From f9798743b8dca628c2273c818b28d82ffb31a785 Mon Sep 17 00:00:00 2001
From: nullprop <git@nullprop.sh>
Date: Sat, 11 Nov 2023 17:31:04 +0200
Subject: [PATCH] Pass roughness & metalness factors to shader

---
 res/shaders/globals.wgsl |  7 +++++++
 res/shaders/pbr.wgsl     | 10 ++++++----
 src/core/material.rs     | 30 ++++++++++++++++++++++++------
 src/core/state.rs        | 13 +++++++++++++
 4 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/res/shaders/globals.wgsl b/res/shaders/globals.wgsl
index 772670b..70eaf6b 100644
--- a/res/shaders/globals.wgsl
+++ b/res/shaders/globals.wgsl
@@ -27,6 +27,13 @@ struct GlobalUniforms {
 @group(0) @binding(2)
 var<uniform> global_uniforms: GlobalUniforms;
 
+struct MaterialUniform {
+    metallic_factor: f32,
+    rougness_factor: f32,
+    _padding1: f32,
+    _padding2: f32,
+}
+
 struct VertexInput {
     @location(0) position: vec3<f32>,
     @location(1) tex_coords: vec2<f32>,
diff --git a/res/shaders/pbr.wgsl b/res/shaders/pbr.wgsl
index ab4fc71..85677f1 100644
--- a/res/shaders/pbr.wgsl
+++ b/res/shaders/pbr.wgsl
@@ -67,6 +67,9 @@ var t_roughness_metalness: texture_2d<f32>;
 @group(2) @binding(5)
 var s_roughness_metalness: sampler;
 
+@group(2) @binding(6)
+var<uniform> material_uniform: MaterialUniform;
+
 @fragment
 fn fs_main(vert: VertexOutput) -> @location(0) vec4<f32> {
     // textures
@@ -76,10 +79,9 @@ fn fs_main(vert: VertexOutput) -> @location(0) vec4<f32> {
         t_roughness_metalness, s_roughness_metalness, vert.tex_coords);
 
     let albedo = object_color.xyz;
-    // TODO: pass factors to shader
-    let roughness = object_roughness_metalness.y * 1.0;
-    let metalness = object_roughness_metalness.z * 1.0;
-    
+    let roughness = object_roughness_metalness.y * material_uniform.rougness_factor;
+    let metalness = object_roughness_metalness.z * material_uniform.metallic_factor;
+
     var total_radiance: vec3<f32>;
 
     let in_light = sample_direct_light(vert.world_position);
diff --git a/src/core/material.rs b/src/core/material.rs
index 34e782b..071c64f 100644
--- a/src/core/material.rs
+++ b/src/core/material.rs
@@ -1,3 +1,4 @@
+use wgpu::util::DeviceExt;
 use crate::core::texture::Texture;
 
 pub struct Material {
@@ -5,13 +6,17 @@ pub struct Material {
     pub diffuse_texture: Texture,
     pub normal_texture: Texture,
     pub metallic_roughness_texture: Texture,
-    // TODO pass to shader
-    pub metallic_factor: f32,
-    // TODO pass to shader
-    pub roughness_factor: f32,
+    pub material_uniform: MaterialUniform,
     pub bind_group: wgpu::BindGroup,
 }
 
+#[repr(C)]
+#[derive(Debug, Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct MaterialUniform {
+    // metallic, roughness, none, none
+    pub factors: [f32; 4],
+}
+
 impl Material {
     pub fn new(
         device: &wgpu::Device,
@@ -23,6 +28,15 @@ impl Material {
         roughness_factor: f32,
         layout: &wgpu::BindGroupLayout,
     ) -> Self {
+        let material_uniform = MaterialUniform {
+            factors: [metallic_factor, roughness_factor, 0.0, 0.0]
+        };
+        let material_uniform_buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some("Material Uniform UB"),
+            contents: bytemuck::cast_slice(&[material_uniform]),
+            usage: wgpu::BufferUsages::UNIFORM | wgpu::BufferUsages::COPY_DST,
+        });
+
         let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
             layout,
             entries: &[
@@ -53,6 +67,11 @@ impl Material {
                     binding: 5,
                     resource: wgpu::BindingResource::Sampler(&metallic_roughness_texture.sampler),
                 },
+                // uniform
+                wgpu::BindGroupEntry {
+                    binding: 6,
+                    resource: material_uniform_buffer.as_entire_binding(),
+                }
             ],
             label: None,
         });
@@ -62,8 +81,7 @@ impl Material {
             diffuse_texture,
             normal_texture,
             metallic_roughness_texture,
-            metallic_factor,
-            roughness_factor,
+            material_uniform,
             bind_group,
         }
     }
diff --git a/src/core/state.rs b/src/core/state.rs
index d1c7cfd..7ecb3f0 100644
--- a/src/core/state.rs
+++ b/src/core/state.rs
@@ -5,6 +5,7 @@ use std::time::Duration;
 
 use wgpu::util::DeviceExt;
 use winit::{event::*, window::Window};
+use crate::core::material::MaterialUniform;
 
 use super::camera::{Camera, CameraController, CameraUniform};
 use super::instance::{Instance, InstanceRaw};
@@ -305,6 +306,7 @@ impl State {
 
         let geometry_depth_bind_group = State::create_geometry_depth_bind_group(&device, &geometry_depth_bind_group_layout, &geometry_depth_texture);
 
+        let material_uniform_size = mem::size_of::<MaterialUniform>() as u64;
         let texture_bind_group_layout =
             device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                 entries: &[
@@ -359,6 +361,17 @@ impl State {
                         ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
                         count: None,
                     },
+                    // material uniform
+                    wgpu::BindGroupLayoutEntry {
+                        binding: 6,
+                        visibility: wgpu::ShaderStages::FRAGMENT,
+                        ty: wgpu::BindingType::Buffer {
+                            ty: wgpu::BufferBindingType::Uniform,
+                            has_dynamic_offset: false,
+                            min_binding_size: wgpu::BufferSize::new(material_uniform_size),
+                        },
+                        count: None,
+                    },
                 ],
                 label: Some("texture_bind_group_layout"),
             });