global_light_mgr.h

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/*! \file
  \brief  The disti::GlobalLightMgr.

  \par Copyright Information

  Copyright (c) 2017 by The DiSTI Corporation.<br>
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  This Software contains proprietary trade secrets of DiSTI and may not be
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  NO WARRANTY. THE SOFTWARE IS PROVIDED "AS-IS," WITHOUT WARRANTY OF ANY KIND,
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*/
#ifndef _GLOBAL_LIGHT_MGR_H
#define _GLOBAL_LIGHT_MGR_H

#include "dynamic_array.h"
#include "gls_include.h"
#include "util.h"

namespace disti
{
class GlsLightSource;
class GlsEyePoint;
class GlobalLightMgrThreadMap;

/*
 * This singleton class is responsible for keeping track of the GlsLightSource objects
 * currently affecting the OpenGL lighting state and changing the state
 * when needed.
 */
class GlobalLightMgr
{
public:
    /** List of the currently active lights
      * The number of the light is equal to it's array index.
      * (i.e. The light at index 0 is GL_LIGHT0) */
    typedef DynamicArray<GlsLightSource*> LightingState;

protected:
    /** helper class for maintaining one global light mgr per calling thread */
    friend class GlobalLightMgrThreadMap;

    static GLS_EXPORT unsigned int     MAX_OPENGL_LIGHTS;   /** The value of glGetIntegerv(GL_MAX_LIGHTS); */
    LightingState                      _currentOpenGLState; /** The current OpenGL lighting state */
    LightingState                      _currentState;       /** This will become the _currentOpenglState when a lit object draws */
    DynamicArray<GlsLightSource*>      _tempOpenGLLights;   /** Store temporary light source pointers (only used in InitializeStateFromOpenGL) */
    DynamicStack<LightingState, false> _lightingStateStack; /** As each component draws it will push it's lighting state on the stack */

    bool  _reapplyLights;
    bool  _enableNormalize;
    bool* _activeLights;

    GLS_EXPORT GlobalLightMgr();

public:
    virtual GLS_EXPORT ~GlobalLightMgr();

    /** \return  The singleton to the one instance of GlobalLightMgr*/
    static GLS_EXPORT GlobalLightMgr& Instance();

    /** \return The value of GL_MAX_LIGHTS */
    static inline unsigned int GlMaxLights() { return MAX_OPENGL_LIGHTS; }

    /** Push the current lighting state onto the stack */
    void GLS_EXPORT PushLightingState();

    /** Push the current lighting state off the stack */
    void GLS_EXPORT PopLightingState();

    /** Flags the need to reapply the lights.  This may
      * be necessary for special cases where the OpenGL matrices
      * have changed during a traversel.  This can
      * happen when drawing multiple views of the same
      * geometry.
      */
    inline void ReapplyLights() { _reapplyLights = true; }

    /** Set whether or not GL_NORMALIZE is enabled
      * \param enableNormalize  Set GL_NORMALIZE to true or false
      */
    static GLS_EXPORT void EnableNormalize( bool enableNormalize );

    /** Get the state of whether GL_NORMALIZE is enabled
      * \return Whether or not GL_NORMALIZE is enabled
      */
    static GLS_EXPORT bool EnableNormalize();

    /** Set the current lighting state to a new state
      * \param newState  The new lighting state
      */
    void GLS_EXPORT SetLightingState( LightingState& newState );

    /** Get the current lighting state
      * \return  The current lighting state
      */
    const GLS_EXPORT LightingState& GetLightingState( void );

    /** Set OpenGL lighting state to match the current state.
      * If relativeToEyepoint is set, the light will be applied
      * using the modelview matrix calculated from the eyepoint to the light.
      */
    void GLS_EXPORT SetupLighting( GlsEyePoint* relativeToEyepoint = NULL /*(Top Level)*/ );

    /** Clear the lighting stack, create GlsLightSource objects based on the current
      * OpenGL lighting state and store them as the current state.
      */
    void GLS_EXPORT InitializeStateFromOpenGL( void );

    /** Restore the OpenGL state to what it was at the last call to InitializeStateFromOpenGL() */
    void GLS_EXPORT RestoreOpenGLState( void );

    /** Get a boolean mask of the active lights
      * \return A boolean array with a bitmask of the currently active lights
      */
    GLS_EXPORT bool* GetActiveLightsMask( void );

    /** Get a bitmask of the active lights
      * \return An unsigned integer with each bit representing a light turned on/off
      */
    GLS_EXPORT unsigned int GetActiveLightsBitMask( void );

    /** Get the number of active lights.  Really is the max index(+1) of lights that
      * you need to cycle through to have taken all of them into account (in case of
      * holes in the list created by an outside party).
      * \return An integer representing the (max) number of currently active lights
      */
    GLS_EXPORT unsigned int GetNumActiveLights( void );
};

} // namespace disti

#endif