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/** @file aiLight.h
 *  @brief Defines the aiLight data structure
 */

#ifndef __AI_LIGHT_H_INC__
#define __AI_LIGHT_H_INC__

#include "aiTypes.h"

#ifdef __cplusplus
extern "C" {
#endif

// ---------------------------------------------------------------------------
/** Enumerates all supported types of light sources.
 */
enum aiLightSourceType
{
	aiLightSource_UNDEFINED     = 0x0,

	//! A directional light source has a well-defined direction
	//! but is infinitely far away. That's quite a good 
	//! approximation for sun light.
	aiLightSource_DIRECTIONAL   = 0x1,

	//! A point light source has a well-defined position
	//! in space but no direction - it emits light in all
	//! directions. A normal bulb is a point light.
	aiLightSource_POINT         = 0x2,

	//! A spot light source emits light in a specific 
	//! angle. It has a position and a direction it is pointing to.
	//! A good example for a spot light is a light spot in
	//! sport arenas.
	aiLightSource_SPOT          = 0x3,


	/** This value is not used. It is just there to force the
	 *  compiler to map this enum to a 32 Bit integer.
	 */
#ifndef SWIG
	_aiLightSource_Force32Bit = 0x9fffffff
#endif
};

// ---------------------------------------------------------------------------
/** Helper structure to describe a light source.
 *
 *  Assimp supports multiple sorts of light sources, including
 *  directional, point and spot lights. All of them are defined with just
 *  a single structure and distinguished by their parameters.
 *  Note - some file formats (such as 3DS, ASE) export a "target point" -
 *  the point a spot light is looking at (it can even be animated). Assimp
 *  writes the target point as a subnode of a spotlights's main node,
 *  called "<spotName>.Target". However, this is just additional information
 *  then, the transformation tracks of the main node make the
 *  spot light already point in the right direction.
*/
struct aiLight
{
	/** The name of the light source.
	 *
	 *  There must be a node in the scenegraph with the same name.
	 *  This node specifies the position of the light in the scene
	 *  hierarchy and can be animated.
	 */
	C_STRUCT aiString mName;

	/** The type of the light source.
 	 *
	 * aiLightSource_UNDEFINED is not a valid value for this member.
	 */
	C_ENUM aiLightSourceType mType;

	/** Position of the light source in space. Relative to the
	 *  transformation of the node corresponding to the light.
	 *
	 *  The position is undefined for directional lights.
	 */
	C_STRUCT aiVector3D mPosition;

	/** Direction of the light source in space. Relative to the
	 *  transformation of the node corresponding to the light.
	 *
	 *  The direction is undefined for point lights. The vector
	 *  may be normalized, but it needn't.
	 */
	C_STRUCT aiVector3D mDirection;

	/** Constant light attenuation factor. 
	 *
	 *  The intensity of the light source at a given distance 'd' from
	 *  the light's position is
	 *  @code
	 *  Atten = 1/( att0 + att1 * d + att2 * d*d)
	 *  @endcode
	 *  This member corresponds to the att0 variable in the equation.
	 *  Naturally undefined for directional lights.
	 */
	float mAttenuationConstant;

	/** Linear light attenuation factor. 
	 *
	 *  The intensity of the light source at a given distance 'd' from
	 *  the light's position is
	 *  @code
	 *  Atten = 1/( att0 + att1 * d + att2 * d*d)
	 *  @endcode
	 *  This member corresponds to the att1 variable in the equation.
	 *  Naturally undefined for directional lights.
	 */
	float mAttenuationLinear;

	/** Quadratic light attenuation factor. 
	 *  
	 *  The intensity of the light source at a given distance 'd' from
	 *  the light's position is
	 *  @code
	 *  Atten = 1/( att0 + att1 * d + att2 * d*d)
	 *  @endcode
	 *  This member corresponds to the att2 variable in the equation.
	 *  Naturally undefined for directional lights.
	 */
	float mAttenuationQuadratic;

	/** Diffuse color of the light source
	 *
	 *  The diffuse light color is multiplied with the diffuse 
	 *  material color to obtain the final color that contributes
	 *  to the diffuse shading term.
	 */
	C_STRUCT aiColor3D mColorDiffuse;

	/** Specular color of the light source
	 *
	 *  The specular light color is multiplied with the specular
	 *  material color to obtain the final color that contributes
	 *  to the specular shading term.
	 */
	C_STRUCT aiColor3D mColorSpecular;

	/** Ambient color of the light source
	 *
	 *  The ambient light color is multiplied with the ambient
	 *  material color to obtain the final color that contributes
	 *  to the ambient shading term. Most renderers will ignore
	 *  this value it, is just a remaining of the fixed-function pipeline
	 *  that is still supported by quite many file formats.
	 */
	C_STRUCT aiColor3D mColorAmbient;

	/** Inner angle of a spot light's light cone.
	 *
	 *  The spot light has maximum influence on objects inside this
	 *  angle. The angle is given in radians. It is 2PI for point 
	 *  lights and undefined for directional lights.
	 */
	float mAngleInnerCone;

	/** Outer angle of a spot light's light cone.
	 *
	 *  The spot light does not affect objects outside this angle.
	 *  The angle is given in radians. It is 2PI for point lights and 
	 *  undefined for directional lights. The outer angle must be
	 *  greater than or equal to the inner angle.
	 *  It is assumed that the application uses a smooth
	 *  interpolation between the inner and the outer cone of the
	 *  spot light. 
	 */
	float mAngleOuterCone;

#ifdef __cplusplus

	aiLight()
		:	mType                 (aiLightSource_UNDEFINED)
		,	mAttenuationConstant  (0.f)
		,   mAttenuationLinear    (1.f)
		,   mAttenuationQuadratic (0.f)
		,	mAngleInnerCone       ((float)AI_MATH_TWO_PI)
		,	mAngleOuterCone       ((float)AI_MATH_TWO_PI)
	{
	}

#endif
};

#ifdef __cplusplus
}
#endif


#endif // !! __AI_LIGHT_H_INC__
