01043bf83a
# Objective Standard material defaults are currently strange, and the docs are wrong re: metallic. ## Solution Change the defaults to be similar to [Godot](https://github.com/godotengine/godot/pull/62756). --- ## Changelog #### Changed - `StandardMaterial` now defaults to a dielectric material (0.0 `metallic`) with 0.5 `perceptual_roughness`. ## Migration Guide `StandardMaterial`'s default have now changed to be a fully dielectric material with medium roughness. If you want to use the old defaults, you can set `perceptual_roughness = 0.089` and `metallic = 0.01` (though metallic should generally only be set to 0.0 or 1.0).
473 lines
19 KiB
Rust
473 lines
19 KiB
Rust
use crate::{
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AlphaMode, Material, MaterialPipeline, MaterialPipelineKey, PBR_PREPASS_SHADER_HANDLE,
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PBR_SHADER_HANDLE,
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};
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use bevy_asset::Handle;
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use bevy_math::Vec4;
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use bevy_reflect::{std_traits::ReflectDefault, FromReflect, Reflect, TypeUuid};
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use bevy_render::{
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color::Color, mesh::MeshVertexBufferLayout, render_asset::RenderAssets, render_resource::*,
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texture::Image,
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};
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/// A material with "standard" properties used in PBR lighting
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/// Standard property values with pictures here
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/// <https://google.github.io/filament/Material%20Properties.pdf>.
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///
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/// May be created directly from a [`Color`] or an [`Image`].
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#[derive(AsBindGroup, Reflect, FromReflect, Debug, Clone, TypeUuid)]
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#[uuid = "7494888b-c082-457b-aacf-517228cc0c22"]
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#[bind_group_data(StandardMaterialKey)]
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#[uniform(0, StandardMaterialUniform)]
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#[reflect(Default, Debug)]
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pub struct StandardMaterial {
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/// The color of the surface of the material before lighting.
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///
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/// Doubles as diffuse albedo for non-metallic, specular for metallic and a mix for everything
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/// in between. If used together with a `base_color_texture`, this is factored into the final
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/// base color as `base_color * base_color_texture_value`
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///
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/// Defaults to [`Color::WHITE`].
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pub base_color: Color,
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/// The texture component of the material's color before lighting.
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/// The actual pre-lighting color is `base_color * this_texture`.
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///
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/// See [`base_color`] for details.
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///
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/// You should set `base_color` to [`Color::WHITE`] (the default)
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/// if you want the texture to show as-is.
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///
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/// Setting `base_color` to something else than white will tint
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/// the texture. For example, setting `base_color` to pure red will
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/// tint the texture red.
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///
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/// [`base_color`]: StandardMaterial::base_color
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#[texture(1)]
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#[sampler(2)]
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pub base_color_texture: Option<Handle<Image>>,
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// Use a color for user friendliness even though we technically don't use the alpha channel
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// Might be used in the future for exposure correction in HDR
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/// Color the material "emits" to the camera.
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///
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/// This is typically used for monitor screens or LED lights.
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/// Anything that can be visible even in darkness.
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///
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/// The emissive color is added to what would otherwise be the material's visible color.
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/// This means that for a light emissive value, in darkness,
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/// you will mostly see the emissive component.
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///
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/// The default emissive color is black, which doesn't add anything to the material color.
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///
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/// Note that **an emissive material won't light up surrounding areas like a light source**,
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/// it just adds a value to the color seen on screen.
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pub emissive: Color,
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/// The emissive map, multiplies pixels with [`emissive`]
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/// to get the final "emitting" color of a surface.
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///
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/// This color is multiplied by [`emissive`] to get the final emitted color.
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/// Meaning that you should set [`emissive`] to [`Color::WHITE`]
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/// if you want to use the full range of color of the emissive texture.
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///
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/// [`emissive`]: StandardMaterial::emissive
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#[texture(3)]
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#[sampler(4)]
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pub emissive_texture: Option<Handle<Image>>,
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/// Linear perceptual roughness, clamped to `[0.089, 1.0]` in the shader.
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///
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/// Defaults to `0.5`.
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///
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/// Low values result in a "glossy" material with specular highlights,
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/// while values close to `1` result in rough materials.
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///
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/// If used together with a roughness/metallic texture, this is factored into the final base
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/// color as `roughness * roughness_texture_value`.
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///
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/// 0.089 is the minimum floating point value that won't be rounded down to 0 in the
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/// calculations used.
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//
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// Technically for 32-bit floats, 0.045 could be used.
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// See <https://google.github.io/filament/Filament.html#materialsystem/parameterization/>
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pub perceptual_roughness: f32,
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/// How "metallic" the material appears, within `[0.0, 1.0]`.
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///
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/// This should be set to 0.0 for dielectric materials or 1.0 for metallic materials.
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/// For a hybrid surface such as corroded metal, you may need to use in-between values.
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///
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/// Defaults to `0.00`, for dielectric.
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///
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/// If used together with a roughness/metallic texture, this is factored into the final base
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/// color as `metallic * metallic_texture_value`.
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pub metallic: f32,
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/// Metallic and roughness maps, stored as a single texture.
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///
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/// The blue channel contains metallic values,
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/// and the green channel contains the roughness values.
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/// Other channels are unused.
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///
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/// Those values are multiplied by the scalar ones of the material,
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/// see [`metallic`] and [`perceptual_roughness`] for details.
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///
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/// Note that with the default values of [`metallic`] and [`perceptual_roughness`],
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/// setting this texture has no effect. If you want to exclusively use the
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/// `metallic_roughness_texture` values for your material, make sure to set [`metallic`]
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/// and [`perceptual_roughness`] to `1.0`.
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///
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/// [`metallic`]: StandardMaterial::metallic
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/// [`perceptual_roughness`]: StandardMaterial::perceptual_roughness
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#[texture(5)]
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#[sampler(6)]
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pub metallic_roughness_texture: Option<Handle<Image>>,
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/// Specular intensity for non-metals on a linear scale of `[0.0, 1.0]`.
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///
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/// Use the value as a way to control the intensity of the
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/// specular highlight of the material, i.e. how reflective is the material,
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/// rather than the physical property "reflectance."
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///
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/// Set to `0.0`, no specular highlight is visible, the highlight is strongest
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/// when `reflectance` is set to `1.0`.
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///
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/// Defaults to `0.5` which is mapped to 4% reflectance in the shader.
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#[doc(alias = "specular_intensity")]
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pub reflectance: f32,
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/// Used to fake the lighting of bumps and dents on a material.
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///
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/// A typical usage would be faking cobblestones on a flat plane mesh in 3D.
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///
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/// # Notes
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///
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/// Normal mapping with `StandardMaterial` and the core bevy PBR shaders requires:
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/// - A normal map texture
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/// - Vertex UVs
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/// - Vertex tangents
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/// - Vertex normals
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///
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/// Tangents do not have to be stored in your model,
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/// they can be generated using the [`Mesh::generate_tangents`] method.
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/// If your material has a normal map, but still renders as a flat surface,
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/// make sure your meshes have their tangents set.
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///
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/// [`Mesh::generate_tangents`]: bevy_render::mesh::Mesh::generate_tangents
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#[texture(9)]
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#[sampler(10)]
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pub normal_map_texture: Option<Handle<Image>>,
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/// Normal map textures authored for DirectX have their y-component flipped. Set this to flip
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/// it to right-handed conventions.
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pub flip_normal_map_y: bool,
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/// Specifies the level of exposure to ambient light.
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///
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/// This is usually generated and stored automatically ("baked") by 3D-modelling software.
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///
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/// Typically, steep concave parts of a model (such as the armpit of a shirt) are darker,
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/// because they have little exposed to light.
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/// An occlusion map specifies those parts of the model that light doesn't reach well.
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///
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/// The material will be less lit in places where this texture is dark.
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/// This is similar to ambient occlusion, but built into the model.
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#[texture(7)]
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#[sampler(8)]
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pub occlusion_texture: Option<Handle<Image>>,
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/// Support two-sided lighting by automatically flipping the normals for "back" faces
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/// within the PBR lighting shader.
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///
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/// Defaults to `false`.
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/// This does not automatically configure backface culling,
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/// which can be done via `cull_mode`.
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pub double_sided: bool,
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/// Whether to cull the "front", "back" or neither side of a mesh.
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/// If set to `None`, the two sides of the mesh are visible.
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///
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/// Defaults to `Some(Face::Back)`.
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/// In bevy, the order of declaration of a triangle's vertices
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/// in [`Mesh`] defines the triangle's front face.
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///
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/// When a triangle is in a viewport,
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/// if its vertices appear counter-clockwise from the viewport's perspective,
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/// then the viewport is seeing the triangle's front face.
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/// Conversely, if the vertices appear clockwise, you are seeing the back face.
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///
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/// In short, in bevy, front faces winds counter-clockwise.
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///
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/// Your 3D editing software should manage all of that.
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///
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/// [`Mesh`]: bevy_render::mesh::Mesh
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// TODO: include this in reflection somehow (maybe via remote types like serde https://serde.rs/remote-derive.html)
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#[reflect(ignore)]
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pub cull_mode: Option<Face>,
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/// Whether to apply only the base color to this material.
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///
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/// Normals, occlusion textures, roughness, metallic, reflectance, emissive,
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/// shadows, alpha mode and ambient light are ignored if this is set to `true`.
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pub unlit: bool,
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/// Whether to enable fog for this material.
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pub fog_enabled: bool,
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/// How to apply the alpha channel of the `base_color_texture`.
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///
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/// See [`AlphaMode`] for details. Defaults to [`AlphaMode::Opaque`].
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pub alpha_mode: AlphaMode,
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/// Re-arrange render ordering.
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///
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/// A material with a positive depth bias will render closer to the
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/// camera while negative values cause the material to render behind
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/// other objects. This is independent of the viewport.
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///
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/// `depth_bias` only affects render ordering. This means that for opaque materials,
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/// `depth_bias` will only have any effect if two materials are overlapping,
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/// which only serves as a [z-fighting] resolver.
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///
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/// `depth_bias` can however reorder [`AlphaMode::Blend`] materials.
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/// This is useful if your transparent materials are not rendering
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/// in the expected order.
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///
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/// [z-fighting]: https://en.wikipedia.org/wiki/Z-fighting
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pub depth_bias: f32,
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}
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impl Default for StandardMaterial {
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fn default() -> Self {
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StandardMaterial {
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// White because it gets multiplied with texture values if someone uses
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// a texture.
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base_color: Color::rgb(1.0, 1.0, 1.0),
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base_color_texture: None,
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emissive: Color::BLACK,
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emissive_texture: None,
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// Matches Blender's default roughness.
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perceptual_roughness: 0.5,
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// Metallic should generally be set to 0.0 or 1.0.
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metallic: 0.0,
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metallic_roughness_texture: None,
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// Minimum real-world reflectance is 2%, most materials between 2-5%
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// Expressed in a linear scale and equivalent to 4% reflectance see
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// <https://google.github.io/filament/Material%20Properties.pdf>
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reflectance: 0.5,
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occlusion_texture: None,
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normal_map_texture: None,
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flip_normal_map_y: false,
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double_sided: false,
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cull_mode: Some(Face::Back),
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unlit: false,
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fog_enabled: true,
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alpha_mode: AlphaMode::Opaque,
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depth_bias: 0.0,
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}
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}
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}
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impl From<Color> for StandardMaterial {
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fn from(color: Color) -> Self {
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StandardMaterial {
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base_color: color,
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alpha_mode: if color.a() < 1.0 {
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AlphaMode::Blend
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} else {
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AlphaMode::Opaque
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},
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..Default::default()
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}
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}
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}
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impl From<Handle<Image>> for StandardMaterial {
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fn from(texture: Handle<Image>) -> Self {
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StandardMaterial {
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base_color_texture: Some(texture),
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..Default::default()
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}
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}
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}
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// NOTE: These must match the bit flags in bevy_pbr/src/render/pbr_types.wgsl!
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bitflags::bitflags! {
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/// Bitflags info about the material a shader is currently rendering.
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/// This is accessible in the shader in the [`StandardMaterialUniform`]
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#[repr(transparent)]
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pub struct StandardMaterialFlags: u32 {
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const BASE_COLOR_TEXTURE = (1 << 0);
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const EMISSIVE_TEXTURE = (1 << 1);
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const METALLIC_ROUGHNESS_TEXTURE = (1 << 2);
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const OCCLUSION_TEXTURE = (1 << 3);
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const DOUBLE_SIDED = (1 << 4);
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const UNLIT = (1 << 5);
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const TWO_COMPONENT_NORMAL_MAP = (1 << 6);
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const FLIP_NORMAL_MAP_Y = (1 << 7);
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const FOG_ENABLED = (1 << 8);
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const ALPHA_MODE_RESERVED_BITS = (Self::ALPHA_MODE_MASK_BITS << Self::ALPHA_MODE_SHIFT_BITS); // ← Bitmask reserving bits for the `AlphaMode`
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const ALPHA_MODE_OPAQUE = (0 << Self::ALPHA_MODE_SHIFT_BITS); // ← Values are just sequential values bitshifted into
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const ALPHA_MODE_MASK = (1 << Self::ALPHA_MODE_SHIFT_BITS); // the bitmask, and can range from 0 to 7.
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const ALPHA_MODE_BLEND = (2 << Self::ALPHA_MODE_SHIFT_BITS); //
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const ALPHA_MODE_PREMULTIPLIED = (3 << Self::ALPHA_MODE_SHIFT_BITS); //
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const ALPHA_MODE_ADD = (4 << Self::ALPHA_MODE_SHIFT_BITS); // Right now only values 0–5 are used, which still gives
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const ALPHA_MODE_MULTIPLY = (5 << Self::ALPHA_MODE_SHIFT_BITS); // ← us "room" for two more modes without adding more bits
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const NONE = 0;
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const UNINITIALIZED = 0xFFFF;
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}
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}
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impl StandardMaterialFlags {
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const ALPHA_MODE_MASK_BITS: u32 = 0b111;
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const ALPHA_MODE_SHIFT_BITS: u32 = 32 - Self::ALPHA_MODE_MASK_BITS.count_ones();
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}
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/// The GPU representation of the uniform data of a [`StandardMaterial`].
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#[derive(Clone, Default, ShaderType)]
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pub struct StandardMaterialUniform {
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/// Doubles as diffuse albedo for non-metallic, specular for metallic and a mix for everything
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/// in between.
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pub base_color: Vec4,
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// Use a color for user friendliness even though we technically don't use the alpha channel
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// Might be used in the future for exposure correction in HDR
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pub emissive: Vec4,
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/// Linear perceptual roughness, clamped to [0.089, 1.0] in the shader
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/// Defaults to minimum of 0.089
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pub roughness: f32,
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/// From [0.0, 1.0], dielectric to pure metallic
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pub metallic: f32,
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/// Specular intensity for non-metals on a linear scale of [0.0, 1.0]
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/// defaults to 0.5 which is mapped to 4% reflectance in the shader
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pub reflectance: f32,
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/// The [`StandardMaterialFlags`] accessible in the `wgsl` shader.
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pub flags: u32,
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/// When the alpha mode mask flag is set, any base color alpha above this cutoff means fully opaque,
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/// and any below means fully transparent.
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pub alpha_cutoff: f32,
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}
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impl AsBindGroupShaderType<StandardMaterialUniform> for StandardMaterial {
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fn as_bind_group_shader_type(&self, images: &RenderAssets<Image>) -> StandardMaterialUniform {
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let mut flags = StandardMaterialFlags::NONE;
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if self.base_color_texture.is_some() {
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flags |= StandardMaterialFlags::BASE_COLOR_TEXTURE;
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}
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if self.emissive_texture.is_some() {
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flags |= StandardMaterialFlags::EMISSIVE_TEXTURE;
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}
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if self.metallic_roughness_texture.is_some() {
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flags |= StandardMaterialFlags::METALLIC_ROUGHNESS_TEXTURE;
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}
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if self.occlusion_texture.is_some() {
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flags |= StandardMaterialFlags::OCCLUSION_TEXTURE;
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}
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if self.double_sided {
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flags |= StandardMaterialFlags::DOUBLE_SIDED;
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}
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if self.unlit {
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flags |= StandardMaterialFlags::UNLIT;
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}
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if self.fog_enabled {
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flags |= StandardMaterialFlags::FOG_ENABLED;
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}
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let has_normal_map = self.normal_map_texture.is_some();
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if has_normal_map {
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if let Some(texture) = images.get(self.normal_map_texture.as_ref().unwrap()) {
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match texture.texture_format {
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// All 2-component unorm formats
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TextureFormat::Rg8Unorm
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| TextureFormat::Rg16Unorm
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| TextureFormat::Bc5RgUnorm
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| TextureFormat::EacRg11Unorm => {
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flags |= StandardMaterialFlags::TWO_COMPONENT_NORMAL_MAP;
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}
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_ => {}
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}
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}
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if self.flip_normal_map_y {
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flags |= StandardMaterialFlags::FLIP_NORMAL_MAP_Y;
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}
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}
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// NOTE: 0.5 is from the glTF default - do we want this?
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let mut alpha_cutoff = 0.5;
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match self.alpha_mode {
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AlphaMode::Opaque => flags |= StandardMaterialFlags::ALPHA_MODE_OPAQUE,
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AlphaMode::Mask(c) => {
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alpha_cutoff = c;
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flags |= StandardMaterialFlags::ALPHA_MODE_MASK;
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}
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AlphaMode::Blend => flags |= StandardMaterialFlags::ALPHA_MODE_BLEND,
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AlphaMode::Premultiplied => flags |= StandardMaterialFlags::ALPHA_MODE_PREMULTIPLIED,
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AlphaMode::Add => flags |= StandardMaterialFlags::ALPHA_MODE_ADD,
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AlphaMode::Multiply => flags |= StandardMaterialFlags::ALPHA_MODE_MULTIPLY,
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};
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StandardMaterialUniform {
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base_color: self.base_color.as_linear_rgba_f32().into(),
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emissive: self.emissive.into(),
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roughness: self.perceptual_roughness,
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metallic: self.metallic,
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reflectance: self.reflectance,
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flags: flags.bits(),
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alpha_cutoff,
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}
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}
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}
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#[derive(Clone, PartialEq, Eq, Hash)]
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pub struct StandardMaterialKey {
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normal_map: bool,
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cull_mode: Option<Face>,
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}
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impl From<&StandardMaterial> for StandardMaterialKey {
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fn from(material: &StandardMaterial) -> Self {
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StandardMaterialKey {
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normal_map: material.normal_map_texture.is_some(),
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cull_mode: material.cull_mode,
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}
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}
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}
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impl Material for StandardMaterial {
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fn specialize(
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_pipeline: &MaterialPipeline<Self>,
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descriptor: &mut RenderPipelineDescriptor,
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_layout: &MeshVertexBufferLayout,
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key: MaterialPipelineKey<Self>,
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) -> Result<(), SpecializedMeshPipelineError> {
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if key.bind_group_data.normal_map {
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if let Some(fragment) = descriptor.fragment.as_mut() {
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fragment
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.shader_defs
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.push("STANDARDMATERIAL_NORMAL_MAP".into());
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}
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}
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descriptor.primitive.cull_mode = key.bind_group_data.cull_mode;
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if let Some(label) = &mut descriptor.label {
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*label = format!("pbr_{}", *label).into();
|
||
}
|
||
Ok(())
|
||
}
|
||
|
||
fn prepass_fragment_shader() -> ShaderRef {
|
||
PBR_PREPASS_SHADER_HANDLE.typed().into()
|
||
}
|
||
|
||
fn fragment_shader() -> ShaderRef {
|
||
PBR_SHADER_HANDLE.typed().into()
|
||
}
|
||
|
||
#[inline]
|
||
fn alpha_mode(&self) -> AlphaMode {
|
||
self.alpha_mode
|
||
}
|
||
|
||
#[inline]
|
||
fn depth_bias(&self) -> f32 {
|
||
self.depth_bias
|
||
}
|
||
}
|