2 files changed, 77 insertions, 0 deletions
diff --git a/src/sim/lib/force.rs b/src/sim/lib/force.rs
new file mode 100644
index 0000000..50b5c70
--- /dev/null
+++ b/src/sim/lib/force.rs
@@ -0,0 +1,76 @@
+use glam::Vec2;
+use rand::random_range;
+
+use crate::sim::{
+    cell::{
+        cell::Cell,
+        materials::{MaterialId, fire::FireCellView},
+    },
+    cell_sim::world::World,
+    particle_sim::{ParticleManager, particle::Particle},
+    rb_sim::RbSimManager,
+};
+
+pub fn apply_explosion(
+    centre: Vec2,
+    radius: i32,
+    force_offset: Vec2,
+    force_multiplier: f32,
+    next_seqno: u64,
+    particle_manager: &mut ParticleManager,
+    world: &mut World,
+    rbsm: &mut RbSimManager,
+) {
+    let get_vel = |pos: Vec2| {
+        let d = pos.distance(centre);
+        if d < 0.001 {
+            return Vec2::ZERO;
+        }
+        let dir = (pos - centre) / d;
+        let falloff = 1.0 - (d / radius as f32);
+        return (force_offset + dir) * force_multiplier * random_range(0.5..1.5) * falloff;
+    };
+
+    // cell grid
+    for x in -radius..radius {
+        for y in -radius..radius {
+            if x.pow(2) + y.pow(2) < radius.pow(2) {
+                // if there's a cell, convert it to a particle
+                let pos = Vec2::new(centre.x + x as f32, centre.y + y as f32);
+                let ipos = pos.round().as_ivec2();
+                if let Some(cell) = world.get_cell_from_game_position(ipos.x, ipos.y) {
+                    let mut fire = Cell::from_material(MaterialId::Fire);
+                    fire.set_ticks_lived(300);
+                    fire.match_parity(next_seqno);
+
+                    if cell.material == MaterialId::Void && random_range(0.0..1.0) > 0.5 {
+                        if random_range(0.0..1.0) > 0.1 {
+                            world.set_cell_from_game_position(ipos.x, ipos.y, fire, false);
+                        } else {
+                            let vel = get_vel(pos);
+                            particle_manager.particles.push(Particle::new(
+                                pos,
+                                vel,
+                                MaterialId::Fire,
+                                1.0,
+                            ));
+                        }
+                    } else {
+                        world.set_cell_from_game_position(ipos.x, ipos.y, fire, false);
+                        if random_range(0.0..1.0) > 0.6 {
+                            let vel = get_vel(pos);
+                            particle_manager.particles.push(Particle::new(
+                                pos,
+                                vel,
+                                cell.material,
+                                5.0,
+                            ));
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    // rigidbodies
+}
diff --git a/src/sim/lib/mod.rs b/src/sim/lib/mod.rs
index 1d802dc..a00d7e6 100644
--- a/src/sim/lib/mod.rs
+++ b/src/sim/lib/mod.rs
@@ -1 +1,2 @@
+pub mod force;
 pub mod marching_squares;