Modifying Parts
Find out what every part does and what its fields mean.
ScriptableObjects field values save all the changes you make during development in the editor, but not in the build, that's the feature of ScriptableObjects.
However, the changes to which scriptable object parts the controller uses that were made during runtime are reset, as well as the value type fields (such as CustomizableSet object fields, used preset field, SteerSpeed, and DrivetrainType).
To save the changes made during play mode, check the following toggle:
Acceleration parts
The engine provides torque to the drive wheels of the vehicle.
Torque Curve
To change the properties of the engine, open TorqueCurve.
Torque Curve looks like this:
Where the X-axis represents the rpm, the Y-axis - the amount of torque.
The leftmost key is the idle rpm of the engine. Idle rpm can't be less than 0.
The rightmost key is the maximum rpm the engine can handle.
Horsepower
The horsepower label shows the approximate amount of horsepower the engine can produce, taking into account additional boost from the forced induction system.
Max Speed
The max speed field defines the maximum speed that the engine can handle. If the car tries to go beyond this maximum, the opposite force would be applied.
An optional field where you can assign a Forced Induction Scriptable Object.
Handling Parts
Tires define the steering and acceleration properties of the vehicle.
Steering Stiffness
Steering stiffness defines the cornering ability of a vehicle. The higher the value, the more the wheels want to go in the direction they are facing. Therefore, low values are more suitable for drift and high values - for grip.
Sideways Grip Curve
The sideways grip curve acts as a multiplier to the steering stiffness. The value is based on how fast the vehicle is going compared to the max speed it can reach (current car speed / max car speed.)
The sideways grip curve of a vehicle with a normal grip can look like this, letting the vehicle take sharp turns at low speeds but become less stable and understeery as the car reaches the top speed:
Sideways Slip Curve
The sideways slip curve is another multiplier to the steering stiffness. It is based on the dot product of the vehicle movement and vehicle forward vector (the value is read from 1 - dot product).
At a value of 0 the car is moving precisely where it is facing, there is 0 slip, so a value of key[0] will be used.
When the car is sliding perpendicularly, the slip equals 1, so a value of the last key will be used.
It gives the effect of the vehicle losing some traction and sliding, not being able to move in the way the tires are pointing.
Note that the wheels that move perpendicularly to their forward vector should have maximum resistance to motion, so as the slip value approaches 1, the curve value should increase, like this:
Forward Grip
The forward grip value defines how much force the wheel can handle before it starts slipping.
When accelerating, the weight of the vehicle shifts to the rear, increasing the load on the wheel axle. If the amount of torque provided to the drive wheel is bigger than the wheel load multiplied by the forward grip, the wheel starts slipping.
In case of the wheel slip, the car has slightly worse acceleration.
Drift Tires
Drift tires have specific properties for the rear wheels. Even if you configure the drift tire values and assign the tire scriptable object to the front wheels, they will have no effect.
The first thing to note, if you used to make "drift" tires the old way, is that the drift tire should have normal steering stiffness and sideways grip curve values, like you would set on a grip tire.
Until the tires lose traction, they will have the maximum steering stiffness (from the Steering Stiffness and Sideways Grip Curve) and will not take into account the Sideways Slip Curve.
After losing traction, the tires will also start taking into account the Sideways Slip Curve. For proper drift, the curve should start with low values and eventually reach high value, simulating strong resistance to orthogonal motion.
Drift Tire Properties (Applied only during drift)
Preserve Velocity Multiplier
The "Preserve Velocity Multiplier" is a multiplier to the additional force (the tire's forward vector projected on the rigidbody's velocity), which helps the vehicle to maintain and gain speed during drift. Values too high can result in unnatural or broken acceleration, the recommended range of values is [0.9-1.1]
Preserve Velocity For Angle Curve
This curve is an additional multiplier to the "Preserve Velocity Multiplier" based on the angle of the drift. X-axis is the dot product between the vehicle's velocity and tire's right axis, Y-axis is a multiplier. Increasing the multiplier as the drift angle increases helps the car to not lose speed.
Auto Straightening Strength
Auto Straightening Strength is a multiplier to the natural force that counteracts the drift force. Increasing this value can help exit the drift more easily, thus giving more control to the player. This value is scaled by the angle of the drift (the less the angle the higher the force) and rigidbody's angular velocity around the Y axis (rapid transitions during drift lower this force).
Auto Straightening Filter
Auto Straightening Filter scales the amount of the force that straightens the vehicle depending on the drift angle. This value is used as a power the drift angle is taken to, thus increasing this value drastically lowers the influence of higher angle drifts.
No Acceleration Effect Multiplier
"No Acceleration Effect Multiplier" multiplies the resulting straightening force when there is 0 acceleration input from the user.
Drift Enter Conditions
Angular Velocity Change Rate
"Angular Velocity Change Rate" is a threshold that can cause the vehicle to start drifting if overcame. This value is scaled by the rigidbody's angular drag, thus making drift initiation less likely at higher speed (drag is increased depending on the Vehicle Body's "Cornering Resistance Curve"). If tuned correctly, this value can make the vehicle enter the drift only by inertia drift (the angular acceleration of the rigidbody will be high after changing the movement direction quickly enough.)
Forward Grip
"Forward Grip" property in the "Drift Parameters" is the same property that in your normal tires, it has been duplicated to show that it can be another reason for the vehicle to start drifting. If the torque, applied to the wheel is higher than the current load on the tire multiplied by the forward grip, the vehicle can start drifting. (load increases on the rear wheels during acceleration and reduces during deceleration).
Drift Exit Conditions
Min Drift Angle
Drift Angle is represented as a dot product between the rigidbody's velocity and the tire's right axis. If the drift angle is below this value, the vehicle can stop drifting.
Min Angular Velocity
If the rigidbody's angular velocity is below this value, the vehicle can stop drifting. Note that during drift transitions where the direction the vehicle is moving changes rapidly, the angular velocity will be higher than when just turning or drifting in 1 direction.
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