Add PBR textures (#1632)

This PR adds normal maps on top of PBR #1554. Once that PR lands, the changes should look simpler.

Edit: Turned out to be so little extra work, I added metallic/roughness texture too. And occlusion and emissive.

Co-authored-by: Carter Anderson <mcanders1@gmail.com>

Author: mtsr

crates/bevy_gltf/src/loader.rs

@@ -95,6 +95,12 @@ async fn load_gltf<'a, 'b>(
         if let Some(texture) = material.occlusion_texture() {
             linear_textures.insert(texture.texture().index());
         }
+        if let Some(texture) = material
+            .pbr_metallic_roughness()
+            .metallic_roughness_texture()
+        {
+            linear_textures.insert(texture.texture().index());
+        }
     }
 
     let mut meshes = vec![];
@@ -122,6 +128,13 @@ async fn load_gltf<'a, 'b>(
                 mesh.set_attribute(Mesh::ATTRIBUTE_NORMAL, vertex_attribute);
             }
 
+            if let Some(vertex_attribute) = reader
+                .read_tangents()
+                .map(|v| VertexAttributeValues::Float4(v.collect()))
+            {
+                mesh.set_attribute(Mesh::ATTRIBUTE_TANGENT, vertex_attribute);
+            }
+
             if let Some(vertex_attribute) = reader
                 .read_tex_coords(0)
                 .map(|v| VertexAttributeValues::Float2(v.into_f32().collect()))
@@ -279,23 +292,72 @@ async fn load_gltf<'a, 'b>(
 
 fn load_material(material: &Material, load_context: &mut LoadContext) -> Handle<StandardMaterial> {
     let material_label = material_label(&material);
+
     let pbr = material.pbr_metallic_roughness();
-    let texture_handle = if let Some(info) = pbr.base_color_texture() {
+
+    let color = pbr.base_color_factor();
+    let base_color_texture = if let Some(info) = pbr.base_color_texture() {
+        // TODO: handle info.tex_coord() (the *set* index for the right texcoords)
+        let label = texture_label(&info.texture());
+        let path = AssetPath::new_ref(load_context.path(), Some(&label));
+        Some(load_context.get_handle(path))
+    } else {
+        None
+    };
+
+    let normal_map = if let Some(normal_texture) = material.normal_texture() {
+        // TODO: handle normal_texture.scale
+        // TODO: handle normal_texture.tex_coord() (the *set* index for the right texcoords)
+        let label = texture_label(&normal_texture.texture());
+        let path = AssetPath::new_ref(load_context.path(), Some(&label));
+        Some(load_context.get_handle(path))
+    } else {
+        None
+    };
+
+    let metallic_roughness_texture = if let Some(info) = pbr.metallic_roughness_texture() {
+        // TODO: handle info.tex_coord() (the *set* index for the right texcoords)
+        let label = texture_label(&info.texture());
+        let path = AssetPath::new_ref(load_context.path(), Some(&label));
+        Some(load_context.get_handle(path))
+    } else {
+        None
+    };
+
+    let occlusion_texture = if let Some(occlusion_texture) = material.occlusion_texture() {
+        // TODO: handle occlusion_texture.tex_coord() (the *set* index for the right texcoords)
+        // TODO: handle occlusion_texture.strength() (a scalar multiplier for occlusion strength)
+        let label = texture_label(&occlusion_texture.texture());
+        let path = AssetPath::new_ref(load_context.path(), Some(&label));
+        Some(load_context.get_handle(path))
+    } else {
+        None
+    };
+
+    let emissive = material.emissive_factor();
+    let emissive_texture = if let Some(info) = material.emissive_texture() {
+        // TODO: handle occlusion_texture.tex_coord() (the *set* index for the right texcoords)
+        // TODO: handle occlusion_texture.strength() (a scalar multiplier for occlusion strength)
         let label = texture_label(&info.texture());
         let path = AssetPath::new_ref(load_context.path(), Some(&label));
         Some(load_context.get_handle(path))
     } else {
         None
     };
 
-    let color = pbr.base_color_factor();
     load_context.set_labeled_asset(
         &material_label,
         LoadedAsset::new(StandardMaterial {
             base_color: Color::rgba(color[0], color[1], color[2], color[3]),
-            base_color_texture: texture_handle,
+            base_color_texture,
             roughness: pbr.roughness_factor(),
             metallic: pbr.metallic_factor(),
+            metallic_roughness_texture,
+            normal_map,
+            double_sided: material.double_sided(),
+            occlusion_texture,
+            emissive: Color::rgba(emissive[0], emissive[1], emissive[2], 1.0),
+            emissive_texture,
             unlit: material.unlit(),
             ..Default::default()
         }),

crates/bevy_pbr/src/material.rs

@@ -24,7 +24,21 @@ pub struct StandardMaterial {
     pub metallic: f32,
     /// Specular intensity for non-metals on a linear scale of [0.0, 1.0]
     /// defaults to 0.5 which is mapped to 4% reflectance in the shader
+    #[shader_def]
+    pub metallic_roughness_texture: Option<Handle<Texture>>,
     pub reflectance: f32,
+    #[shader_def]
+    pub normal_map: Option<Handle<Texture>>,
+    #[render_resources(ignore)]
+    #[shader_def]
+    pub double_sided: bool,
+    #[shader_def]
+    pub occlusion_texture: Option<Handle<Texture>>,
+    // Use a color for user friendliness even though we technically don't use the alpha channel
+    // Might be used in the future for exposure correction in HDR
+    pub emissive: Color,
+    #[shader_def]
+    pub emissive_texture: Option<Handle<Texture>>,
     #[render_resources(ignore)]
     #[shader_def]
     pub unlit: bool,
@@ -45,7 +59,13 @@ impl Default for StandardMaterial {
             metallic: 0.01,
             // Minimum real-world reflectance is 2%, most materials between 2-5%
             // Expressed in a linear scale and equivalent to 4% reflectance see https://google.github.io/filament/Material%20Properties.pdf
+            metallic_roughness_texture: None,
             reflectance: 0.5,
+            normal_map: None,
+            double_sided: false,
+            occlusion_texture: None,
+            emissive: Color::BLACK,
+            emissive_texture: None,
             unlit: false,
         }
     }

crates/bevy_pbr/src/render_graph/pbr_pipeline/pbr.frag

@@ -48,6 +48,10 @@ layout(location = 0) in vec3 v_WorldPosition;
 layout(location = 1) in vec3 v_WorldNormal;
 layout(location = 2) in vec2 v_Uv;
 
+#ifdef STANDARDMATERIAL_NORMAL_MAP
+layout(location = 3) in vec4 v_WorldTangent;
+#endif
+
 layout(location = 0) out vec4 o_Target;
 
 layout(set = 0, binding = 0) uniform CameraViewProj {
@@ -83,10 +87,38 @@ layout(set = 3, binding = 4) uniform StandardMaterial_metallic {
     float metallic;
 };
 
-layout(set = 3, binding = 5) uniform StandardMaterial_reflectance {
+#    ifdef STANDARDMATERIAL_METALLIC_ROUGHNESS_TEXTURE
+layout(set = 3, binding = 5) uniform texture2D StandardMaterial_metallic_roughness_texture;
+layout(set = 3,
+       binding = 6) uniform sampler StandardMaterial_metallic_roughness_texture_sampler;
+#    endif
+
+layout(set = 3, binding = 7) uniform StandardMaterial_reflectance {
     float reflectance;
 };
 
+#    ifdef STANDARDMATERIAL_NORMAL_MAP
+layout(set = 3, binding = 8) uniform texture2D StandardMaterial_normal_map;
+layout(set = 3,
+       binding = 9) uniform sampler StandardMaterial_normal_map_sampler;
+#    endif
+
+#    if defined(STANDARDMATERIAL_OCCLUSION_TEXTURE)
+layout(set = 3, binding = 10) uniform texture2D StandardMaterial_occlusion_texture;
+layout(set = 3,
+       binding = 11) uniform sampler StandardMaterial_occlusion_texture_sampler;
+#    endif
+
+layout(set = 3, binding = 12) uniform StandardMaterial_emissive {
+    vec4 emissive;
+};
+
+#    if defined(STANDARDMATERIAL_EMISSIVE_TEXTURE)
+layout(set = 3, binding = 13) uniform texture2D StandardMaterial_emissive_texture;
+layout(set = 3,
+       binding = 14) uniform sampler StandardMaterial_emissive_texture_sampler;
+#    endif
+
 #    define saturate(x) clamp(x, 0.0, 1.0)
 const float PI = 3.141592653589793;
 
@@ -258,10 +290,46 @@ void main() {
 
 #ifndef STANDARDMATERIAL_UNLIT
     // calculate non-linear roughness from linear perceptualRoughness
+#    ifdef STANDARDMATERIAL_METALLIC_ROUGHNESS_TEXTURE
+    vec4 metallic_roughness = texture(sampler2D(StandardMaterial_metallic_roughness_texture, StandardMaterial_metallic_roughness_texture_sampler), v_Uv);
+    // Sampling from GLTF standard channels for now
+    float metallic = metallic * metallic_roughness.b;
+    float perceptual_roughness = perceptual_roughness * metallic_roughness.g;
+#    endif
+
     float roughness = perceptualRoughnessToRoughness(perceptual_roughness);
 
     vec3 N = normalize(v_WorldNormal);
 
+#    ifdef STANDARDMATERIAL_NORMAL_MAP
+    vec3 T = normalize(v_WorldTangent.xyz);
+    vec3 B = cross(N, T) * v_WorldTangent.w;
+#    endif
+
+#    ifdef STANDARDMATERIAL_DOUBLE_SIDED
+    N = gl_FrontFacing ? N : -N;
+#        ifdef STANDARDMATERIAL_NORMAL_MAP
+    T = gl_FrontFacing ? T : -T;
+    B = gl_FrontFacing ? B : -B;
+#        endif
+#    endif
+
+#    ifdef STANDARDMATERIAL_NORMAL_MAP
+    mat3 TBN = mat3(T, B, N);
+    N = TBN * normalize(texture(sampler2D(StandardMaterial_normal_map, StandardMaterial_normal_map_sampler), v_Uv).rgb * 2.0 - 1.0);
+#    endif
+
+#    ifdef STANDARDMATERIAL_OCCLUSION_TEXTURE
+    float occlusion = texture(sampler2D(StandardMaterial_occlusion_texture, StandardMaterial_occlusion_texture_sampler), v_Uv).r;
+#    else
+    float occlusion = 1.0;
+#    endif
+
+#    ifdef STANDARDMATERIAL_EMISSIVE_TEXTURE
+    // TODO use .a for exposure compensation in HDR
+    emissive.rgb *= texture(sampler2D(StandardMaterial_emissive_texture, StandardMaterial_emissive_texture_sampler), v_Uv).rgb;
+#    endif
+
     vec3 V = normalize(CameraPos.xyz - v_WorldPosition.xyz);
     // Neubelt and Pettineo 2013, "Crafting a Next-gen Material Pipeline for The Order: 1886"
     float NdotV = max(dot(N, V), 1e-4);
@@ -310,7 +378,9 @@ void main() {
     vec3 diffuse_ambient = EnvBRDFApprox(diffuseColor, 1.0, NdotV);
     vec3 specular_ambient = EnvBRDFApprox(F0, perceptual_roughness, NdotV);
 
-    output_color.rgb = light_accum + (diffuse_ambient + specular_ambient) * AmbientColor;
+    output_color.rgb = light_accum;
+    output_color.rgb += (diffuse_ambient + specular_ambient) * AmbientColor * occlusion;
+    output_color.rgb += emissive.rgb * output_color.a;
 
     // tone_mapping
     output_color.rgb = reinhard_luminance(output_color.rgb);

crates/bevy_pbr/src/render_graph/pbr_pipeline/pbr.vert

@@ -4,6 +4,10 @@ layout(location = 0) in vec3 Vertex_Position;
 layout(location = 1) in vec3 Vertex_Normal;
 layout(location = 2) in vec2 Vertex_Uv;
 
+#ifdef STANDARDMATERIAL_NORMAL_MAP
+layout(location = 3) in vec4 Vertex_Tangent;
+#endif
+
 layout(location = 0) out vec3 v_WorldPosition;
 layout(location = 1) out vec3 v_WorldNormal;
 layout(location = 2) out vec2 v_Uv;
@@ -12,6 +16,10 @@ layout(set = 0, binding = 0) uniform CameraViewProj {
     mat4 ViewProj;
 };
 
+#ifdef STANDARDMATERIAL_NORMAL_MAP
+layout(location = 3) out vec4 v_WorldTangent;
+#endif
+
 layout(set = 2, binding = 0) uniform Transform {
     mat4 Model;
 };
@@ -21,5 +29,8 @@ void main() {
     v_WorldPosition = world_position.xyz;
     v_WorldNormal = mat3(Model) * Vertex_Normal;
     v_Uv = Vertex_Uv;
+#ifdef STANDARDMATERIAL_NORMAL_MAP
+    v_WorldTangent = vec4(mat3(Model) * Vertex_Tangent.xyz, Vertex_Tangent.w);
+#endif
     gl_Position = ViewProj * world_position;
 }

crates/bevy_render/src/mesh/mesh.rs

@@ -237,6 +237,9 @@ impl Mesh {
     /// The direction the vertex normal is facing in.
     /// Use in conjunction with [`Mesh::set_attribute`]
     pub const ATTRIBUTE_NORMAL: &'static str = "Vertex_Normal";
+    /// The direction of the vertex tangent. Used for normal mapping
+    pub const ATTRIBUTE_TANGENT: &'static str = "Vertex_Tangent";
+
     /// Where the vertex is located in space. Use in conjunction with [`Mesh::set_attribute`]
     pub const ATTRIBUTE_POSITION: &'static str = "Vertex_Position";
     /// Texture coordinates for the vertex. Use in conjunction with [`Mesh::set_attribute`]

crates/bevy_render/src/shader/mod.rs

@@ -23,3 +23,4 @@ pub struct ShaderLayout {
 
 pub const GL_VERTEX_INDEX: &str = "gl_VertexIndex";
 pub const GL_INSTANCE_INDEX: &str = "gl_InstanceIndex";
+pub const GL_FRONT_FACING: &str = "gl_FrontFacing";

crates/bevy_render/src/shader/shader_reflect.rs

@@ -3,7 +3,7 @@ use crate::{
         BindGroupDescriptor, BindType, BindingDescriptor, BindingShaderStage, InputStepMode,
         UniformProperty, VertexAttribute, VertexBufferLayout, VertexFormat,
     },
-    shader::{ShaderLayout, GL_INSTANCE_INDEX, GL_VERTEX_INDEX},
+    shader::{ShaderLayout, GL_FRONT_FACING, GL_INSTANCE_INDEX, GL_VERTEX_INDEX},
     texture::{TextureSampleType, TextureViewDimension},
 };
 use bevy_core::AsBytes;
@@ -33,6 +33,7 @@ impl ShaderLayout {
                 for input_variable in module.enumerate_input_variables(None).unwrap() {
                     if input_variable.name == GL_VERTEX_INDEX
                         || input_variable.name == GL_INSTANCE_INDEX
+                        || input_variable.name == GL_FRONT_FACING
                     {
                         continue;
                     }

examples/3d/load_gltf.rs

@@ -1,21 +1,39 @@
-use bevy::prelude::*;
+use bevy::{pbr::AmbientLight, prelude::*};
 
 fn main() {
     App::build()
+        .insert_resource(AmbientLight {
+            color: Color::WHITE,
+            brightness: 1.0 / 5.0f32,
+        })
         .insert_resource(Msaa { samples: 4 })
         .add_plugins(DefaultPlugins)
         .add_startup_system(setup.system())
+        .add_system(rotator_system.system())
         .run();
 }
 
 fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
     commands.spawn_scene(asset_server.load("models/FlightHelmet/FlightHelmet.gltf#Scene0"));
-    commands.spawn_bundle(LightBundle {
-        transform: Transform::from_xyz(4.0, 5.0, 4.0),
-        ..Default::default()
-    });
     commands.spawn_bundle(PerspectiveCameraBundle {
         transform: Transform::from_xyz(0.7, 0.7, 1.0).looking_at(Vec3::new(0.0, 0.3, 0.0), Vec3::Y),
         ..Default::default()
     });
+    commands
+        .spawn_bundle(LightBundle {
+            transform: Transform::from_xyz(3.0, 5.0, 3.0),
+            ..Default::default()
+        })
+        .insert(Rotates);
+}
+
+/// this component indicates what entities should rotate
+struct Rotates;
+
+fn rotator_system(time: Res<Time>, mut query: Query<&mut Transform, With<Rotates>>) {
+    for mut transform in query.iter_mut() {
+        *transform = Transform::from_rotation(Quat::from_rotation_y(
+            (4.0 * std::f32::consts::PI / 20.0) * time.delta_seconds(),
+        )) * *transform;
+    }
 }