From 966aabc6490d8c3b55e43ebe68f6e4198a9ce0d4 Mon Sep 17 00:00:00 2001
From: Verox001 <verox@cimeyclust.com>
Date: Tue, 6 May 2025 18:13:42 +0200
Subject: [PATCH] Made the Sun a directional light source and fixed some
 lighting bugs, which affect the sun to have a shadow

---
 simulator/src/main.rs        |  2 ++
 solar_engine/src/render.rs   |  5 +++++
 solar_engine/src/shader.wgsl | 22 ++++++++++++++++------
 3 files changed, 23 insertions(+), 6 deletions(-)

diff --git a/simulator/src/main.rs b/simulator/src/main.rs
index c5e3e22..e6b9afb 100644
--- a/simulator/src/main.rs
+++ b/simulator/src/main.rs
@@ -85,6 +85,8 @@ pub async fn run() {
                         },
                         scale: 0.05,
                         shape: solar_engine::Shape::Sphere,
+                        always_lit: i == 0, // Sun
+                        is_transparent: false
                     }
                 })
                 .collect();
diff --git a/solar_engine/src/render.rs b/solar_engine/src/render.rs
index 5b23370..da1f440 100644
--- a/solar_engine/src/render.rs
+++ b/solar_engine/src/render.rs
@@ -22,6 +22,8 @@ pub struct RenderInstance {
     pub color: [f32; 3],
     pub scale: f32,
     pub shape: Shape,
+    pub always_lit: bool,
+    pub is_transparent: bool
 }
 
 impl RenderInstance {
@@ -32,6 +34,7 @@ impl RenderInstance {
         InstanceRaw {
             model: model.into(),
             color: self.color,
+            flags: (self.always_lit as u32) | ((self.is_transparent as u32) << 1)
         }
     }
 }
@@ -41,6 +44,7 @@ impl RenderInstance {
 pub struct InstanceRaw {
     model: [[f32; 4]; 4],
     color: [f32; 3],
+    flags: u32,
 }
 
 impl InstanceRaw {
@@ -54,6 +58,7 @@ impl InstanceRaw {
                 wgpu::VertexAttribute { offset: 32, shader_location: 7, format: wgpu::VertexFormat::Float32x4 },
                 wgpu::VertexAttribute { offset: 48, shader_location: 8, format: wgpu::VertexFormat::Float32x4 },
                 wgpu::VertexAttribute { offset: 64, shader_location: 9, format: wgpu::VertexFormat::Float32x3 },
+                wgpu::VertexAttribute { offset: 76, shader_location: 10, format: wgpu::VertexFormat::Uint32 },
             ],
         }
     }
diff --git a/solar_engine/src/shader.wgsl b/solar_engine/src/shader.wgsl
index 4bd2e89..2368ee3 100644
--- a/solar_engine/src/shader.wgsl
+++ b/solar_engine/src/shader.wgsl
@@ -10,6 +10,7 @@ struct InstanceInput {
     @location(7) model_row2: vec4<f32>,
     @location(8) model_row3: vec4<f32>,
     @location(9) color: vec3<f32>,
+    @location(10) flags: u32,
 };
 
 struct VSOutput {
@@ -17,6 +18,7 @@ struct VSOutput {
     @location(0) frag_color: vec3<f32>,
     @location(1) world_pos: vec3<f32>,
     @location(2) normal: vec3<f32>,
+    @location(3) flags: u32,
 };
 
 struct Globals {
@@ -57,19 +59,27 @@ fn vs_main(vertex: VertexInput, instance: InstanceInput) -> VSOutput {
     out.frag_color = instance.color * vertex.color;
     out.world_pos = world_position;
     out.normal = normalize(normal_matrix * vertex.normal);
+    out.flags = instance.flags;
 
     return out;
 }
 
 @fragment
 fn fs_main(input: VSOutput) -> @location(0) vec4<f32> {
-    var lighting: vec3<f32> = vec3<f32>(0.0);
+    var lighting: vec3<f32>;
 
-    for (var i = 0u; i < 10u; i = i + 1u) {
-        let light = lights[i];
-        let light_dir = normalize(light.position - input.world_pos);
-        let diff = max(dot(input.normal, light_dir), 0.0);
-        lighting += light.color * light.intensity * diff;
+    let always_lit = (input.flags & 0x1u) != 0u;
+
+    if (always_lit) {
+        return vec4<f32>(input.frag_color * 2.0, 1.0);
+    } else {
+        lighting = vec3<f32>(0.0);
+        for (var i = 0u; i < 10u; i = i + 1u) {
+            let light = lights[i];
+            let light_dir = normalize(light.position - input.world_pos);
+            let diff = max(dot(input.normal, light_dir), 0.0);
+            lighting += light.color * light.intensity * diff;
+        }
     }
 
     let final_color = input.frag_color * lighting;