From e4e0c3078fd8a4e37fd565624c8fc2bc8322b4d6 Mon Sep 17 00:00:00 2001
From: Verox001 <verox@cimeyclust.com>
Date: Wed, 7 May 2025 20:12:10 +0200
Subject: [PATCH] Implemented lighting buffer resize and pre-calculated range
 by min_attenuation

---
 simulator/src/main.rs        | 18 +++++++-----------
 solar_engine/src/light.rs    | 34 ++++++++++++++++++++++++++++++----
 solar_engine/src/shader.wgsl | 12 +++++++-----
 3 files changed, 44 insertions(+), 20 deletions(-)

diff --git a/simulator/src/main.rs b/simulator/src/main.rs
index 06f14bf..fff855d 100644
--- a/simulator/src/main.rs
+++ b/simulator/src/main.rs
@@ -52,16 +52,12 @@ pub async fn run() {
             let sun_pos = bodies[0].position / 1.496e11;
 
             state.light_manager.clear();
-            state.light_manager.add_light(Light {
-                position: sun_pos.cast::<f32>().unwrap(),
-                direction: Vector3::new(0.0, 0.0, 0.0),
-                color: Vector3::from([1.0, 1.0, 0.8]),
-                intensity: 5.0,
-                range: 100000000.0,
-                inner_cutoff: 0.0,
-                light_type: LightType::Point,
-                outer_cutoff: 0.0,
-            });
+            state.light_manager.add_light(Light::new_point(
+                sun_pos.cast::<f32>().unwrap(),
+                Vector3::from([1.0, 1.0, 0.8]),
+                5.0,
+                1.0 / 1000.0,
+            ));
 
             let instances = bodies
                 .iter()
@@ -78,7 +74,7 @@ pub async fn run() {
                         scale: 0.05,
                         shape: solar_engine::Shape::Sphere,
                         always_lit: i == 0, // Sun
-                        is_transparent: false
+                        is_transparent: false,
                     }
                 })
                 .collect();
diff --git a/solar_engine/src/light.rs b/solar_engine/src/light.rs
index 3e56e05..d1e1d75 100644
--- a/solar_engine/src/light.rs
+++ b/solar_engine/src/light.rs
@@ -1,5 +1,5 @@
 use bytemuck::{Pod, Zeroable};
-use cgmath::{EuclideanSpace, Matrix4, Point3, Transform, Vector3};
+use cgmath::{EuclideanSpace, Matrix4, Point3, Transform, Vector3, Zero};
 use wgpu::util::DeviceExt;
 
 #[repr(u32)]
@@ -53,6 +53,21 @@ impl Light {
             outer_cutoff: self.outer_cutoff,
         }
     }
+
+    pub fn new_point(position: Vector3<f32>, color: Vector3<f32>, intensity: f32, min_attenuation: f32) -> Self {
+        let range = (intensity / min_attenuation).sqrt().max(1.0);
+
+        Self {
+            light_type: LightType::Point,
+            position,
+            direction: Vector3::zero(),
+            color,
+            intensity,
+            range,
+            inner_cutoff: 0.0,
+            outer_cutoff: 0.0,
+        }
+    }
 }
 
 pub struct LightManager {
@@ -263,6 +278,20 @@ impl LightManager {
         queue: &wgpu::Queue,
         assignment: &ClusterAssignment,
     ) {
+        let new_index_bytes = assignment.cluster_light_indices.len() * std::mem::size_of::<u32>();
+        let new_offset_bytes = assignment.cluster_offsets.len() * std::mem::size_of::<[u32; 2]>();
+
+        let needs_resize = self.cluster_buffers.as_ref().map(|buffers| {
+            let index_size_ok = new_index_bytes <= buffers.light_indices.size() as usize;
+            let offset_size_ok = new_offset_bytes <= buffers.offsets.size() as usize;
+            !(index_size_ok && offset_size_ok)
+        }).unwrap_or(true);
+
+        if needs_resize {
+            let buffers = self.create_cluster_buffers(device, assignment);
+            self.cluster_buffers = Some(buffers);
+        }
+
         if let Some(buffers) = &self.cluster_buffers {
             queue.write_buffer(&buffers.light_indices, 0, bytemuck::cast_slice(&assignment.cluster_light_indices));
 
@@ -273,9 +302,6 @@ impl LightManager {
                 .collect();
 
             queue.write_buffer(&buffers.offsets, 0, bytemuck::cast_slice(&offset_pairs));
-        } else {
-            let buffers = self.create_cluster_buffers(device, assignment);
-            self.cluster_buffers = Some(buffers);
         }
     }
 
diff --git a/solar_engine/src/shader.wgsl b/solar_engine/src/shader.wgsl
index 46930e0..62a0c3c 100644
--- a/solar_engine/src/shader.wgsl
+++ b/solar_engine/src/shader.wgsl
@@ -123,10 +123,6 @@ fn fs_main(input: VSOutput) -> @location(0) vec4<f32> {
     let offset = offset_info.x;
     let count = offset_info.y;
 
-    if (always_lit) {
-        return vec4<f32>(input.frag_color, 2.0);
-    }
-
     for (var i = 0u; i < count; i = i + 1u) {
         let light_index = cluster_light_indices[offset + i];
         let light = all_lights[light_index];
@@ -159,7 +155,13 @@ fn fs_main(input: VSOutput) -> @location(0) vec4<f32> {
             default: {}
         }
 
-        lighting += light_contrib;
+        if (!always_lit) {
+            lighting += light_contrib;
+        }
+    }
+
+    if (always_lit) {
+        lighting = vec3<f32>(1.0, 1.0, 1.0) * 2.0;
     }
 
     return vec4<f32>(input.frag_color * lighting, 1.0);