resolved conflicts between force field and main branch

Cargo.toml

@@ -15,6 +15,7 @@ exclude = ["examples/*.gif", ".github"]
 [dependencies]
 bytemuck = "1.5"
 rand = "0.8"
+rand_pcg = "0.3"
 serde = { version = "1.0", features = ["derive"] }
 anyhow = "1.0"
 ron = "0.7"

examples/force_field.rs

@@ -113,7 +113,7 @@ fn setup(
         }
         .init(PositionSphereModifier {
             radius: BALL_RADIUS,
-            speed: 0.2,
+            speed: Value::Uniform((0.1, 0.3)),
             dimension: ShapeDimension::Surface,
             ..Default::default()
         })

src/lib.rs

@@ -170,6 +170,19 @@ impl ToWgslString for Vec4 {
     }
 }
 
+impl ToWgslString for Value<f32> {
+    fn to_wgsl_string(&self) -> String {
+        match self {
+            Self::Single(x) => x.to_wgsl_string(),
+            Self::Uniform((a, b)) => format!(
+                "rand() * ({1} - {0}) + {0}",
+                a.to_wgsl_string(),
+                b.to_wgsl_string(),
+            ),
+        }
+    }
+}
+
 /// Visual effect made of particles.
 ///
 /// The particle effect component represent a single instance of a visual effect. The

src/modifiers.rs

@@ -3,8 +3,7 @@ use bevy::prelude::*;
 use crate::{
     asset::{InitLayout, RenderLayout, UpdateLayout},
     gradient::Gradient,
-    // render::FFNUM,
-    ToWgslString,
+    ToWgslString, Value,
 };
 
 /// Maximum number of components in the force field.
@@ -54,7 +53,7 @@ pub struct PositionCircleModifier {
     /// The circle radius.
     pub radius: f32,
     /// The radial speed of the particles on spawn.
-    pub speed: f32,
+    pub speed: Value<f32>,
     /// The shape dimension to spawn from.
     pub dimension: ShapeDimension,
 }
@@ -125,7 +124,7 @@ pub struct PositionSphereModifier {
     /// The sphere radius.
     pub radius: f32,
     /// The radial speed of the particles on spawn.
-    pub speed: f32,
+    pub speed: Value<f32>,
     /// The shape dimension to spawn from.
     pub dimension: ShapeDimension,
 }
@@ -231,41 +230,6 @@ impl UpdateModifier for AccelModifier {
     }
 }
 
-// /// The [`ForceFieldParam`] allows for an either an attractive or a repulsive force originating
-// /// from a point source.
-// #[derive(Clone, Copy, PartialEq)]
-// pub enum ForceType {
-//     /// Linear attractive or repulsive force.
-//     Linear,
-
-//     /// Quadratic attractive or repulsive force.
-//     Quadratic,
-
-//     /// Cubic attractive or repulsive force.
-//     Cubic,
-
-//     /// None is the default. No force field is applied.
-//     None,
-// }
-
-// impl Default for ForceType {
-//     fn default() -> Self {
-//         ForceType::None
-//     }
-// }
-
-// impl ForceType {
-//     /// Converts the instance of ForceType into an integer, preparing to be sent to the GPU.
-//     pub fn to_int(self) -> i32 {
-//         match self {
-//             ForceType::Linear => 1,
-//             ForceType::Quadratic => 2,
-//             ForceType::Cubic => 3,
-//             ForceType::None => -1,
-//         }
-//     }
-// }
-
 /// Parameters for the components making the force field.
 #[derive(Clone, Copy)]
 pub struct ForceFieldParam {

src/render/mod.rs

@@ -36,6 +36,7 @@ use std::{borrow::Cow, cmp::Ordering, num::NonZeroU64, ops::Range};
 use crate::{
     asset::EffectAsset,
     modifiers::{ForceFieldParam, FFNUM},
+    spawn::{new_rng, Random},
     Gradient, ParticleEffect, ToWgslString,
 };
 
@@ -776,7 +777,8 @@ pub(crate) fn extract_effects(
 
             // Tick the effect's spawner to determine the spawn count for this frame
             let spawner = effect.spawner(&asset.spawner);
-            let spawn_count = spawner.tick(dt);
+            let rng = &mut new_rng();
+            let spawn_count = spawner.tick(dt, rng);
 
             // Extract the acceleration
             let accel = asset.update_layout.accel;