Godot Rust: Working through “Dodge the Creeps!”

player.rs

// player.rs

use gd;
use gd::{ GodotString, Vector2 };
use gd::init::{ Property, PropertyHint, PropertyUsage };

const DEFAULT_SPEED: f64 = 400.0;

godot_class! {
    class Player: gd::Area2D {
        fields {
            speed: f64,
            screen_size: gd::Vector2,
        }

        setup(builder) {
            builder.add_property(
                Property {
                    name: "player/speed",
                    default: DEFAULT_SPEED,
                    hint: PropertyHint::None,
                    getter: |this: &mut Player| this.speed,
                    setter: |this: &mut Player, val| this.speed = val,
                    usage: PropertyUsage::DEFAULT,
                }
            );
        }

        constructor(header) {
            Player {
                header,
                speed: DEFAULT_SPEED,
                screen_size: Vector2::new(480.0, 720.0),
            }
        }

        export fn _ready(&mut self) {
            let parent = self.as_parent();

            self.screen_size = parent.get_viewport()
                .expect("should have a viewport")
                .get_size();
        }

        export fn _process(&mut self, delta: f64) {
            let mut vel = Vector2::new(0.0, 0.0);
            let input = gd::Input::godot_singleton();

            if input.is_action_pressed(GodotString::from_str("ui_right")) {
                vel.x += 1.0;
            }

            if input.is_action_pressed(GodotString::from_str("ui_left")) {
                vel.x -= 1.0;
            }

            if input.is_action_pressed(GodotString::from_str("ui_down")) {
                vel.y += 1.0;
            }

            if input.is_action_pressed(GodotString::from_str("ui_up")) {
                vel.y -= 1.0;
            }

            if vel.length() > 0.0 {
                // TODO: How to make this shorter?
                let mut sprite = self
                    .as_parent()
                    .as_node_2d()
                    .get_node(gd::NodePath::from_str("AnimatedSprite"))
                    .expect("Should have an attached AnimatedSprite node!")
                    .cast::<gd::AnimatedSprite>()
                    .expect("Should be castable to AnimatedSprite!");

                sprite.play();
            }
        }
    }
}