#include "colors.inc"
#include "textures.inc"

background {White}

#declare fieldlinecolor=<0,1,0,0.9>;
#declare vvectorcolor=<0,0,1>;
#declare forcevectorcolor=<1,0,0>;

#declare smallwidth=0.05;
#declare normalwidth=0.1;
#declare largewidth=0.15;

#declare BVecLength=6;
#declare VVecLength=2;

#declare kr=0.2;

#macro MakeFieldVec (mylength,mywidth,veccolor)
  merge {
    cylinder { 
        <0, 0, 0>, <0, 0, mylength>, mywidth pigment 
        { color veccolor }
    }
    cone { 
        <0, 0, mylength>, mywidth+0.1, <0, 0, mylength+1>, 0 pigment 
        { color veccolor }
    }
  }
#end

#macro MakeParticle (particleLocation)
  sphere {
    particleLocation, kr
    pigment {color Black}
  }
#end

#declare torusMajor=1.5;
#declare torusMinor=0.05;
#macro MakeAngleIndicator (Pos, Angle)
    object {
            difference {
                    torus {
                      torusMajor, torusMinor
                      rotate z*-90
                    }
                union {
                    object {
                     box { <-2*torusMajor, -2*torusMajor, -2*torusMajor>, <2*torusMajor, 2*torusMajor, 0> }
                     rotate x*(-90)
                    }
                    object {
                     box { <-2*torusMajor, -2*torusMajor, -2*torusMajor>, <2*torusMajor, 2*torusMajor, 0> }
                     rotate x*(+90-Angle)
                    }
                }
            }
            pigment { Black }
        translate Pos
    }
#end


// create background plane

box {
  <0, 0, 0>, <10,16,0.001>
  pigment {color <1,1,1,0.9>}
  translate <-2, -2, 0>
} 


// create magnetic field vectors

#for (XCount,0,2)
  #for (YCount,0,3)
    object {
        MakeFieldVec (BVecLength,smallwidth,fieldlinecolor) 
        translate <3*XCount, 4*YCount, 0>
    }
  #end
#end



// particle 1: velocity vector and force vector (velocity 0° to magnetic field)

#declare Pos=<6, 12, 0>;
object {
   MakeFieldVec (VVecLength,normalwidth,vvectorcolor)
   rotate <0, 0, 0>
   translate Pos
}
MakeParticle (Pos)



// particle 2: velocity vector and force vector (velocity 30° to magnetic field)


#declare Pos=<6, 8, 0>;
#declare Angle=30;
object {
   MakeFieldVec (VVecLength,normalwidth,vvectorcolor)
   rotate <-1*Angle, 0, 0>
   translate Pos
}
object {
   MakeFieldVec (3*sin(radians(Angle))*VVecLength,normalwidth,forcevectorcolor)
   rotate <0, -90, 0>
   translate Pos
}
MakeParticle (Pos)
MakeAngleIndicator (Pos,Angle)



// particle 3: velocity vector and force vector (velocity 60° to magnetic field)


#declare Pos=<6, 4, 0>;
#declare Angle=60;
object {
   MakeFieldVec (VVecLength,normalwidth,vvectorcolor)
   rotate <-1*Angle, 0, 0>
   translate Pos
}
object {
   MakeFieldVec (3*sin(radians(Angle))*VVecLength,normalwidth,forcevectorcolor)
   rotate <0, -90, 0>
   translate Pos
}
MakeParticle (Pos)
MakeAngleIndicator (Pos,Angle)
                   


// particle 4: velocity vector and force vector (velocity 90° to magnetic field)

#declare Pos=<6, 0, 0>;
#declare Angle=90;
object {
   MakeFieldVec (VVecLength,normalwidth,vvectorcolor)
   rotate <-1*Angle, 0, 0>
   translate Pos
}
object {
   MakeFieldVec (3*VVecLength,normalwidth,forcevectorcolor)
   rotate <0, -90, 0>
   translate Pos
}
MakeParticle (Pos)
MakeAngleIndicator (Pos,Angle)


// camera & lights

#declare campos=<17, 14, 14>;
camera {
    location campos
    look_at <3, 6, 0>
}

light_source {
  campos 
  color White 
}