Tutorial: how to build a free controllable vehicle

intruder on 4/5/2011 at 21:54

Before going into any details, I want to sum up what vehicles created with this tutorial can do and what they can't do.
There are possibly other, maybe even easier means to get a vehicle moving in DromEd. This is just my idea of getting it work!

The proposed solution offers:
- free control over the vehicle (all 3 axes)
- collision detection with objects and solid terrain

Limitations:
- vehicles can't be used on uneven terrain (only angles near 90° work)
- vehicles move with constant velocity
- vehicles can't turn, but they can move sidewards instead

Therefore, this tutorial is best suited for constructing:
- submarines
- motorboats
- cranes
- airships
- balloons

The following 4 steps are required to build vehicles with DromEd:
1. Create a free controllable vehicle
2. Attach the player to the vehicle
3. Prevent unlimited acceleration
4. Enable collision with objects and terrain

1. Create a free controllable vehicle
1. Download and install tnhScript ((http://thiefmissions.com/telliamed/tnhscript21.zip) download)
2. Load tnhscript into your mission
3. Create an arbitrary physical object, e.g. a HugeCrate and call it "Vehicle"
4. Create two markers somewhere in your level (you need two markers for each axis; we will only add sidewards movement for the sake of simplicity)
5. Give each marker the (http://dromed.whoopdedo.org/tnhscript/trapmoverelative) TrapMoveRelative-script
6. Select one marker, name it "Left" and add the following property "Editor -> Design Note: dx=10"
7. Select the other marker, name it "Right" and add the following property "Editor -> Design Note: dx=-10"
8. Link both markers with your vehicle via ControlDevice
9. Create two buttons, name them "Button_Left" and "Button_Right", and link both to your vehicle via PhysAttach
10. Link "Button_Left" via ControlDevice to the marker called "Left"
11. Link "Button_Right" via ControlDevice to the marker called "Right"

If you now start the game, you will be able to control your "vehicle" by pressing the buttons.

2. Attach the player to the vehicle
Use any tutorial for CamVator sequences etc. as a reference how to accomplish this.

3. Prevent unlimited acceleration
You might have noticed that you can accelerate the vehicle each time you press a button until you reach Warp 9...
What we want to do now is the following. Each time a button is frobbed, the link between this button and the corresponding marker will be removed. Frobbing the "opposite" button re-creates the link.
We will use conversations to accomplish this.

[the following assumes that you have a blueroom and a conversation AI from Step #2]

1. Create 2 new conversation markers, name one "Conv_Left" and the other "Conv_Right"
2. Create 2 new buttons, name on "Button_MoveLeft" and the other "Button_MoveRight"
3. Remove the ControlDevice-links from "Button_Left" and "Button_Right"
4. Add a ControlDevice-link from "Button_Left" to "Conv_Left"
5. Add a ControlDevice-link from "Button_Right" to "Conv_Right"
6. Add a ControlDevice-link from "Button_MoveLeft" to "Left"
7. Add a ControlDevice-link from "Button_MoveRight" to "Right"
8. Create a new quest variable and name it "MoveSidewards", initialize it to "0"
9. Create a new QuestVarTrap, name it "QVar_MoveLeft", add "Trap -> QVar: -1:MoveSidewards"
10. Create a new QuestVarTrap, name it "QVar_MoveRight", add "Trap -> QVar: +1:MoveSidewards"
11. Add a ControlDevice-link from "Button_MoveLeft" to "QVar_MoveLeft"
12. Add a ControlDevice-link from "Button_MoveRight" to "QVar_MoveRight"
13. Create a new conversation marker, call it "AddSidewardsMovement" and add the following conversation steps:

Actor: ActorOne
Flags: [None]
Action: Add Link
Argument 1: ControlDevice
Argument 2: Conv_Left
Argument 3: Button_Left

Actor: ActorOne
Flags: [None]
Action: Add Link
Argument 1: ControlDevice
Argument 2: Conv_Right
Argument 3: Button_Right

14. Create a new QuestVarTrigger, name it "DetectNoSidewardsMovement" and add "Trap -> QVar: "0:MoveSidewards"
15. Add a ControlDevice-link from "DetectNoSidewardsMovement" to "AddSidewardsMovement"
16. Add the following conversation steps to "Conv_Left":

Actor: ActorOne
Flags: [None]
Action: Remove Link
Argument 1: ControlDevice
Argument 2: Conv_Left
Argument 3: Button_Left

Actor: ActorOne
Flags: [None]
Action: Frob Object
Argument 1: Button_MoveLeft
Argument 2:
Argument 3:

Actor: ActorOne
Flags: [None]
Action: Add Link
Argument 1: ControlDevice
Argument 2: Conv_Right
Argument 3: Button_Right

17. Add the following conversation steps to "Conv_Right":

Actor: ActorOne
Flags: [None]
Action: Remove Link
Argument 1: ControlDevice
Argument 2: Conv_Right
Argument 3: Button_Right

Actor: ActorOne
Flags: [None]
Action: Frob Object
Argument 1: Button_MoveRight
Argument 2:
Argument 3:

Actor: ActorOne
Flags: [None]
Action: Add Link
Argument 1: ControlDevice
Argument 2: Conv_Left
Argument 3: Button_Left

If you now start the game, you will notice that your vehicle will move with a constant velocity and pressing the same button more than once has no effect.

4. Enable collision with objects and terrain
The last remaining issue you've most likely already noticed is the lack of collision with objects and terrain. Your vehicle moves straight through everything, which we are going to change now.
What we are going to do now is to add some sensors to your vehicle which are able to detect other objects and walls and stop your vehicle when it collides with them.

We need:
- sensor messages / sensor impulses
- sensors emitting such impulses
- your vehicle reacting on such sensor messages

We will use emitter-traps which will be attached (PhysAttach) to your vehicle. They emit a constant stream of sensor projectiles, i.e. the sensor impulses.
To limit the range of each sensor, we are going to destroy the projectile shortly after emitting it. If the projectile however collides with something before being removed, it will send out a sensor message which is then picked up by your vehicle.

1. Create a new stimuli archetype, name it "DirectionStim"
2. Create a new archetype under "DirectionStim", name it "LeftStim"
3. Create a new archetype under "DirectionStim", name it "RightStim"
4. Save the gamesys and restart DromEd
5. Create a new archetype under "physical", name it "Sensors", add the following property:

Renderer -> Render Type: Not Rendererd

6. Create a new archetype under "Sensors", name it "SensorMsg", add the following properties:

Tweq -> ModelState: On, [None], 0, 0
Tweq -> Models:
Halt: Destroy Object
AnimC: Sim
MiscC: [None]
CurveC: [None]
Rate: 100

Physics -> Projectile -> Faces Velocity: TRUE
Physics -> Projectile -> Initial Velocity: 20, 0, 0
Physics -> Model -> Type Sphere, 1, FALSE, FALSE
Physics -> Model -> Attributes -> Gravity: 0%
Physics -> Misc -> Collision Type: Bounce, Slay on Impact

7. Create a new archetype under "Sensors", name it "SensorResponse", add the following properties:

Tweq -> ModelState: On, [None], 0, 0
Tweq -> Models:
Halt: Destroy Object
AnimC: Sim
MiscC: [None]
CurveC: [None]
Rate: 100

8. Create a new archetype under "Sensors", name it "SensorEmitter", add the following properties:

Tweq -> EmitterState: [None], [None], 0, 0
Tweq -> Emit:
Halt: Continue
AnimC: NoLimit, Sim
MiscC: [None]
CurveC: [None]
Rate: 150
Max frames: 0
Emit what: SensorMsg

S -> Scripts: TweqOnOff

Physics -> Misc -> Collision Type: Bounce

9. Create a new archetype under "SensorResponse", name it "LeftResponse", add the following property:

Act/React -> Sources:
Object: LeftResponse
Stimulus: LeftStim
Propagator: Radius [Radius: 32, Flags: [None], Dispersion: None] (Note: the radius depends on the size of your vehicle)
Intensity: 10 [Flags: Destroy Object On Completion, Period: 500, Max Firings: 1, Intensity Slope: 0]

10. Create a new archetype under "SensorResponse", name it "RightResponse", add the following property:

Act/React -> Sources:
Object: RightResponse
Stimulus: RightStim
Propagator: Radius [Radius: 32, Flags: [None], Dispersion: None] (Note: the radius depends on the size of your vehicle)
Intensity: 10 [Flags: Destroy Object On Completion, Period: 500, Max Firings: 1, Intensity Slope: 0]

11. Create a new archetype under "SensorMsg", name it "LeftMsg", add the following property:

Links -> Corpse:
From: LeftMsg
To: LeftResponse

12. Create a new archetype under "SensorMsg", name it "RightMsg", add the following property:

Links -> Corpse:
From: RightMsg
To: RightResponse

13. Create a new archetype under "SensorEmitter", name it "LeftEmitter", add the following property:

Tweq -> Emit:
Halt: Continue
AnimC: NoLimit, Sim
MiscC: [None]
CurveC: [None]
Rate: 150
Max frames: 0
Emit what: LeftMsg

14. Create a new archetype under "SensorEmitter", name it "RightEmitter", add the following property:

Tweq -> Emit:
Halt: Continue
AnimC: NoLimit, Sim
MiscC: [None]
CurveC: [None]
Rate: 150
Max frames: 0
Emit what: RightMsg

15. Create an instance of "LeftEmitter" (name it "LeftEmit") and "RightEmitter" (name it "RightEmit") and link both via PhysAttach with your vehicle
16. Add a ControlDevice-link from "Button_Left" to "LeftEmit"
17. Add a ControlDevice-link from "Button_Right" to "RightEmit"
18. Create 2 new inverters, name on "LeftInverter" and the other one "RightInverter"
19. Add a ControlDevice-link from "Button_Left" to "LeftInverter"
20. Add a ControlDevice-link from "Button_Right" to "RightInverter"
21. Add a ControlDevice-link from "LeftInverter" to "RightEmit"
22. Add a ControlDevice-link from "RightInverter" to "LeftEmit"
23. Add the following 2 receptrons to your vehicle:

Object: Vehicle
Stimulus: LeftStim
Min Intensity: 0 [No Min = true]
Max Intensity: 0 [No Max = true]
Effect: Frob Object
Target Object: Button_Right

Object: Vehicle
Stimulus: RightStim
Min Intensity: 0 [No Min = true]
Max Intensity: 0 [No Max = true]
Effect: Frob Object
Target Object: Button_Left

What happens now is the following:
If your vehicle moves close to a wall, the sensor-projectile will collide with the wall and get destroyed. The Corpse-link creates a sensor-response which sends out his stim. Your vehicle detects the stims and frobs the button, opposite to the current driving direction, thereby stopping the vehicle.

Here is a small test mission to demonstrate a submarine capable of moving to the left, right, forward and backward:
(http://www.file-upload.net/download-3408592/SubmarineTest.rar.html) Demo (Note: tnhScript 2.1 is required)

darthsLair on 4/5/2011 at 23:43

Wow Intruder, You are a great teacher ! Thanks for this Tutorial ! Now where did I put my "Tunnel digging machine"?

Tannar on 5/5/2011 at 00:20

Awesome! That's a nice tutorial you've done. Thanks, Steffen!

intruder on 5/5/2011 at 08:20

Thanks!

I added one minor improvement:
All sensors are active once the game starts although the submarine is not moving. Therefore I changed the "Tweq -> EmitterState"-property to:

Tweq -> EmitterState: [None], [None], 0, 0

Also, I found one problem:
If the vehicle collides, let's say with something to its left side, it will stop and all is fine. If you then press the left button again, it will move a bit to the left but collide again. Still fine. If you frob the left button a third time, the vehicle will move through the wall as the collision sensor is still disabled.

The easiest solution would be:
Always keep the sensors on. However, this would result in the vehicle moving to the right as soon as it collides with something to its left and vice versa.

On the other hand, if you collide with something, you will be bounced back.

LarryG on 5/5/2011 at 13:15

Quote Posted by intruder

On the other hand, if you collide with something, you will be bounced back.

Bumper Cars! Too bad you can't turn.

intruder on 5/5/2011 at 14:01

Nice idea :D

Nameless Voice on 5/5/2011 at 18:53

I wrote a script for a fully controllable vehicle once, but unfortunately it was one of the few scripts I lost the source code for in a disk crash, and I never remade it. I still have a demo mission with a remote-controlled barrel and the appropriate (ancient) version of NVScript to run it somewhere, though...

Ricebug on 6/5/2011 at 19:54

Quote Posted by intruder

- vehicles can't turn, but they can move sidewards instead

Telliamed helped me on Crooked Town, making a coal car follow a curved path. Unfortunately, when I got my hands on it, things got fouled up and it was scrapped in total disgust. No special scripts were needed if I remember correctly.

LarryG on 6/5/2011 at 23:14

That was probably an elevator (sideways) following a prescribed path, not a vehicle you could direct.

Ricebug on 7/5/2011 at 00:40

Quote Posted by LarryG

That was probably an elevator (sideways) following a prescribed path, not a vehicle you could direct.

You're right, now that I remember. The coal car followed TerrPts.