Merge pull request #62 from dimforge/salva

Testbed: remove code related to salva and add a plugin system

7 files changed, 105 insertions, 311 deletions

diff --git a/build/rapier_testbed2d/Cargo.toml b/build/rapier_testbed2d/Cargo.toml
index 08c0893..273595f 100644
--- a/build/rapier_testbed2d/Cargo.toml
+++ b/build/rapier_testbed2d/Cargo.toml
@@ -39,7 +39,6 @@ flexbuffers = "0.1"
 Inflector  = "0.11"
 md5 = "0.7"
 
-
 [dependencies.rapier2d]
 path = "../rapier2d"
 version = "0.3"
diff --git a/src/dynamics/rigid_body.rs b/src/dynamics/rigid_body.rs
index a1a23a0..303d1a0 100644
--- a/src/dynamics/rigid_body.rs
+++ b/src/dynamics/rigid_body.rs
@@ -370,6 +370,12 @@ impl RigidBody {
         self.apply_impulse(impulse, wake_up);
         self.apply_torque_impulse(torque_impulse, wake_up);
     }
+
+    /// The velocity of the given world-space point on this rigid-body.
+    pub fn velocity_at_point(&self, point: &Point<f32>) -> Vector<f32> {
+        let dpt = point - self.world_com;
+        self.linvel + self.angvel.gcross(dpt)
+    }
 }
 
 /// A builder for rigid-bodies.
diff --git a/src/geometry/shape.rs b/src/geometry/shape.rs
index ec43bf7..5c96f68 100644
--- a/src/geometry/shape.rs
+++ b/src/geometry/shape.rs
@@ -64,6 +64,8 @@ pub trait Shape: RayCast<f32> + PointQuery<f32> + DowncastSync {
         None
     }
 
+    // TODO: add a compute_local_aabb method?
+
     /// Computes the AABB of this shape.
     fn compute_aabb(&self, position: &Isometry<f32>) -> AABB<f32>;
 
diff --git a/src_testbed/engine.rs b/src_testbed/engine.rs
index 52b9ca9..ff5e1ef 100644
--- a/src_testbed/engine.rs
+++ b/src_testbed/engine.rs
@@ -15,15 +15,11 @@ use rapier::dynamics::{RigidBodyHandle, RigidBodySet};
 use rapier::geometry::{Collider, ColliderHandle, ColliderSet};
 //use crate::objects::capsule::Capsule;
 //use crate::objects::convex::Convex;
-//#[cfg(feature = "fluids")]
-//use crate::objects::fluid::Fluid as FluidNode;
 //#[cfg(feature = "dim3")]
 //use crate::objects::mesh::Mesh;
 //use crate::objects::plane::Plane;
 //#[cfg(feature = "dim2")]
 //use crate::objects::polyline::Polyline;
-//#[cfg(feature = "fluids")]
-//use crate::objects::FluidRenderingMode;
 use crate::objects::capsule::Capsule;
 #[cfg(feature = "dim3")]
 use crate::objects::cone::Cone;
@@ -58,22 +54,12 @@ impl GraphicsWindow for Window {
 pub struct GraphicsManager {
     rand: Pcg32,
     b2sn: HashMap<RigidBodyHandle, Vec<Node>>,
-    #[cfg(feature = "fluids")]
-    f2sn: HashMap<FluidHandle, FluidNode>,
-    #[cfg(feature = "fluids")]
-    boundary2sn: HashMap<BoundaryHandle, FluidNode>,
     b2color: HashMap<RigidBodyHandle, Point3<f32>>,
     c2color: HashMap<ColliderHandle, Point3<f32>>,
     b2wireframe: HashMap<RigidBodyHandle, bool>,
-    #[cfg(feature = "fluids")]
-    f2color: HashMap<FluidHandle, Point3<f32>>,
     ground_color: Point3<f32>,
     camera: Camera,
     ground_handle: Option<RigidBodyHandle>,
-    #[cfg(feature = "fluids")]
-    fluid_rendering_mode: FluidRenderingMode,
-    #[cfg(feature = "fluids")]
-    render_boundary_particles: bool,
 }
 
 impl GraphicsManager {
@@ -96,21 +82,11 @@ impl GraphicsManager {
             camera,
             rand: Pcg32::seed_from_u64(0),
             b2sn: HashMap::new(),
-            #[cfg(feature = "fluids")]
-            f2sn: HashMap::new(),
-            #[cfg(feature = "fluids")]
-            boundary2sn: HashMap::new(),
             b2color: HashMap::new(),
             c2color: HashMap::new(),
-            #[cfg(feature = "fluids")]
-            f2color: HashMap::new(),
             ground_color: Point3::new(0.5, 0.5, 0.5),
             b2wireframe: HashMap::new(),
             ground_handle: None,
-            #[cfg(feature = "fluids")]
-            fluid_rendering_mode: FluidRenderingMode::StaticColor,
-            #[cfg(feature = "fluids")]
-            render_boundary_particles: false,
         }
     }
 
@@ -118,20 +94,6 @@ impl GraphicsManager {
         self.ground_handle = handle
     }
 
-    #[cfg(feature = "fluids")]
-    pub fn set_fluid_rendering_mode(&mut self, mode: FluidRenderingMode) {
-        self.fluid_rendering_mode = mode;
-    }
-
-    #[cfg(feature = "fluids")]
-    pub fn enable_boundary_particles_rendering(&mut self, enabled: bool) {
-        self.render_boundary_particles = enabled;
-
-        for sn in self.boundary2sn.values_mut() {
-            sn.scene_node_mut().set_visible(enabled);
-        }
-    }
-
     pub fn clear(&mut self, window: &mut Window) {
         for sns in self.b2sn.values_mut() {
             for sn in sns.iter_mut() {
@@ -141,17 +103,7 @@ impl GraphicsManager {
             }
         }
 
-        #[cfg(feature = "fluids")]
-        for sn in self.f2sn.values_mut().chain(self.boundary2sn.values_mut()) {
-            let node = sn.scene_node_mut();
-            window.remove_graphics_node(node);
-        }
-
         self.b2sn.clear();
-        #[cfg(feature = "fluids")]
-        self.f2sn.clear();
-        #[cfg(feature = "fluids")]
-        self.boundary2sn.clear();
         self.c2color.clear();
         self.b2color.clear();
         self.b2wireframe.clear();
@@ -170,15 +122,6 @@ impl GraphicsManager {
         self.b2sn.remove(&body);
     }
 
-    #[cfg(feature = "fluids")]
-    pub fn set_fluid_color(&mut self, f: FluidHandle, color: Point3<f32>) {
-        self.f2color.insert(f, color);
-
-        if let Some(n) = self.f2sn.get_mut(&f) {
-            n.set_color(color)
-        }
-    }
-
     pub fn set_body_color(&mut self, b: RigidBodyHandle, color: Point3<f32>) {
         self.b2color.insert(b, color);
 
@@ -234,6 +177,10 @@ impl GraphicsManager {
         }
     }
 
+    pub fn next_color(&mut self) -> Point3<f32> {
+        Self::gen_color(&mut self.rand)
+    }
+
     fn gen_color(rng: &mut Pcg32) -> Point3<f32> {
         let mut color: Point3<f32> = rng.gen();
         color *= 1.5;
@@ -258,49 +205,6 @@ impl GraphicsManager {
         color
     }
 
-    #[cfg(feature = "fluids")]
-    pub fn add_fluid(
-        &mut self,
-        window: &mut Window,
-        handle: FluidHandle,
-        fluid: &Fluid<f32>,
-        particle_radius: f32,
-    ) {
-        let rand = &mut self.rand;
-        let color = *self
-            .f2color
-            .entry(handle)
-            .or_insert_with(|| Self::gen_color(rand));
-
-        self.add_fluid_with_color(window, handle, fluid, particle_radius, color);
-    }
-
-    #[cfg(feature = "fluids")]
-    pub fn add_boundary(
-        &mut self,
-        window: &mut Window,
-        handle: BoundaryHandle,
-        boundary: &Boundary<f32>,
-        particle_radius: f32,
-    ) {
-        let color = self.ground_color;
-        let node = FluidNode::new(particle_radius, &boundary.positions, color, window);
-        self.boundary2sn.insert(handle, node);
-    }
-
-    #[cfg(feature = "fluids")]
-    pub fn add_fluid_with_color(
-        &mut self,
-        window: &mut Window,
-        handle: FluidHandle,
-        fluid: &Fluid<f32>,
-        particle_radius: f32,
-        color: Point3<f32>,
-    ) {
-        let node = FluidNode::new(particle_radius, &fluid.positions, color, window);
-        self.f2sn.insert(handle, node);
-    }
-
     pub fn add(
         &mut self,
         window: &mut Window,
@@ -642,23 +546,6 @@ impl GraphicsManager {
     }
     */
 
-    #[cfg(feature = "fluids")]
-    pub fn draw_fluids(&mut self, liquid_world: &LiquidWorld<f32>) {
-        for (i, fluid) in liquid_world.fluids().iter() {
-            if let Some(node) = self.f2sn.get_mut(&i) {
-                node.update_with_fluid(fluid, self.fluid_rendering_mode)
-            }
-        }
-
-        if self.render_boundary_particles {
-            for (i, boundary) in liquid_world.boundaries().iter() {
-                if let Some(node) = self.boundary2sn.get_mut(&i) {
-                    node.update_with_boundary(boundary)
-                }
-            }
-        }
-    }
-
     pub fn draw(&mut self, _bodies: &RigidBodySet, colliders: &ColliderSet, window: &mut Window) {
         // use kiss3d::camera::Camera;
         // println!(
diff --git a/src_testbed/lib.rs b/src_testbed/lib.rs
index e077bb1..21ac06a 100644
--- a/src_testbed/lib.rs
+++ b/src_testbed/lib.rs
@@ -22,7 +22,8 @@ extern crate bitflags;
 extern crate log;
 
 pub use crate::engine::GraphicsManager;
-pub use crate::testbed::Testbed;
+pub use crate::plugin::TestbedPlugin;
+pub use crate::testbed::{PhysicsState, Testbed};
 
 #[cfg(all(feature = "dim2", feature = "other-backends"))]
 mod box2d_backend;
@@ -32,6 +33,7 @@ mod nphysics_backend;
 pub mod objects;
 #[cfg(all(feature = "dim3", feature = "other-backends"))]
 mod physx_backend;
+mod plugin;
 mod testbed;
 mod ui;
 
diff --git a/src_testbed/plugin.rs b/src_testbed/plugin.rs
new file mode 100644
index 0000000..7ad018b
--- /dev/null
+++ b/src_testbed/plugin.rs
@@ -0,0 +1,12 @@
+use crate::testbed::PhysicsState;
+use kiss3d::window::Window;
+use na::Point3;
+
+pub trait TestbedPlugin {
+    fn init_graphics(&mut self, window: &mut Window, gen_color: &mut dyn FnMut() -> Point3<f32>);
+    fn clear_graphics(&mut self, window: &mut Window);
+    fn run_callbacks(&mut self, window: &mut Window, physics: &mut PhysicsState, t: f32);
+    fn step(&mut self, physics: &mut PhysicsState);
+    fn draw(&mut self);
+    fn profiling_string(&self) -> String;
+}
diff --git a/src_testbed/testbed.rs b/src_testbed/testbed.rs
index 66b5953..07b4570 100644
--- a/src_testbed/testbed.rs
+++ b/src_testbed/testbed.rs
@@ -4,8 +4,7 @@ use std::path::Path;
 use std::rc::Rc;
 
 use crate::engine::GraphicsManager;
-#[cfg(feature = "fluids")]
-use crate::objects::FluidRenderingMode;
+use crate::plugin::TestbedPlugin;
 use crate::ui::TestbedUi;
 use crossbeam::channel::Receiver;
 use kiss3d::camera::Camera;
@@ -29,8 +28,6 @@ use rapier::geometry::{
 };
 use rapier::math::Vector;
 use rapier::pipeline::{ChannelEventCollector, PhysicsPipeline, QueryPipeline};
-#[cfg(feature = "fluids")]
-use salva::{coupling::ColliderCouplingSet, object::FluidHandle, LiquidWorld};
 
 #[cfg(all(feature = "dim2", feature = "other-backends"))]
 use crate::box2d_backend::Box2dWorld;
@@ -185,6 +182,8 @@ pub struct PhysicsState {
     pub joints: JointSet,
     pub pipeline: PhysicsPipeline,
     pub query_pipeline: QueryPipeline,
+    pub integration_parameters: IntegrationParameters,
+    pub gravity: Vector<f32>,
 }
 
 impl PhysicsState {
@@ -197,6 +196,8 @@ impl PhysicsState {
             joints: JointSet::new(),
             pipeline: PhysicsPipeline::new(),
             query_pipeline: QueryPipeline::new(),
+            integration_parameters: IntegrationParameters::default(),
+            gravity: Vector::y() * -9.81,
         }
     }
 }
@@ -225,25 +226,14 @@ pub struct TestbedState {
     pub timestep_id: usize,
 }
 
-#[cfg(feature = "fluids")]
-struct FluidsState {
-    world: LiquidWorld<f32>,
-    coupling: ColliderCouplingSet<f32, RigidBodyHandle>,
-}
-
 pub struct Testbed {
     builders: Vec<(&'static str, fn(&mut Testbed))>,
-    #[cfg(feature = "fluids")]
-    fluids: Option<FluidsState>,
-    gravity: Vector<f32>,
-    integration_parameters: IntegrationParameters,
     physics: PhysicsState,
     graphics: GraphicsManager,
     nsteps: usize,
     camera_locked: bool, // Used so that the camera can remain the same before and after we change backend or press the restart button.
     callbacks: Callbacks,
-    #[cfg(feature = "fluids")]
-    callbacks_fluids: CallbacksFluids,
+    plugins: Vec<Box<dyn TestbedPlugin>>,
     time: f32,
     hide_counters: bool,
     //    persistant_contacts: HashMap<ContactId, bool>,
@@ -264,20 +254,6 @@ pub struct Testbed {
 type Callbacks =
     Vec<Box<dyn FnMut(&mut Window, &mut PhysicsState, &PhysicsEvents, &mut GraphicsManager, f32)>>;
 
-#[cfg(feature = "fluids")]
-type CallbacksFluids = Vec<
-    Box<
-        dyn FnMut(
-            &mut Window,
-            &mut LiquidWorld<f32>,
-            &mut ColliderCouplingSet<f32, RigidBodyHandle>,
-            &mut PhysicsState,
-            &mut GraphicsManager,
-            f32,
-        ),
-    >,
->;
-
 impl Testbed {
     pub fn new_empty() -> Testbed {
         let graphics = GraphicsManager::new();
@@ -330,8 +306,6 @@ impl Testbed {
             thread_pool,
         };
 
-        let gravity = Vector::y() * -9.81;
-        let integration_parameters = IntegrationParameters::default();
         let contact_channel = crossbeam::channel::unbounded();
         let proximity_channel = crossbeam::channel::unbounded();
         let event_handler = ChannelEventCollector::new(proximity_channel.0, contact_channel.0);
@@ -343,14 +317,9 @@ impl Testbed {
 
         Testbed {
             builders: Vec::new(),
-            #[cfg(feature = "fluids")]
-            fluids: None,
-            gravity,
-            integration_parameters,
             physics,
             callbacks: Vec::new(),
-            #[cfg(feature = "fluids")]
-            callbacks_fluids: Vec::new(),
+            plugins: Vec::new(),
             graphics,
             nsteps: 1,
             camera_locked: false,
@@ -404,6 +373,14 @@ impl Testbed {
         self.hide_counters = false;
     }
 
+    pub fn integration_parameters_mut(&mut self) -> &mut IntegrationParameters {
+        &mut self.physics.integration_parameters
+    }
+
+    pub fn physics_state_mut(&mut self) -> &mut PhysicsState {
+        &mut self.physics
+    }
+
     pub fn set_world(&mut self, bodies: RigidBodySet, colliders: ColliderSet, joints: JointSet) {
         self.set_world_with_gravity(bodies, colliders, joints, Vector::y() * -9.81)
     }
@@ -417,7 +394,7 @@ impl Testbed {
     ) {
         println!("Num bodies: {}", bodies.len());
         println!("Num joints: {}", joints.len());
-        self.gravity = gravity;
+        self.physics.gravity = gravity;
         self.physics.bodies = bodies;
         self.physics.colliders = colliders;
         self.physics.joints = joints;
@@ -451,8 +428,8 @@ impl Testbed {
                 || self.state.selected_backend == PHYSX_BACKEND_TWO_FRICTION_DIR
             {
                 self.physx = Some(PhysxWorld::from_rapier(
-                    self.gravity,
-                    &self.integration_parameters,
+                    self.physics.gravity,
+                    &self.physics.integration_parameters,
                     &self.physics.bodies,
                     &self.physics.colliders,
                     &self.physics.joints,
@@ -466,7 +443,7 @@ impl Testbed {
         {
             if self.state.selected_backend == NPHYSICS_BACKEND {
                 self.nphysics = Some(NPhysicsWorld::from_rapier(
-                    self.gravity,
+                    self.physics.gravity,
                     &self.physics.bodies,
                     &self.physics.colliders,
                     &self.physics.joints,
@@ -475,19 +452,6 @@ impl Testbed {
         }
     }
 
-    #[cfg(feature = "fluids")]
-    pub fn set_liquid_world(
-        &mut self,
-        mut liquid_world: LiquidWorld<f32>,
-        coupling: ColliderCouplingSet<f32, RigidBodyHandle>,
-    ) {
-        liquid_world.counters.enable();
-        self.fluids = Some(FluidsState {
-            world: liquid_world,
-            coupling,
-        });
-    }
-
     pub fn set_builders(&mut self, builders: Vec<(&'static str, fn(&mut Self))>) {
         self.state.example_names = builders.iter().map(|e| e.0).collect();
         self.builders = builders
@@ -515,25 +479,10 @@ impl Testbed {
         self.graphics.set_collider_initial_color(collider, color);
     }
 
-    #[cfg(feature = "fluids")]
-    pub fn set_fluid_color(&mut self, fluid: FluidHandle, color: Point3<f32>) {
-        self.graphics.set_fluid_color(fluid, color);
-    }
-
     pub fn set_body_wireframe(&mut self, body: RigidBodyHandle, wireframe_enabled: bool) {
         self.graphics.set_body_wireframe(body, wireframe_enabled);
     }
 
-    #[cfg(feature = "fluids")]
-    pub fn set_fluid_rendering_mode(&mut self, mode: FluidRenderingMode) {
-        self.graphics.set_fluid_rendering_mode(mode)
-    }
-
-    #[cfg(feature = "fluids")]
-    pub fn enable_boundary_particles_rendering(&mut self, enabled: bool) {
-        self.graphics.enable_boundary_particles_rendering(enabled)
-    }
-
     //    pub fn world(&self) -> &Box<WorldOwner> {
     //        &self.world
     //    }
@@ -576,13 +525,21 @@ impl Testbed {
 
     fn clear(&mut self, window: &mut Window) {
         self.callbacks.clear();
-        #[cfg(feature = "fluids")]
-        self.callbacks_fluids.clear();
         //        self.persistant_contacts.clear();
         //        self.state.grabbed_object = None;
         //        self.state.grabbed_object_constraint = None;
         self.state.can_grab_behind_ground = false;
         self.graphics.clear(window);
+
+        for plugin in &mut self.plugins {
+            plugin.clear_graphics(window);
+        }
+
+        self.plugins.clear();
+    }
+
+    pub fn add_plugin(&mut self, plugin: impl TestbedPlugin + 'static) {
+        self.plugins.push(Box::new(plugin));
     }
 
     pub fn add_callback<
@@ -594,23 +551,6 @@ impl Testbed {
         self.callbacks.push(Box::new(callback));
     }
 
-    #[cfg(feature = "fluids")]
-    pub fn add_callback_with_fluids<
-        F: FnMut(
-                &mut Window,
-                &mut LiquidWorld<f32>,
-                &mut ColliderCouplingSet<f32, RigidBodyHandle>,
-                &mut PhysicsState,
-                &mut GraphicsManager,
-                f32,
-            ) + 'static,
-    >(
-        &mut self,
-        callback: F,
-    ) {
-        self.callbacks_fluids.push(Box::new(callback));
-    }
-
     pub fn run(mut self) {
         let mut args = env::args();
         let mut benchmark_mode = false;
@@ -649,11 +589,11 @@ impl Testbed {
                         && (backend_id == PHYSX_BACKEND_PATCH_FRICTION
                             || backend_id == PHYSX_BACKEND_TWO_FRICTION_DIR)
                     {
-                        self.integration_parameters.max_velocity_iterations = 1;
-                        self.integration_parameters.max_position_iterations = 4;
+                        self.physics.integration_parameters.max_velocity_iterations = 1;
+                        self.physics.integration_parameters.max_position_iterations = 4;
                     } else {
-                        self.integration_parameters.max_velocity_iterations = 4;
-                        self.integration_parameters.max_position_iterations = 1;
+                        self.physics.integration_parameters.max_velocity_iterations = 4;
+                        self.physics.integration_parameters.max_position_iterations = 1;
                     }
                     // Init world.
                     (builder.1)(&mut self);
@@ -665,14 +605,12 @@ impl Testbed {
                             if self.state.selected_backend == RAPIER_BACKEND {
                                 #[cfg(feature = "parallel")]
                                 {
-                                    let gravity = &self.gravity;
-                                    let params = &self.integration_parameters;
                                     let physics = &mut self.physics;
                                     let event_handler = &self.event_handler;
                                     self.state.thread_pool.install(|| {
                                         physics.pipeline.step(
-                                            gravity,
-                                            params,
+                                            &physics.gravity,
+                                            &physics.integration_parameters,
                                             &mut physics.broad_phase,
                                             &mut physics.narrow_phase,
                                             &mut physics.bodies,
@@ -685,8 +623,8 @@ impl Testbed {
 
                                 #[cfg(not(feature = "parallel"))]
                                 self.physics.pipeline.step(
-                                    &self.gravity,
-                                    &self.integration_parameters,
+                                    &self.physics.gravity,
+                                    &self.physics.integration_parameters,
                                     &mut self.physics.broad_phase,
                                     &mut self.physics.narrow_phase,
                                     &mut self.physics.bodies,
@@ -700,25 +638,6 @@ impl Testbed {
                                 self.physics
                                     .query_pipeline
                                     .update(&self.physics.bodies, &self.physics.colliders);
-
-                                #[cfg(feature = "fluids")]
-                                {
-                                    fluids_time = instant::now();
-                                    if let Some(fluids) = &mut self.fluids {
-                                        let dt = self.world.timestep();
-                                        let gravity = &self.world.gravity;
-                                        fluids.world.step_with_coupling(
-                                            dt,
-                                            gravity,
-                                            &mut fluids.coupling.as_manager_mut(
-                                                &self.physics.colliders,
-                                                &mut self.physics.bodies,
-                                            ),
-                                        );
-                                    }
-
-                                    fluids_time = instant::now() - fluids_time;
-                                }
                             }
 
                             #[cfg(all(feature = "dim2", feature = "other-backends"))]
@@ -743,7 +662,7 @@ impl Testbed {
                                     //                        println!("Step");
                                     self.physx.as_mut().unwrap().step(
                                         &mut self.physics.pipeline.counters,
-                                        &self.integration_parameters,
+                                        &self.physics.integration_parameters,
                                     );
                                     self.physx.as_mut().unwrap().sync(
                                         &mut self.physics.bodies,
@@ -757,7 +676,7 @@ impl Testbed {
                                 if self.state.selected_backend == NPHYSICS_BACKEND {
                                     self.nphysics.as_mut().unwrap().step(
                                         &mut self.physics.pipeline.counters,
-                                        &self.integration_parameters,
+                                        &self.physics.integration_parameters,
                                     );
                                     self.nphysics.as_mut().unwrap().sync(
                                         &mut self.physics.bodies,
@@ -1254,8 +1173,14 @@ impl State for Testbed {
     }
 
     fn step(&mut self, window: &mut Window) {
+        let prev_example = self.state.selected_example;
+
         if let Some(ui) = &mut self.ui {
-            ui.update(window, &mut self.integration_parameters, &mut self.state);
+            ui.update(
+                window,
+                &mut self.physics.integration_parameters,
+                &mut self.state,
+            );
         }
 
         // Handle UI actions.
@@ -1299,7 +1224,13 @@ impl State for Testbed {
                     .action_flags
                     .set(TestbedActionFlags::EXAMPLE_CHANGED, false);
                 self.clear(window);
+
+                if self.state.selected_example != prev_example {
+                    self.physics.integration_parameters = IntegrationParameters::default();
+                }
+
                 self.builders[self.state.selected_example].1(self);
+
                 self.camera_locked = false;
             }
 
@@ -1338,6 +1269,11 @@ impl State for Testbed {
                     if let Ok(w) = snapshot.restore() {
                         self.clear(window);
                         self.graphics.clear(window);
+
+                        for plugin in &mut self.plugins {
+                            plugin.clear_graphics(window);
+                        }
+
                         self.set_world(w.3, w.4, w.5);
                         self.physics.broad_phase = w.1;
                         self.physics.narrow_phase = w.2;
@@ -1363,19 +1299,9 @@ impl State for Testbed {
                     );
                 }
 
-                #[cfg(feature = "fluids")]
-                {
-                    if let Some(fluids) = &self.fluids {
-                        let radius = fluids.world.particle_radius();
-
-                        for (handle, fluid) in fluids.world.fluids().iter() {
-                            self.graphics.add_fluid(window, handle, fluid, radius);
-                        }
-
-                        for (handle, boundary) in fluids.world.boundaries().iter() {
-                            self.graphics.add_boundary(window, handle, boundary, radius);
-                        }
-                    }
+                for plugin in &mut self.plugins {
+                    let graphics = &mut self.graphics;
+                    plugin.init_graphics(window, &mut || graphics.next_color());
                 }
             }
 
@@ -1410,7 +1336,7 @@ impl State for Testbed {
                 .contains(TestbedStateFlags::SUB_STEPPING)
                 != self.state.flags.contains(TestbedStateFlags::SUB_STEPPING)
             {
-                self.integration_parameters.return_after_ccd_substep =
+                self.physics.integration_parameters.return_after_ccd_substep =
                     self.state.flags.contains(TestbedStateFlags::SUB_STEPPING);
             }
 
@@ -1458,23 +1384,18 @@ impl State for Testbed {
             self.handle_special_event(window, event);
         }
 
-        #[cfg(feature = "fluids")]
-        let mut fluids_time = 0.0;
-
         if self.state.running != RunMode::Stop {
             for _ in 0..self.nsteps {
                 self.state.timestep_id += 1;
                 if self.state.selected_backend == RAPIER_BACKEND {
                     #[cfg(feature = "parallel")]
                     {
-                        let gravity = &self.gravity;
-                        let params = &self.integration_parameters;
                         let physics = &mut self.physics;
                         let event_handler = &self.event_handler;
                         self.state.thread_pool.install(|| {
                             physics.pipeline.step(
-                                gravity,
-                                params,
+                                &physics.gravity,
+                                &physics.integration_parameters,
                                 &mut physics.broad_phase,
                                 &mut physics.narrow_phase,
                                 &mut physics.bodies,
@@ -1489,8 +1410,8 @@ impl State for Testbed {
 
                     #[cfg(not(feature = "parallel"))]
                     self.physics.pipeline.step(
-                        &self.gravity,
-                        &self.integration_parameters,
+                        &self.physics.gravity,
+                        &self.physics.integration_parameters,
                         &mut self.physics.broad_phase,
                         &mut self.physics.narrow_phase,
                         &mut self.physics.bodies,
@@ -1505,23 +1426,8 @@ impl State for Testbed {
                         .query_pipeline
                         .update(&self.physics.bodies, &self.physics.colliders);
 
-                    #[cfg(feature = "fluids")]
-                    {
-                        fluids_time = instant::now();
-                        if let Some(fluids) = &mut self.fluids {
-                            let dt = self.world.timestep();
-                            let gravity = &self.world.gravity;
-                            fluids.world.step_with_coupling(
-                                dt,
-                                gravity,
-                                &mut fluids.coupling.as_manager_mut(
-                                    &self.physics.colliders,
-                                    &mut self.physics.bodies,
-                                ),
-                            );
-                        }
-
-                        fluids_time = instant::now() - fluids_time;
+                    for plugin in &mut self.plugins {
+                        plugin.step(&mut self.physics)
                     }
                 }
 
@@ -1530,7 +1436,7 @@ impl State for Testbed {
                     if self.state.selected_backend == BOX2D_BACKEND {
                         self.box2d.as_mut().unwrap().step(
                             &mut self.physics.pipeline.counters,
-                            &self.integration_parameters,
+                            &self.physics.integration_parameters,
                         );
                         self.box2d
                             .as_mut()
@@ -1547,7 +1453,7 @@ impl State for Testbed {
                         //                        println!("Step");
                         self.physx.as_mut().unwrap().step(
                             &mut self.physics.pipeline.counters,
-                            &self.integration_parameters,
+                            &self.physics.integration_parameters,
                         );
                         self.physx
                             .as_mut()
@@ -1561,7 +1467,7 @@ impl State for Testbed {
                     if self.state.selected_backend == NPHYSICS_BACKEND {
                         self.nphysics.as_mut().unwrap().step(
                             &mut self.physics.pipeline.counters,
-                            &self.integration_parameters,
+                            &self.physics.integration_parameters,
                         );
                         self.nphysics
                             .as_mut()
@@ -1580,20 +1486,8 @@ impl State for Testbed {
                     )
                 }
 
-                #[cfg(feature = "fluids")]
-                {
-                    if let Some(fluid_state) = &mut self.fluids {
-                        for f in &mut self.callbacks_fluids {
-                            f(
-                                window,
-                                &mut fluid_state.world,
-                                &mut fluid_state.coupling,
-                                &mut self.physics,
-                                &mut self.graphics,
-                                self.time,
-                            )
-                        }
-                    }
+                for plugin in &mut self.plugins {
+                    plugin.run_callbacks(window, &mut self.physics, self.time)
                 }
 
                 self.events.poll_all();
@@ -1605,7 +1499,7 @@ impl State for Testbed {
                 //                    #[cfg(feature = "log")]
                 //                    debug!("{}", self.world.counters);
                 //                }
-                self.time += self.integration_parameters.dt();
+                self.time += self.physics.integration_parameters.dt();
             }
         }
 
@@ -1613,11 +1507,8 @@ impl State for Testbed {
         self.graphics
             .draw(&self.physics.bodies, &self.physics.colliders, window);
 
-        #[cfg(feature = "fluids")]
-        {
-            if let Some(fluids) = &self.fluids {
-                self.graphics.draw_fluids(&fluids.world)
-            }
+        for plugin in &mut self.plugins {
+            plugin.draw();
         }
 
         if self.state.flags.contains(TestbedStateFlags::CONTACT_POINTS) {
@@ -1676,14 +1567,9 @@ CCD: {:.2}ms
                 counters.ccd.solver_time.time(),
             );
 
-            #[cfg(feature = "fluids")]
-            {
-                profile = format!(
-                    r#"{}
-Fluids: {:.2}ms
-                    "#,
-                    profile, fluids_time,
-                )
+            for plugin in &self.plugins {
+                let plugin_profile = plugin.profiling_string();
+                profile = format!("{}\n{}", profile, plugin_profile,)
             }
         }