Add camera movement when using the arrow keys. (#75)

* Add camera movement

Author: sunreef

resources/input.ron

@@ -15,5 +15,23 @@
     "SlowDown": [
         [Key(Subtract)]
     ],
+    "CameraMoveUp": [
+        [Key(Up)]
+    ],
+    "CameraMoveDown": [
+        [Key(Down)]
+    ],
+    "CameraMoveLeft": [
+        [Key(Left)]
+    ],
+    "CameraMoveRight": [
+        [Key(Right)]
+    ],
+    "CameraMoveForward": [
+        [Key(LShift), Key(Up)]
+    ],
+    "CameraMoveBackward": [
+        [Key(LShift), Key(Down)]
+    ],
   },
 )

src/states/main_game.rs

@@ -37,6 +37,11 @@ impl MainGameState {
         MainGameState {
             dispatcher: DispatcherBuilder::new()
                 .with_pool(pool)
+                .with(
+                    camera_movement::CameraMovementSystem::default(),
+                    "camera_movement",
+                    &[],
+                )
                 .with(perception::SpatialGridSystem, "spatial_grid", &[])
                 .with(
                     perception::EntityDetectionSystem,

src/systems/camera_movement.rs

@@ -0,0 +1,46 @@
+use amethyst::{
+    core::{Named, Time, Transform},
+    ecs::*,
+    input::InputHandler,
+    renderer::Camera,
+};
+
+#[derive(Default)]
+pub struct CameraMovementSystem {}
+
+impl<'s> System<'s> for CameraMovementSystem {
+    type SystemData = (
+        ReadStorage<'s, Camera>,
+        ReadStorage<'s, Named>,
+        WriteStorage<'s, Transform>,
+        Read<'s, InputHandler<String, String>>,
+        Read<'s, Time>,
+    );
+
+    fn run(&mut self, (cameras, names, mut transforms, input_handler, time): Self::SystemData) {
+        let delta_time = time.delta_real_seconds();
+        let move_factor = 12.0 * delta_time;
+        for (_, name, transform) in (&cameras, &names, &mut transforms).join() {
+            if name.name == "Main camera" {
+                if input_handler.action_is_down("CameraMoveUp").unwrap() {
+                    transform.move_up(move_factor);
+                }
+                if input_handler.action_is_down("CameraMoveDown").unwrap() {
+                    transform.move_down(move_factor);
+                }
+                if input_handler.action_is_down("CameraMoveLeft").unwrap() {
+                    transform.move_left(move_factor);
+                }
+                if input_handler.action_is_down("CameraMoveRight").unwrap() {
+                    transform.move_right(move_factor);
+                }
+                if input_handler.action_is_down("CameraMoveForward").unwrap() {
+                    transform.move_forward(move_factor);
+                }
+                if input_handler.action_is_down("CameraMoveBackward").unwrap() {
+                    transform.move_backward(move_factor);
+                }
+            }
+        }
+    }
+}

src/systems/mod.rs

@@ -1,4 +1,5 @@
 pub mod behaviors;
+pub mod camera_movement;
 pub mod collision;
 pub mod combat;
 pub mod debug;

src/systems/movement.rs

@@ -16,7 +16,6 @@ impl<'s> System<'s> for MovementSystem {
             if movement.velocity.magnitude() > movement.max_movement_speed {
                 movement.velocity = movement.velocity.normalize() * movement.max_movement_speed;
             }
-
             transform.translate_x(movement.velocity.x * delta_time);
             transform.translate_y(movement.velocity.y * delta_time);
         }