From eac787be3fbcaf2096f697bb3f783665adc925a0 Mon Sep 17 00:00:00 2001
From: popertots <popertots@gmail.com>
Date: Fri, 20 Mar 2026 17:10:54 +0000
Subject: [PATCH] feat: runtime-configurable VSync via config.toml
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

[display]
vsync = "mailbox"   # "vsync" | "mailbox" | "uncapped"

VsyncMode enum with custom Deserialize — accepts string values in toml.
apply_vsync_setting system reads GameConfig on every frame, updates
Window.present_mode immediately on change. No restart needed.
---
 config.toml      |  3 +++
 src/config.rs    | 31 +++++++++++++++++++++++++++++++
 src/world/mod.rs | 18 +++++++++++++++++-
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/config.toml b/config.toml
index fbb1c42..419b4cd 100644
--- a/config.toml
+++ b/config.toml
@@ -1,5 +1,8 @@
 initial_chunk_radius = 15
 
+[display]
+vsync = "mailbox"
+
 [spawn_counts]
 dorfs = 5
 pigs = 5
diff --git a/src/config.rs b/src/config.rs
index 9c5199d..64fdec9 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -8,6 +8,37 @@ use std::sync::OnceLock;
 pub struct GameConfig {
     pub initial_chunk_radius: i32,
     pub spawn_counts: SpawnCounts,
+    #[serde(default)]
+    pub display: DisplaySettings,
+}
+
+#[derive(Debug, Deserialize, Clone, Default)]
+pub struct DisplaySettings {
+    #[serde(default)]
+    pub vsync: VsyncMode,
+}
+
+#[derive(Debug, Clone, Copy, Default, PartialEq, Eq)]
+pub enum VsyncMode {
+    #[default]
+    Vsync,
+    Mailbox,
+    Uncapped,
+}
+
+impl<'de> Deserialize<'de> for VsyncMode {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        match s.as_str() {
+            "vsync" => Ok(VsyncMode::Vsync),
+            "mailbox" => Ok(VsyncMode::Mailbox),
+            "uncapped" => Ok(VsyncMode::Uncapped),
+            _ => Ok(VsyncMode::Vsync),
+        }
+    }
 }
 
 #[derive(Debug, Deserialize, Clone)]
diff --git a/src/world/mod.rs b/src/world/mod.rs
index 2238158..4be608b 100644
--- a/src/world/mod.rs
+++ b/src/world/mod.rs
@@ -1,6 +1,6 @@
 use crate::{
     camera,
-    config::GameConfig,
+    config::{GameConfig, VsyncMode},
     world::generation::{
         generate_chunk_fauna, generate_chunk_foliage, generate_chunk_forrestry,
         generate_chunk_weathering_and_precipitation, apply_terrain_blobs, spawn_terrain_tasks,
@@ -18,6 +18,21 @@ pub use chunks::management::*;
 pub use textures::management::*;
 pub use tiles::{prefabs::*, rendering::*, visibility::*};
 
+pub fn apply_vsync_setting(
+    config: Res<GameConfig>,
+    mut windows: Query<&mut Window>,
+) {
+    if config.is_changed() {
+        if let Ok(mut window) = windows.single_mut() {
+            window.present_mode = match config.display.vsync {
+                VsyncMode::Vsync => bevy::window::PresentMode::AutoVsync,
+                VsyncMode::Mailbox => bevy::window::PresentMode::Mailbox,
+                VsyncMode::Uncapped => bevy::window::PresentMode::AutoNoVsync,
+            };
+        }
+    }
+}
+
 pub struct WorldPlugin;
 
 impl Plugin for WorldPlugin {
@@ -58,6 +73,7 @@ impl Plugin for WorldPlugin {
                         .after(crate::entities::item::item_tile_management_system),
                     tiles::track_benchmark,
                     tiles::render_bench_report_system,
+                    apply_vsync_setting,
                     handle_tile_occlusion_updates,
                     tiles::spawn_tilemap_chunks,
                     tiles::on_camera_z_changed,