From 306a983d14211e3e8b14c105dc516f704b90a016 Mon Sep 17 00:00:00 2001
From: marceline-cramer <cramermarceline@gmail.com>
Date: Wed, 2 Feb 2022 13:15:58 -0700
Subject: [PATCH] Surface normals

---
 src/main.rs     |  5 +++++
 src/mesh.rs     |  6 ++++++
 src/renderer.rs |  2 +-
 src/shader.wgsl | 14 ++++++++++----
 4 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 8278897..ebf2962 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -46,6 +46,11 @@ fn load_model() -> (MeshData, TextureData) {
                 m.mesh.positions[t + 2],
                 -m.mesh.positions[t + 1],
             ],
+            normal: [
+                m.mesh.normals[t],
+                m.mesh.normals[t + 2],
+                -m.mesh.normals[t + 1],
+            ],
             tex_coords: [m.mesh.texcoords[i * 2], 1.0 - m.mesh.texcoords[i * 2 + 1]],
         });
     }
diff --git a/src/mesh.rs b/src/mesh.rs
index 1fccd7b..5a264ab 100644
--- a/src/mesh.rs
+++ b/src/mesh.rs
@@ -2,6 +2,7 @@
 #[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
 pub struct Vertex {
     pub position: [f32; 3],
+    pub normal: [f32; 3],
     pub tex_coords: [f32; 2],
 }
 
@@ -19,6 +20,11 @@ impl Vertex {
                 wgpu::VertexAttribute {
                     offset: std::mem::size_of::<[f32; 3]>() as wgpu::BufferAddress,
                     shader_location: 1,
+                    format: wgpu::VertexFormat::Float32x3,
+                },
+                wgpu::VertexAttribute {
+                    offset: std::mem::size_of::<[f32; 6]>() as wgpu::BufferAddress,
+                    shader_location: 2,
                     format: wgpu::VertexFormat::Float32x2,
                 },
             ],
diff --git a/src/renderer.rs b/src/renderer.rs
index 3f229e9..afcda33 100644
--- a/src/renderer.rs
+++ b/src/renderer.rs
@@ -159,7 +159,7 @@ impl Renderer {
                 topology: wgpu::PrimitiveTopology::TriangleList,
                 strip_index_format: None,
                 front_face: wgpu::FrontFace::Ccw,
-                cull_mode: None,
+                cull_mode: Some(wgpu::Face::Back),
                 polygon_mode: wgpu::PolygonMode::Fill,
                 unclipped_depth: false,
                 conservative: false,
diff --git a/src/shader.wgsl b/src/shader.wgsl
index a714970..b11e1a8 100644
--- a/src/shader.wgsl
+++ b/src/shader.wgsl
@@ -22,13 +22,15 @@ struct PointLightData {
 
 struct VertexInput {
   [[location(0)]] position: vec3<f32>;
-  [[location(1)]] tex_coords: vec2<f32>;
+  [[location(1)]] normal: vec3<f32>;
+  [[location(2)]] tex_coords: vec2<f32>;
 };
 
 struct VertexOutput {
   [[builtin(position)]] clip_position: vec4<f32>;
   [[location(0)]] position: vec3<f32>;
-  [[location(1)]] tex_coords: vec2<f32>;
+  [[location(1)]] normal: vec3<f32>;
+  [[location(2)]] tex_coords: vec2<f32>;
 };
 
 [[group(0), binding(0)]]
@@ -50,10 +52,12 @@ fn vs_main(
 ) -> VertexOutput {
   let transform = meshes.instances[mesh_idx].transform;
   let world_pos = transform * vec4<f32>(vertex.position, 1.0);
+  let world_normal = transform * vec4<f32>(vertex.normal, 0.0);
 
   var out: VertexOutput;
   out.clip_position = camera.vp * world_pos;
   out.position = world_pos.xyz;
+  out.normal = world_normal.xyz;
   out.tex_coords = vertex.tex_coords;
   return out;
 }
@@ -63,12 +67,14 @@ fn fs_main(
   frag: VertexOutput,
 ) -> [[location(0)]] vec4<f32> {
   let albedo = textureSample(t_albedo, s_albedo, frag.tex_coords).rgb;
+  let normal = normalize(frag.normal);
 
   var lum = vec3<f32>(0.0);
   for(var i = 0; i < 4; i = i + 1) {
     let light = point_lights.lights[i];
-    let light_relative = frag.position - light.center.xyz;
-    let diffuse = albedo / dot(light_relative, light_relative);
+    let light_relative = light.center.xyz - frag.position;
+    let received = dot(normal, normalize(light_relative));
+    let diffuse = (albedo * received) / dot(light_relative, light_relative);
     lum = lum + (diffuse * light.intensity.rgb);
   }