fire, optimize viewport rendering

5 files changed, 123 insertions, 35 deletions

diff --git a/src/sim/cell.rs b/src/sim/cell.rs
index 2e26ddc..d3ca302 100644
--- a/src/sim/cell.rs
+++ b/src/sim/cell.rs
@@ -4,6 +4,20 @@ use crate::sim::materials::MaterialId;
 pub struct Cell {
     pub material: MaterialId,
     pub flags: u8,
+    pub data: u16,
+}
+
+impl Cell {
+    const FLAG_PARITY: u8 = 0b0000_0001;
+
+    #[inline]
+    pub fn parity(self) -> u8 {
+        self.flags & Self::FLAG_PARITY
+    }
+    #[inline]
+    pub fn flip_parity(&mut self) {
+        self.flags ^= Self::FLAG_PARITY;
+    }
 }
 
 impl Cell {
@@ -11,9 +25,14 @@ impl Cell {
         Cell {
             material: MaterialId::Void,
             flags: 0,
+            data: 0,
         }
     }
     pub fn from_material(material: MaterialId) -> Cell {
-        Cell { material, flags: 0 }
+        Cell {
+            material,
+            flags: 0,
+            data: 0,
+        }
     }
 }
diff --git a/src/sim/materials/fire.rs b/src/sim/materials/fire.rs
new file mode 100644
index 0000000..b155986
--- /dev/null
+++ b/src/sim/materials/fire.rs
@@ -0,0 +1,53 @@
+use rand::RngExt;
+
+use crate::sim::{cell::Cell, materials::MaterialId, sim::UpdateCtx};
+
+trait FireCellView {
+    fn get_ticks_lived(self) -> u16;
+    fn set_ticks_lived(&mut self, ticks: u16) -> ();
+    fn is_flammable(self) -> bool;
+}
+
+impl FireCellView for Cell {
+    fn get_ticks_lived(self) -> u16 {
+        self.data
+    }
+    fn set_ticks_lived(&mut self, ticks: u16) -> () {
+        self.data = ticks;
+    }
+    // this could be a property of the material def, I think it's better here for now
+    fn is_flammable(self) -> bool {
+        [MaterialId::Wood].contains(&self.material)
+    }
+}
+
+#[inline]
+pub fn sim_update(ctx: &mut UpdateCtx) {
+    let ticks_lived = ctx.cell.get_ticks_lived();
+    // 2 seconds
+    if ticks_lived > 240 {
+        // kill ourselves, with a chance to turn into ash
+        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.set_cell(0, 0, Cell::void());
+        }
+        return;
+    }
+
+    // 4 times in our lifespan, try to spread in a random direction
+    // since it's random, fire may die out if there's nothing in that direction
+    // a 1-thick line of flammable cells has a 31% chance to die each iteration
+    if ticks_lived % 60 == 0 {
+        let (dx, dy) = (ctx.rng.random_range(-1..=1), ctx.rng.random_range(-1..=1));
+        if let Some(target) = ctx.get_cell(dx, dy)
+            && target.is_flammable()
+        {
+            ctx.set_cell(dx, dy, Cell::from_material(MaterialId::Fire));
+        }
+    }
+
+    ctx.cell.set_ticks_lived(ticks_lived + 1);
+    ctx.set_cell(0, 0, *ctx.cell);
+}
diff --git a/src/sim/materials/mod.rs b/src/sim/materials/mod.rs
index d2d0e0e..764318a 100644
--- a/src/sim/materials/mod.rs
+++ b/src/sim/materials/mod.rs
@@ -1,5 +1,6 @@
 use crate::sim::sim::UpdateCtx;
 
+mod fire;
 mod gas;
 mod sand;
 mod water;
@@ -12,6 +13,7 @@ pub enum MaterialId {
     Wood,
     Water,
     Gas,
+    Fire,
 }
 
 pub struct MaterialDef {
@@ -21,7 +23,7 @@ pub struct MaterialDef {
     pub sim_update: Option<fn(ctx: &mut UpdateCtx) -> ()>,
 }
 
-static MATERIALS: [MaterialDef; 5] = [
+static MATERIALS: [MaterialDef; 6] = [
     MaterialDef {
         name: "Void",
         color: (0x00, 0x00, 0x00, 0x00),
@@ -52,15 +54,23 @@ static MATERIALS: [MaterialDef; 5] = [
         density: 10,
         sim_update: Some(gas::sim_update),
     },
+    MaterialDef {
+        name: "Fire",
+        color: (0xFC, 0x66, 0x00, 0xAA),
+        // for now this matches wood
+        density: 50,
+        sim_update: Some(fire::sim_update),
+    },
 ];
 
 impl MaterialId {
-    pub const ALL: [MaterialId; 5] = [
+    pub const ALL: [MaterialId; 6] = [
         MaterialId::Void,
         MaterialId::Sand,
         MaterialId::Wood,
         MaterialId::Water,
         MaterialId::Gas,
+        MaterialId::Fire,
     ];
     #[inline]
     pub fn def(self) -> &'static MaterialDef {
diff --git a/src/sim/sim.rs b/src/sim/sim.rs
index 4c6d908..84c3126 100644
--- a/src/sim/sim.rs
+++ b/src/sim/sim.rs
@@ -1,6 +1,7 @@
 use std::marker::PhantomData;
 
 use fxhash::FxHashMap;
+use rand::{Rng, SeedableRng, rngs::SmallRng};
 use rayon::iter::{IntoParallelRefIterator, ParallelIterator};
 
 use crate::{
@@ -30,17 +31,6 @@ impl<'a> ChunkAccess<'a> {
 
 unsafe impl Sync for ChunkAccess<'_> {}
 
-pub struct UpdateCtx<'a, 'b, 'c> {
-    pub chunks: &'a mut [Option<&'b mut Chunk>; 9],
-    pub seqno: u64,
-    pub seqno_parity: u8,
-
-    pub x: i32,
-    pub y: i32,
-    pub cell: &'c mut Cell,
-    pub material: &'c MaterialDef,
-}
-
 fn get_cell(chunks: &[Option<&mut Chunk>; 9], x: i32, y: i32) -> Option<Cell> {
     let dcx = x.div_euclid(CHUNK_SIZE);
     let dcy = y.div_euclid(CHUNK_SIZE);
@@ -74,17 +64,28 @@ pub fn set_cell(chunks: &mut [Option<&mut Chunk>; 9], x: i32, y: i32, cell: Cell
         if let Some(chunk) = &mut chunks[(dcx + 1 + (dcy + 1) * 3) as usize] {
             chunk.set_cell_at_local_position(nc_x, nc_y, cell);
             chunk.needs_texture_update = true;
-            chunk.sleeping = false;
         }
     } else {
         if let Some(target) = &mut chunks[4] {
             target.set_cell_at_local_position(x as u8, y as u8, cell);
             target.needs_texture_update = true;
-            target.sleeping = false;
         }
     }
 }
 
+pub struct UpdateCtx<'a, 'b, 'c> {
+    pub chunks: &'a mut [Option<&'b mut Chunk>; 9],
+    pub seqno: u64,
+    pub seqno_parity: u8,
+
+    pub x: i32,
+    pub y: i32,
+    pub cell: &'c mut Cell,
+    pub material: &'c MaterialDef,
+
+    pub rng: &'c mut dyn Rng,
+}
+
 impl UpdateCtx<'_, '_, '_> {
     pub fn get_cell(&self, dx: i32, dy: i32) -> Option<Cell> {
         let x = self.x + dx;
@@ -92,7 +93,7 @@ impl UpdateCtx<'_, '_, '_> {
         get_cell(self.chunks, x, y)
     }
 
-    fn set_cell(&mut self, dx: i32, dy: i32, cell: Cell) {
+    pub fn set_cell(&mut self, dx: i32, dy: i32, cell: Cell) {
         // cannot move out of the neighbourhood, but also cannot move to the edge of the neighbourhood
         // as this would wake a chunk outside of the neighbourhood
         debug_assert!(dx > -15 && dx < 15);
@@ -122,8 +123,8 @@ impl UpdateCtx<'_, '_, '_> {
 
 pub fn sim_tick_chunk(chunks: &mut [Option<&mut Chunk>; 9], seqno: u64) {
     puffin::profile_function!();
-    // scan bottom to top to enable contiguous falling
     let seqno_parity = (seqno as u8) & 0b1;
+    let mut rng = SmallRng::seed_from_u64(seqno);
 
     if chunks[4].is_some() {
         for y in (0..CHUNK_SIZE).rev() {
@@ -135,24 +136,28 @@ pub fn sim_tick_chunk(chunks: &mut [Option<&mut Chunk>; 9], seqno: u64) {
                 };
 
                 let mut cell = get_cell(chunks, x, y).unwrap();
-                if cell.flags & 0b1 == seqno_parity {
-                    // flip the parity bit
-                    // TODO if the cell doesn't move this doesn't stay
-                    cell.flags = cell.flags ^ 0b1;
-                    let material = cell.material.def();
+                let material = cell.material.def();
+
+                if let Some(update) = material.sim_update {
+                    if cell.parity() == seqno_parity {
+                        cell.flip_parity();
+                        // apply the flipped parity in case the sim target doesn't
+                        set_cell(chunks, x, y, cell);
+
+                        let mut update_ctx = UpdateCtx {
+                            chunks,
+                            seqno,
+                            seqno_parity,
 
-                    let mut update_ctx = UpdateCtx {
-                        chunks,
-                        seqno,
-                        seqno_parity,
+                            x,
+                            y,
+                            cell: &mut cell,
+                            material,
 
-                        x,
-                        y,
-                        cell: &mut cell,
-                        material,
-                    };
+                            // TODO this is platform-dependent, will break for multiplayer
+                            rng: &mut rng,
+                        };
 
-                    if let Some(update) = material.sim_update {
                         update(&mut update_ctx);
                     }
                 }
diff --git a/src/sim/world.rs b/src/sim/world.rs
index 6645d4e..5993b10 100644
--- a/src/sim/world.rs
+++ b/src/sim/world.rs
@@ -48,6 +48,7 @@ impl World {
             self.chunks[idx].set_cell_at_local_position(dx, dy, cell);
             // this is a temporary hack
             self.chunks[idx].sleeping = sleeping;
+            self.chunks[idx].needs_texture_update = true;
         }
     }
 
@@ -63,8 +64,8 @@ impl World {
             chunk_position_to_chunk_idx: FxHashMap::default(),
         };
 
-        for y in -10..10 {
-            for x in -10..10 {
+        for y in -10..1 {
+            for x in -100..100 {
                 world.insert(x, y, Chunk::void());
             }
         }