#version 3.8;
global_settings{ assumed_gamma 1.0 	ambient_light	0.01
 }


#declare Orrery_Camera_Horizontal	= -90;			// asind(tand(30));
#declare Orrery_Camera_Vertical		= 0;			// 45;
#declare Orrery_Camera_Aspect		= image_height/image_width;
#declare Orrery_Camera_Distance		= 4;			// was 32
#declare Orrery_Camera_Rotate		= <Orrery_Camera_Horizontal,0,Orrery_Camera_Vertical>;
#declare Orrery_Camera_Scale		= 2;
#declare Orrery_Camera_Translate	= <0,0,0>;
#declare Orrery_Camera_Up			= +z * 2 * Orrery_Camera_Aspect;
#declare Orrery_Camera_Right		= +x * 2;
#declare Orrery_Camera_Location		= -y * Orrery_Camera_Distance;
#declare Orrery_Camera_Direction	= +y * Orrery_Camera_Distance;
#declare Orrery_Camera_Transform = transform
{
	rotate		Orrery_Camera_Rotate
	scale		Orrery_Camera_Scale
	translate	Orrery_Camera_Translate
};

//------------------------------------------------------------------------------
// LIGHTS


light_source
{
	<+1,+1,+1,> * 100
	color rgb	1
	parallel
	point_at 0
//	shadowless
}
light_source
{
	<+1,+1,+1,> * 100
	color rgb	1
	rotate +z * 270
	parallel
	point_at 0
	shadowless
}
camera
{
	location Orrery_Camera_Location
	direction Orrery_Camera_Direction
	up Orrery_Camera_Up
	right Orrery_Camera_Right
	transform {Orrery_Camera_Transform}
}


background {color srgb 3/4}


#local obliquity = 23.43928;					// deg, obliquity of Earth pole axis
#local d = 2458383.500000;						// Julian day, A.D. 2018 Sep 22, 00:00:00.0
#local T = d / 36525;							// Julian century
#local alpha_0 = 0.00 - 0.641 * T;				// deg, right ascension
#local delta_0 = 90.00 - 0.557 * T;				// deg, declination
#local W = 190.147 + 360.9856235 * d;			// deg, prime meridian orientation


#declare sphere_coo = <0,0,1>;
/*
#declare sphere_coo = vrotate(sphere_coo, z * (W));
#declare sphere_coo = vrotate(sphere_coo, x * (90-delta_0));
#declare sphere_coo = vrotate(sphere_coo, z * (90+alpha_0));
#declare sphere_coo = vrotate(sphere_coo, x * (-obliquity));
*/


#declare TILT_AXIS = vrotate( x, (90+alpha_0)*z );
/* same as 
#declare TILT_AXIS = vrotate( y, alpha_0*z );
*/
#include "transforms.inc"

#declare sphere_trans = transform
{
	rotate z * W
  Axis_Rotate_Trans( TILT_AXIS, 90-delta_0 )
	//rotate x * (90-delta_0)
	//rotate z * (90+alpha_0)
	rotate x * -obliquity
}

#declare fudge_trans = transform
{
	//rotate y * -85
}


union
{
	sphere
	{
		0, 1
		pigment
		{
			image_map
			{
				jpeg "2k_earth_daymap.jpg"
				map_type 1
			}
			scale <-1,1,1>
			rotate +x * 90
//			rotate +z * 180
		}
	}
	cylinder
	{
		-z * 1.1, +z * 1.1, 0.01
		pigment {color srgb y+z}
		finish {ambient 0 diffuse 1 emission 1/2}
	}
	transform {sphere_trans}
	transform {fudge_trans}
}


// frame markers
cylinder
{
	0, x * 3, 0.01
	pigment {color srgb x}
	finish {ambient 0 diffuse 1 emission 1/2}
}
cylinder
{
	0, y * 3, 0.01
	pigment {color srgb y}
	finish {ambient 0 diffuse 1 emission 1/2}
}
cylinder
{
	0, z * 3, 0.01
	pigment {color srgb z}
	finish {ambient 0 diffuse 1 emission 1/2}
}

//
// Tilting axis
cylinder 
{ 0, TILT_AXIS*3, 0.01
	pigment {color srgb <1,1,0> }
	finish {ambient 0 diffuse 1 emission 1/2}
}

// calculated positions
/*
sphere
{
	+sphere_coo, 0.02
	pigment {color srgb x+y}
	finish {ambient 0 diffuse 1 emission 1/2}
	transform {fudge_trans}
}
sphere
{
	-sphere_coo, 0.02
	pigment {color srgb x+y}
	finish {ambient 0 diffuse 1 emission 1/2}
	transform {fudge_trans}
}

*/