From a01c21f8658e239fd6eaed06189fcbe9ae9bea52 Mon Sep 17 00:00:00 2001
From: Valentin Popov <valentin@popov.link>
Date: Sat, 18 Jul 2026 19:30:27 +0400
Subject: [PATCH] feat(render): consume world snapshot transforms

---
 apps/fparkan-game/src/main.rs   | 99 ++++++++++++++++++++++++++++++---
 docs/tomes/07-implementation.md |  7 +++
 2 files changed, 99 insertions(+), 7 deletions(-)

diff --git a/apps/fparkan-game/src/main.rs b/apps/fparkan-game/src/main.rs
index 2ec347e..90effa7 100644
--- a/apps/fparkan-game/src/main.rs
+++ b/apps/fparkan-game/src/main.rs
@@ -54,7 +54,7 @@ use fparkan_terrain::TerrainWorld;
 use fparkan_vfs::DirectoryVfs;
 #[cfg(test)]
 use fparkan_world::OriginalObjectId;
-use fparkan_world::WorldSnapshot;
+use fparkan_world::{TransformState, WorldSnapshot};
 use serde::Deserialize;
 use std::num::NonZeroUsize;
 use std::path::PathBuf;
@@ -1024,12 +1024,14 @@ fn render_snapshot_with_assets(
                 material_slots: vec![material],
                 material_index: 0,
                 pipeline_state: fparkan_render::LegacyPipelineState::default(),
-                transform: mission_drafts
-                    .and_then(|drafts| drafts.get(index))
-                    .map_or_else(
-                        || identity_transform(index_to_f32(index)),
-                        mission_position_scale_transform,
-                    ),
+                transform: snapshot_transform(snapshot, *handle).unwrap_or_else(|| {
+                    mission_drafts
+                        .and_then(|drafts| drafts.get(index))
+                        .map_or_else(
+                            || identity_transform(index_to_f32(index)),
+                            mission_position_scale_transform,
+                        )
+                }),
                 range: IndexRange { start: 0, count: 3 },
                 stable_order,
             });
@@ -1041,6 +1043,40 @@ fn render_snapshot_with_assets(
     }
 }
 
+fn snapshot_transform(
+    snapshot: &WorldSnapshot,
+    handle: fparkan_world::ObjectHandle,
+) -> Option<[f32; 16]> {
+    snapshot
+        .transforms
+        .iter()
+        .find_map(|(candidate, transform)| (*candidate == handle).then_some(*transform))
+        .map(transform_state_position_scale_transform)
+}
+
+fn transform_state_position_scale_transform(transform: TransformState) -> [f32; 16] {
+    let position = transform.position.map(f32::from_bits);
+    let scale = transform.scale.map(f32::from_bits);
+    [
+        scale[0],
+        0.0,
+        0.0,
+        position[0],
+        0.0,
+        scale[1],
+        0.0,
+        position[1],
+        0.0,
+        0.0,
+        scale[2],
+        position[2],
+        0.0,
+        0.0,
+        0.0,
+        1.0,
+    ]
+}
+
 fn mission_position_scale_transform(draft: &MissionObjectDraft) -> [f32; 16] {
     [
         draft.scale[0],
@@ -1781,6 +1817,55 @@ mod tests {
         );
     }
 
+    #[test]
+    fn render_snapshot_prefers_world_transform_over_mission_draft() -> Result<(), String> {
+        let handle = ObjectHandle {
+            generation: 1,
+            slot: 0,
+        };
+        let snapshot = WorldSnapshot {
+            tick: Tick(1),
+            objects: vec![handle],
+            transforms: vec![(
+                handle,
+                TransformState {
+                    position: [
+                        100.0_f32.to_bits(),
+                        200.0_f32.to_bits(),
+                        300.0_f32.to_bits(),
+                    ],
+                    orientation: [0; 3],
+                    scale: [4.0_f32.to_bits(), 5.0_f32.to_bits(), 6.0_f32.to_bits()],
+                },
+            )],
+            events: Vec::new(),
+            hash: StateHash([0; 32]),
+        };
+        let drafts = vec![MissionObjectDraft {
+            original_id: None,
+            resource_name_raw: Vec::new(),
+            identity_or_clan_raw: 0,
+            position: [1.0; 3],
+            orientation_raw: [0.0; 3],
+            scale: [1.0; 3],
+            visual_ids: Vec::new(),
+            properties: Vec::new(),
+        }];
+
+        let commands = render_snapshot_commands_with_assets(&snapshot, None, Some(&drafts))?;
+        let RenderCommand::Draw(draw) = &commands.commands[1] else {
+            return Err("expected draw".to_string());
+        };
+        assert_eq!(
+            draw.transform,
+            [
+                4.0, 0.0, 0.0, 100.0, 0.0, 5.0, 0.0, 200.0, 0.0, 0.0, 6.0, 300.0, 0.0, 0.0, 0.0,
+                1.0
+            ]
+        );
+        Ok(())
+    }
+
     #[test]
     fn render_snapshot_preserves_mission_original_object_id() -> Result<(), String> {
         let snapshot = WorldSnapshot {
diff --git a/docs/tomes/07-implementation.md b/docs/tomes/07-implementation.md
index d9c6f80..c48fea2 100644
--- a/docs/tomes/07-implementation.md
+++ b/docs/tomes/07-implementation.md
@@ -390,6 +390,13 @@ deterministic ticks. This is the state foundation for a future route/movement
 controller; it does not claim recovered velocity, collision or original
 behavior-controller semantics.
 
+The ordinary planning renderer now consumes this snapshot state before falling
+back to a mission draft. Its current transform bridge applies the preserved
+position and non-uniform scale only; raw orientation remains uninterpreted in
+this backend-neutral path. A GOG AutoDemo planning run on 2026-07-18 completed
+two ticks with eight objects, 66 draws and state hash
+`a54855a4f47ffa380911228f295dd49a9a7b88d6ff271a23db48ba318b1fbbb4`.
+
 Записывается начальная миссия, seed, input events, network messages и значения
 внешних часов. На контрольных ticks сохраняется canonical state hash: