C#UnityPhysics

Driving Simulator

We created a realistic driving experience using Unity.

Source code

Role

Physics Engineer

Timeframe

May 2024 - June 2024

Stack

3 technologies

Project overview

As part of a 10 week project we created a realistic driving experience using Unity. We chose to create Silverstone using a height map. We have also created our completely custom car controller.

Challenge

I was responsible for creating the physics part of the game. In this process I had to find a way to create the most realistic way possible of recreating a car. I also had to make sure this system worked for everyone by adding in controller support.

Solution

I decided not to use Unity's wheel collider but instead make my own multi script system. This gave me complete control over track conditions, weather conditions, tyre compounds, and more.

Outcome

I learned how to create sophisticated systems using Unity's PhysX engine. In this process I have used all the tricks in the engine to get the best result. I have also seen all the flaws in the engine and its performance and how to work around it.

The suspension travel and the current point in suspension.

The grip force in the corner shown.

Suspension

Uses real world values for the setup of the suspension.

SuspensionV2.cs

private void Suspension()
    {
        //calculating the total travel the spring has
        float totalTravel = highestPoint.y - lowestPoint.y;
        
        //calculating how compressed the spring is
        float targetPos = travel * targetPosition + lowestPoint.y;
        currentTravel = targetPos - tyre.transform.localPosition.y;
        travelFactor = Mathf.Abs(currentTravel) / (totalTravel / 2);
        
        //checking the progression of the spring
        float progressionFactor = progressionCurve.Evaluate(travelFactor);
        
        //calculating the velocity of the spring
        float springVelocity = (currentTravel - lastTimestepTravel) / Time.fixedDeltaTime;
        lastTimestepTravel = currentTravel;
        
        //calculating the amount of force the spring should press
        float force = -Mathf.Sign(currentTravel) * stiffness * progressionFactor - springVelocity * damper;
        
        //check how much force would be pushed to both sides
        if (tyre.isGrounded && force >= 0)
        {
            ApplyForces(force);
        }
        else
        {
            ApplyForces(force / 2);
        }
    }

Tyres

Creates the grip of the car.

TyreV2.cs

private float LateralGrip()
    {
        //check if the car is on the ground
        if (!isGrounded)
        {
            return 0f;
        }
        
        //calculate the velocity in the tyres direction
        float dotProduct = Vector3.Dot(transform.right, carRb.GetPointVelocity(transform.position).normalized);
        dotProduct = Mathf.Clamp(dotProduct, -1, 1);
        
        //calculate the force that the car pushes against the tyres direction and get the factor from the curve
        float idealForce = carRb.mass * (carRb.velocity.magnitude * dotProduct);
        float availableGrip = latGripCurve.Evaluate(Mathf.Abs(dotProduct));
        
        //add al the modifiers for the grip and put the force to the right direction
        float totalForce = idealForce * latGripBending * availableGrip;
        
        //calculate the max and lost force that the tyre can handle
        latMaximumGrip = idealForce;
        lostLatTorque = totalForce - idealForce * latGripBending;
        
        return totalForce;
    }

Interested in work like this?

I enjoy building products that need more than a surface-level redesign: the kind of work where UI, data, tooling, and operational clarity all matter together.

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