Switch to property-based force application.

examples/amethyst.rs

@@ -9,7 +9,6 @@ use amethyst::renderer::{
 };
 use amethyst::{Application, GameData, GameDataBuilder, SimpleState, StateData};
 use nphysics_ecs_dumb::bodies::DynamicBody;
-use nphysics_ecs_dumb::forces::DefaultForceGenerators;
 use nphysics_ecs_dumb::nphysics::math::{Point, Velocity};
 use nphysics_ecs_dumb::systems::PhysicsBundle;
 use num_traits::identities::One;
@@ -111,7 +110,7 @@ fn main() -> amethyst::Result<()> {
     let game_data = GameDataBuilder::default()
         .with_bundle(TransformBundle::new())?
         .with_bundle(
-            PhysicsBundle::<DefaultForceGenerators>::new().with_dep(&["transform_system"]),
+            PhysicsBundle::new().with_dep(&["transform_system"]),
         )?
         .with_bundle(RenderBundle::new(pipe, Some(display_config)))?;
 

src/bodies.rs

@@ -1,7 +1,7 @@
 use amethyst::ecs::world::Index;
 use amethyst::ecs::{Component, FlaggedStorage};
 use nalgebra::Matrix3;
-use nphysics3d::math::{Point, Velocity};
+use nphysics3d::math::{Point, Velocity, Force};
 use nphysics3d::object::BodyHandle;
 use std::collections::HashMap;
 
@@ -37,6 +37,7 @@ impl DynamicBody {
             mass,
             angular_mass,
             center_of_mass,
+            external_forces: Force::<f32>::zero(),
         })
     }
 
@@ -63,6 +64,8 @@ pub struct RigidPhysicsBody {
     pub mass: f32,
     pub angular_mass: Matrix3<f32>,
     pub center_of_mass: Point<f32>,
+
+    pub external_forces: Force<f32>,
 }
 
 /// Multipart physics body, for use in `PhysicsBody` Component. Not implemented yet.

src/lib.rs

@@ -4,7 +4,6 @@ pub extern crate nphysics3d as nphysics;
 extern crate num_traits;
 
 pub mod bodies;
-pub mod forces;
 pub mod systems;
 
 pub type World = self::nphysics::world::World<f32>;

src/systems/mod.rs

@@ -1,42 +1,30 @@
 mod physics_stepper;
 mod sync_bodies_from_physics;
 mod sync_bodies_to_physics;
-mod sync_force_generators_to_physics;
 mod sync_gravity_to_physics;
 
-use crate::forces::ForceGenerators;
 use amethyst::core::bundle::{Result, SystemBundle};
 use amethyst::core::specs::DispatcherBuilder;
-use core::marker::PhantomData;
 
 pub use self::physics_stepper::PhysicsStepperSystem;
 pub use self::sync_bodies_from_physics::SyncBodiesFromPhysicsSystem;
 pub use self::sync_bodies_to_physics::SyncBodiesToPhysicsSystem;
-pub use self::sync_force_generators_to_physics::SyncForceGeneratorsToPhysicsSystem;
 pub use self::sync_gravity_to_physics::SyncGravityToPhysicsSystem;
 
 // TODO: Implement contact events, use Entity id's instead of nphysics handles.
 // contact_events.iter_write(physical_world.contact_events());
 
-pub const SYNC_FORCE_GENERATORS_TO_PHYSICS_SYSTEM: &str = "sync_force_generators_to_physics_system";
 pub const SYNC_BODIES_TO_PHYSICS_SYSTEM: &str = "sync_bodies_to_physics_system";
 pub const SYNC_GRAVITY_TO_PHYSICS_SYSTEM: &str = "sync_gravity_to_physics_system";
 pub const PHYSICS_STEPPER_SYSTEM: &str = "physics_stepper_system";
 pub const SYNC_BODIES_FROM_PHYSICS_SYSTEM: &str = "sync_bodies_from_physics_system";
 
 #[derive(Default)]
-pub struct PhysicsBundle<'a, F>
-where
-    F: ForceGenerators,
-{
+pub struct PhysicsBundle<'a> {
     dep: &'a [&'a str],
-    phantom_force_generators: PhantomData<F>,
 }
 
-impl<'a, F> PhysicsBundle<'a, F>
-where
-    F: ForceGenerators,
-{
+impl<'a> PhysicsBundle<'a> {
     pub fn new() -> Self {
         Default::default()
     }
@@ -47,16 +35,8 @@ where
     }
 }
 
-impl<'a, 'b, 'c, F: 'a> SystemBundle<'a, 'b> for PhysicsBundle<'c, F>
-where
-    F: ForceGenerators,
-{
+impl<'a, 'b, 'c> SystemBundle<'a, 'b> for PhysicsBundle<'c> {
     fn build(self, builder: &mut DispatcherBuilder<'a, 'b>) -> Result<()> {
-        builder.add(
-            SyncForceGeneratorsToPhysicsSystem::<F>::new(),
-            SYNC_FORCE_GENERATORS_TO_PHYSICS_SYSTEM,
-            self.dep,
-        );
         builder.add(
             SyncBodiesToPhysicsSystem::new(),
             SYNC_BODIES_TO_PHYSICS_SYSTEM,
@@ -72,7 +52,6 @@ where
             PhysicsStepperSystem::new(),
             PHYSICS_STEPPER_SYSTEM,
             &[
-                SYNC_FORCE_GENERATORS_TO_PHYSICS_SYSTEM,
                 SYNC_BODIES_TO_PHYSICS_SYSTEM,
                 SYNC_GRAVITY_TO_PHYSICS_SYSTEM,
             ],

src/systems/sync_bodies_to_physics.rs

@@ -97,6 +97,7 @@ impl<'a> System<'a> for SyncBodiesToPhysicsSystem {
                             .unwrap();
 
                         physical_body.set_velocity(rigid_body.velocity);
+                        physical_body.apply_force(&rigid_body.external_forces);
                     }
                     DynamicBody::Multibody(_) => {
                         // TODO
@@ -112,6 +113,7 @@ impl<'a> System<'a> for SyncBodiesToPhysicsSystem {
 
                         physical_body.set_position(try_convert(transform.0).unwrap());
                         physical_body.set_velocity(rigid_body.velocity);
+                        physical_body.apply_force(&rigid_body.external_forces);
 
                         // if you changed the mass properties at all... too bad!
                     }