Looking to make a simple trajectory mod that shows where the vehicle will be a second in the future

Alright so this time I'll try to be helpful lol. So you can find the trajectory/predicted position of the vehicle just by integrating the acceleration and velocity to find the relative position of an object after a given delta time and adding that to the current position. Although as delta time gets bigger, the error of the predicted trajectory gets larger. And to actually do the integration the following code would do just that:

Code:

local acc = vec3(obj:getSensorX(), obj:getSensorY(), obj:getSensorZ())
local vel = vec3(obj:getVelocity())
local pos = vec3(obj:getPosition())

--Delta time (the time in the future to find the predicted position)
local dt = 1

--New Predicted Velocity after time dt
local new_vel = acc * dt + vel

--New Predicted Position after time dt
local new_pos = new_vel * dt + pos

And you can use debugDrawProxy:drawSphere(radius, position, color) for example to draw the new position as a sphere.

Make a global function that contains all this code so that you can call it from the UI app code with the following function:
bngApi.activeObjectLua('lua_function_name');

Put this all into a .lua file in your mod directory for example for etk 800: "mods\unpacked\your_mod_name\vehicles\etk800\lua"

And you want to call this global function on every game update.

Anyways, you should look at other mods too for reference on making a UI app. But here's a link to creating a UI app that's pretty basic: https://wiki.beamng.com/My_First_App

Good Luck!

 

Is there any reason why it only works on the ETK 800 specifically? Isn't it possible to just put it in the common LUA folder?

 

From looking at other mods, it doesn't seem like you can share a single Lua file across all vehicles and I've tried putting it in a common/lua directory but to no avail. And so you literally have to copy and paste the file across every single vehicle directory if you want the Lua file to be executed by every single vehicle (look at the Torque Converter Clutch Lockup Switch mod for example).

 

Have you tried in lua/common instead? That's the directory where things like vehicle controller are

 

Oh, good to know. I'm pretty sure there's something I used in my mods that is in lua/common though, maybe the light bar controller?

 

Wait now I remember, the unfinished mod by me is there lol, that's why I remembered the location. The mod for explosion-based jump system for cars. (Unfinished because it requires precise ajustment of thrusters per suspension settings and can be completely different for 2 configs of the same vehicle, so it makes no sense to release it without configs, so it will just be a part of a big mod pack by me and my friend.)

 

Unfortunately none of those directories make it work. I've tried:

• lua/common
• lua/common/controller
• lua/vehicle/
• lua/vehicle/controller
• vehicles/common/lua
• vehicles/common/lua/controller
• vehicles/lua/controller
• vehicles/lua

What sort of error are you getting?

 

Press '~' to open up the console and send me a screenshot of the error message and send me what code you have written up so far.

 

Try

Code:

obj.debugDrawProxy:drawSphere(0.25, new_pos:toFloat3(), color(0,0,255,255))

instead and see if that works. Also put all that code into a global lua function, so that you can call it multiple times from your UI app:

Code:

local M = {}

function drawTrajectory()
    --code goes here
end

return M

--- Post updated ---
But if you just want to test what you got right now if you don't have UI app code, then I guess you can test it with the updateGFX function (basically a function that gets called every time the game updates the graphics I guess).

Code:

local M = {}

local function updateGFX(gfx_dt)
    local acc = vec3(obj:getSensorX(), obj:getSensorY(), obj:getSensorZ())
    local vel = vec3(obj:getVelocity())
    local pos = vec3(obj:getPosition())

    --Delta time (the time in the future to find the predicted position)
    local dt = 1

    --New Predicted Velocity after time dt
    local new_vel = acc * dt + vel

    --New Predicted Position after time dt
    local new_pos = new_vel * dt + pos
  
    obj.debugDrawProxy:drawSphere(0.25, new_pos:toFloat3(), color(0,0,255,255))
end

M.updateGFX = updateGFX

return M

--- Post updated ---
Okay so I have finally tested the code and now realize that the acceleration vector is local to the car and not the world so here is the updated code:

Code:

local M = {}

local function updateGFX(gfx_dt)
    local debugDrawer = obj.debugDrawProxy
  
    local acc = -vec3(obj:getSensorX(), obj:getSensorY(), obj:getSensorZ())
  
    --Rotate local acc vector by direction of car in global space
    acc = quatFromDir(vec3(obj:getDirectionVector()), vec3(0,0,1)) * acc
  
    local vel = vec3(obj:getVelocity())
    local pos = vec3(obj:getPosition())

    --Delta time (the time in the future to find the predicted position)
    local dt = 0.5

    --New Predicted Velocity after time dt
    local new_vel = acc * dt + vel

    --New Predicted Position after time dt
    local new_pos = new_vel * dt + pos
  
    debugDrawer:drawSphere(0.25, new_pos:toFloat3(), color(0,0,255,255))
end

M.updateGFX = updateGFX

return M

--- Post updated ---
If you are looking for better trajectory predicting, then I would suggest using different integration methods such as "Velocity Verlet" or even the "4th Order Runge Kutta Method (RK4)". But FYI those are a little bit trickier to implement. Here's a website that describes how to implement these if your interested:
https://jdickinsongames.wordpress.com/2015/01/22/numerical-integration-in-games-development-2/

 

Lol I'm afraid there aren't many tutorials on making mods in BeamNG using Lua nor is the current documentation that great. So how I've learned (kind of) to make mods in BeamNG is just by looking at other people's mods and experimenting. I guess you could try looking at the game's Lua source code or UI app code but it's a bit overwhelming lol.

Also one tip I've got is that if you want to figure out all the functions/fields of an object/class, use the "dump(object_of_interest)" function. If that gives you the result like "<userdata>" for example, then use "dump(getmetatable(object_of_interest))" and that may work. And if you find a function/field that looks of interest, then you can just search for that in the Lua directory in the installation folder for the game (BeamNG.drive\lua) to find out how to use it, like what parameters it needs and what it returns.

Anyways, here's a couple of links of BeamNG's documentation:
https://documentation.beamng.com/programming/index.html
https://wiki.beamng.com/Lua:Reference
https://wiki.beamng.com/Streams

 

"lua/vehicle/extensions" doesn't work either