AC Modding Questions Thread

[AccAkut]

well yes its easy to do, but realistically it requires you to rip the model from the GT40s kn5
to tailor the new lights to it, and ripping Kunos model is something not allowed on this forum hence people won't openly reply to it. You've got to ask somewhere else @M4RTYMCF1Y

 

[Hoksu]

Two questions regarding skinning.
1) What is the point of having AO in a reflection map? I have just used plain colors
2) How do you make txNormal files?

 

[Stereo]

Two questions regarding skinning.
1) What is the point of having AO in a reflection map? I have just used plain colors
2) How do you make txNormal files?

1) ambient occlusion in principle measures how many directions from that pixel are occluded by other parts of the object. The reflections are of scenery, so it's also the number of directions that can't reflect. Not really real, but better than having stuff 'behind' other stuff still reflect. In stuff like seams where you know for a fact that they reflect deeper into the seam from any viewing angle you'd want to paint it black.
2) you'll want a plugin for your image editor, or some 3d editor that can make them. Usually within an image editor you'll get something that converts a greyscale heightmap into a normalmap, maybe it'll also have ways to convert other types of image into normalmap.

 

[Amir Vodokotlic]

In the wings app.

Is the front downforce percent figure correct or not?

From calculations it seems to be reading ~10% lower than it should be unless I am not understanding whats considered front of car and what is rear. When calculating aero balance.

If cgh is (0,0,0) position.

Than everything in aero position in plus direction (z direction) is considered front no?

So adding up front wing/splitter and dividing it by (front and rear total downforce)

should give aero balance...

 

[garyjpaterson]

In the wings app.

Is the front downforce percent figure correct or not?

From calculations it seems to be reading ~10% lower than it should be unless I am not understanding whats considered front of car and what is rear. When calculating aero balance.

If cgh is (0,0,0) position.

Than everything in aero position in plus direction (z direction) is considered front no?

So adding up front wing/splitter and dividing it by (front and rear total downforce)

should give aero balance...

Got to remember where on the car is the force applied, outside of the wheelbase the force will increase a lot on the closest axle and slightly reduce on the other axle. Forces within the wheelbase will increase on both axles.

I wouldn’t know how to calculate that, but outside of not taking into account drag induced downforce, it should be accurate.

 

[mclarenf1papa]

In the wings app.

Is the front downforce percent figure correct or not?

From calculations it seems to be reading ~10% lower than it should be unless I am not understanding whats considered front of car and what is rear. When calculating aero balance.

If cgh is (0,0,0) position.

Than everything in aero position in plus direction (z direction) is considered front no?

So adding up front wing/splitter and dividing it by (front and rear total downforce)

should give aero balance...

Short answer's no. If you have a wing producing drag and it's not always at ground height, it'll change the "downforce" distribution. The app doesn't calculate that, so you need to do it yourself.

Also, no. Everything forward of the CoG has a component at each axle (if the "wing" is forward of the front axle, the component at the rear axle will be negative; the inverse is also true). The math to calculate each component is just simple ratios.

But as I said, even if you do that correctly, you still need to factor in the change in tire load due to drag since it's not shown in the app.

 

[Amir Vodokotlic]

Short answer's no. If you have a wing producing drag and it's not always at ground height, it'll change the "downforce" distribution. The app doesn't calculate that, so you need to do it yourself.

Also, no. Everything forward of the CoG has a component at each axle (if the "wing" is forward of the front axle, the component at the rear axle will be negative; the inverse is also true). The math to calculate each component is just simple ratios.

But as I said, even if you do that correctly, you still need to factor in the change in tire load due to drag since it's not shown in the app.

Ah got it, .........sorta.
So for simple terms say I have just 3 wings (front, rear, body)
With body at (0,0,0) producing drag only.
Front and rear only making downforce no CD. Separated at distance on front of axle and rear axle.
I lock down the CD/CL at constant values.
Will that give correct front downforce? Or I still need to factor in tire load?

Also is it necessary to go all through those calculations with tire load or just trust the wings app reading.

 

[mclarenf1papa]

Ah got it, .........sorta.
So for simple terms say I have just 3 wings (front, rear, body)
With body at (0,0,0) producing drag only.
Front and rear only making downforce no CD. Separated at distance on front of axle and rear axle.
I lock down the CD/CL at constant values.
Will that give correct front downforce? Or I still need to factor in tire load?

Also is it necessary to go all through those calculations with tire load or just trust the wings app reading.

The wings app only calculated tire load from the "CL" of the "wings," actual downforce distribution requires that the load at the wheels from the CD of the wings be calculated.

In other words, if you make the CL of the "wings" at each axle the same number, the app will show 50% front downforce. In reality, if you have any element not at ground height producing drag, it'll be less than 50%.

 

[Danny kung]

Hi all I really need to get my car moving! (pun intended)
I notice there aren't any tutorials here for physics. Am I missing something? Where to look?
How do you go about making physics for a car if you're new?

My thread: https://www.racedepartment.com/threads/basics-of-getting-your-mod-car-in-game.158568/#post-2815177

 

[Amir Vodokotlic]

The wings app only calculated tire load from the "CL" of the "wings," actual downforce distribution requires that the load at the wheels from the CD of the wings be calculated.

In other words, if you make the CL of the "wings" at each axle the same number, the app will show 50% front downforce. In reality, if you have any element not at ground height producing drag, it'll be less than 50%.

Just to be clear when you're saying ground height you're referring to center of gravity ground height?

So if I place just 1 wing with CD above cgh height (like 0,0.5,0) than tire load will go down at front and increase at rear due to CD. (Assuming 50% weight distribution/2.5 wheelbase. )

 

[mclarenf1papa]

Just to be clear when you're saying ground height you're referring to center of gravity ground height?

So if I place just 1 wing with CD above cgh height (like 0,0.5,0) than tire load will go down at front and increase at rear due to CD. (Assuming 50% weight distribution/2.5 wheelbase. )

Uh, no, ground height would mean at the height of the ground. CoG height would mean CoG height.

 

[Amir Vodokotlic]

Uh, no, ground height would mean at the height of the ground. CoG height would mean CoG height.

Agh, now I am really lost.

Trying to figure out I used formula k car. Mass 1000 kg/50% weight distribution/2.5 meter wheelbase.

Added just one wing span 1 chord 1 at (0,0,0) which was GH of 358 mm being equal to cgh height.

At 200 km/h (125 mph)
With no CD/CL
Load front left and right (2200N)
Load rear left and right (2800N)
Ground height=358mm
Drag=0kg

At CD=1 CL=0 the loads stayed the same along with ground height. (2200/2800 front/rear)
Ground height=358mm
Drag=195kg

At CD=1 and CL = 1.

Load front left and right (3200 N)
Load rear left and right (3800N)
Ground height=348mm
Drag and lift = 195kg


The wings app is reporting front distribution 50% as you said earlier it would.

So much less would it be at front? due to wing being 348 mm above ground .

 

[Ghoults]

If you calculate the moments you'll notice that your drag force has a moment arm length of your cog height. From that you can then calculate how the drag changes the balance of the aerodynamic loads on the axles. Basically you'll have 3 equations:

(1) F_front + F_rear + mass*g = 0
(2) F_drag*cog_height + F_rear*wheelbase + mass*g*longitudinal_distance_from_front_axle_to_cog = 0
(3) F_drag*cog_height - F_front*wheelbase - mass*g*(wheelbase - longitudinal_distance_from_front_axle_to_cog) = 0

Solve F_front and F_rear which are the loads on front and rear axle. F_drag is your speed dependant drag force.

So if
mass = 1000kg
wheelbase = 2.5m -> longitudinal_distance_from_front_axle_to_cog = 2.5m / 2 = 1.25m
F_drag is 195kg*9,81m/s^2
cog_height = 0.358m

you get
F_front = (-) 4631N = 472kg
F_rear = (-) 5179N = 527.9kg
And check 1000kg*9.81m/s^2 = 4631N + 5179N = close enuff

so what mclarenpapa is trying to say. As long as your drag force has a moment arm it will cause load difference to the axles. If your drag force is at cog height then cog height is your moment arm. If your drag force is at ground level then your moment arm is 0 and if you make it 0 in the above equations you get same front and rear axle loads

 

[Ben O'Bro]

Hey
Question regarding animating an object available in the pits options, like the cop lights in the Transit, or hard roof for the Viper.
Well how is it rigged (ok i didn't look in the data files)

But main question, can you animate something, for example you set a wing rotation, or windshield for a jeep willis on/off
Does it take 2 objects, or can you rotate an object with a dummy ?

 

[garyjpaterson]

Hey
Question regarding animating an object available in the pits options, like the cop lights in the Transit, or hard roof for the Viper.
Well how is it rigged (ok i didn't look in the data files)

But main question, can you animate something, for example you set a wing rotation, or windshield for a jeep willis on/off
Does it take 2 objects, or can you rotate an object with a dummy ?

Yeah just animate the dummy, name it whatever you want, export it as whatever you want.

Add a 'wing' in aero.ini (even if its not a wing, like those lights on the Transit). Then reference it in wing_animations (try messing with INVERT=1 if its doing the opposite of what you expect), linking the wing number to the animation name. Finally make sure to add the 'wing' to the setup.ini so you can play with it ingame.

For this wing I had both a dummy for the wing angle, and one more to move the position of the locating bolt.

 

[AccAkut]

Hey
Question regarding animating an object available in the pits options, like the cop lights in the Transit, or hard roof for the Viper.
Well how is it rigged (ok i didn't look in the data files)

But main question, can you animate something, for example you set a wing rotation, or windshield for a jeep willis on/off
Does it take 2 objects, or can you rotate an object with a dummy ?

you can take as many as you like, just make sure you include them in the specific fbx export. Also can use any sort of modification, rotation, translation, scale (my Audi used "scale to zero" to make the wing foils disappear)

 

[mclarenf1papa]

If you calculate the moments you'll notice that your drag force has a moment arm length of your cog height. From that you can then calculate how the drag changes the balance of the aerodynamic loads on the axles. Basically you'll have 3 equations:

(1) F_front + F_rear + mass*g = 0
(2) F_drag*cog_height + F_rear*wheelbase + mass*g*longitudinal_distance_from_front_axle_to_cog = 0
(3) F_drag*cog_height - F_front*wheelbase - mass*g*(wheelbase - longitudinal_distance_from_front_axle_to_cog) = 0

Solve F_front and F_rear which are the loads on front and rear axle. F_drag is your speed dependant drag force.

So if
mass = 1000kg
wheelbase = 2.5m -> longitudinal_distance_from_front_axle_to_cog = 2.5m / 2 = 1.25m
F_drag is 195kg*9,81m/s^2
cog_height = 0.358m

you get
F_front = (-) 4631N = 472kg
F_rear = (-) 5179N = 527.9kg
And check 1000kg*9.81m/s^2 = 4631N + 5179N = close enuff

so what mclarenpapa is trying to say. As long as your drag force has a moment arm it will cause load difference to the axles. If your drag force is at cog height then cog height is your moment arm. If your drag force is at ground level then your moment arm is 0 and if you make it 0 in the above equations you get same front and rear axle loads

Yeah, this. I didn’t particularly want to go into the math behind it, thanks for doing so.

 

[Ben O'Bro]

3dsmax & mirror object

how do you make the mapping properly on the mirrors so the ratio of reflection is correct?
i always struggle on this...

 

[garyjpaterson]

3dsmax & mirror object
View attachment 267674

how do you make the mapping properly on the mirrors so the ratio of reflection is correct?
i always struggle on this...

The ratio is supposed to be 4 to 1, I think the included template in the dev folder is 2 to 1, so I just stretched mine to the correct ratio and use that.

 

[f1mania]

Hello,

I'm working on a track where I have a semi-closed tunnel (a bit like Monaco Tunnel).

I would like to know how can I light up this erea. I understood we can make a glowing material, but it will not really light my scene, isn't it? How can I do?

Don't look at texture, great part are just testing textures!