From 3a562fb6ebf3ecfc0bfd9583444cac89d9ca9cfe Mon Sep 17 00:00:00 2001
From: Florian RICHER <florian.richer@protonmail.com>
Date: Thu, 29 May 2025 16:38:45 +0200
Subject: [PATCH] camera: Fix Y inverted

---
 src/core/render/primitives/camera.rs | 10 +++++++++-
 src/game/main_scene.rs               |  2 +-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/core/render/primitives/camera.rs b/src/core/render/primitives/camera.rs
index 34950ce..f1f48d7 100644
--- a/src/core/render/primitives/camera.rs
+++ b/src/core/render/primitives/camera.rs
@@ -11,6 +11,14 @@ use crate::core::{input::InputManager, timer::Timer};
 
 use super::mvp::MVP;
 
+// See docs/OPENGL_VULKAN_DIFF.md
+const OPENGL_TO_VULKAN_Y_AXIS_FLIP: Mat4 = Mat4 {
+    x_axis: Vec4::new(1.0, 0.0, 0.0, 0.0),
+    y_axis: Vec4::new(0.0, -1.0, 0.0, 0.0),
+    z_axis: Vec4::new(0.0, 0.0, 1.0, 0.0),
+    w_axis: Vec4::new(0.0, 0.0, 0.0, 1.0),
+};
+
 #[derive(Default)]
 pub struct Camera {
     projection: Mat4,
@@ -90,7 +98,7 @@ impl Camera {
         );
 
         MVP {
-            model: Mat4::IDENTITY.to_cols_array_2d(),
+            model: OPENGL_TO_VULKAN_Y_AXIS_FLIP.to_cols_array_2d(),
             view: view_matrix.to_cols_array_2d(),
             projection: self.projection.to_cols_array_2d(),
         }
diff --git a/src/game/main_scene.rs b/src/game/main_scene.rs
index 0aa18ac..03f54ea 100644
--- a/src/game/main_scene.rs
+++ b/src/game/main_scene.rs
@@ -43,7 +43,7 @@ impl Scene for MainScene {
             scene_context.swapchain_format,
         )?;
 
-        let camera = Camera::new(Mat4::perspective_rh_gl(
+        let camera = Camera::new(Mat4::perspective_rh(
             std::f32::consts::FRAC_PI_2,
             scene_context.aspect_ratio,
             0.01,