movement + collision untested and unsued (but for real this time)

src/physics_body.rs

@@ -0,0 +1,38 @@
+use bevy::{prelude::*, render::renderer};
+
+#[derive(Component)]
+#[require(Transform)]
+pub struct PhysicsBody {
+    pub mass: f32,
+    pub force: Vec2,
+    pub velocity: Vec2,
+    pub drag: f32, // velocity multiplied each physics update by (1-drag)
+}
+
+impl Default for PhysicsBody {
+    fn default() -> Self {
+        Self {
+            mass: 1.0,
+            force: Vec2::ZERO,
+            velocity: Vec2::ZERO,
+            drag: 0.0,
+        }
+    }
+}
+
+pub fn integrate(mut query: Query<(&mut Transform, &mut PhysicsBody)>, time: Res<Time<Fixed>>) {
+    for (mut transform, mut physicsbody) in &mut query {
+        let force = physicsbody.force;
+        let mass = physicsbody.mass;
+        let drag = physicsbody.drag;
+        let delta_secs = time.delta_secs();
+
+        physicsbody.velocity += force * delta_secs / mass;
+        // Drag because stability is good you know
+        physicsbody.velocity *= 1.0 - drag;
+
+        transform.translation.x += physicsbody.velocity.x * delta_secs;
+        transform.translation.y += physicsbody.velocity.y * delta_secs;
+        physicsbody.force = Vec2::ZERO;
+    }
+}