feat: add Automobilista 2 support

README.md

@@ -19,10 +19,10 @@ A lightweight sim racing telemetry overlay. Displays pedal inputs, steering angl
 
 ## Supported games
 
-| Game                          |
-| ----------------------------- |
-| Assetto Corsa Competizione    |
-| Automobilista 2 (in progress) |
+| Game                          | Notes                                    |
+| ----------------------------- |------------------------------------------|
+| Assetto Corsa Competizione    |                                          |
+| Automobilista 2               | [Enable shared memory](#automobilista-2) |
 
 ## Installation
 
@@ -37,6 +37,10 @@ Download the latest `.exe` from the [Releases](../../releases) page. No installe
 
 The overlay fades out when your cursor leaves it and reappears on hover.
 
+## Automobilista 2
+
+Enable shared memory: (from the main menu) `Options (top right) > System > Shared Memory` and setting it to `Project CARS 2`
+
 ## Building from source
 
 Requires [Rust](https://rustup.rs/) (stable).

src/plugins/ams2/ams2_plugin.rs

@@ -19,12 +19,6 @@ mod game_state {
     pub const FRONT_END: u32 = 1;
 }
 
-/// Decodes the packed `mGearNumGears` field.
-/// Lower nibble stores gear+1: 0→Reverse(-1), 1→Neutral(0), 2→1st(1), …
-#[cfg(windows)]
-fn decode_gear(gear_num_gears: u32) -> i32 {
-    (gear_num_gears & 0x0F) as i32 - 1
-}
 
 pub struct Ams2Plugin {
     #[cfg(windows)]
@@ -126,7 +120,7 @@ impl GamePlugin for Ams2Plugin {
             // Steering: normalised -1..1 → degrees (450° half-lock matches ACC convention)
             let steering_angle = unsafe { mem.unfiltered_steering() }.clamp(-1.0, 1.0) * 450.0;
             let speed = unsafe { mem.speed() }; // already m/s
-            let gear = decode_gear(unsafe { mem.gear_num_gears() });
+            let gear = unsafe { mem.gear() };
             let abs_active = unsafe { mem.anti_lock_active() };
 
             let vehicle = VehicleTelemetry {

src/plugins/ams2/shared_memory.rs

@@ -6,6 +6,7 @@
 #![allow(dead_code)]
 
 use anyhow::{anyhow, Result};
+use winapi::um::errhandlingapi::GetLastError;
 use winapi::um::handleapi::CloseHandle;
 use winapi::um::memoryapi::{MapViewOfFile, OpenFileMappingW, UnmapViewOfFile, FILE_MAP_READ};
 use winapi::um::winnt::HANDLE;
@@ -30,7 +31,10 @@ impl Ams2SharedMemory {
             let wide = to_wide(Self::MAPPING_NAME);
             let h = OpenFileMappingW(FILE_MAP_READ, 0, wide.as_ptr());
             if h.is_null() {
-                return Err(anyhow!("AMS2 shared memory not found — is AMS2 running?"));
+                let err = GetLastError();
+                return Err(anyhow!(
+                    "AMS2 shared memory not found (Windows error {err}) — is AMS2 running with Shared Memory enabled in Options → Gameplay?"
+                ));
             }
             let ptr = MapViewOfFile(h, FILE_MAP_READ, 0, 0, 0) as *const u8;
             if ptr.is_null() {
@@ -68,42 +72,50 @@ impl Ams2SharedMemory {
         self.ptr.add(offset).read_volatile()
     }
 
-    // ── pCars2 field accessors ─────────────────────────────────────────────
+    // ── AMS2 field accessors ───────────────────────────────────────────────
     //
-    // Offsets verified against the pCars2 SDK SharedMemory.h:
-    //   offset 8     = mGameState (u32)
-    //   offset 10524 = mUnfilteredThrottle (f32)
-    //   offset 10528 = mUnfilteredBrake    (f32)
-    //   offset 10532 = mUnfilteredSteering (f32)  [-1..1 normalised]
-    //   offset 10536 = mUnfilteredClutch   (f32)
-    //   offset 10916 = mSpeed              (f32, m/s)
-    //   offset 10932 = mGearNumGears       (u32, packed nibbles)
-    //   offset 10940 = mAntiLockActive     (u8 bool)
+    // Offsets computed from SharedMemory.h (MSVC default pack=8, effective pack=4):
+    //
+    //   ParticipantInfo is 100 bytes:
+    //     bool mIsActive(1) + char mName[64](64) + pad(3) + float[3](12) +
+    //     float(4) + uint(4) + uint(4) + uint(4) + int(4) = 100 bytes
+    //
+    //   Main struct header before participant array: 28 bytes
+    //   Participant array: 64 × 100 = 6400 bytes → ends at offset 6428
+    //
+    //   offset    8 = mGameState           (u32)
+    //   offset 6428 = mUnfilteredThrottle  (f32)
+    //   offset 6432 = mUnfilteredBrake     (f32)
+    //   offset 6436 = mUnfilteredSteering  (f32)  [-1..1 normalised]
+    //   offset 6440 = mUnfilteredClutch    (f32)
+    //   offset 6848 = mSpeed               (f32, m/s)
+    //   offset 6876 = mGear                (i32, -1=Reverse 0=Neutral 1=1st …)
+    //   offset 6888 = mAntiLockActive      (u8 bool)
 
     pub unsafe fn game_state(&self) -> u32 {
         self.u32_at(8)
     }
     pub unsafe fn unfiltered_throttle(&self) -> f32 {
-        self.f32_at(10524)
+        self.f32_at(6428)
     }
     pub unsafe fn unfiltered_brake(&self) -> f32 {
-        self.f32_at(10528)
+        self.f32_at(6432)
     }
     pub unsafe fn unfiltered_steering(&self) -> f32 {
-        self.f32_at(10532)
+        self.f32_at(6436)
     }
     pub unsafe fn unfiltered_clutch(&self) -> f32 {
-        self.f32_at(10536)
+        self.f32_at(6440)
     }
     pub unsafe fn speed(&self) -> f32 {
-        self.f32_at(10916)
+        self.f32_at(6848)
     }
-    /// Lower nibble = gear encoded as gear+1 (0→R, 1→N, 2→1st …)
-    pub unsafe fn gear_num_gears(&self) -> u32 {
-        self.u32_at(10932)
+    /// mGear: -1 = Reverse, 0 = Neutral, 1 = 1st gear, etc.
+    pub unsafe fn gear(&self) -> i32 {
+        (self.ptr.add(6876) as *const i32).read_volatile()
     }
     pub unsafe fn anti_lock_active(&self) -> bool {
-        self.u8_at(10940) != 0
+        self.u8_at(6888) != 0
     }
 }
 

src/plugins/registry.rs

@@ -26,7 +26,7 @@ impl PluginRegistry {
     /// Discover available plugins
     fn discover_plugins() -> Vec<String> {
         #[cfg(windows)]
-        return vec!["assetto_competizione".to_string()];
+        return vec!["assetto_competizione".to_string(), "ams2".to_string()];
 
         #[cfg(not(windows))]
         return vec!["test".to_string()];