Show HN: SpaceX Dragon simulator docking autopilot in Clojure (opens in new tab)

I would like to see a real autopilot written in javascript that you can paste into the console.

  let a = setInterval(() => { 
      // retrieve values from simulation
      let roll = fixedRotationZ;
      let pitch = fixedRotationX;
      let yaw = fixedRotationY;
      let rpy = new THREE.Vector3(roll, pitch, yaw);
  
      let rollRate = -rateRotationZ/10.0;
      let pitchRate = -rateRotationX/10.0;
      let yawRate = -rateRotationY/10.0;
  
      let rpyRate = new THREE.Vector3(rollRate, pitchRate, yawRate);
  
      let pos = camera.position.clone();
      let posRate = motionVector.clone();
      let targetPos = issObject.position.clone();
  
      let targetRpy = new THREE.Vector3(0,0,0);
      let dRpy = targetRpy.clone().sub(rpy);
  
      // P-controller controls target roll,pitch,yaw-rate (targetRpyRate) to reach target orientation
      let targetRpyRate = new THREE.Vector3(
          dRpy.x/1.0, 
          dRpy.y/1.0, 
          dRpy.z/1.0
      );
  
      let minRpyRate = new THREE.Vector3(-1.5, -1.5, -1.5);
      let maxRpyRate = new THREE.Vector3(+1.5, +1.5, +1.5);
      targetRpyRate.clamp(minRpyRate, maxRpyRate)
  
      let dRpyRate = targetRpyRate.clone().sub(rpyRate);
   
      // don't calculate with displayed x,y,z but the internal coordinates 
      // (z-axis is forward and backward)
      let dPos = targetPos.clone().sub(pos);
      let d = dPos.length();
      // P-controller controls target motion (targetPosRate) to reach target position
      let targetPosRate = new THREE.Vector3(
          dPos.x / 100.0,
          dPos.y / 100.0,
          dPos.z / 100.0
      );
      let minPosRate = new THREE.Vector3(-0.1, -0.1, -0.01);
      let maxPosRate = new THREE.Vector3(+0.1, +0.1, +0.01);
  
      // thresholds for bang contRol
      let dRpyRateControlThreshold = new THREE.Vector3(0.0, 0.0, 0.0);
      let dPosRateControlThreshold = new THREE.Vector3(0.001, 0.001, 0.001);
  
      // define some phases where we want to have different movement behaviour
  
      if (dRpyRate.length() > 0.1)
      {
          // not correctly oriented, stop movement
          targetPosRate.x = 0;
          targetPosRate.y = 0;
          targetPosRate.z = 0;
      }
      else if (Math.abs(dPos.z) < 20)
      {
          // we are very close, slow approach, larger P-control in lateral
          // directions to correct remaining errors
          minPosRate.z = -0.005;
          maxPosRate.z = +0.005;
          dPosRateControlThreshold.x = 0.01;
          dPosRateControlThreshold.y = 0.01;
          targetPosRate.x = dPos.x;
          targetPosRate.y = dPos.y;
      }
      else if (Math.abs(dPos.z) < 50)
      {
          // we are getting, close, slow down
          minPosRate.z = -0.01;
          maxPosRate.z = +0.01;
  
          minPosRate.x = -0.01;
          minPosRate.y = -0.01;
          maxPosRate.x = +0.01;
          maxPosRate.y = +0.01;
      }
      else if (Math.abs(dPos.z) < 100)
      {
          // slow down
          minPosRate.z = -0.1;
          maxPosRate.z = +0.1;
      }
      else if ((Math.abs(dPos.x) < 0.05) && (Math.abs(dPos.y) < 0.05))
      {
          // lateral position correct, use maximum approaching speed
          minPosRate.z = -0.2;
          maxPosRate.z = +0.2;
      }
      targetPosRate.clamp(minPosRate, maxPosRate);
      let dPosRate = targetPosRate.clone().sub(posRate);
          
      // bang control to reach target roll pitch and yaw rate
      if (dRpyRate.x < -dRpyRateControlThreshold.x)
          rollRight();
      else if (dRpyRate.x > +dRpyRateControlThreshold.x)
          rollLeft();
      if (dRpyRate.y < -dRpyRateControlThreshold.y)
          pitchDown();
      else if (dRpyRate.y > +dRpyRateControlThreshold.y)
          pitchUp();
      if (dRpyRate.z < -dRpyRateControlThreshold.z)
          yawRight();
      else if (dRpyRate.z > +dRpyRateControlThreshold.z)
          yawLeft();
  
      // bang control to reach target motion
      if (dPosRate.x < -dPosRateControlThreshold.x)
          translateLeft();
      else if (dPosRate.x > +dPosRateControlThreshold.x)
          translateRight();
      if (dPosRate.y < -dPosRateControlThreshold.y)
          translateDown();
      else if (dPosRate.y > +dPosRateControlThreshold.y)
          translateUp();
      if (dPosRate.z < -dPosRateControlThreshold.z)
          translateForward();
      else if (dPosRate.z > +dPosRateControlThreshold.z)
          translateBackward();
  
  },100);

That makes it sound you approach this from a haughty presumptuous, uncharitable angle.

It sounds like you exclude the possibility that the author did not try it "your way" first, for example, but found a simpler way to implement it.

"That's not the most obvious to do it IMO" or "I would have preferred to do it like this..." are much better ways to approach this. Programs should be beautiful and understandable, but "idiomatic" sounds it excludes lots of simple beautiful solutions to a problem out of pure dogma.

Nowadays I write web applications like everyone else on the planet and use Java, JS and/or Clojure (when I can get away with it).

But cool little project, nonetheless.

KSP was also 100% the reason I managed dock with the simulator on the first try, because in a way it was more like the 50th-100th try, just using a different interface.