From Physics

Assets/Scripts/MovingSphere.cs

@@ -0,0 +1,155 @@
+using UnityEngine;
+
+public class MovingSphere : MonoBehaviour
+{
+    [SerializeField, Range(0f, 100f)]
+    private float maxSpeed = 10f;
+
+    [SerializeField, Range(0f, 100f)]
+    private float maxAcceleration = 10f, maxAirAcceleration = 1f;
+
+    [SerializeField, Range(0f, 10f)]
+    private float jumpHeight = 2f;
+
+    [SerializeField, Range(0, 5)]
+    private int maxAirJumps = 0;
+
+    [SerializeField, Range(0f, 90f)]
+    private float maxGroundAngle = 25f;
+
+    private Rigidbody body;
+
+    private Vector3 desiredVelocity = new Vector3(0f, 0f, 0f);
+    private bool desiredJump = false;
+
+    private int groundContactCount;
+    private bool onGround => groundContactCount > 0;
+    private int jumpPhase;
+    private Vector3 velocity;
+    private Vector3 contactNormal;
+    private float minGroundDotProduct;
+
+    private void OnValidate()
+    {
+        minGroundDotProduct = Mathf.Cos(maxGroundAngle * Mathf.Deg2Rad);
+    }
+
+    private void Awake()
+    {
+        body = GetComponent<Rigidbody>();
+        OnValidate();
+    }
+
+    private void Update()
+    {
+        Vector2 playerInput;
+        playerInput.x = Input.GetAxis("Horizontal");
+        playerInput.y = Input.GetAxis("Vertical");
+        playerInput = Vector2.ClampMagnitude(playerInput, 1f);
+        desiredVelocity = new Vector3(playerInput.x, 0f, playerInput.y) * maxSpeed;
+
+        desiredJump |= Input.GetButtonDown("Jump");
+    }
+
+    private void FixedUpdate()
+    {
+        UpdateState();
+
+        AdjustVelocity();
+
+        if (desiredJump)
+        {
+            desiredJump = false;
+            Jump();
+        }
+
+        body.velocity = velocity;
+
+        ClearState();
+    }
+
+    private void UpdateState()
+    {
+        velocity = body.velocity;
+        if (onGround)
+        {
+            jumpPhase = 0;
+            if (groundContactCount > 1)
+            {
+                contactNormal.Normalize();
+            }
+        }
+        else
+        {
+            contactNormal = Vector3.up;
+        }
+    }
+
+    private void OnCollisionEnter(Collision collision)
+    {
+        EvaluateCollision(collision);
+    }
+    
+    private void OnCollisionStay(Collision collision)
+    {
+        EvaluateCollision(collision);
+    }
+
+    private void EvaluateCollision(Collision collision)
+    {
+        for (int i = 0; i < collision.contactCount; i++)
+        {
+            var normal = collision.GetContact(i).normal;
+            if (normal.y >= minGroundDotProduct)
+            {
+                groundContactCount += 1;
+                contactNormal += normal;
+            }
+        }
+    }
+
+    private void Jump()
+    {
+        if (onGround || jumpPhase < maxAirJumps)
+        {
+            jumpPhase++;
+            float jumpSpeed = Mathf.Sqrt(-2f * Physics.gravity.y * jumpHeight);
+            float alignedSpeed = Vector3.Dot(velocity, contactNormal);
+            if (alignedSpeed > 0f)
+            {
+                jumpSpeed = Mathf.Max(jumpSpeed - alignedSpeed, 0f);
+            }
+            velocity += contactNormal * jumpSpeed;
+        }
+    }
+
+    private void AdjustVelocity()
+    {
+        Vector3 xAxis = ProjectOnContactPlane(Vector3.right).normalized;
+        Vector3 zAxis = ProjectOnContactPlane(Vector3.forward).normalized;
+
+        float currentX = Vector3.Dot(velocity, xAxis);
+        float currentZ = Vector3.Dot(velocity, zAxis);
+        
+        float acceleration = onGround ? maxAcceleration : maxAirAcceleration;
+        float maxSpeedChange = acceleration * Time.deltaTime;
+
+        float newX =
+            Mathf.MoveTowards(currentX, desiredVelocity.x, maxSpeedChange);
+        float newZ =
+            Mathf.MoveTowards(currentZ, desiredVelocity.z, maxSpeedChange);
+
+        velocity += xAxis * (newX - currentX) + zAxis * (newZ - currentZ);
+    }
+
+    private Vector3 ProjectOnContactPlane(Vector3 vector)
+    {
+        return vector - contactNormal * Vector3.Dot(vector, contactNormal);
+    }
+
+    void ClearState()
+    {
+        groundContactCount = 0;
+        contactNormal = Vector3.zero;
+    }
+}

Assets/Scripts/MovingSphere.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 50beb4685c906ba49b7db3438cc30dfc
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: