import graph3;
import three;
import settings;
outformat="pdf";
settings.render = 0;
settings.prc = false;

usepackage("fourier");
defaultpen(font("T1","fut\textfamilyextension","m","n"));


size(300, 300);

// Set the camera.
currentprojection=perspective(16,-8,4);


void drawArrowX()
{
  real x0 = 12.8;
  real halfWidth = 0.02;
  real lineLength = 0.5;
  real arrowHalfWidth = 0.10;
  real arrowLength = 0.2;
  
  draw(
       (x0,-halfWidth,0)
    -- (x0 + lineLength,-halfWidth,0)
    -- (x0 + lineLength,-halfWidth - arrowHalfWidth,0)
    -- (x0 + lineLength + arrowLength,0,0)
    -- (x0 + lineLength,halfWidth + arrowHalfWidth,0)
    -- (x0 + lineLength,halfWidth,0)
    -- (x0,halfWidth,0)
    -- cycle );
}

void drawArrowY(real x, real v)
{
  real arrowHalfWidth = 0.07;
  real arrowLength = 0.2;
  
  real absV = abs(v);
  real dir = v / absV;
  real newV = dir * (absV - arrowLength);
  
  draw( (x, 0, 0) -- (x, newV, 0));
  
  draw(
       ( x - arrowHalfWidth, newV, 0)
    -- ( x, v, 0)
    -- ( x + arrowHalfWidth, newV, 0)
    -- cycle );
}

void drawArrowZ(real x, real v)
{
  real arrowHalfWidth = 0.07;
  real arrowLength = 0.2;
  
  real absV = abs(v);
  real dir = v / absV;
  real newV = dir * (absV - arrowLength);
  
  draw( (x, 0, 0) -- (x, 0, newV));
  
  draw(
       ( x - arrowHalfWidth, 0, newV)
    -- ( x, 0, v)
    -- ( x + arrowHalfWidth, 0, newV)
    -- cycle );
}

void drawSineArrowsY(int i)
{
  real x;
  real z;
  
  x = pi * i + pi * 0.1;
  z = -2 * sin(x);
  drawArrowY(x, z);
  x = pi * i + pi * 0.3;
  z = -2 * sin(x);
  drawArrowY(x, z);
  x = pi * i + pi * 0.5;
  z = -2 * sin(x);
  drawArrowY(x, z);
  x = pi * i + pi * 0.7;
  z = -2 * sin(x);
  drawArrowY(x, z);
  x = pi * i + pi * 0.9;
  z = -2 * sin(x);
  drawArrowY(x, z);
}

void drawSineArrowsZ(int i)
{
  real x;
  real z;
  
  x = pi * i + pi * 0.1;
  z = 2 * sin(x);
  drawArrowZ(x, z);
  x = pi * i + pi * 0.3;
  z = 2 * sin(x);
  drawArrowZ(x, z);
  x = pi * i + pi * 0.5;
  z = 2 * sin(x);
  drawArrowZ(x, z);
  x = pi * i + pi * 0.7;
  z = 2 * sin(x);
  drawArrowZ(x, z);
  x = pi * i + pi * 0.9;
  z = 2 * sin(x);
  drawArrowZ(x, z);
}

void drawArrowsY()
{
  drawSineArrowsY(0);
  drawSineArrowsY(1);
  drawSineArrowsY(2);
  drawSineArrowsY(3);
}

void drawArrowsZ()
{
  drawSineArrowsZ(0);
  drawSineArrowsZ(1);
  drawSineArrowsZ(2);
  drawSineArrowsZ(3);
}

void drawLambdaBarX()
{
  real x0 = pi * 0.5;
  real x1 = pi * 2.5;
  real m = 0.5 * (x1 + x0);
  real z = 2.3;
  real halfWidth = 0.07;
  
  draw( (x0, 0.0, z) -- (x1, 0.0, z) );
  draw( (x0, 0.0, z - halfWidth) -- (x0, 0.0, z + halfWidth) );
  draw( (x1, 0.0, z - halfWidth) -- (x1, 0.0, z + halfWidth) );
  
  draw("$\lambda$",(m,0,2.6));
}


real x1(real x) {return x;}
real y1(real x) {return 0.0;}
real z1(real x) {return 2.0 * sin(x);}

real x2(real x) {return x;}
real y2(real x) {return -2.0 * sin(x);}
real z2(real x) {return 0.0;}


// Draw the arrows.
drawArrowX();
drawArrowsY();
drawArrowsZ();

// Draw the sines.
draw(graph(x1,y1,z1,0.0,4pi));
draw(graph(x2,y2,z2,0.0,4pi));

// Draw the wave length meter.
drawLambdaBarX();

draw("$\vec E$",(10,0,-2));
draw("$\vec B$",(12,0,1.5));