Feature/Add movement interpolation (#5)

- Updated Player class to use maxSpeed, acceleration, and deceleration for smoother movement.
- Introduced velocity vector for more responsive control and smoother diagonal movement.
- Enhanced update method to calculate target velocity based on input and apply easing for acceleration and deceleration.
- Implemented boundary checks to stop movement when hitting the edges of the play area.

Reviewed-on: #5
Co-authored-by: Juan Sebastian Montoya <juansmm@outlook.com>
Co-committed-by: Juan Sebastian Montoya <juansmm@outlook.com>

index.html

@@ -153,7 +153,10 @@
         class Player extends GameObject {
             constructor(scene, groundSize) {
                 super(scene, groundSize);
-                this.speed = 0.15;
+                this.maxSpeed = 0.15;
+                this.acceleration = 0.08;
+                this.deceleration = 0.12;
+                this.velocity = new THREE.Vector3(0, 0, 0);
             }
             
             createMesh() {
@@ -170,31 +173,69 @@
             }
             
             initialize() {
+                // Initialize velocity (needed because initialize is called from parent constructor)
+                if (!this.velocity) {
+                    this.velocity = new THREE.Vector3(0, 0, 0);
+                }
                 this.reset();
             }
             
             reset() {
                 this.setPosition(0, 0.5, 0);
                 this.mesh.rotation.y = 0;
+                if (this.velocity) {
+                    this.velocity.set(0, 0, 0);
+                }
             }
             
             update(keys) {
-                const moveVector = new THREE.Vector3();
+                // Calculate target velocity based on input
+                const targetVelocity = new THREE.Vector3(0, 0, 0);
                 
-                if (keys['w'] || keys['arrowup']) moveVector.z -= this.speed;
-                if (keys['s'] || keys['arrowdown']) moveVector.z += this.speed;
-                if (keys['a'] || keys['arrowleft']) moveVector.x -= this.speed;
-                if (keys['d'] || keys['arrowright']) moveVector.x += this.speed;
+                if (keys['w'] || keys['arrowup']) targetVelocity.z -= this.maxSpeed;
+                if (keys['s'] || keys['arrowdown']) targetVelocity.z += this.maxSpeed;
+                if (keys['a'] || keys['arrowleft']) targetVelocity.x -= this.maxSpeed;
+                if (keys['d'] || keys['arrowright']) targetVelocity.x += this.maxSpeed;
                 
-                this.mesh.position.add(moveVector);
+                // Smoothly interpolate velocity towards target
+                const isMoving = targetVelocity.length() > 0;
+                const accelRate = isMoving ? this.acceleration : this.deceleration;
+                
+                // Calculate velocity difference for each axis
+                const velDiffX = targetVelocity.x - this.velocity.x;
+                const velDiffZ = targetVelocity.z - this.velocity.z;
+                
+                // Apply easing to each axis independently for smoother diagonal movement
+                if (Math.abs(velDiffX) > 0.001) {
+                    this.velocity.x += velDiffX * accelRate;
+                } else {
+                    this.velocity.x = targetVelocity.x;
+                }
+                
+                if (Math.abs(velDiffZ) > 0.001) {
+                    this.velocity.z += velDiffZ * accelRate;
+                } else {
+                    this.velocity.z = targetVelocity.z;
+                }
+                
+                // Apply velocity to position
+                this.mesh.position.add(this.velocity);
                 
                 // Boundary checks
                 const boundary = this.groundSize / 2 - 0.5;
                 this.mesh.position.x = Math.max(-boundary, Math.min(boundary, this.mesh.position.x));
                 this.mesh.position.z = Math.max(-boundary, Math.min(boundary, this.mesh.position.z));
                 
+                // Stop velocity if hitting boundary
+                if (Math.abs(this.mesh.position.x) >= boundary) {
+                    this.velocity.x = 0;
+                }
+                if (Math.abs(this.mesh.position.z) >= boundary) {
+                    this.velocity.z = 0;
+                }
+                
                 // Rotate player based on movement
-                if (moveVector.length() > 0) {
+                if (this.velocity.length() > 0.01) {
                     this.mesh.rotation.y += 0.1;
                 }
             }