#ifndef GPUTRAIL_VARIABLES_CS_INCLUDED
#define GPUTRAIL_VARIABLES_CS_INCLUDED

#include "GPUTrailInput.cginc"
#include "GPUTrailVertex.cginc"

// #define LERP_TYPE_NONE 0
// #define LERP_TYPE_SPLINE 1

struct Trail
{
	float startTime;
	uint totalInputNum;
};

struct Node
{
    float3 pos;
    float time;
	half4 color;
};

uint _TrailNum;
uint _NodeNumPerTrail;
uint _InputNodeNum;
// uint _LerpType;
float _MinNodeDistance;
float _Time;
float _Life;
float3 _ToCameraDir; // for orthographics camera
float3 _CameraPos;   // for perspective camera
float _StartWidth;
float _EndWidth;


uint calcTrailIdx(uint nodeIdx)
{
	return nodeIdx / _NodeNumPerTrail;
}
uint calcNodeIdx(uint trailIdx, uint nodeIdxInTrail)
{
	return (trailIdx * _NodeNumPerTrail) + (nodeIdxInTrail % _NodeNumPerTrail);
}

inline bool useToCameraDir()
{
	return all(_ToCameraDir == 0);
}

inline float3 calcToCameraDir(float3 pos)
{
	return useToCameraDir() ? normalize(_CameraPos - pos) : _ToCameraDir;
}

#endif // GPUTRAIL_VARIABLES_CS_INCLUDED