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Handling 3rd Person Camera Physics with SphereCast's

 ·  ☕ 2 min read

Hello again internet! Let’s dive into how to manage camera physics in your third person cameras using SphereCasts.

SphereCast’s expand upon what you might know about raycasts projecting a beam through your scene that can detect physical objects in the scene and let you know if it’s hit them. Unlike a raycast though a SphereCast includes a radius. This can prevent the detection from going through tight spaces or between closely aligned Game Objects.

To showcase this, we’re going to build a quick 3rd Person Camera in a scene that has some narrow alleyways. In order to prevent our camera from clipping geometry inside those alleyways and to prevent it from ending up in a narrow space we’ll project a sphere using a SphereCast. This gives our camera some safety and improves the quality of the camera positioning.

You can find more information about SphereCast’s in Unity’s documentation here: https://docs.unity3d.com/ScriptReference/Physics.SphereCast.html


The code we wrote in this video is here if you’d like to try it yourself!

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using UnityEngine;

public class ThirdPersonCamera : MonoBehaviour
{
    public float cameraSpeed;
    public Transform cameraTransform;
    public float cameraDistance;
    public float radius = 0.25f;

    void Update()
    {
        // Multiplying quaternions adds them together
        this.transform.rotation *= Quaternion.Euler(0, cameraSpeed * Input.GetAxis("Mouse X"), 0);

        // Move Camera back until we get near a Physics Collider
        Ray ray = new Ray(this.transform.position, -this.transform.forward);
        RaycastHit hit;
        if (Physics.SphereCast(ray, radius, out hit, cameraDistance))
        {
            cameraTransform.localPosition = Vector3.back * hit.distance;
        }
        else
        {
            cameraTransform.localPosition = Vector3.back * cameraDistance;
        }
    }

    // Draw a Gizmo around where the camera has been projected to.
    void OnDrawGizmos()
    {
        Gizmos.color = Color.blue;
        Gizmos.DrawWireSphere(cameraTransform.position, radius);
    }
}

Looking for an introduction to Raycasts? Check out my video on Raycasting in Unity: https://worldofzero.com/videos/detecting-objects-with-raycasts-in-unity3d/

If your interested in some of my other Cloud based videos I stream at twitch.tv/MicrosoftDeveloper regularly and some of my other videos can be found on the Microsoft Reactor YouTube channel: https://www.youtube.com/c/MicrosoftReactor1

I currently run events out of the Microsoft Reactor in San Francisco as well! If your nearby and want to learn things or join a workshop in person checkout our meetup group. https://www.meetup.com/Microsoft-Reactor-San-Francisco/

Join the World of Zero Discord Server: https://discord.gg/hU5Kq2u


Sam Wronski
WRITTEN BY
Sam Wronski
Maker of things, currently helping build cloud things @ Microsoft. World of Zero is a personal project disconnected from my professional work. Lets make something awesome together!