Added sticky particles

content/effects.toml

@@ -1,75 +1,71 @@
 [effect."small explosion"]
 sprite = "effect::explosion::small"
 lifetime = "inherit"
-inherit_velocity = "target"
 size = 8.0
 size_rng = 1.6
 angle_rng = 360
-velocity_scale_parent = 1.0
 fade = 0.2
 fade_rng = 0.1
+velocity.sticky = "parent"
 
 
 [effect."large explosion"]
 sprite = "effect::explosion::large"
 lifetime = "inherit"
-inherit_velocity = "target"
 size = 25.0
 size_rng = 5.0
 angle_rng = 360
-velocity_scale_parent = 1.0
 fade = 0.2
 fade_rng = 0.1
+velocity.sticky = "parent"
 
 
 [effect."huge explosion"]
 sprite = "effect::explosion::huge"
 lifetime = "inherit"
-inherit_velocity = "target"
 size = 50.0
 size_rng = 10.0
 angle_rng = 360
-velocity_scale_parent = 1.0
 fade = 0.2
 fade_rng = 0.1
+velocity.sticky = "parent"
 
 
 [effect."blue spark"]
 sprite = "effect::spark::blue"
 lifetime = 0.5
 lifetime_rng = 0.5
-inherit_velocity = "parent"
 size = 4.0
 size_rng = 2.0
 angle_rng = 360
 angvel_rng = 0.0
-velocity_scale_parent = 1.0
 fade = 0.2
 fade_rng = 0.1
+velocity.sticky = "parent"
+
 
 [effect."yellow spark"]
 sprite = "effect::spark::yellow"
 lifetime = "inherit"
-inherit_velocity = "parent"
 size = 4.0
 size_rng = 2.0
 angle_rng = 360
 angvel_rng = 0.0
-velocity_scale_parent = 1.0
 fade = 0.2
 fade_rng = 0.1
+velocity.sticky = "parent"
+
 
 [effect."red spark"]
 sprite = "effect::spark::red"
 lifetime = "inherit"
-inherit_velocity = "parent"
 size = 4.0
 size_rng = 1.0
 angle_rng = 360
 angvel_rng = 0.0
-velocity_scale_parent = 1.0
 fade = 0.2
 fade_rng = 0.1
+velocity.sticky = "parent"
 
 
 # Every effect has a parent, some effects have a target
@@ -90,12 +86,11 @@ angvel = 0.0     # Angular velocity at creation
 
 
 # Total velocity is sum of parent + target velocities with scale applied
-velocity_scale_parent = 0.0     # Multiply velocity by this value 
+velocity.scale_parent = 0.0     # Multiply velocity by this value 
-velocity_scale_parent_rng = 0.0 # random variation of scale
+velocity.scale_parent_rng = 0.0 # random variation of scale
-velocity_scale_target = 1.0
+velocity.scale_target = 1.0
-velocity_scale_target_rng = 1.0
+velocity.scale_target_rng = 1.0
-
+velocity.direction_rng = 0.0    # Random variation of travel direction, in degrees, applied to velocity vector (/2 each side?)
-direction_rng = 0.0 # Random variation of travel direction, in degrees, applied to velocity vector (/2 each side?)
 
 fade = 0.2
 fade_rng = 0.1

content/outfits.toml

@@ -54,4 +54,4 @@ gun.projectile.impact_effect = "blaster impact"
 gun.projectile.expire_effect.sprite = "effect::blaster"
 gun.projectile.expire_effect.lifetime = "inherit"
 gun.projectile.expire_effect.size = 3.0
-gun.projectile.expire_effect.velocity_scale_parent = 1.0
+gun.projectile.expire_effect.velocity.scale_parent = 1.0

crates/content/src/part/effect.rs

@@ -23,13 +23,26 @@ pub(crate) mod syntax {
 		pub angle_rng: Option<f32>,
 		pub angvel: Option<f32>,
 		pub angvel_rng: Option<f32>,
-		pub velocity_scale_parent: Option<f32>,
+
-		pub velocity_scale_parent_rng: Option<f32>,
-		pub velocity_scale_target: Option<f32>,
-		pub velocity_scale_target_rng: Option<f32>,
-		pub direction_rng: Option<f32>,
 		pub fade: Option<f32>,
 		pub fade_rng: Option<f32>,
+
+		pub velocity: EffectVelocity,
+	}
+
+	#[derive(Debug, Deserialize)]
+	#[serde(untagged)]
+	pub enum EffectVelocity {
+		Sticky {
+			sticky: String,
+		},
+		Explicit {
+			scale_parent: Option<f32>,
+			scale_parent_rng: Option<f32>,
+			scale_target: Option<f32>,
+			scale_target_rng: Option<f32>,
+			direction_rng: Option<f32>,
+		},
 	}
 
 	#[derive(Debug, Deserialize)]
@@ -69,12 +82,38 @@ pub(crate) mod syntax {
 				}
 			};
 
+			let velocity = match self.velocity {
+				EffectVelocity::Explicit {
+					scale_parent,
+					scale_parent_rng,
+					scale_target,
+					scale_target_rng,
+					direction_rng,
+				} => super::EffectVelocity::Explicit {
+					scale_parent: scale_parent.unwrap_or(0.0),
+					scale_parent_rng: scale_parent_rng.unwrap_or(0.0),
+					scale_target: scale_target.unwrap_or(0.0),
+					scale_target_rng: scale_target_rng.unwrap_or(0.0),
+					direction_rng: direction_rng.unwrap_or(0.0) / 2.0,
+				},
+				EffectVelocity::Sticky { sticky } => {
+					if sticky == "parent" {
+						super::EffectVelocity::StickyParent
+					} else if sticky == "target" {
+						super::EffectVelocity::StickyTarget
+					} else {
+						bail!("bad sticky specification `{}`", sticky);
+					}
+				}
+			};
+
 			let handle = EffectHandle {
 				index: content.effects.len(),
 			};
 			content.effects.push(super::Effect {
 				handle,
 				sprite,
+				velocity,
 				size: self.size,
 				size_rng: self.size_rng.unwrap_or(0.0),
 				lifetime,
@@ -83,11 +122,6 @@ pub(crate) mod syntax {
 				angle_rng: to_radians(self.angle_rng.unwrap_or(0.0) / 2.0),
 				angvel: to_radians(self.angvel.unwrap_or(0.0)),
 				angvel_rng: to_radians(self.angvel_rng.unwrap_or(0.0)),
-				velocity_scale_parent: self.velocity_scale_parent.unwrap_or(0.0),
-				velocity_scale_parent_rng: self.velocity_scale_parent_rng.unwrap_or(0.0),
-				velocity_scale_target: self.velocity_scale_target.unwrap_or(0.0),
-				velocity_scale_target_rng: self.velocity_scale_target_rng.unwrap_or(0.0),
-				direction_rng: self.direction_rng.unwrap_or(0.0) / 2.0,
 				fade: self.fade.unwrap_or(0.0),
 				fade_rng: self.fade_rng.unwrap_or(0.0),
 			});
@@ -157,27 +191,43 @@ pub struct Effect {
 	/// Random angvel variation
 	pub angvel_rng: f32,
 
-	/// The amount of this effect's parent's velocity to inherit
-	pub velocity_scale_parent: f32,
-
-	/// Parent velocity random variation
-	pub velocity_scale_parent_rng: f32,
-
-	/// The amount of this effect's parent's target velocity to inherit.
-	/// If there is no target, this is zero.
-	pub velocity_scale_target: f32,
-
-	/// Target velocity random variation
-	pub velocity_scale_target_rng: f32,
-
-	/// Travel direction random variation
-	pub direction_rng: f32,
-
 	/// Fade this effect out over this many seconds as it ends
 	pub fade: f32,
 
-	/// Random fade ariation
+	/// Random fade variation
 	pub fade_rng: f32,
+
+	/// How to compute this effect's velocity
+	pub velocity: EffectVelocity,
+}
+
+/// How to compute an effect's velocity
+#[derive(Debug, Clone)]
+pub enum EffectVelocity {
+	/// Stick to parent
+	StickyParent,
+
+	/// Stick to target.
+	/// Zero velocity if no target is given.
+	StickyTarget,
+
+	/// Compute velocity from parent and target
+	Explicit {
+		/// How much of the parent's velocity to inherit
+		scale_parent: f32,
+
+		/// Random variation of scale_parent
+		scale_parent_rng: f32,
+
+		/// How much of the target's velocity to keep
+		scale_target: f32,
+
+		/// Random variation of scale_target
+		scale_target_rng: f32,
+
+		/// Random variation of travel direction
+		direction_rng: f32,
+	},
 }
 
 impl crate::Build for Effect {

crates/system/src/phys/objects/effect.rs

@@ -1,7 +1,7 @@
-use galactica_content::{Content, EffectHandle, SpriteAutomaton};
+use galactica_content::{Content, EffectHandle, EffectVelocity, SpriteAutomaton};
-use nalgebra::{Rotation2, Vector2};
+use nalgebra::{Point2, Rotation2, Vector2};
 use rand::Rng;
-use rapier2d::dynamics::{RigidBodyBuilder, RigidBodyHandle, RigidBodyType};
+use rapier2d::dynamics::{RevoluteJointBuilder, RigidBodyBuilder, RigidBodyHandle, RigidBodyType};
 
 use crate::phys::{PhysStepResources, PhysWrapper};
 
@@ -35,25 +35,18 @@ impl PhysEffect {
 		ct: &Content,
 		wrapper: &mut PhysWrapper,
 		effect: EffectHandle,
+		// Where to spawn the particle, in world space.
 		pos: Vector2<f32>,
-		parent_angle: f32,
+		parent: RigidBodyHandle,
-		parent_velocity: Vector2<f32>,
+		target: Option<RigidBodyHandle>,
-		target_velocity: Vector2<f32>,
 	) -> Self {
 		let effect = ct.get_effect(effect);
+
 		let mut rng = rand::thread_rng();
-
+		let parent_body = wrapper.get_rigid_body(parent).unwrap();
-		let velocity = {
+		let parent_angle = parent_body.rotation().angle();
-			let a =
+		let parent_pos = *parent_body.translation();
-				rng.gen_range(-effect.velocity_scale_parent_rng..=effect.velocity_scale_parent_rng);
+		let parent_velocity = parent_body.velocity_at_point(parent_body.center_of_mass());
-			let b =
-				rng.gen_range(-effect.velocity_scale_target_rng..=effect.velocity_scale_target_rng);
-
-			let velocity = ((effect.velocity_scale_parent + a) * parent_velocity)
-				+ ((effect.velocity_scale_target + b) * target_velocity);
-
-			Rotation2::new(rng.gen_range(-effect.direction_rng..=effect.direction_rng)) * velocity
-		};
 
 		let angvel = if effect.angvel_rng == 0.0 {
 			effect.angvel
@@ -66,17 +59,65 @@ impl PhysEffect {
 			parent_angle + effect.angle + rng.gen_range(-effect.angle_rng..=effect.angle_rng)
 		};
 
-		let rb = RigidBodyBuilder::new(RigidBodyType::KinematicVelocityBased)
+		let target_velocity = {
+			if let Some(target) = target {
+				let target_body = wrapper.get_rigid_body(target).unwrap();
+				target_body.velocity_at_point(&Point2::new(pos.x, pos.y))
+			} else {
+				Vector2::new(0.0, 0.0)
+			}
+		};
+
+		match effect.velocity {
+			EffectVelocity::StickyTarget | EffectVelocity::StickyParent => {
+				let rigid_body = wrapper.insert_rigid_body(
+					RigidBodyBuilder::new(RigidBodyType::Dynamic)
+						.additional_mass(f32::MIN_POSITIVE)
 						.position(pos.into())
 						.rotation(angle)
 						.angvel(angvel)
-			.linvel(velocity);
+						.build(),
+				);
+
+				match effect.velocity {
+					EffectVelocity::StickyParent => {
+						let d = Rotation2::new(-parent_angle) * (pos - parent_pos);
+
+						wrapper.add_joint(
+							rigid_body,
+							parent,
+							RevoluteJointBuilder::new()
+								.local_anchor1(Point2::new(0.0, 0.0))
+								.local_anchor2(Point2::new(d.x, d.y)),
+						)
+					}
+					EffectVelocity::StickyTarget => {
+						if target.is_some() {
+							let target_body = wrapper.get_rigid_body(target.unwrap()).unwrap();
+
+							// Correct for rotation, since joint coordinates are relative
+							// and input coordinates are in world space.
+							let d = Rotation2::new(-target_body.rotation().angle())
+								* (pos - target_body.translation());
+
+							wrapper.add_joint(
+								rigid_body,
+								target.unwrap(),
+								RevoluteJointBuilder::new()
+									.local_anchor1(Point2::new(0.0, 0.0))
+									.local_anchor2(Point2::new(d.x, d.y)),
+							)
+						}
+					}
+					_ => unreachable!("lol what?"),
+				};
 
 				PhysEffect {
 					anim: SpriteAutomaton::new(ct, effect.sprite),
-			rigid_body: wrapper.insert_rigid_body(rb.build()),
+					rigid_body,
-			lifetime: 0f32
+					lifetime: 0f32.max(
-				.max(effect.lifetime + rng.gen_range(-effect.lifetime_rng..=effect.lifetime_rng)),
+						effect.lifetime + rng.gen_range(-effect.lifetime_rng..=effect.lifetime_rng),
+					),
 
 					// Make sure size isn't negative. This check should be on EVERY rng!
 					size: 0f32.max(effect.size + rng.gen_range(-effect.size_rng..=effect.size_rng)),
@@ -85,6 +126,48 @@ impl PhysEffect {
 				}
 			}
 
+			EffectVelocity::Explicit {
+				scale_parent,
+				scale_parent_rng,
+				scale_target,
+				scale_target_rng,
+				direction_rng,
+			} => {
+				let velocity = {
+					let a = rng.gen_range(-scale_parent_rng..=scale_parent_rng);
+					let b = rng.gen_range(-scale_target_rng..=scale_target_rng);
+
+					let velocity = ((scale_parent + a) * parent_velocity)
+						+ ((scale_target + b) * target_velocity);
+
+					Rotation2::new(rng.gen_range(-direction_rng..=direction_rng)) * velocity
+				};
+
+				let rigid_body = wrapper.insert_rigid_body(
+					RigidBodyBuilder::new(RigidBodyType::KinematicVelocityBased)
+						.position(pos.into())
+						.rotation(angle)
+						.angvel(angvel)
+						.linvel(velocity)
+						.build(),
+				);
+
+				PhysEffect {
+					anim: SpriteAutomaton::new(ct, effect.sprite),
+					rigid_body,
+					lifetime: 0f32.max(
+						effect.lifetime + rng.gen_range(-effect.lifetime_rng..=effect.lifetime_rng),
+					),
+
+					// Make sure size isn't negative. This check should be on EVERY rng!
+					size: 0f32.max(effect.size + rng.gen_range(-effect.size_rng..=effect.size_rng)),
+					fade: 0f32.max(effect.fade + rng.gen_range(-effect.fade_rng..=effect.fade_rng)),
+					is_destroyed: false,
+				}
+			}
+		}
+	}
+
 	/// Step this effect's state by `t` seconds
 	pub fn step(&mut self, res: &PhysStepResources, wrapper: &mut PhysWrapper) {
 		if self.is_destroyed {

crates/system/src/phys/objects/projectile.rs

@@ -1,5 +1,4 @@
 use galactica_content::{AnimationState, Content, FactionHandle, Projectile, SpriteAutomaton};
-use nalgebra::Vector2;
 use rand::Rng;
 use rapier2d::{dynamics::RigidBodyHandle, geometry::ColliderHandle};
 
@@ -97,35 +96,18 @@ impl PhysProjectile {
 			return;
 		}
 
-		let rigid_body = wrapper.remove_rigid_body(self.rigid_body).unwrap();
+		let rb = wrapper.get_rigid_body(self.rigid_body).unwrap();
-		let mut rng = rand::thread_rng();
-
 		if expire {
 			match &self.content.expire_effect {
 				None => {}
 				Some(handle) => {
-					let x = res.ct.get_effect(*handle);
-					let pos = *rigid_body.translation();
-					let vel = rigid_body.velocity_at_point(rigid_body.center_of_mass());
-					let angle = rigid_body.rotation().angle();
-
-					let velocity = {
-						let a = rng
-							.gen_range(-x.velocity_scale_parent_rng..=x.velocity_scale_parent_rng);
-
-						let velocity = (x.velocity_scale_parent + a) * vel;
-
-						velocity
-					};
-
 					new.effects.push(PhysEffect::new(
 						res.ct,
 						wrapper,
 						*handle,
-						pos,
+						*rb.translation(),
-						angle,
+						self.rigid_body,
-						velocity,
+						None,
-						Vector2::new(0.0, 0.0),
 					));
 				}
 			}

crates/system/src/phys/objects/ship/collapse.rs

@@ -88,17 +88,13 @@ impl ShipCollapseSequence {
 								};
 								let pos = ship_pos + (ship_rot * pos);
 
-								let velocity =
-									rigid_body.velocity_at_point(&Point2::new(pos.x, pos.y));
-
 								new.effects.push(PhysEffect::new(
 									res.ct,
 									wrapper,
 									spawner.effect,
 									pos,
-									0.0,
+									rigid_body_handle,
-									velocity,
+									None,
-									Vector2::new(0.0, 0.0),
 								));
 							}
 						}
@@ -133,16 +129,13 @@ impl ShipCollapseSequence {
 
 				// Position, adjusted for ship rotation
 				let pos = ship_pos + (ship_rot * pos);
-				let vel = rigid_body.velocity_at_point(&Point2::new(pos.x, pos.y));
-
 				new.effects.push(PhysEffect::new(
 					res.ct,
 					wrapper,
 					spawner.effect,
 					pos,
-					0.0,
+					rigid_body_handle,
-					vel,
+					None,
-					Vector2::new(0.0, 0.0),
 				));
 			}
 		}

crates/system/src/phys/objects/ship/ship.rs

@@ -453,16 +453,14 @@ impl PhysShip {
 					};
 
 					let pos = ship_pos + (Rotation2::new(ship_ang) * pos);
-					let velocity = rigid_body.velocity_at_point(&Point2::new(pos.x, pos.y));
 
 					new.effects.push(PhysEffect::new(
 						res.ct,
 						wrapper,
 						e.effect,
-						pos.into(),
+						pos,
-						0.0,
+						self.rigid_body,
-						velocity,
+						None,
-						Vector2::new(0.0, 0.0),
 					));
 				}
 			}

crates/system/src/phys/physsim.rs

@@ -126,25 +126,17 @@ impl PhysSim {
 			// Borrow again, we can only have one at a time
 			let pr = self.wrapper.get_rigid_body(projectile.rigid_body).unwrap();
 			let pos = *pr.translation();
-			let angle = pr.rotation().angle();
 
 			match &projectile.content.impact_effect {
 				None => {}
 				Some(x) => {
-					let r = ship.rigid_body;
-					let sr = self.wrapper.get_rigid_body(r).unwrap();
-					let parent_velocity = pr.velocity_at_point(pr.center_of_mass());
-					let target_velocity =
-						sr.velocity_at_point(&nalgebra::Point2::new(pos.x, pos.y));
-
 					self.effects.push(PhysEffect::new(
 						res.ct,
 						&mut self.wrapper,
 						*x,
 						pos,
-						angle,
+						projectile.rigid_body,
-						parent_velocity,
+						Some(ship.rigid_body),
-						target_velocity,
 					));
 				}
 			};

crates/system/src/phys/physwrapper.rs

@@ -1,8 +1,8 @@
 use crossbeam::channel::Receiver;
 use rapier2d::{
 	dynamics::{
-		CCDSolver, ImpulseJointSet, IntegrationParameters, IslandManager, MultibodyJointSet,
+		CCDSolver, GenericJoint, ImpulseJointSet, IntegrationParameters, IslandManager,
-		RigidBody, RigidBodyHandle, RigidBodySet,
+		MultibodyJointSet, RigidBody, RigidBodyHandle, RigidBodySet,
 	},
 	geometry::{BroadPhase, Collider, ColliderHandle, ColliderSet, CollisionEvent, NarrowPhase},
 	na::vector,
@@ -16,12 +16,12 @@ pub struct PhysWrapper {
 	im: IslandManager,
 	bp: BroadPhase,
 	np: NarrowPhase,
-	ij: ImpulseJointSet,
 	mj: MultibodyJointSet,
 	ccd: CCDSolver,
 
 	rigid_body_set: RigidBodySet,
 	collider_set: ColliderSet,
+	joint_set: ImpulseJointSet,
 
 	collision_handler: ChannelEventCollector,
 
@@ -42,7 +42,6 @@ impl PhysWrapper {
 			im: IslandManager::new(),
 			bp: BroadPhase::new(),
 			np: NarrowPhase::new(),
-			ij: ImpulseJointSet::new(),
 			mj: MultibodyJointSet::new(),
 			ccd: CCDSolver::new(),
 			collision_queue,
@@ -50,6 +49,7 @@ impl PhysWrapper {
 
 			rigid_body_set: RigidBodySet::new(),
 			collider_set: ColliderSet::new(),
+			joint_set: ImpulseJointSet::new(),
 		}
 	}
 
@@ -64,7 +64,7 @@ impl PhysWrapper {
 			&mut self.np,
 			&mut self.rigid_body_set,
 			&mut self.collider_set,
-			&mut self.ij,
+			&mut self.joint_set,
 			&mut self.mj,
 			&mut self.ccd,
 			None,
@@ -79,7 +79,7 @@ impl PhysWrapper {
 			body,
 			&mut self.im,
 			&mut self.collider_set,
-			&mut self.ij,
+			&mut self.joint_set,
 			&mut self.mj,
 			true,
 		);
@@ -121,4 +121,14 @@ impl PhysWrapper {
 		self.collider_set
 			.insert_with_parent(collider, parent_handle, &mut self.rigid_body_set)
 	}
+
+	/// Add an impulse joint between two bodies
+	pub fn add_joint(
+		&mut self,
+		body1: RigidBodyHandle,
+		body2: RigidBodyHandle,
+		joint: impl Into<GenericJoint>,
+	) {
+		self.joint_set.insert(body1, body2, joint, false);
+	}
 }