better explosions

6 files changed, 99 insertions, 41 deletions

diff --git a/src/main.rs b/src/main.rs
index c947f05..e066e56 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -28,6 +28,7 @@ use crate::{
             materials::{MaterialId, fire::FireCellView},
         },
         cell_sim::{sim::sim_tick, world::World},
+        lib::force::apply_explosion,
         particle_sim::{ParticleManager, particle::Particle},
         rb_sim::{DebugRenderMode, RbSimManager, debug_ops::DebugOperator},
         write_rb_entity_to_world,
@@ -157,40 +158,16 @@ impl App {
         {
             let mouse = Vec2::new(lm.0, lm.1);
             self.input.trigger_test_4 = false;
-            let r: i32 = 30;
-            for x in -r..r {
-                for y in -r..r {
-                    if x.pow(2) + y.pow(2) < r.pow(2) {
-                        // if there's a cell, convert it to a particle
-                        let pos = Vec2::new(mouse.x + x as f32, mouse.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(self.sim_seqno + 1);
-                            if cell.material == MaterialId::Void && random_range(0.0..1.0) > 0.5 {
-                                world.set_cell_from_game_position(ipos.x, ipos.y, fire, false);
-                            } else {
-                                world.set_cell_from_game_position(ipos.x, ipos.y, fire, false);
-                                if random_range(0.0..1.0) > 0.6 {
-                                    let d = pos.distance(mouse);
-                                    if d < 0.001 {
-                                        continue;
-                                    } // skip the center cell
-                                    let dir = (pos - mouse) / d; // normalize, reusing d
-                                    let falloff = 1.0 - (d / r as f32); // 1 at center, 0 at edge
-                                    let vel = (Vec2::new(0.0, -0.6) + dir)
-                                        * 300.0
-                                        * random_range(0.5..1.5)
-                                        * falloff;
-                                    pm.particles
-                                        .push(Particle::new(pos, vel, cell.material, 5.0));
-                                }
-                            }
-                        }
-                    }
-                }
-            }
+            apply_explosion(
+                mouse,
+                30,
+                Vec2::new(0.0, -0.6),
+                300.0,
+                self.sim_seqno,
+                pm,
+                world,
+                rbsm,
+            );
         }
 
         // --TEST DRAWING--
diff --git a/src/renderer/mod.rs b/src/renderer/mod.rs
index 2aabd48..233d66b 100644
--- a/src/renderer/mod.rs
+++ b/src/renderer/mod.rs
@@ -13,7 +13,7 @@ use crate::{
     sim::{
         cell::materials::MaterialId,
         cell_sim::world::World,
-        particle_sim::{ParticleManager, particle::Particle},
+        particle_sim::ParticleManager,
         rb_sim::{RbSimManager, debug_render::DebugVertex, rb_entity::RbEntity},
     },
 };
@@ -42,7 +42,7 @@ struct RendererInstance {
 struct RendererParticle {
     position: [f32; 2],
     data: u32,
-    _padding: u32,
+    life: f32,
 }
 
 fn srgb_to_linear(channel: u8) -> f32 {
@@ -771,7 +771,7 @@ impl RendererState {
                 .map(|p| RendererParticle {
                     position: [p.position.x, p.position.y],
                     data: p.material as u32,
-                    _padding: 0,
+                    life: p.life,
                 })
                 .collect();
 
diff --git a/src/shader/particle.wgsl b/src/shader/particle.wgsl
index 704cfbe..3dd61a9 100644
--- a/src/shader/particle.wgsl
+++ b/src/shader/particle.wgsl
@@ -6,6 +6,7 @@ struct Camera {
 struct Particle {
     position: vec2f,
     data: u32,
+    life: f32,
 };
 
 @group(0) @binding(0) var<uniform> camera: Camera;
@@ -16,6 +17,8 @@ struct VertexOutput {
     @builtin(position) clip_position: vec4<f32>,
     @location(0) world: vec2<f32>,
     @location(1) @interpolate(flat) instance: u32,
+    @location(2) @interpolate(flat) material: u32,
+    @location(3) @interpolate(flat) life: f32,
 };
 
 @vertex
@@ -33,6 +36,8 @@ fn vs_main(
     out.clip_position = vec4f((world - camera.centre) * camera.scale, 0.0, 1.0);
     out.world = world;
     out.instance = n;
+    out.material = particle.data & 0xFF;
+    out.life = particle.life;
 
     return out;
 }
@@ -41,6 +46,6 @@ fn vs_main(
 fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
     let particle = particles[in.instance];
     // TODO can pack more in here and shift
-    let c = palette[particle.data];
-    return c;
+    let c = palette[in.material];
+    return vec4<f32>(c.r, c.g, c.b, c.a * smoothstep(0.0, 1, in.life));
 }
diff --git a/src/sim/cell/materials/fire.rs b/src/sim/cell/materials/fire.rs
index f582a0c..2a1225e 100644
--- a/src/sim/cell/materials/fire.rs
+++ b/src/sim/cell/materials/fire.rs
@@ -34,11 +34,11 @@ pub fn sim_update(ctx: &mut UpdateCtx) {
         // we have a chance to live longer--roughly ?% chance of living an extra second
         if ctx.rng.random_range(0.0..1.0) > 0.9 {
             // kill ourselves, with a chance to turn into ash
-            ctx.do_rewrite = false;
             if ctx.rng.random_range(0.0..1.0) > 0.8 {
                 // TODO ash material
                 // ctx.set_cell(0, 0, Cell::from_material(MaterialId::Sand));
             } else {
+                ctx.do_rewrite = false;
                 ctx.set_cell(0, 0, Cell::void());
             }
             return;
@@ -77,5 +77,4 @@ pub fn sim_update(ctx: &mut UpdateCtx) {
     }
 
     ctx.cell.set_ticks_lived(ticks_lived + 1);
-    ctx.set_cell(0, 0, *ctx.cell);
 }
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;