A Greasemonkey user script for SpaceX ISS SIM - useful to enable hard mode (no HUD) - optionally disable collissions, realistic orbital mechanics and other fun stuff

ISS-SIM-Customizer.user.js

// ==UserScript==
// @name     SpaceX ISS-SIM-Customizer
// @version  0.000015
// @author CorvusCorax
// @match https://iss-sim.spacex.com/
// @description A Greasemonkey user script for SpaceX ISS SIM - useful to enable hard mode (no HUD) - optionally disable collissions, realistic orbital mechanics and other fun stuff
// @include https://iss-sim.spacex.com/
// @license Creative Commons - CC BY 4.0
// ==/UserScript==

// add menu to configure iss-sim to settings DOM tree
var JQ=document.querySelector.bind(document)
JQ("#settings .modal-inner").innerHTML+='<div id="setting-tesla" class="setting active">TESLA:<br><span>HIDDEN EASTEREGG</span></div><div id="setting-space" class="setting active">SPACE:<br><span>RESTRICTED</span></div><div id="setting-hud" class="setting active">HUD:<br><span>ONLINE</span></div><div id="setting-limits" class="setting active">DOCKING CONSTRAINTS:<br><span>ORIGINAL SIM +-0.2deg</span></div><div id="setting-collision" class="setting active">COLLISIONS:<br><span>ENABLED</span></div><div id="setting-dock" class="setting active">ISS DOCKING PORT:<br><span>IDA-2</span></div><div id="setting-challenge" class="setting active">CHALLENGE:<br><span>DOCK</span></div>'
JQ("#hud").innerHTML+='<div id="rendezvous" class="hud-item" style="position: absolute; top: 15%; left: 15%; width: 110px; margin: 0; text-align: center; text-shadow: 0 0 10px #000; display: none;"><div class="label">RNDVZ</div><div id="rendezvous-phase" class="rate"></div><div id="rendezvous-time" class="rate"></div><div id="rendezvous-deltav" class="rate"></div><div id="rendezvous-deltat" class="rate"></div></div><div id="orbit" class="hud-item" style="position: absolute; top: 15%; right: 15%; width: 90px; margin: 0; text-align: center; text-shadow: 0 0 10px #000; display: none;"><div class="label">ORBIT</div><div id="orbit-vel" class="rate"></div><div id="orbit-alt" class="rate"></div><div id="orbit-apogee" class="rate"></div><div id="orbit-perigee" class="rate"></div><div id="orbit-period" class="rate"></div></div>'
JQ("#x-range .distance").style.width="100px"
JQ("#y-range .distance").style.width="100px"
JQ("#z-range .distance").style.width="100px"
{
  var d=document.createElement('DIV')
  d.id="propellant"
  d.class="hud-item"
  d.style="position: absolute; top: 15%; left: 5%; width: 100px; margin: 0; text-align: left; text-shadow: 0 0 12px #000; display: none; "
  d.innerHTML='<div class="label">DELTA-V BUDGET</div><div id="prop-used" class="rate"></div><div id="prop-left" class="rate"></div><div class="label">MAIN BURN (M)</div><div id="burn-onoff" class="rate">OFF</div><div class="label">STATS</div><div id="stats-mission" class="rate"></div><div id="stats-real" class="rate"></div><div id="stats-fps" class="rate"></div>'
  JQ("#hud").after(d)
}

// The main functionality override must be loaded AFTER ISS-SIM has finished loading.
function GMInitializer() {

  // allow realistic orbital mechanics
  window.GMisOrbitalMechanics = 1

  // override gravity toggler function
  // Bug: Tampermonkey extension for firefox does not support overriding functions already bound to event listeners
  // Fix: Unbind event listener, bind our own instead
  $("#setting-gravity").removeEventListener("click", toggleGravity, !1)
  $("#setting-gravity").removeEventListener("touchstart", toggleGravity, !1)

  var GMAmbientLight = new THREE.AmbientLight(0xffffff, 0.1);
  toggleGravity = function() {
    if (!GMisChallenge || GMisTrajectoryVisible) return // cannot switch of gravity when trying rendezvous manouver or showing trajectory
    GMisOrbitalMechanics = GMisOrbitalMechanics<3 ? GMisOrbitalMechanics+1 : 1
    switch (GMisOrbitalMechanics) {
      case 1:
        (isGravity = !0, $("#setting-gravity").classList.add("active"), $("#setting-gravity span").innerHTML = "ON")
        break;
      case 2:
        (isGravity = !1, $("#setting-gravity span").innerHTML = "PROPER ORBITAL MECHANICS")
        $("#setting-gravity").classList.add("active")
        $("#orbit").style.display="block"
        $("#rendezvous").style.display="block"
        // Have earth the correct way around, and ISS in correct orbit
        earthObject.rotation.fromArray([0,0,(-90+51) * Math.PI/180.0])
        camera.children.push(GMAmbientLight)
        GMSpeedMeasure=0 // force end speed measurement - fluctuating deltaT messes up orbits
        break;
      case 3:
        ($("#setting-gravity").classList.remove("active"), $("#setting-gravity span").innerHTML = "OFF")
        $("#orbit").style.display="none"
        $("#rendezvous").style.display="none"
        // Revert back to ISS-SIM reverse earth
        earthObject.rotation.fromArray([0,0,51 * Math.PI/180.0])
        starsObject.rotation.fromArray([0,0,0])
        lightISS_Primary.position.set(0, 4e10, 4e10)
        camera.children.pop(GMAmbientLight)
        issObject.children[3].children[0].children[0].children[6].children[8].children[6].children[6].children[3].rotation.x=60*Math.PI/180.0
        issObject.children[3].children[0].children[0].children[6].children[8].children[7].children[6].children[3].rotation.x=60*Math.PI/180.0
        break;
    }
  }

  $("#setting-gravity").addEventListener("click", toggleGravity, !1)
  $("#setting-gravity").addEventListener("touchstart", toggleGravity, !1)

  // unhide the Tesla
  window.GMisTeslaHidden = 1

  function GMToggleTeslaHidden() {
    GMisTeslaHidden ? (GMisTeslaHidden = !1, $("#setting-tesla span").innerHTML = "VISIBLE") : (GMisTeslaHidden = !0, $("#setting-tesla span").innerHTML = "HIDDEN EASTEREGG")
  }

  $("#setting-tesla").addEventListener("click", GMToggleTeslaHidden, !1)
  $("#setting-tesla").addEventListener("touchstart", GMToggleTeslaHidden, !1)

  // unrestrict space
  window.GMisSpaceRestricted = 1

  function GMToggleSpaceRestricted() {
    GMisSpaceRestricted ? (GMisSpaceRestricted = !1, $("#setting-space span").innerHTML = "INFINITE") : (GMisChallenge && ( GMisSpaceRestricted = !0, $("#setting-space span").innerHTML = "RESTRICTED"))
  }

  $("#setting-space").addEventListener("click", GMToggleSpaceRestricted, !1)
  $("#setting-space").addEventListener("touchstart", GMToggleSpaceRestricted, !1)

  // HUD visible
  window.GMHUDStatus = 1
  window.GMisHUDVisible = 1
  window.GMisTrajectoryVisible = 0

  function GMshowHUD() {
    issObject.children[4].visible=true
    issObject.children[5].visible=true
    issObject.children[6].visible=true
    issObject.children[7].visible=true
    $("#hud").style.display="block"
    $("#hud-tips").style.display="block"
    $("#hud-worms").style.display="block"
  }

  function GMhideHUD() {
    issObject.children[4].visible=false
    issObject.children[5].visible=false
    issObject.children[6].visible=false
    issObject.children[7].visible=false
    $("#hud").style.display="none"
    $("#hud-tips").style.display="none"
    $("#hud-worms").style.display="none"
  }

  function GMToggleHUDVisible() {
    GMHUDStatus = GMHUDStatus<3 ? GMHUDStatus+1 : 1
    switch (GMHUDStatus) {
      case 1:
        GMisHUDVisible = !0, $("#setting-hud").classList.add("active"), $("#setting-hud span").innerHTML = "ONLINE", GMshowHUD()
        break;
      case 2:
        ( GMisOrbitalMechanics==2 || ( GMisOrbitalMechanics=1, toggleGravity() ) ), GMisTrajectoryVisible = !0, $("#setting-hud span").innerHTML = "ONLINE + TRAJECTORY"
        break;
      case 3:
        GMisHUDVisible = !1, GMisTrajectoryVisible = !1, $("#setting-hud").classList.remove("active"), $("#setting-hud span").innerHTML = "OFFLINE", GMhideHUD()
        break;
    }
  }

  $("#setting-hud").addEventListener("click", GMToggleHUDVisible, !1)
  $("#setting-hud").addEventListener("touchstart", GMToggleHUDVisible, !1)

  // relaxed limits
  window.GMLimits = 1
  window.GMisFuelLimit = !1
  window.GMisLimitsOriginal = !0

  function GMToggleLimits() {
    GMLimits = GMLimits < 4 ? GMLimits+1 : 1
    switch (GMLimits) {
       case 1:
         GMisLimitsOriginal = !0, $("#setting-limits span").innerHTML = "ORIGINAL SIM +-0.2deg"
         GMisFuelLimit = !1
         break;
       case 2:
         GMisLimitsOriginal = !1, $("#setting-limits span").innerHTML = "IDA SPECS +-4.0deg 0.1m/s"
         GMisFuelLimit = !1
         break;
       case 3:
         GMisLimitsOriginal = !0, $("#setting-limits span").innerHTML = "LIMITED PROPELLANT, ORIGINAL SIM +-0.2deg"
         GMisFuelLimit = !0
         break;
       case 4:
         GMisLimitsOriginal = !1, $("#setting-limits span").innerHTML = "LIMITED PROPELLANT, IDA SPECS +-4.0deg 0.1m/s"
         GMisFuelLimit = !0
         break;
    }
  }

  $("#setting-limits").addEventListener("click", GMToggleLimits, !1)
  $("#setting-limits").addEventListener("touchstart", GMToggleLimits, !1)

  // collision
  window.GMisCollisions = 1

  function GMToggleCollisions() {
    GMisCollisions ? (GMisCollisions = !1, $("#setting-collision").classList.remove("active"), $("#setting-collision span").innerHTML = "DISABLED") : (GMisCollisions = !0, $("#setting-collision").classList.add("active"), $("#setting-collision span").innerHTML = "ENABLED" )
  }

  $("#setting-collision").addEventListener("click", GMToggleCollisions, !1)
  $("#setting-collision").addEventListener("touchstart", GMToggleCollisions, !1)

  // docking ports
  window.GMisDocking = 1
  var GMRotForward = new THREE.Object3D()
  GMRotForward.position.fromArray([0,0,-0.1])
  var GMRotPort = new THREE.Object3D()
  GMRotPort.rotateY(0.5*Math.PI)
  GMRotPort.position.fromArray([-0.1,0,0])
  var GMRotAft = new THREE.Object3D()
  GMRotAft.rotateY(Math.PI)
  GMRotAft.position.fromArray([0,0,0.1])
  var GMRotZenithUS = new THREE.Object3D()
  GMRotZenithUS.rotateX(-0.5*Math.PI)
  GMRotZenithUS.position.fromArray([0,-0.1,0])
  var GMRotNadirUS = new THREE.Object3D()
  GMRotNadirUS.rotateX(0.5*Math.PI)
  GMRotNadirUS.position.fromArray([0,0.1,0])
  var GMRotZenithRU = GMRotAft.clone()
  GMRotZenithRU.rotateX(-0.5*Math.PI)
  GMRotZenithRU.position.fromArray([0,-0.1,0])
  var GMRotNadirRU = GMRotAft.clone()
  GMRotNadirRU.rotateX(0.5*Math.PI)
  GMRotNadirRU.position.fromArray([0,0.1,0])

  var GMPosIDA2 = new THREE.Vector3(0,0,0)
  var GMPosHarmonyZt = new THREE.Vector3(0,3.5,-4.75)
  var GMPosHarmonyNd = new THREE.Vector3(0,-2.1,-4.75)
  var GMPosPMA3 = new THREE.Vector3(12,0,-21)
  var GMPosZvezda = new THREE.Vector3(0,1.5,-53.9)
  var GMPosPoisk = new THREE.Vector3(0,7.0,-40.95)
  var GMPosPirs = new THREE.Vector3(0,-4.1,-40.95)
  var GMPosRassvet = new THREE.Vector3(0,-6.5,-28.0)

  var GMIssRestoreOffset = GMPosIDA2.clone()
  var GMIssApproach = GMRotForward.clone()

  function GMRestoreISSPos() {
    issObject.children[0].position.add(GMIssRestoreOffset)
    issObject.children[1].position.add(GMIssRestoreOffset)
    issObject.children[2].position.add(GMIssRestoreOffset)
    issObject.children[3].position.add(GMIssRestoreOffset)
  }

  function GMSetISSPos() {
    var GMnegRestore = GMIssRestoreOffset.clone()
    GMnegRestore.negate()
    issObject.children[0].position.add(GMnegRestore)
    issObject.children[1].position.add(GMnegRestore)
    issObject.children[2].position.add(GMnegRestore)
    issObject.children[3].position.add(GMnegRestore)
  }

  function GMRingsFront() {
    issObject.children[4].position.fromArray([0,0,20])
    issObject.children[5].position.fromArray([0,0,40])
    issObject.children[6].position.fromArray([0,0,80])
    issObject.children[4].rotation.fromArray([0,0,0])
    issObject.children[5].rotation.fromArray([0,0,0])
    issObject.children[6].rotation.fromArray([0,0,0])
  }

  function GMRingsAft() {
    issObject.children[4].position.fromArray([0,0,-20])
    issObject.children[5].position.fromArray([0,0,-40])
    issObject.children[6].position.fromArray([0,0,-80])
    issObject.children[4].rotation.fromArray([0,Math.PI,0])
    issObject.children[5].rotation.fromArray([0,Math.PI,0])
    issObject.children[6].rotation.fromArray([0,Math.PI,0])
  }

  function GMRingsZenith() {
    issObject.children[4].position.fromArray([0,20,0])
    issObject.children[5].position.fromArray([0,40,0])
    issObject.children[6].position.fromArray([0,80,0])
    issObject.children[4].rotation.fromArray([-0.5*Math.PI,0,0])
    issObject.children[5].rotation.fromArray([-0.5*Math.PI,0,0])
    issObject.children[6].rotation.fromArray([-0.5*Math.PI,0,0])
  }

  function GMRingsNadir() {
    issObject.children[4].position.fromArray([0,-20,0])
    issObject.children[5].position.fromArray([0,-40,0])
    issObject.children[6].position.fromArray([0,-80,0])
    issObject.children[4].rotation.fromArray([0.5*Math.PI,0,0])
    issObject.children[5].rotation.fromArray([0.5*Math.PI,0,0])
    issObject.children[6].rotation.fromArray([0.5*Math.PI,0,0])
  }

  function GMToggleDocking() {
    GMRestoreISSPos()
    GMisDocking = GMisDocking<8 ? GMisDocking+1 : 1
    var name = ""
    switch (GMisDocking) {
      case 1:
        GMIssRestoreOffset.copy(GMPosIDA2)
        GMIssApproach.copy(GMRotForward)
        name = "IDA-2"
        GMRingsFront()
        break;
      case 2:
        GMIssRestoreOffset.copy(GMPosHarmonyZt)
        GMIssApproach.copy(GMRotZenithUS)
        name = "HARMONY ZENITH"
        GMRingsZenith()
        break;
      case 3:
        GMIssRestoreOffset.copy(GMPosHarmonyNd)
        GMIssApproach.copy(GMRotNadirUS)
        name = "HARMONY NADIR"
        GMRingsNadir()
        break;
      case 4:
        GMIssRestoreOffset.copy(GMPosPMA3)
        GMIssApproach.copy(GMRotPort)
        name = "PMA3 ( WATCH RADIATOR! )"
        GMRingsNadir()
        issObject.children[4].position.x=5
        issObject.children[5].position.x=5
        issObject.children[6].position.x=5
        // rotate radiator to allow approach
        issObject.children[3].children[0].children[0].children[6].children[8].children[7].children[5].rotateY(-Math.PI/2)
        break;
      case 5:
        GMIssRestoreOffset.copy(GMPosZvezda)
        GMIssApproach.copy(GMRotAft)
        name = "ZVEZDA"
        GMRingsAft()
        issObject.children[3].children[0].children[0].children[6].children[8].children[7].children[5].rotateY(-Math.PI/2)
        break;
      case 6:
        GMIssRestoreOffset.copy(GMPosPoisk)
        GMIssApproach.copy(GMRotZenithRU)
        name = "POISK"
        GMRingsZenith()
        break;
      case 7:
        GMIssRestoreOffset.copy(GMPosPirs)
        GMIssApproach.copy(GMRotNadirRU)
        name = "PIRS"
        GMRingsNadir()
        break;
      case 8:
        GMIssRestoreOffset.copy(GMPosRassvet)
        GMIssApproach.copy(GMRotNadirRU)
        name = "RASSVET"
        GMRingsNadir()
        break;
    }
    GMSetISSPos()
    $("#setting-dock span").innerHTML = name
  }

  $("#setting-dock").addEventListener("click", GMToggleDocking, !1)
  $("#setting-dock").addEventListener("touchstart", GMToggleDocking, !1)

  // challenge
  window.GMisChallenge = 1

  $("#option-restart").removeEventListener("click", resetPosition, !1)
  $("#option-restart").removeEventListener("touchstart", resetPosition, !1)
  window.GMPhase = 127
  window.GMPerigee = 190
  window.GMApogee = 205
  window.GMInclination = Math.PI*1000 // 3000 odd meters ;)
  resetPosition = function() {
    var px=12,
        py=30,
        pz=50,
        vx=0,
        vy=0,
        vz=0
    if (!GMisChallenge) {
      var phi = new THREE.Euler(-GMPhase*Math.PI/180,0,0),
          r = GMGravBodyRadius+(GMPerigee*1000),
          rref = GMGravBodyCenter.length(),
          a = GMGravBodyRadius+((GMPerigee+GMApogee)*500),
          pos = new THREE.Vector3(0,0,0).sub(GMGravBodyCenter).applyEuler(phi).setLength(r).add(GMGravBodyCenter),
          v = Math.sqrt(GMG*GMMe*((2.0/r)-(1.0/a))),
          omega = Math.sqrt((GMG*GMMe)/rref)/rref,
          vel = new THREE.Vector3(0,0,v).applyEuler(phi).sub(GMCalcPseudoVelocity(pos,omega)).multiplyScalar(GMFixedStepTime)
       px=pos.x + GMInclination // this adds enough challenge by screwing everything just a little bit up
       py=pos.y
       pz=pos.z
       vx=vel.x
       vy=vel.y
       vz=vel.z
    }
    isGameOver=!0, resetMovement(), gsap.to(motionVector, 5, {
        x: vx,
        y: vy,
        z: vz,
        ease: "expo.out"
    }), gsap.to(translationVector, 5, {
        x: 0,
        y: 0,
        z: 0,
        ease: "expo.out"
    }), gsap.to(camera.position, 5, {
        x: px,
        y: py,
        z: pz,
        ease: "expo.out"
    }), gsap.to(camera.rotation, 5, {
        x: -20 * toRAD,
        y: -10 * toRAD,
        z: 15 * toRAD,
        ease: "expo.out",
        onComplete: GMGameStart
    })
  }

  function GMToggleChallenge() {
    GMisChallenge ? ((GMisSpaceRestricted && GMToggleSpaceRestricted()), ( GMisOrbitalMechanics==2 || ( GMisOrbitalMechanics=1, toggleGravity() ) ), GMisChallenge = !1, $("#setting-challenge span").innerHTML = "RENDEZVOUS + DOCK", GMDeltaVBudget=175, resetPosition()) : (GMisChallenge = !0, $("#setting-challenge span").innerHTML = "DOCK", GMDeltaVBudget=25, resetPosition() )
  }

  $("#option-restart").addEventListener("click", resetPosition, !1)
  $("#option-restart").addEventListener("touchstart", resetPosition, !1)
  $("#setting-challenge").addEventListener("click", GMToggleChallenge, !1)
  $("#setting-challenge").addEventListener("touchstart", GMToggleChallenge, !1)

  // lots of functionality here for proper orbital mechanics - start with globals
  var GMCameraRotationHelper = new THREE.Object3D()
  var GMoldTime = 0
  window.GMFixedStepTime = 0.05
  window.GMCurrentFrameTime = 0.05
  window.GMMissionTimer = 0
  window.GMGameTimer = 0

  // fix motion - ISS-SIM keeps all velocities in a per frame format, even though frame timing is varying
  // let's fix that. This function undo's all motion computations and reapply's them with correct timing
  // the alternative would be to reimplement the render() function.
  function GMfixMotion() {
     var k = GMCurrentFrameTime/GMFixedStepTime
     // fix translation
     !isGameOver && isGravity && (camera.position.y = camera.position.y + gravity)
     camera.position.sub(motionVector)
     correctedMotion = motionVector.clone().multiplyScalar(k)
     camera.position.add(correctedMotion)
     !isGameOver && isGravity && (camera.position.y = camera.position.y - (gravity*k))
     // fix rotation
     camera.rotateZ(-currentRotationZ)
     camera.rotateY(-currentRotationY)
     camera.rotateX(-currentRotationX)
     camera.rotateX(currentRotationX*k)
     camera.rotateY(currentRotationY*k)
     camera.rotateZ(currentRotationZ*k)
  }

  window.GMDeltaVUsed = 0
  window.GMDeltaVBudget = 25
  var GMOldMotionVector = new THREE.Vector3()
  var GMOldRotation = new THREE.Vector3()

  // calculate gravity - for proper orbital mechanics - needs coordinate system translation
  // due to rotating coordinate reference frame used by ISS-SIM
  window.GMGravBodyCenter = new THREE.Vector3(0,-6821000 ,0) // hardcode in case earth object is not spawned yet 450 km orbit
  window.GMGravBodyRadius = 6371000
  window.GMGravBodyAtmosphereRadius = GMGravBodyRadius + 80000
  window.GMG = 6.6743015e-11
  window.GMMe = 5.9722e+24
  // var GMMe = 5.9722e+28 // black hole earth to test orbital mechanics
  window.GMIssOrbitAxis = new THREE.Vector3(1,0,0)

  // energy is sum of gravitational portential and kinematic
  function GMOrbitEnergy(v,p) {
    var r = Math.abs(p.distanceTo(GMGravBodyCenter)),
        eP = -GMG*GMMe / r,
        eV = 0.5 * (v.length()**2)
    return eP + eV
  }

  // function to calculate pseudo velocity coming from rotating reference frame at any point
  function GMCalcPseudoVelocity(position,omega) {
    var pseudoCenter = GMGravBodyCenter.clone()
    // frame rotates around x axis - this makes this easy
    pseudoCenter.x = position.x
    var radius = Math.abs(position.distanceTo(pseudoCenter))
    return pseudoCenter.clone().sub(position).normalize().cross(GMIssOrbitAxis).multiplyScalar(radius*omega)
  }

  // function to calculate local gravity vector
  function GMCalcLocalGravityVector(position) {
    var r = Math.abs(position.distanceTo(GMGravBodyCenter))
    var grav = GMG*GMMe / (r**2)
    var earthVector = GMGravBodyCenter.clone().sub(position).normalize()
    return earthVector.clone().multiplyScalar(grav)
  }

  function GMprintTime(time) {
    var res=""
    if (time<0) {
      res="-"
      time=-time
    }
    res += Math.floor(time/60).toString().padStart(2,"0")
    res += ":"
    res += Math.floor(time%60).toString().padStart(2,"0")
    return res
  }

  // this function calculates the orbital mechanics creates in a rotating reference frame
  // for that we compute a single motion step at orbital velocity with earth gravity acting,
  // then transform it back into the rotating ref frame
  function GMOrbitalMotion() {
    var mu = GMG*GMMe
    var GMIssAngularVelocity = Math.sqrt(mu/GMGravBodyCenter.length())/GMGravBodyCenter.length()

    // calculating a motion step in rotating reference frame is now in its own class
    // - warning hack: in every time step motionVector is added to camera
    // but we prefer doing that ourselves so we substract motionVector now so the renderer can re-add it
    var p = camera.position.clone().sub(motionVector.clone().multiplyScalar(GMCurrentFrameTime/GMFixedStepTime))
    var o = new GMOrbiter(p, motionVector.clone().multiplyScalar(1.0/GMFixedStepTime))
    o.advance(GMCurrentFrameTime)

    // copy new velocity into motion vector
    motionVector.copy(o.v).multiplyScalar(GMFixedStepTime)

    // apply new position to camera
    camera.position.copy(o.p)

    // calculate some orbital parameters for display

    var r = Math.abs(camera.position.distanceTo(GMGravBodyCenter))
    var v = o.vs.length()
    var gammacos = o.vs.clone().normalize().dot(camera.position.clone().sub(GMGravBodyCenter).normalize())
    var gamma = Math.acos(gammacos)
    var gammasin = Math.sin(gamma)
    // semi major axis and eccentricity
    var a = 1.0 / ( (2/r) - ((v**2) / mu) )
    var e = Math.sqrt( (((r*(v**2)/mu)-1)**2)*gammasin**2 + gammacos**2 )
    // periapis and apoapsis
    var peri = a*(1-e), apo = a*(1+e)
    // phase angle between ISS and Dragon - as seen from earth
    var v1 = camera.position.clone().sub(GMGravBodyCenter).normalize()
    var v2 = new THREE.Vector3(0,0,0).sub(GMGravBodyCenter).normalize()
    var phase = v1.angleTo(v2)
    if (v1.clone().cross(v2).dot(GMIssOrbitAxis)<0) phase=-phase

    // a2 = r2 - circular ISS orbit
    var a2 = GMGravBodyCenter.length()

    // v3/a3/e3 hypothetical transfer orbit from current orbit (including gamma) to ISS - solve for DeltaV
    var v3 = Math.sqrt(-2.0*a2*mu*((a2 - r)/(((r**3)*(gammasin**2)) - ((a2**2)*r))))
    var a3 = 1.0 / ( (2/r) - ((v3**2) / mu) )
    var e3 = Math.sqrt( (((r*(v3**2)/mu)-1)**2)*gammasin**2 + gammacos**2 )

    // calculate true anomaly of transfer orbit
    var phi = Math.acos(((a3*(1.0-e3**2))-r)/(e3*r))
    if (gammacos<0) phi=-phi // correct for descending half orbit

    // calculate time spent in transfer orbit - using Mean Anomaly M via eccentric anomaly E
    var n = Math.sqrt(mu/a3**3)
    var E = Math.acos((e3+Math.cos(phi))/(1.0+(e3*Math.cos(phi))))
    var M = E-(e3*Math.sin(E))
    if (gammacos<0) M=-M // once again correct for descending half

    // calculate time of arrival - depends if we make a transfer up (destination at Apogee)
    // or down (ISS is at perigee) and current Mean Anomaly
    var rtime
    if (a2>a3) {
      rtime = Math.PI - M
    } else {
      rtime = (2.0*Math.PI) - M
    }
    if (rtime<0) rtime+=2.0*Math.PI
    if (rtime>2.0*Math.PI) rtime-=2.0*Math.PI
    rtime=rtime/n

    // calculate periods
    var T = 2.0 * Math.PI * Math.sqrt( a**3 / mu )
    var T2 = 2.0 * Math.PI * Math.sqrt( a2**3 / mu )

    // calculate phase after transfer
    var pafter
    if (a2>a3) {
      pafter = phase+GMIssAngularVelocity*rtime-(Math.PI-phi)
    } else {
      pafter = phase+GMIssAngularVelocity*rtime-((2.0*Math.PI)-phi)
    }
    if (pafter < -Math.PI) pafter+=2.0*Math.PI
    if (pafter > Math.PI) pafter-=2.0*Math.PI

    // burn T=0 is when phase-after-transfer is zero. But rate at which phase is shrinking depends
    // on current orbit - this timing is inaccurate, we don't take the current orbits Mean Anomaly into account
    // but its "good enough" to give the hobby astronaut a good idea when to fire thrusters
    var pdelta = 2.0*Math.PI*(T2-T)/T2
    var btime = -T2*(pafter/pdelta)
    $("#orbit-vel").innerHTML="Vel: "+v.toFixed(1)+" m/s"
    $("#orbit-alt").innerHTML="Alt: "+((r-GMGravBodyRadius)/1000).toFixed(1)+" km"
    $("#orbit-apogee").innerHTML="Ap: "+((apo-GMGravBodyRadius)/1000).toFixed(1)+" km"
    $("#orbit-perigee").innerHTML="Pe: "+((peri-GMGravBodyRadius)/1000).toFixed(1)+" km"
    $("#orbit-period").innerHTML="Prd: "+GMprintTime(T)
    $("#rendezvous-phase").innerHTML="Phs: "+(phase*180.0/Math.PI).toFixed(1)+"°"
    $("#rendezvous-time").innerHTML="Ht: "+GMprintTime(rtime)+"⇒"+(pafter*180.0/Math.PI).toFixed(1)+"°"
    $("#rendezvous-deltav").innerHTML="Dv: "+((v3-v).toFixed(1))+" m/s"
    $("#rendezvous-deltat").innerHTML="Dt: "+GMprintTime(btime)

    // rotate earth more correctly
    earthMesh.rotateY(-1e-4) // undo default rotation
    earthMesh.rotateY(((2*Math.PI)/(24*60*60))*GMCurrentFrameTime) // and rotate eastwards (natural earth rotation)
    starsObject.rotateX(-GMIssAngularVelocity*GMCurrentFrameTime)
    earthObject.rotateOnWorldAxis(GMIssOrbitAxis,-GMIssAngularVelocity*GMCurrentFrameTime) // while perceived rotation is west
    lightISS_Primary.position.applyEuler(new THREE.Euler(-GMIssAngularVelocity*GMCurrentFrameTime,0,0)) // rotate sun
    // follow sun with ISS with solar panels
    issObject.children[3].children[0].children[0].children[6].children[8].children[6].children[6].children[3].rotateX(-GMIssAngularVelocity*GMCurrentFrameTime)
    issObject.children[3].children[0].children[0].children[6].children[8].children[7].children[6].children[3].rotateX(-GMIssAngularVelocity*GMCurrentFrameTime)
  }

  // helper class to accurately calculate orbital motion of any object in ISS rotating reference frame
  class GMOrbiter {
    constructor(p,v) {
      this.p = (new THREE.Vector3()).copy(p)
      this.v = (new THREE.Vector3()).copy(v)
      this.vs = new THREE.Vector3()
    }
    clone() {
      var c = new GMOrbiter(this.p,this.v)
      c.vs.copy(this.vs)
      return c
    }
    advance(t) {
      var mu = GMG*GMMe
      // velocity of rotating reference frame
      var GMIssAngularVelocity = Math.sqrt(mu/GMGravBodyCenter.length())/GMGravBodyCenter.length()
      var pseudoCamMotion = GMCalcPseudoVelocity(this.p,GMIssAngularVelocity)

      // calculate local gravity vector and magnitude
      var gravityVector = GMCalcLocalGravityVector(this.p)

      // calculate current effective velocity vector and direction
      var pseudoVelocity = this.v.clone().add(pseudoCamMotion)

      // calculate orbital energy
      var GMEnergy = GMOrbitEnergy(pseudoVelocity, this.p)

      // calculate change in position and velocity in stationary coordinate system...
      var pseudoNextVel1 = pseudoVelocity.clone().add(gravityVector.clone().multiplyScalar(t))
      var averageVel1 = pseudoVelocity.clone().add(pseudoNextVel1).multiplyScalar(0.5)
      var pseudoNextPos1 = this.p.clone().add(averageVel1.clone().multiplyScalar(t))

      // iterative, 2 step for higher accuracy (that algo has a name, I forgot that name)
      var gravityVector2 = GMCalcLocalGravityVector(pseudoNextPos1)
      var averageGrav = gravityVector.clone().add(gravityVector2).multiplyScalar(0.5)
      var pseudoNextVel = pseudoVelocity.clone().add(averageGrav.clone().multiplyScalar(t))
      var averageVel2 = pseudoVelocity.clone().add(pseudoNextVel).multiplyScalar(0.5)

      var pseudoNextPos = this.p.clone().add(averageVel2.clone().multiplyScalar(t))

      // convert new position back into rotating coordinate frame at time t+1
      this.p.copy(pseudoNextPos.clone().sub(GMGravBodyCenter).applyAxisAngle(GMIssOrbitAxis,-GMIssAngularVelocity*t).add(GMGravBodyCenter))

      // same with velocity
      var newPseudoMotion = GMCalcPseudoVelocity(this.p,GMIssAngularVelocity)
      var newPseudoVelocity = pseudoNextVel.clone().applyAxisAngle(GMIssOrbitAxis,-GMIssAngularVelocity*t)

      // correct orbital energy to prevent drifting
      var velEnergyRequired = GMEnergy - (-mu / Math.abs(this.p.distanceTo(GMGravBodyCenter)))
      var velocityRequired = Math.sqrt( 2.0*velEnergyRequired )
      this.vs.copy(newPseudoVelocity.clone().normalize().multiplyScalar(velocityRequired))
      this.v.copy(this.vs.clone().sub(newPseudoMotion))
    }
  }

  window.GMTrajectoryStep=20.0

  // Show expected trajectory
  function GMShowTrajectory() {
    var o = new GMOrbiter(camera.position, motionVector.clone().multiplyScalar(1.0/GMFixedStepTime))
    var timestep = GMTrajectoryStep / (motionVector.length()/GMFixedStepTime) // calculate length of time iteration
    var iters=1
    if (!(timestep<1.0)) timestep=1.0; // prevent div by zero or extreme accuracy degradation
    var ot=o.clone()
    ot.advance(timestep)
    var l=ot.clone().p.sub(o.p).length()
    iters=Math.floor((GMTrajectoryStep/l)+0.5)
    if (!(iters<10000)) { // prevent div by zero
        GMTrajectoryObject.visible = false
	return
    }
    if (!(iters<100)) iters=100; // prevent processing time explosions
    for (var t=0; t<GMTrajectoryLength; t++) {
       o.advance(timestep)
       for (var t2=1;t2<iters;t2++) o.advance(timestep)
       GMTrajectoryObject.children[t].position.copy(o.p)
    }
  }

  // override some functions from ISS SIM with modified versions to implement this functionality
  // start with some helper functions
  function GMAddReason(a,b) {
    return a != "" ? a + ", " + b : b
  }

  window.GMTimeLapse = 1
  window.GMBurn=0
  window.GMBurnTimer=0

  checkCollision = function() {
    // fix time stepping - do not allow big time jumps to ensure smoothness
    var GMnewTime=Date.now()
    if ( GMoldTime < GMnewTime - 100 ) {
       GMoldTime = GMnewTime - 100
    }
    GMCurrentFrameTime = 0.001 * ( GMnewTime - GMoldTime )
    GMoldTime=GMnewTime
    GMfixMotion()

    GMTrajectoryObject.visible = false

    if (!0 !== isGameOver) {

      // Main Burn incl. timer
      if (GMBurn == 1){
        GMBurnTimer+=GMCurrentFrameTime
        $("#translate-forward-button").click()
      }
      $("#burn-onoff").innerHTML = (GMBurn == 1 ? '<span style="color:red">ON&nbsp;' + GMprintTime(GMBurnTimer)+"."+(GMBurnTimer%1.0).toFixed(2).toString().substring(2) + '</span>' : "OFF")
      
      // timing
      GMMissionTimer+=GMCurrentFrameTime
      GMGameTimer+=GMCurrentFrameTime
      $("#stats-mission").innerHTML="Mis: "+GMprintTime(GMMissionTimer)+"."+(GMMissionTimer%1.0).toFixed(2).toString().substring(2)
      $("#stats-real").innerHTML="Sim: "+GMprintTime(GMGameTimer)+"."+(GMGameTimer%1.0).toFixed(2).toString().substring(2)
      $("#stats-fps").innerHTML=(1.0/GMCurrentFrameTime).toFixed(1)+" fps"

      // DeltaV update:
      GMDeltaVUsed+=motionVector.clone().sub(GMOldMotionVector).length()/GMFixedStepTime
      var rotationDeltaV=Math.abs(GMOldRotation.x-currentRotationX) + Math.abs(GMOldRotation.y-currentRotationY) + Math.abs(GMOldRotation.z-currentRotationZ)
      GMDeltaVUsed+=0.02*rotationDeltaV*180/(Math.PI*moveSpeed)
      $("#prop-used").innerHTML="Used: "+(GMDeltaVUsed*1.0).toFixed(1)+" m/s"
      $("#prop-left").innerHTML="Budg: "+(GMDeltaVBudget-GMDeltaVUsed).toFixed(1)+" m/s"
      $("#propellant").style.display="block"
      // calculate gravity if applicable
      if (GMisOrbitalMechanics==2) {
        GMOrbitalMotion()
      }
      // time lapse
      var realFrameTime = GMCurrentFrameTime
      GMCurrentFrameTime = GMFixedStepTime // force k factor 1.0 for fast forward frames
      var ti
      for (ti=1; ti < GMTimeLapse; ti++) {
        camera.position.add(motionVector)
        !isGameOver && isGravity && (camera.position.y = camera.position.y - (gravity))
        camera.rotateX(currentRotationX)
        camera.rotateY(currentRotationY)
        camera.rotateZ(currentRotationZ)
        earthMesh.rotateY(1e-4)
        GMMissionTimer+=GMCurrentFrameTime
        // calculate gravity if applicable
        if (GMisOrbitalMechanics==2) {
          GMOrbitalMotion()
        }
      }
      GMCurrentFrameTime = realFrameTime
      // save motion vectors for deltaV update
      GMOldMotionVector.copy(motionVector)
      GMOldRotation.set(currentRotationX,currentRotationY,currentRotationZ)

      if (GMisOrbitalMechanics==2 && GMisTrajectoryVisible) {
        GMTrajectoryObject.visible = true
        GMShowTrajectory()
      }

      var GMIssTarget = issObject.position.clone()
      GMIssTarget.add(GMIssApproach.position)
      GMCameraRotationHelper.quaternion.copy(camera.quaternion)
      GMCameraRotationHelper.quaternion.multiply(GMIssApproach.quaternion.clone().inverse())
      var e = hitRaycaster.intersectObjects(hitArray, !0),
          t = Math.abs(camera.position.distanceTo(issObject.position)),
          t2 = Math.abs(camera.position.distanceTo(GMIssTarget)),
          a = Math.abs(GMCameraRotationHelper.rotation.x / toRAD),
          r = Math.abs(GMCameraRotationHelper.rotation.y / toRAD),
          o = Math.abs(GMCameraRotationHelper.rotation.z / toRAD),
          i = Math.abs(motionVector.x),
          n = Math.abs(motionVector.y),
          s = Math.abs(motionVector.z),
          ar = Math.sqrt(a*a+r*r),
          rxy = Math.sqrt(currentRotationX*currentRotationX + currentRotationY*currentRotationY) / toRAD,
          rz = Math.abs(currentRotationZ) / toRAD

      if (hitDistance = t > .5 ? 1 : .1, hitRaycaster.far = hitDistance, updateRateColor(i >= .02 || n >= .02 || s >= .02 ? "warning" : i > toleranceRate || n > toleranceRate || s > toleranceRate ? "caution" : "normal"), GMisCollisions && e.length > 0 && ($("#fail-message").innerHTML = "You made contact with the International Space Station.", hideInterface("fail")), GMisCollisions && Math.abs(camera.position.distanceTo(GMGravBodyCenter)) < GMGravBodyAtmosphereRadius && ($("#fail-message").innerHTML = "You re-entered earth atmosphere.", hideInterface("fail")), GMisSpaceRestricted && t > 500 && ($("#fail-message").innerHTML = "You are too far away from the International Space Station.", hideInterface("fail")), GMisFuelLimit && GMDeltaVUsed > GMDeltaVBudget && ($("#fail-message").innerHTML = "You used too much propellant.", hideInterface("fail")), t < .2 && t2 < t) {
        var GMInLimits = true, l = ""
        if (GMisLimitsOriginal) {
          if (!(a <= toleranceRotation && r <= toleranceRotation && o <= toleranceRotation)) {
            l=GMAddReason(l,"ROTATION ANGLE")
            GMInLimits = false
          }
          if (!(i <= toleranceRate && n <= toleranceRate && s <= toleranceRate)) {
            l=GMAddReason(l,"SPEED")
            GMInLimits = false
          }
        } else {
          // correct speeds for m/s instead of m/frame
          i=i/GMFixedStepTime
          n=n/GMFixedStepTime
          s=s/GMFixedStepTime
          rxy=rxy/GMFixedStepTime
          rz=rz/GMFixedStepTime
          var dx = Math.abs(camera.position.x-issObject.position.x),
              dy = Math.abs(camera.position.y-issObject.position.y),
              dz = Math.abs(camera.position.z-issObject.position.z)
          if (dz>=0.1) {
            l=GMAddReason(l,"OFFSET-X > 0.1")
            GMInLimits = false
          }
          if (dx>=0.1) {
            l=GMAddReason(l,"OFFSET-Y > 0.1")
            GMInLimits = false
          }
          if (dy>=0.1) {
            l=GMAddReason(l,"OFFSET-Z > 0.1")
            GMInLimits = false
          }
          if (s>=0.1) {
            l=GMAddReason(l,"VELOCITY-X > 0.1")
            GMInLimits = false
          }
          if (i>=0.1) {
            l=GMAddReason(l,"VELOCITY-Y > 0.1")
            GMInLimits = false
          }
          if (n>=0.1) {
            l=GMAddReason(l,"VELOCITY-Z > 0.1")
            GMInLimits = false
          }
          if (ar>=4) {
            l=GMAddReason(l,"ANGLE (PITCH/YAW) > 4")
            GMInLimits = false
          }
          if (o>=4) {
            l=GMAddReason(l,"ROLL ANGLE > 4")
            GMInLimits = false
          }
          if (rxy>=0.2) {
            l=GMAddReason(l,"ROTATION (PITCH/YAW) > 0.2")
            GMInLimits = false
          }
          if (rz>=0.2) {
            l=GMAddReason(l,"ROLL RATE > 0.2")
            GMInLimits = false
          }
        }
        if (GMInLimits) {
          hideInterface("success")
        } else {
          $("#fail-message").innerHTML = "The following errors occurred: <span class='red'>" + l + "<span>"
          hideInterface("fail")
        }
      }
    }
  }

  renderTesla = function() {
    (!GMisTeslaHidden || camera.rotation.y > 2.5 || camera.rotation.y < -2.5 ? (isTeslaCreated || createTesla(), isTeslaLoaded && (teslaMesh.visible = !0)) : isTeslaLoaded && (teslaMesh.visible = !1))
  }

  // The NAVBall became a bit more complicated, since we would like it to be in Earth frame
  // but we are in a rotating reference frame in an inclined earth orbit
  // Helper function to calculate rotation between 2 orthogonal vector pairs
  function GMRotateVectorPairs(u0, v0, u2, v2) {
    var q2 = new THREE.Quaternion().setFromUnitVectors(u0, u2)
    var v1 = v2.clone().applyQuaternion(q2.clone().conjugate())
    var v0_proj = v0.projectOnPlane(u0)
    var v1_proj = v1.projectOnPlane(u0)
    var angleInPlane = v0_proj.angleTo(v1_proj)
    if (v1_proj.dot(new THREE.Vector3().crossVectors(u0, v0)) < 0) {
      angleInPlane *= -1
    }
    var q1 = new THREE.Quaternion().setFromAxisAngle(u0, angleInPlane)
    var q = new THREE.Quaternion().multiplyQuaternions(q2, q1)
    return q
  }

  // override navball rendering to show earth/orbit instead of ISS relative
  renderNavball = function() {
    if (navballCreated) {
        var rotAxis=new THREE.Vector3(0,1,0)
        var pAxis=new THREE.Vector3(0,0,1)
        var camVector = camera.position.clone().sub(GMGravBodyCenter).normalize()
        var earthRotAxis = rotAxis.clone().applyQuaternion(earthObject.quaternion).normalize()
        var vectorToEast = camVector.clone().cross(earthRotAxis).normalize()
        var q = GMRotateVectorPairs(rotAxis,pAxis,camVector,vectorToEast)
        var e = camera.quaternion.clone().conjugate().multiply(q)

        navballObject.setRotationFromQuaternion(e)
    }
  }

  renderOrb = function() {
    if (isOrbCreated) {
      orbYawObject.rotation.y = GMisHUDVisible ? -camera.rotation.y : 0.0, orbPitchObject.rotation.x = GMisHUDVisible ? -camera.rotation.x : 0.0, orbRollObject.rotation.z = GMisHUDVisible ? -camera.rotation.z : 0.0
      var e = orbFadeTarget.getWorldPosition(new THREE.Vector3), i
      for (i = 0; i < orbSpriteArray.length; i++) {
        var t = orbSpriteArray[i].getWorldPosition(new THREE.Vector3),
            a = Math.abs(t.distanceTo(e))
        orbSpriteArray[i].material.uniforms.u_opacity.value = GMisHUDVisible ? opacityDistanceClamp(a, 5, 2, 1) : 0.0
      }
    }
  }

  // this is just a bugfix for rough versus fine rotation control
  updatePrecision = function(e) {
    "rotation" === e && (rotationPulseSize = .5 === rotationPulseSize ? (rateSpeedSize=2,1) : (rateSpeedSize=1,.5),  $("#rotation-controls").classList.toggle("large"), $("#precision-rotation-status").classList.toggle("large"), $("#hud-tips").classList.toggle("rotation-large")), "translation" === e && (translationPulseSize = .001 === translationPulseSize ? .005 : .001, $("#translation-controls").classList.toggle("large"), $("#precision-translation-status").classList.toggle("large"), $("#hud-tips").classList.toggle("translation-large"))
  }

  // this is overridden to reset some variables each new game/attempt
  GMGameStart = function() {
    GMDeltaVUsed=0
    GMOldMotionVector.copy(motionVector)
    GMOldRotation.set(currentRotationX, currentRotationY, currentRotationZ)
    GMMissionTimer=0
    GMGameTimer=0
    isGameOver=!1
  }
  $("#fail-button").removeEventListener("click", showInterface, !1)
  $("#fail-button").removeEventListener("touchstart", showInterface, !1)
  $("#success-button").removeEventListener("click", showInterface, !1)
  $("#success-button").removeEventListener("touchstart", showInterface, !1)
  // the annoying thing is the need to duplicate the entire function
  // for the change of a single onComplete property
  window.GMshowInterface = function() {
    showInterface()
    setTimeout(GMGameStart,5000)
  }
  $("#fail-button").addEventListener("click", GMshowInterface, !1)
  $("#fail-button").addEventListener("touchstart", GMshowInterface, !1)
  $("#success-button").addEventListener("click", GMshowInterface, !1)
  $("#success-button").addEventListener("touchstart", GMshowInterface, !1)


  // extra keys - z/y for toggle translation precision - x for toggle rotation precision, c,v,b for time lapse
  document.addEventListener("keyup", function(e) {
    if (!isGameOver) switch (e.keyCode || e.which) {
      case 89:
      case 90:
        toggleTranslation()
        break;
      case 88:
        toggleRotation()
        break;
      case 67:
        GMTimeLapse=1
        break;
      case 77: //M key - main burn & timer
        GMBurn == 1 ? GMBurn=0 : GMBurn=1
        if (GMBurn == 0) GMBurnTimer=0
        break;
      case 86:
        GMTimeLapse>=10 ? GMTimeLapse/=10 : GMTimeLapse=1
        break;
      case 66:
        GMTimeLapse<=100 ? GMTimeLapse*=10 : GMTimeLapse=1000
        break;
    }
  })

  // make 30 spheres for trajectory visualization
  window.GMTrajectoryObject = new THREE.Object3D()
  var GMTrajectoryLength = 30
  for (var t=0; t<GMTrajectoryLength; t++) {
    var scale=0.25
    if (((t+1)%10)==0) {
      scale=0.75
    }
    GMTrajectoryObject.add(new THREE.Mesh(new THREE.SphereGeometry(scale,6,6), new THREE.MeshBasicMaterial({
      transparent: true,
      opacity: 0.75,
      color: 2413309,
    })))
  }
  GMTrajectoryObject.visible=false
  scene.add(GMTrajectoryObject)

  $("#intro-step1 .animate").innerHTML="<span class=\"red\">ISS-SIM-Customizer</span> user script v 0.000015 by <span class=\"green\">CorvusCorax</span> loaded succesfully - check settings page for details.<br/>Use [x] and [y]/[z] keys to toggle precision thrust for translation/rotation.<br/>Use [b],[v] for time warp +-, [c] resets time warp.<br/>"+$("#intro-step1 .animate").innerHTML
}

// delayed execution after SpaceX sim loads
var GMscript = document.createElement('script')
GMscript.type = "text/javascript"
GMscript.innerHTML = GMInitializer.toString() + "\n" + "window.addEventListener('load', GMInitializer)" + "\n"
document.getElementsByTagName('head')[0].appendChild(GMscript)

//end