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  Code author: Jernej Barbic
  Research: Jernej Barbic, Doug L. James
  Version: 1.0

  A class that makes it possible to read OpenGL lighting parameters from a text configuration file.
  Usage is simple: read the configuration file during initialization (using the constructor), 
  then call "LightScene" inside your OpenGL display routine, after setting up the modelview and projection matrices.
  
  The configuration file syntax supports the following parameters (listed with their types and default values):

  Global parameters:
  ------------------

  globalAmbientIntensity (float, 0.0)
  localViewer (bool, true)
  twoSidedLighting (bool, false)
  enableAmbientTerm (bool, true)
  enableDiffuseTerm (bool, true)
  enableSpecularTerm (bool, true)
  
  Light-specific parameters:
  --------------------------

  Up to 8 simultaneous lights are supported. 
  Each light has the following parameters (listed here for light 0) :
  lightEnabled_0 (bool, false)
  position_0_X (float, 0.0)
  position_0_Y (float, 0.0)
  position_0_Z (float, 0.0)
  position_0_DIR (float, 1.0)
  lightIntensity_0 (float, 1.0)

  Light 0 is located at (position_0_X, position_0_Y, position_0_Z).
  position_0_DIR should be 0 for directional light, and 1 for a point light source

  For the other lights, replace "0" with one of "1", "2", ..., "7".
  For example: lightEnabled_4 controls whether light 4 is enabled or not.

  See also example.lighting for an example of a lighting configuration file.
*/

#ifndef _LIGHTING_H_
#define _LIGHTING_H_

#include <stdlib.h>
#include <string.h>

#ifdef WIN32
  #include <windows.h>
#endif

#include "openGL-headers.h"
#include "macros.h"

class Lighting
{
public:

  // read OpenGL lighting parameters from a configuration file
  Lighting(char * configFilename);

  // call this inside your OpenGL display routine, after setting up the modelview and projection matrices
  void LightScene(); 

  inline void GetLightPosition(int lightID, float * pos);
  inline void GetLightAmbientTerm(int lightID, float * Ka);
  inline void GetLightDiffuseTerm(int lightID, float * Kd);
  inline void GetLightSpecularTerm(int lightID, float * Ks);
  inline float GetLightIntensity(int lightID);
  inline float GetAmbientIntensity();
  inline bool IsLightEnabled(int lightID);
  inline bool IsAmbientEnabled() { return enableAmbientTerm; }
  inline bool IsDiffuseEnabled() { return enableDiffuseTerm; }
  inline bool IsSpecularEnabled() { return enableSpecularTerm; }

protected:
  float ambientIntensity;
  bool localViewer, twoSidedLighting;
  bool lightEnabled[8];
  float lightPosition[32];
  float lKa[32], lKd[32], lKs[32];
  float lightIntensity[8];
  bool enableAmbientTerm, enableDiffuseTerm, enableSpecularTerm;
};

inline float Lighting::GetLightIntensity(int lightID)
{
  return lightIntensity[lightID];
}

inline void Lighting::GetLightPosition(int lightID, float * pos)
{
  memcpy(pos, &(lightPosition[4*lightID]), 4* sizeof(float));
}

inline void Lighting::GetLightAmbientTerm(int lightID, float * Ka)
{
  memcpy(Ka, &(lKa[4*lightID]), 4* sizeof(float));
}

inline void Lighting::GetLightDiffuseTerm(int lightID, float * Kd)
{
  memcpy(Kd, &(lKd[4*lightID]), 4* sizeof(float));
}

inline void Lighting::GetLightSpecularTerm(int lightID, float * Ks)
{
  memcpy(Ks, &(lKs[4*lightID]), 4* sizeof(float));
}

inline float Lighting::GetAmbientIntensity()
{
  return ambientIntensity;
}

inline bool Lighting::IsLightEnabled(int lightID)
{
  return lightEnabled[lightID];
}

#endif

