Solved Any tips on preventing minecart derail during high speed turns?

I'm using the following code to increase the max speed of a minecart that passes over a powered rail.

Code:java

@EventHandler
    public void onCartMove(VehicleMoveEvent event){
        Vehicle vehicle = event.getVehicle();
        if(vehicle.getPassenger() != null && vehicle instanceof org.bukkit.entity.Minecart){
            Entity passenger = vehicle.getPassenger();
            org.bukkit.entity.Minecart cart = (org.bukkit.entity.Minecart) event.getVehicle();
            Location loc = cart.getLocation();
            Vector vel = cart.getVelocity();
            if(loc.getBlock().getType() == Material.POWERED_RAIL){
                cart.setMaxSpeed(1.0D); // default maxspeed is 0.4D
                vel.multiply(1.25);
                cart.setVelocity(vel);
            }
        }
    }
}

Unfortunately, whenever the speedy minecart goes around a turn it derails at a 45 degree angle. I've tried for a few hours to fix it with minimal success. Does anyone know how to solve this issue? It would be very much appreciated

 

Surfdudeboy Did you already try to cancel VehicleDestroyEvent?

 

Bammerbom
I haven't. I'll try that although I have my doubts.
---
Edit: No dice.

 

In one of the recent snapshots, minecarts were sped up a ton (which got removed cause everyone hated it), and people made special turns that helped it not derail, I'd look at some of those designs.

 

The only thing I can think of is lowering the max speed, since getting when a minecart derails is quite difficult.

 

Necrodoom Phasesaber Bammerbom
I think I found the solution: Detect if a hill/curve is near and then slow down the cart. I'll post code after I tweak it to perfection.

 

Surfdudeboy
The minecart derailing feature has been removed in Minecraft 1.8

 

The Gaming Grunts
Are you saying that in 1.8 minecarts wont derail at high speed?

Nevermind, you were mistaken. Communication error. I'm talking about 1.7.9 . The extra speed feature from 14w11a is being undone because the Engine can't handle it. (You don't say.) The derailing bug will persist in 1.8.

 

Surfdudeboy

For more info: http://minecraft.gamepedia.com/Minecart#Temporary_minecart_changes_in_1.8

 

The Gaming Grunts@Bammerbom Phasesaber Necrodoom
Ah. now we are on the same page.

Anyways here is how I am preventing my high speed carts from flying off corners or stopping on hills:

Code:java

    static Main plugin;
    private HashMap<UUID,Double> previousSpeed = new HashMap<UUID,Double>();
    private ArrayList<UUID> hasNotPassed = new ArrayList<UUID>();
    private final double MAX_SPEED = 3D;
    private final double BOOSTER_MULTIPLIER = 1.25D;
    @EventHandler
    public void onCartMove(VehicleMoveEvent event){
        Vehicle vehicle = event.getVehicle();
        if(vehicle.getPassenger() != null && vehicle instanceof org.bukkit.entity.Minecart){ //Is a minecart and has a pasenger?
            org.bukkit.entity.Minecart cart = (org.bukkit.entity.Minecart) event.getVehicle();
            Location loc = cart.getLocation();
            Vector vel = cart.getVelocity();
            Rails rail = null;
            try{ rail = (Rails)cart.getLocation().getBlock().getState().getData();
            }catch (ClassCastException e){return;}
            UUID id = cart.getUniqueId();
            Double currentSpeed = vel.length();
            if(rail.getItemType() == Material.POWERED_RAIL && !hasNotPassed.contains(id)){ //Makes carts go fast. Checks for being slowed down.
                cart.setMaxSpeed(MAX_SPEED);
                vel.multiply(BOOSTER_MULTIPLIER);
                cart.setVelocity(vel);
            }
            Double pSpeed = null;
            try {
                pSpeed = previousSpeed.get(id);
            }catch (NullPointerException e){
                pSpeed = null;}
            Location testLoc = loc;
            int dist = (int) MAX_SPEED;
            if(!hasNotPassed.contains(id)){
                for(int i = 1; i<dist ; i++){
                    testLoc.add(vel.normalize().multiply(i));
                    Rails testRail;
                    try{
                        testRail = (Rails) testLoc.getBlock().getState().getData();
                    }catch (ClassCastException e){
                        break;}
 
                    if(testRail != null){
 
                        if((testRail.isCurve() || testRail.isOnSlope())){// all of this code tests if there is a curve or slope slightly ahead of the cart.
                            previousSpeed.put(id, currentSpeed);
                            hasNotPassed.add(id);
                            cart.setMaxSpeed(0.4D);
                            return;
                        }
                    }
                }
            }
            if(rail.isCurve() || rail.isOnSlope()){//when it passes over the hill or curve, flag it as having passed it.
                hasNotPassed.remove(id);
                cart.setMaxSpeed(0.4D);
            }
 
            else if(pSpeed != null && !hasNotPassed.contains(id) && !rail.isCurve() && !rail.isOnSlope()){ //If it is passed, set it back to its origional speed.
                cart.setMaxSpeed(MAX_SPEED);
                Vector newVel =  cart.getVelocity().normalize().multiply(pSpeed);
                cart.setVelocity(newVel);
                previousSpeed.remove(id);
            }       
        }
    }

The only issue is that it is fairly costly in terms of CPU cycles. I went from 1% CPU use to 3% as I rode a rail. I never derail though ^-^

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Surfdudeboy maybe have a quick check if the block change is >1? I don't know the VehicleMoveEvent itself, but it saves time when handling PlayerMoveEvent.

 

gabizou Good idea.