bring back pre-0.30 player controls

src/physics/Hitbox.hpp

@@ -58,7 +58,6 @@ struct Hitbox {
     glm::vec3 velocity;
     glm::vec3 scale {1.0f, 1.0f, 1.0f};
     float linearDamping = 0.5;
-    float friction = 1.0f;
     float verticalDamping = 1.0f;
     bool grounded = false;
     float gravityScale = 1.0f;
@@ -68,7 +67,10 @@ struct Hitbox {
     float elasticity = 0.0f;
     std::string material;
     std::string groundMaterial;
+
+    // FIXME: only one must survive
     glm::vec3 groundVelocity {};
+    glm::vec3 actualGroundVelocity {};
     
     glm::vec3 prevPosition {};
     glm::vec3 prevVelocity {};
@@ -94,4 +96,8 @@ struct Hitbox {
             prevPosition = vec;
         }
     }
+
+    glm::vec3 getSurfaceVelocity() const {
+        return velocity - actualGroundVelocity;
+    }
 };