From 248fb742b03aef4195c874b96c3e23c855e21e0a Mon Sep 17 00:00:00 2001
From: Jens Pitkanen <jens@neon.moe>
Date: Sat, 18 Apr 2020 23:05:03 +0300
Subject: [PATCH] Add sliding down slopes

---
 Assets/Prefabs/Player/Player.prefab | 14 ++++++-----
 Assets/Scripts/PlayerController.cs  | 36 +++++++++++++++++++++++++++--
 2 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/Assets/Prefabs/Player/Player.prefab b/Assets/Prefabs/Player/Player.prefab
index 957657a..2b1d632 100644
--- a/Assets/Prefabs/Player/Player.prefab
+++ b/Assets/Prefabs/Player/Player.prefab
@@ -56,7 +56,7 @@ Camera:
     y: 0
     width: 1
     height: 1
-  near clip plane: 0.1
+  near clip plane: 0.05
   far clip plane: 200
   field of view: 75
   orthographic: 0
@@ -204,12 +204,14 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: 6b513dcf57a19464b92ff712f770f105, type: 3}
   m_Name: 
   m_EditorClassIdentifier: 
-  MovementSpeed: 4
+  MovementSpeed: 3
   JumpVelocity: 4
+  SlideVelocity: 3
   JumpGracePeriod: 0.2
-  Antislipperiness: 10
+  Antislipperiness: 20
   AntislipperinessInAir: 3
   Grounded: 0
+  GroundNormal: {x: 0, y: 0, z: 0}
 --- !u!143 &6125707630481988371
 CharacterController:
   m_ObjectHideFlags: 0
@@ -222,9 +224,9 @@ CharacterController:
   m_Enabled: 1
   serializedVersion: 2
   m_Height: 1.8
-  m_Radius: 0.25
-  m_SlopeLimit: 45
-  m_StepOffset: 0.3
+  m_Radius: 0.1
+  m_SlopeLimit: 30
+  m_StepOffset: 0.05
   m_SkinWidth: 0.08
   m_MinMoveDistance: 0.001
   m_Center: {x: 0, y: 0.9, z: 0}
diff --git a/Assets/Scripts/PlayerController.cs b/Assets/Scripts/PlayerController.cs
index 449242d..79b3203 100644
--- a/Assets/Scripts/PlayerController.cs
+++ b/Assets/Scripts/PlayerController.cs
@@ -6,6 +6,7 @@ using UnityEngine;
 public class PlayerController : MonoBehaviour {
     public float MovementSpeed;
     public float JumpVelocity;
+    public float SlideVelocity;
     [Tooltip("How long after falling off a ledge can the player still jump?")]
     public float JumpGracePeriod;
     [Tooltip("Lower values make the movement feel floatier.")]
@@ -15,12 +16,14 @@ public class PlayerController : MonoBehaviour {
 
     [Header("Runtime values")]
     public bool Grounded;
+    public Vector3 GroundNormal;
 
     private CharacterController Character;
 
     private Vector3 GroundVelocity = new Vector3();
     private float FallingVelocity;
     private float LastGroundedTime;
+    private float SlideStartTime;
 
     private void Awake() {
         Character = GetComponent<CharacterController>();
@@ -32,8 +35,14 @@ public class PlayerController : MonoBehaviour {
     }
 
     private void Update() {
+        Vector3 CurrentVelocity = new Vector3();
+        GroundNormal = RaycastGroundNormal();
+
+        // Sliding
+        bool Sliding = Grounded && Vector3.Angle(GroundNormal, Vector3.up) > Character.slopeLimit;
+
         // Groundedness stuff and gravity
-        if (Character.isGrounded) {
+        if (Character.isGrounded && !Sliding) {
             FallingVelocity = Mathf.Max(0, FallingVelocity);
             LastGroundedTime = Time.time;
         } else {
@@ -46,6 +55,7 @@ public class PlayerController : MonoBehaviour {
             FallingVelocity = JumpVelocity;
             Grounded = false;
         }
+        CurrentVelocity += FallingVelocity * Vector3.up;
 
         float SlippyFactor = Grounded ? Antislipperiness : AntislipperinessInAir;
 
@@ -58,12 +68,34 @@ public class PlayerController : MonoBehaviour {
         float TargetSpeed = MovementSpeed; // Tweak this to enable running or stuff
         Vector3 Move = transform.forward * Input.GetAxis("Vertical") + transform.right * Input.GetAxis("Horizontal");
         if (Move.magnitude > 0) {
+            if (Grounded) {
+                TargetSpeed *= Vector3.Dot(Vector3.up, GroundNormal);
+            }
             float CurrentSpeed = Vector3.Dot(Move, GroundVelocity);
             float SpeedDiff = TargetSpeed - CurrentSpeed;
             float Acceleration = Mathf.Min(SpeedDiff, TargetSpeed * SlippyFactor * Time.deltaTime);
             GroundVelocity += Move * Acceleration;
         }
+        CurrentVelocity += GroundVelocity;
 
-        Character.Move((GroundVelocity + FallingVelocity * Vector3.up) * Time.deltaTime);
+        // Sliiide
+        if (Sliding) {
+            CurrentVelocity = Vector3.ProjectOnPlane(CurrentVelocity, GroundNormal);
+            CurrentVelocity += Vector3.ProjectOnPlane(-Vector3.up, GroundNormal) * SlideVelocity;
+        }
+
+        Character.Move(CurrentVelocity * Time.deltaTime);
+    }
+
+    private Vector3 RaycastGroundNormal() {
+        RaycastHit Hit;
+        if (Physics.CapsuleCast(
+                transform.position + Vector3.up * Character.radius,
+                transform.position + Vector3.up * (Character.height - Character.radius),
+                Character.radius, -Vector3.up, out Hit, Character.skinWidth * 2)) {
+            return Hit.normal;
+        } else {
+            return Vector3.up;
+        }
     }
 }