#version 3.7;
#include "colors.inc"
#include "skies.inc"

global_settings{assumed_gamma 1.70}
#debug concat("@@F:", str(frame_number,0,0), "\n")


// Move a Vector from, to, increment 
#macro MoveV(_from, _to, __i)
	<_from.x+((_to.x-_from.x)*__i),
	 _from.y+((_to.y-_from.y)*__i),
	 _from.z+((_to.z-_from.z)*__i)>
#end

// Animate this segment of the clock from 0 to 1
#macro AniSegment(_start, _end)
	((myclock-_start)/(_end-_start))
#end

// return a vector as a debug string (truncated precision) 
#macro vdebug(vec)
	concat("<", str(vec.x,0,2), ", ",str(vec.y,0,2), ", ", str(vec.z,0,2), ">")
#end

// Convert this vector into its angle
#macro VtoA(V)
	#local _V=vnormalize(V);
	#local rZ=degrees(acos(_V.z));
	#local rY=0;
	#if (_V.y != 0)
		#local rY=degrees(atan2(_V.x,_V.y));
	#end
	#debug concat("rY/Z=", str(rY,0,3), ", ", str(rZ,0,3), "\n")
	<-rZ,0,-rY>
#end

#declare myclock=clock*4;

#declare Camera=<0,10,0>;
#declare Lookat=<0,10,1>;

// swivel up and down around the camera
#local loffset0=<2,2,0>;
#local loffset1=<2,-1,-2>;
#local loffset2=<-2,1,-2>;
#local loffset3=<-2,-2,2>;

#switch (myclock)
	#range(0,1)
		#local _i=AniSegment(0,1);
		#declare Lookat=Lookat+MoveV(<0,0,0>,loffset0,_i);
		#break
	#range(1,2)
		#local _i=AniSegment(1,2);
		#declare Lookat=Lookat+MoveV(loffset0,loffset1,_i);
		#break
	#range(2,3)
		#local _i=AniSegment(2,3);
		#declare Lookat=Lookat+MoveV(loffset1,loffset2,_i);
		#break
	#range(3,4)
		#local _i=AniSegment(3,4);
		#declare Lookat=Lookat+MoveV(loffset2,loffset3,_i);
		#break
#end

#debug concat("Lookat=", vdebug(Lookat), "\n")
#local V=vnormalize(Lookat-Camera);
sphere {V+Camera,0.02 pigment {Red}}		

#local foo=<0,0,10>;
#local fooVec=Lookat-Camera;
#local fooRot=VtoA(fooVec);
#local foof=vrotate(foo, fooRot);
#debug concat ("fooRot=", vdebug(fooRot), "\n")
sphere {foof+Camera, 0.5 pigment {Cyan}}
#debug concat ("foof=", vdebug(foof), "\n")

#local bar=<1,0,10>;
//#local barRot=VtoA(bar-Camera);
#local bar=vrotate(bar, fooRot);
sphere {bar+Camera, 0.51 pigment {Green}}
#debug concat ("bar=", vdebug(bar), "\n")

camera {
	location Camera
	look_at	 Lookat
}

light_source {<0,20,0> rgb 1}
sky_sphere { S_Cloud3 rotate y * 180}
plane { y, 0
	texture {
		checker
		texture {
			pigment {ForestGreen}
		},
		texture {
			pigment{White}
		}
	}
	scale 12
}

#debug "@@end\n"