Support front face configuration for meshes

blade-render/code/fill-gbuf.wgsl

@@ -30,9 +30,9 @@ var sampler_nearest: sampler;
 struct HitEntry {
     index_buf: u32,
     vertex_buf: u32,
+    winding: f32,
     // packed quaternion
     geometry_to_world_rotation: u32,
-    pad: u32,
     geometry_to_object: mat4x3<f32>,
     prev_object_to_world: mat4x3<f32>,
     base_color_texture: u32,
@@ -105,7 +105,7 @@ fn main(@builtin(global_invocation_id) global_id: vec3<u32>) {
         let positions = intersection.object_to_world * mat3x4(
             vec4<f32>(positions_object[0], 1.0), vec4<f32>(positions_object[1], 1.0), vec4<f32>(positions_object[2], 1.0)
         );
-        flat_normal = normalize(cross(positions[1].xyz - positions[0].xyz, positions[2].xyz - positions[0].xyz));
+        flat_normal = entry.winding * normalize(cross(positions[1].xyz - positions[0].xyz, positions[2].xyz - positions[0].xyz));
 
         let barycentrics = vec3<f32>(1.0 - intersection.barycentrics.x - intersection.barycentrics.y, intersection.barycentrics);
         let position_object = vec4<f32>(positions_object * barycentrics, 1.0);

blade-render/code/ray-trace.wgsl

@@ -297,14 +297,12 @@ fn estimate_target_score_with_occlusion(
 
 fn evaluate_sample(ls: LightSample, surface: Surface, start_pos: vec3<f32>, debug_len: f32) -> f32 {
     let dir = map_equirect_uv_to_dir(ls.uv);
-    if (dot(dir, surface.flat_normal) <= 0.0)
-    {
+    if (dot(dir, surface.flat_normal) <= 0.0) {
         return 0.0;
     }
 
     let brdf = evaluate_brdf(surface, dir);
-    if (brdf <= 0.0)
-    {
+    if (brdf <= 0.0) {
         return 0.0;
     }
 

blade-render/src/model/mod.rs

@@ -1,6 +1,6 @@
 use std::{
     borrow::Cow,
     collections::hash_map::{Entry, HashMap},
     fmt, hash, mem,
     ops::Range,
     ptr, str,
@@ -50,6 +50,7 @@
 
 pub struct Model {
     pub name: String,
+    pub winding: f32,
     pub geometries: Vec<Geometry>,
     pub materials: Vec<Material>,
     pub vertex_buffer: blade_graphics::Buffer,
@@ -163,6 +164,7 @@
 #[derive(blade_macros::Flat)]
 pub struct CookedModel<'a> {
     name: &'a [u8],
+    winding: f32,
     materials: Vec<CookedMaterial<'a>>,
     geometries: Vec<CookedGeometry<'a>>,
 }
@@ -272,14 +274,26 @@
     }
 }
 
-#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
+pub enum FrontFace {
+    Clockwise,
+    CounterClockwise,
+}
+impl Default for FrontFace {
+    fn default() -> Self {
+        Self::CounterClockwise
+    }
+}
+
+#[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
 pub struct Meta {
     pub generate_tangents: bool,
+    pub front_face: FrontFace,
 }
 
 impl fmt::Display for Meta {
     fn fmt(&self, _f: &mut fmt::Formatter) -> fmt::Result {
-        Ok(())
+        Ok(()) //TODO
     }
 }
 
@@ -456,11 +470,11 @@
 
     fn cook(
         &self,
         source: &[u8],
         extension: &str,
         meta: Meta,
         cooker: Arc<blade_asset::Cooker<Self>>,
         exe_context: &choir::ExecutionContext,
     ) {
         match extension {
             #[cfg(feature = "asset")]
@@ -496,6 +510,10 @@
                 let mut sources = slab::Slab::new();
                 let mut model = CookedModel {
                     name: &[],
+                    winding: match meta.front_face {
+                        FrontFace::Clockwise => -1.0,
+                        FrontFace::CounterClockwise => 1.0,
+                    },
                     materials: Vec::new(),
                     geometries: Vec::new(),
                 };
@@ -756,6 +774,7 @@
 
         Model {
             name: String::from_utf8_lossy(model.name).into_owned(),
+            winding: model.winding,
             geometries,
             materials,
             vertex_buffer,

blade-render/src/render/mod.rs

@@ -463,8 +463,8 @@ struct PostProcData {
 struct HitEntry {
     index_buf: u32,
     vertex_buf: u32,
+    winding: f32,
     geometry_to_world_rotation: [i8; 4],
-    unused: u32,
     //Note: it's technically `mat4x3` on WGSL side,
     // but it's aligned and sized the same way as `mat4`.
     geometry_to_object: mint::ColumnMatrix4<f32>,
@@ -913,8 +913,8 @@ impl Renderer {
                     vertex_buf: self
                         .vertex_buffers
                         .alloc(model.vertex_buffer.at(vertex_offset)),
+                    winding: model.winding,
                     geometry_to_world_rotation,
-                    unused: 0,
                     geometry_to_object: mint::ColumnMatrix4::from(mint::RowMatrix4 {
                         x: geometry.transform.x,
                         y: geometry.transform.y,

docs/CHANGELOG.md

@@ -3,6 +3,7 @@ Changelog for Blade
 ## blade-0.2 (TBD)
 - high-level engine
 - support object motion
+- support clockwise mesh winding
 
 ## blade-graphics-0.3, blade-render-0.2 (17 Nov 2023)
 - tangent space generation

examples/init/main.rs

@@ -1,6 +1,6 @@
 #![allow(irrefutable_let_patterns)]
 
 use std::{env, path::Path, ptr, sync::Arc};
 
 use blade_graphics as gpu;
 
@@ -179,12 +179,9 @@
             environment_map = Some(texture);
         } else if arg.ends_with(".gltf") {
             println!("\tmodels += {}", arg);
-            let (model, model_task) = asset_hub.models.load(
-                arg,
-                blade_render::model::Meta {
-                    generate_tangents: false,
-                },
-            );
+            let (model, model_task) = asset_hub
+                .models
+                .load(arg, blade_render::model::Meta::default());
             load_finish.depend_on(model_task);
             _object = Some(blade_render::Object::from(model));
         } else {

examples/scene/main.rs

@@ -339,6 +339,7 @@ impl Example {
                 parent.join(&config_object.path),
                 blade_render::model::Meta {
                     generate_tangents: true,
+                    ..Default::default()
                 },
             );
             load_finish.depend_on(model_task);
@@ -983,6 +984,7 @@ impl Example {
             file_path,
             blade_render::model::Meta {
                 generate_tangents: true,
+                ..Default::default()
             },
         );
         self.scene_load_task = Some(model_task.clone());

src/config.rs

@@ -1,3 +1,14 @@
+#[derive(serde::Deserialize)]
+pub enum FrontFace {
+    Cw,
+    Ccw,
+}
+impl Default for FrontFace {
+    fn default() -> Self {
+        Self::Ccw
+    }
+}
+
 fn default_vec() -> mint::Vector3<f32> {
     [0.0; 3].into()
 }
@@ -8,6 +19,8 @@ fn default_scale() -> f32 {
 #[derive(serde::Deserialize)]
 pub struct Visual {
     pub model: String,
+    #[serde(default)]
+    pub front_face: FrontFace,
     #[serde(default = "default_vec")]
     pub pos: mint::Vector3<f32>,
     #[serde(default = "default_vec")]
@@ -19,6 +32,7 @@ impl Default for Visual {
     fn default() -> Self {
         Self {
             model: String::new(),
+            front_face: FrontFace::default(),
             pos: default_vec(),
             rot: default_vec(),
             scale: default_scale(),

src/lib.rs

@@ -622,6 +622,10 @@ impl Engine {
                 format!("{}/{}", self.data_path, visual.model),
                 blade_render::model::Meta {
                     generate_tangents: true,
+                    front_face: match visual.front_face {
+                        config::FrontFace::Cw => blade_render::model::FrontFace::Clockwise,
+                        config::FrontFace::Ccw => blade_render::model::FrontFace::CounterClockwise,
+                    },
                 },
             );
             visuals.push(Visual {