1 files changed, 56 insertions, 0 deletions
diff --git a/src/sim/mod.rs b/src/sim/mod.rs
index 63a9c56..dfc99c3 100644
--- a/src/sim/mod.rs
+++ b/src/sim/mod.rs
@@ -1,3 +1,59 @@
+use crate::{
+    config::CHUNK_SIZE,
+    sim::{cell::materials::MaterialId, cell_sim::world::World, rb_sim::RbSimManager},
+};
+
 pub mod cell;
 pub mod cell_sim;
 pub mod rb_sim;
+
+pub fn write_rb_entity_to_world(
+    world: &mut World,
+    rb_sim_manager: &RbSimManager,
+    rb_entity_id: u32,
+    // make sure these cells will be simulated
+    seqno: u64,
+    // (entity_x, entity_y, cell_x, cell_y)
+) -> Vec<(u8, u8, i32, i32)> {
+    let mut cells_written: Vec<(u8, u8, i32, i32)> = Vec::new();
+    if let Some(rb_entity) = rb_sim_manager.rb_entities.get(&rb_entity_id)
+        && let Some((rb_x, rb_y, cos, sin)) = rb_sim_manager.get_rb_entity_transform(rb_entity_id)
+    {
+        let half_size = CHUNK_SIZE as f32 / 2.0;
+        // half-extent of the rotated grid's axis-aligned bounding box, plus a cell of margin
+        let radius = half_size * (cos.abs() + sin.abs()) + 1.0;
+
+        let world_xl = (rb_x - radius).floor() as i32;
+        let world_xu = (rb_x + radius).ceil() as i32;
+        let world_yl = (rb_y - radius).floor() as i32;
+        let world_yu = (rb_y + radius).ceil() as i32;
+
+        for world_x in world_xl..=world_xu {
+            for world_y in world_yl..=world_yu {
+                // same as shader
+                let d = (world_x as f32 + 0.5 - rb_x, world_y as f32 + 0.5 - rb_y);
+                let q = (d.0.floor() + 0.5, d.1.floor() + 0.5);
+                let (lx, ly) = (
+                    (q.0 * cos + q.1 * sin + half_size).floor() as i32,
+                    (-q.0 * sin + q.1 * cos + half_size).floor() as i32,
+                );
+
+                if lx < 0 || ly < 0 || lx >= CHUNK_SIZE || ly >= CHUNK_SIZE {
+                    continue;
+                }
+
+                let mut cell = rb_entity.get_cell_at_local_position(lx as u8, ly as u8);
+                if cell.material == MaterialId::Void {
+                    continue;
+                }
+
+                cell.match_parity(seqno);
+
+                // TODO: OPTIMIZE!!
+                world.set_cell_from_game_position(world_x, world_y, cell, false);
+                cells_written.push((lx as u8, ly as u8, world_x, world_y));
+            }
+        }
+    }
+    cells_written
+}