CRenderizableDisplayList.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2019, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <mrpt/opengl/CRenderizable.h>

namespace mrpt::opengl
{
#define INVALID_DISPLAY_LIST_ID static_cast<unsigned int>(-1)

/** A renderizable object suitable for rendering with OpenGL's display lists.
 *   The idea is to use the derived classes' ::render() method to save all the
 *primitives
 *   into one display list, then in subsequent rendering events, just execute
 *the list.
 *   This method is normally faster since it avoids the bottleneck between
 *CPU-GPU. On the
 *   other hand, it demands more memory on the graphic card.
 *
 *  Instructions for implementing derived classes:
 *      - Each time the object is modified is some way that modifies its
 *appearance, you must call notifyChange()
 *      - Implement the rendering method: render_dl(), calling to OpenGL
 *primitives
 *as usual. They'll be saved in a display list transparently.
 *
 *  \sa mrpt::opengl::CRenderizable
 * \ingroup mrpt_opengl_grp
 */
class CRenderizableDisplayList : public mrpt::opengl::CRenderizable
{
    DEFINE_VIRTUAL_SERIALIZABLE(CRenderizableDisplayList)

   private:
    /** Display list ID, for derived classes that want to use it (it's
     * automatically deleted and freed on destruction of this base class). */
    mutable unsigned int m_dl;
    /** If using display lists, this is true when the list must be updated (the
     * object changes, it's the first rendering, etc...). */
    mutable bool m_dl_recreate{true};

   protected:
    /** @name Methods accesible or implemented by derived classes
        @{ */

    /** Must be called to notify that the object has changed (so, the display
     * list must be updated) */
    inline void notifyChange() const { m_dl_recreate = true; }
    /** Derived classes must implement this method to the render the object. */
    virtual void render_dl() const = 0;

    /** Optional: If the object has some state in which creating a display list
     * is NOT preferred over direct rendering,
     *  implement this method and return "true" in those cases. */
    virtual bool should_skip_display_list_cache() const { return false; }
    inline void readFromStreamRender(mrpt::serialization::CArchive& in)
    {
        CRenderizable::readFromStreamRender(in);
        notifyChange();
    }

    /** @} */

   public:
    CRenderizableDisplayList();
    ~CRenderizableDisplayList() override;

    /** Render the object, regenerating the display list if needed, otherwise
     * just calling it. */
    void render() const override;

    /** @name Changes the appearance of the object to render (methods from
       CRenderizable that need to be redefined)
        @{ */
    /**Color components in the range [0,255] \return a ref to this */
    CRenderizable& setColorR_u8(const uint8_t r) override
    {
        m_color.R = r;
        notifyChange();
        return *this;
    }
    /**Color components in the range [0,255] \return a ref to this */
    CRenderizable& setColorG_u8(const uint8_t g) override
    {
        m_color.G = g;
        notifyChange();
        return *this;
    }
    /**Color components in the range [0,255] \return a ref to this */
    CRenderizable& setColorB_u8(const uint8_t b) override
    {
        m_color.B = b;
        notifyChange();
        return *this;
    }
    /**Color components in the range [0,255] \return a ref to this */
    CRenderizable& setColorA_u8(const uint8_t a) override
    {
        m_color.A = a;
        notifyChange();
        return *this;
    }
    /** Changes the default object color \return a ref to this */
    CRenderizable& setColor_u8(const mrpt::img::TColor& c) override
    {
        CRenderizable::setColor_u8(c);
        notifyChange();
        return *this;
    }
    /**Color components in the range [0,255] \return a ref to this */
    inline CRenderizable& setColor_u8(
        uint8_t R, uint8_t G, uint8_t B, uint8_t A = 255)
    {
        CRenderizable::setColor_u8(R, G, B, A);
        notifyChange();
        return *this;
    }
    /** @} */
};

}  // namespace mrpt::opengl