<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE X3D PUBLIC "ISO//Web3D//DTD X3D 3.3//EN" "https://www.web3d.org/specifications/x3d-3.3.dtd">
<X3D profile='Immersive' version='3.3' xmlns:xsd='http://www.w3.org/2001/XMLSchema-instance' xsd:noNamespaceSchemaLocation='https://www.web3d.org/specifications/x3d-3.3.xsd'>
  <head>
    <!-- javascript code for rotation calculations was derived from: -->
    <meta content='ChangingFog.x3d' name='title'/>
    <meta content='A Fog node that adjusts as the viewer&apos;s orientation and position changes. This is a good candidate to become a Prototype since Fog does not automatically bind when inlined.' name='description'/>
    <meta content='Matthew Braun' name='creator'/>
    <meta content='20 September 2001' name='created'/>
    <meta content='20 October 2019' name='modified'/>
    <meta content='http://astronomy.swin.edu.au/pbourke/geometry/rotate/' name='reference'/>
    <meta content='Copyright (c) Matthew Braun 2001' name='rights'/>
    <meta content='Fog' name='subject'/>
    <meta content='https://www.web3d.org/x3d/content/examples/X3dForWebAuthors/KelpForestExhibit/ChangingFog.x3d' name='identifier'/>
    <meta content='X3D-Edit 3.3, https://www.web3d.org/x3d/tools/X3D-Edit' name='generator'/>
    <meta content='../license.html' name='license'/>
  </head>
  <Scene>
    <WorldInfo title='ChangingFog.x3d'/>
    <NavigationInfo avatarSize='0.01 0 0'/>
    <Viewpoint description='Start' fieldOfView='0.9' position='0 0 0'/>
    <Viewpoint description='Looking up from start' orientation='1 0 0 1.57' position='0 0 0'/>
    <Viewpoint description='10m above, looking straight up' orientation='1 0 0 1.57' position='0 10 0'/>
    <Viewpoint description='10m above start' position='0 10 0'/>
    <Viewpoint description='10m above, looking straight down' orientation='1 0 0 -1.57' position='0 10 0'/>
    <Viewpoint description='10m below, looking down' orientation='1 0 0 -1.57' position='0 -10 0'/>
    <Viewpoint description='10m below start' position='0 -10 0'/>
    <Viewpoint description='10m below, looking up' orientation='1 0 0 1.57' position='0 -10 0'/>
    <Fog DEF='Water' color='0.2 0.2 0.4' fogType='EXPONENTIAL'/>
    <!-- Proximity sensor must be large enough to encompass the entire scene -->
    <ProximitySensor DEF='ProxSensor' size='1000 1000 1000'/>
    <!-- TimeSensor triggering reduces frequency of calculations for performance reasons. -->
    <TimeSensor DEF='Clock' loop='true'/>
    <Script DEF='ChangeVisibility'>
      <field accessType='inputOnly' name='get_clock_hit' type='SFTime'/>
      <field accessType='initializeOnly' name='run_script' type='SFBool' value='false'/>
      <field accessType='inputOnly' name='get_depth' type='SFVec3f'/>
      <field accessType='outputOnly' name='visibility_changed' type='SFFloat'/>
      <field accessType='inputOnly' name='set_visibility' type='SFRotation'/>
      <!-- <field accessType='initializeOnly' name='checked' type='SFBool' value='false'/> <field accessType='initializeOnly' name='moved' type='SFBool' value='false'/> -->
      <![CDATA[
ecmascript:
// REF: http://astronomy.swin.edu.au/pbourke/geometry/rotate/

function initialize () {
   visibility = 20;
   depth = 0;
   pos = (0,0,0);
   Browser.println ('Position output from ProximitySensor.');
}

function get_clock_hit (clock_msg) {
     run_script = true;
}

function get_depth ( position ) {

   pos = position;
   depth = position[1] - 30;   

}

function set_visibility( rotation ) {

 if (run_script) {

//z coordinate of the default viewpoint direction(0,0,-1)
   initZ = -1;  

   rX = rotation[0];  // x coordinate of the rotation
   rY = rotation[1];  // y coordinate of the rotation
   rZ = rotation[2];  // z coordinate of the rotation

   theta = rotation[3];  // angle of rotation in radians
	
Browser.println ('theta:' + theta);
     
   cosTheta = Math.cos(theta);
   sinTheta = Math.sin(theta);

Browser.println ('cosTheta:' + cosTheta + ' sinTheta:'+ sinTheta);


// calculate the y coordinate of the point after rotation
/* there are 8 other terms in the full conversion, but 6 are equal
to zero because of the choice of a starting point on the z-axis. The
other two are not calculated since all we need is the y coordinate
*/
   finalY = ((1 - cosTheta) * rY * rZ - rX * sinTheta) * initZ;

Browser.println ('final y:' + finalY);

//calculate the elevation/depression angle of the final point location

   elevation = Math.asin(finalY);

Browser.println ('elevation:' + elevation);

   directionFactor = 1 + 0.2 * (4 * elevation / Math.PI);
   depthAdjust = (60 + depth)/60
   depthFactor = Math.max(depthAdjust,0.05);

   visibility_changed =  60 * depthFactor * directionFactor; 
   Browser.println ('depth=' + depth + ', elevation=' + elevation + 
        ', visibility_changed=' + visibility_changed);
   run_script = false;
   
 }
}
]]>
    </Script>
    <ROUTE fromField='cycleTime' fromNode='Clock' toField='get_clock_hit' toNode='ChangeVisibility'/>
    <ROUTE fromField='position_changed' fromNode='ProxSensor' toField='get_depth' toNode='ChangeVisibility'/>
    <ROUTE fromField='orientation_changed' fromNode='ProxSensor' toField='set_visibility' toNode='ChangeVisibility'/>
    <ROUTE fromField='visibility_changed' fromNode='ChangeVisibility' toField='visibilityRange' toNode='Water'/>
    <!-- A set of arrows is used to show visibility and direction -->
    <Transform DEF='Pointer' translation='0 0 -15'>
      <Transform translation='0 4 0'>
        <Shape>
          <Cone bottomRadius='0.4'/>
          <Appearance DEF='ShapeApp'>
            <Material ambientIntensity='0.8' diffuseColor='1 1 0.3' shininess='0.6'/>
          </Appearance>
        </Shape>
      </Transform>
      <Shape>
        <Cylinder height='6' radius='0.2'/>
        <Appearance USE='ShapeApp'/>
      </Shape>
    </Transform>
    <Transform translation='0 10 0'>
      <Transform USE='Pointer'/>
    </Transform>
    <Transform translation='0 -10 0'>
      <Transform USE='Pointer'/>
    </Transform>
    <!-- A pair of disks used to show visibility -->
    <Transform translation='0 15 0'>
      <Shape DEF='Disk'>
        <Cylinder height='0.01'/>
        <Appearance USE='ShapeApp'/>
      </Shape>
    </Transform>
    <Transform translation='0 -15 0'>
      <Shape USE='Disk'/>
    </Transform>
    <!-- An indexed face set box used to bound the working area -->
    <Transform scale='20 20 20'>
      <Shape DEF='IFSBox'>
        <Appearance>
          <Material diffuseColor='1 1 1'/>
        </Appearance>
        <IndexedFaceSet ccw='false' colorIndex='0 2 2 2 2 1' colorPerVertex='false' coordIndex='0 1 2 3 -1 7 6 5 4 -1 0 4 5 1 -1 1 5 6 2 -1 2 6 7 3 -1 3 7 4 0'>
          <Coordinate point='-1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 -1.0 -1.0 1.0 -1.0 -1.0 -1.0 1.0 1.0 -1.0 1.0 1.0 -1.0 -1.0 -1.0 -1.0 -1.0'/>
          <Color color='1 1 1 0 0 0 0.2 0.2 0.8'/>
        </IndexedFaceSet>
      </Shape>
    </Transform>
  </Scene>
</X3D>