renderer: Light matrix fixes

cohaereo · cohaereo · commit 902a50495d3f · 2025-06-01T13:30:44.000+02:00
diff --git a/.zed/settings.json b/.zed/settings.json
@@ -0,0 +1,15 @@
+// Folder-specific settings
+//
+// For a full list of overridable settings, and general information on folder-specific settings,
+// see the documentation: https://zed.dev/docs/configuring-zed#settings-files
+{
+  "lsp": {
+    "rust-analyzer": {
+      "initialization_options": {
+        "cargo": {
+          "target": "x86_64-pc-windows-msvc"
+        }
+      }
+    }
+  }
+}
diff --git a/crates/alkahest-data/src/map.rs b/crates/alkahest-data/src/map.rs
@@ -408,7 +408,7 @@ pub struct SLight {
     pub unk30: Vec4,
     pub unk40: [u32; 4],
     pub unk50: Vec4,
-    pub light_to_world: Mat4,
+    pub light_space_transform: Mat4,
     pub unka0: u32,
     pub unka4: u32,
     pub unka8: u32,
@@ -439,7 +439,7 @@ pub struct SShadowingLight {
     pub unk30: Vec4,
     pub unk40: [u32; 4],
     pub unk50: Vec4,
-    pub light_to_world: Mat4,
+    pub light_space_transform: Mat4,
     pub unka0: u32,
     pub unka4: u32,
     pub unka8: u32,
diff --git a/crates/alkahest-renderer/src/ecs/render/light.rs b/crates/alkahest-renderer/src/ecs/render/light.rs
@@ -11,7 +11,7 @@ use genmesh::{
     generators::{IndexedPolygon, SharedVertex},
     Triangulate,
 };
-use glam::{Mat4, UVec2, Vec4, Vec4Swizzles};
+use glam::{Mat4, UVec2, Vec3, Vec4, Vec4Swizzles};
 use windows::Win32::Graphics::{
     Direct3D11::{
         ID3D11Buffer, ID3D11DepthStencilState, D3D11_BIND_INDEX_BUFFER, D3D11_BIND_VERTEX_BUFFER,
@@ -174,7 +174,7 @@ impl LightRenderer {
         debug_label: String,
     ) -> anyhow::Result<Self> {
         Ok(Self {
-            projection_matrix: light.light_to_world,
+            projection_matrix: light.light_space_transform,
             technique_shading: asset_manager.get_or_load_technique(light.technique_shading),
             _technique_volumetrics: asset_manager
                 .get_or_load_technique(light.technique_volumetrics),
@@ -193,7 +193,7 @@ impl LightRenderer {
         debug_label: String,
     ) -> anyhow::Result<Self> {
         Ok(Self {
-            projection_matrix: light.light_to_world,
+            projection_matrix: light.light_space_transform,
             technique_shading: asset_manager.get_or_load_technique(light.technique_shading),
             technique_shading_shadowing: Some(
                 asset_manager.get_or_load_technique(light.technique_shading_shadowing),
@@ -278,27 +278,28 @@ pub fn draw_light_system(renderer: &Renderer, scene: &mut Scene) {
                 return;
             };
 
-            let transform_relative = Transform {
-                translation: transform.translation - view.position.xyz(),
-                // translation: Vec3::ZERO,
-                ..*transform
-            };
+            let local_to_world_scaled = transform.local_to_world() * light.light_space_transform;
+            let view_translation_inverse_mat4 = Mat4::from_translation(-view.position.xyz());
+            let local_to_world_relative =
+                view_translation_inverse_mat4 * transform.local_to_world();
 
-            let transform_mat = transform_relative.local_to_world();
-            let transform_mat_scaled = transform.local_to_world() * light.light_to_world;
+            let (min, max) = compute_light_bounds(light.light_space_transform);
+            let light_local_to_world =
+                compute_light_local_to_world(transform.local_to_world(), min, max);
 
-            externs.simple_geometry = Some(externs::SimpleGeometry {
-                transform: view.world_to_projective * transform_mat_scaled,
-            });
             let existing_deflight = externs.deferred_light.as_ref().cloned().unwrap_or_default();
             externs.deferred_light = Some(externs::DeferredLight {
-                // TODO(cohae): Used for transforming projective textures (see lamps in Altar of Reflection)
-                unk40: Transform::from_translation(view.position.xyz()).local_to_world(),
-                unk80: transform_mat,
+                unk40: (view_translation_inverse_mat4 * light_local_to_world).inverse(),
+                unk80: local_to_world_relative,
+
                 unk100: light.unk50,
 
                 ..existing_deflight
             });
+
+            externs.simple_geometry = Some(externs::SimpleGeometry {
+                transform: view.world_to_projective * local_to_world_scaled,
+            });
         }
 
         light_renderer.draw(renderer, false);
@@ -330,18 +331,20 @@ pub fn draw_light_system(renderer: &Renderer, scene: &mut Scene) {
                 ..*transform
             };
 
-            let transform_mat = transform_relative.local_to_world();
-            let transform_mat_scaled = transform.local_to_world() * light.light_to_world;
+            let local_to_world_scaled = transform.local_to_world() * light.light_space_transform;
+            let view_translation_inverse_mat4 = Mat4::from_translation(-view.position.xyz());
+            let local_to_world_relative =
+                view_translation_inverse_mat4 * transform.local_to_world();
 
-            externs.simple_geometry = Some(externs::SimpleGeometry {
-                transform: view.world_to_projective * transform_mat_scaled,
-            });
+            let (min, max) = compute_light_bounds(light.light_space_transform);
+            let light_local_to_world =
+                compute_light_local_to_world(transform.local_to_world(), min, max);
 
             let existing_deflight = externs.deferred_light.as_ref().cloned().unwrap_or_default();
             externs.deferred_light = Some(externs::DeferredLight {
-                // TODO(cohae): Used for transforming projective textures (see lamps in Altar of Reflection)
-                unk40: Transform::from_translation(view.position.xyz()).local_to_world(),
-                unk80: transform_mat,
+                unk40: (view_translation_inverse_mat4 * light_local_to_world).inverse(),
+                unk80: local_to_world_relative,
+
                 unk100: light.unk50,
                 // unk110: 1.0,
                 // unk114: 2000.0,
@@ -351,6 +354,10 @@ pub fn draw_light_system(renderer: &Renderer, scene: &mut Scene) {
                 ..existing_deflight
             });
 
+            externs.simple_geometry = Some(externs::SimpleGeometry {
+                transform: view.world_to_projective * local_to_world_scaled,
+            });
+
             if let Some(shadowmap) = shadowmap {
                 // TODO(cohae): Unknown what this texture is supposed to be. VS loads the first pixel and uses it as multiplier for the shadowmap UVs
                 renderer
@@ -557,3 +564,71 @@ pub fn update_shadowrenderer_system(
         }
     }
 }
+
+fn compute_light_bounds(light_space_transform: Mat4) -> (Vec3, Vec3) {
+    let mut points = [
+        Vec3::new(-1.0, -1.0, -1.0),
+        Vec3::new(-1.0, -1.0, 1.0),
+        Vec3::new(-1.0, 1.0, -1.0),
+        Vec3::new(-1.0, 1.0, 1.0),
+        Vec3::new(1.0, -1.0, -1.0),
+        Vec3::new(1.0, -1.0, 1.0),
+        Vec3::new(1.0, 1.0, -1.0),
+        Vec3::new(1.0, 1.0, 1.0),
+    ];
+
+    for point in &mut points {
+        let p = light_space_transform.mul_vec4(point.extend(1.0));
+        let point_w_abs = (-p.wwww()).abs();
+        *point = Vec4::select(
+            point_w_abs.cmpge(Vec4::splat(0.0001)),
+            p / p.wwww(),
+            Vec4::W,
+        )
+        .truncate();
+    }
+
+    points
+        .iter()
+        .fold((Vec3::MAX, Vec3::MIN), |(min, max), &point| {
+            (min.min(point), max.max(point))
+        })
+}
+
+fn compute_light_local_to_world(node_local_to_world: Mat4, min: Vec3, max: Vec3) -> Mat4 {
+    let bounds_center = min.midpoint(max);
+    let bounds_half_extents = (max - min) / 2.0;
+
+    // First matrix operation ("mat"):
+    // Each column is computed by scaling one of node_local_to_world’s axes by the corresponding component of bounds_half_extents,
+    // except for the w-axis which is a linear combination of the x, y, and z axes plus the original w-axis.
+    let mat = Mat4 {
+        x_axis: node_local_to_world.x_axis * bounds_half_extents.x,
+        y_axis: node_local_to_world.y_axis * bounds_half_extents.y,
+        z_axis: node_local_to_world.z_axis * bounds_half_extents.z,
+        w_axis: node_local_to_world.x_axis * bounds_center.x
+            + node_local_to_world.y_axis * bounds_center.y
+            + node_local_to_world.z_axis * bounds_center.z
+            + node_local_to_world.w_axis,
+    };
+
+    // Second matrix operation ("mat_scaled"):
+    // Scale the x, y, and z axes by 2, and subtract all three from the w-axis.
+    let mat_scaled = Mat4 {
+        x_axis: mat.x_axis * 2.0,
+        y_axis: mat.y_axis * 2.0,
+        z_axis: mat.z_axis * 2.0,
+        w_axis: mat.w_axis - mat.x_axis - mat.y_axis - mat.z_axis,
+    };
+
+    // Third matrix operation (computing light_local_to_world):
+    // Rearrange the columns of mat_scaled: swap the x and z axes, leaving y and w unchanged.
+    let light_local_to_world = Mat4 {
+        x_axis: mat_scaled.z_axis,
+        y_axis: mat_scaled.y_axis,
+        z_axis: mat_scaled.x_axis,
+        w_axis: mat_scaled.w_axis,
+    };
+
+    light_local_to_world
+}
diff --git a/crates/alkahest-renderer/src/loaders/map.rs b/crates/alkahest-renderer/src/loaders/map.rs
@@ -798,7 +798,7 @@ fn load_datatable_into_scene<R: Read + Seek>(
                 ))
                 .enumerate()
                 {
-                    let shape = LightShape::from_volume_matrix(light.light_to_world);
+                    let shape = LightShape::from_volume_matrix(light.light_space_transform);
                     let transform = Transform {
                         translation: transform.translation.xyz(),
                         rotation: transform.rotation,
@@ -854,7 +854,7 @@ fn load_datatable_into_scene<R: Read + Seek>(
                     renderer.settings.shadow_quality.resolution(),
                 )?;
 
-                let bb = Aabb::from_projection_matrix(light.light_to_world);
+                let bb = Aabb::from_projection_matrix(light.light_space_transform);
 
                 spawn_data_entity(
                     scene,
diff --git a/crates/alkahest/lib/iron.lib b/crates/alkahest/lib/iron.lib
diff --git a/crates/alkahest/src/gui/sodi.rs b/crates/alkahest/src/gui/sodi.rs
@@ -2,7 +2,8 @@ use std::time::Instant;
 
 use alkahest_renderer::{
     icons::{ICON_CAMERA_OFF_OUTLINE, ICON_EYE_LOCK_OUTLINE},
-    resources::AppResources, util::FloatExt,
+    resources::AppResources,
+    util::FloatExt,
 };
 use egui::*;
 use windows_registry::CURRENT_USER;
@@ -33,7 +34,7 @@ impl Sodi {
             Err(e) => {
                 error!("Failed to check SODI acceptance: {e:?}");
                 false
-            },
+            }
         }
     }
 }
@@ -99,7 +100,7 @@ impl GuiView for Sodi {
                                         .color(Color32::WHITE)
                                         .size(128.0),
                                 );
-                                
+
                                 ui.weak(format!("{ICON_CAMERA_OFF_OUTLINE} Capturing disabled"));
                             });
 
