPHA_UNPREMULT,
        } AlphaMode;
        /// Set layer's alpha mode.
        void setAlphaMode(AlphaMode mode);
        /// Get layer's alpha mode (default: BLEND_NONE).
        AlphaMode getAlphaMode() const;

    private:

        std::unique_ptr<Private> _private;

        // Copying not permitted
        CompositionLayer(const CompositionLayer &copy);
};

}

#endif