bevy/assets/shaders/array_texture.wgsl
Marco Buono 91c467ebfc
Gate diffuse and specular transmission behind shader defs (#11627)
# Objective

- Address #10338

## Solution

- When implementing specular and diffuse transmission, I inadvertently
introduced a performance regression. On high-end hardware it is barely
noticeable, but **for lower-end hardware it can be pretty brutal**. If I
understand it correctly, this is likely due to use of masking by the GPU
to implement control flow, which means that you still pay the price for
the branches you don't take;
- To avoid that, this PR introduces new shader defs (controlled via
`StandardMaterialKey`) that conditionally include the transmission
logic, that way the shader code for both types of transmission isn't
even sent to the GPU if you're not using them;
- This PR also renames ~~`STANDARDMATERIAL_NORMAL_MAP`~~ to
`STANDARD_MATERIAL_NORMAL_MAP` for consistency with the naming
convention used elsewhere in the codebase. (Drive-by fix)

---

## Changelog

- Added new shader defs, set when using transmission in the
`StandardMaterial`:
  - `STANDARD_MATERIAL_SPECULAR_TRANSMISSION`;
  - `STANDARD_MATERIAL_DIFFUSE_TRANSMISSION`;
  - `STANDARD_MATERIAL_SPECULAR_OR_DIFFUSE_TRANSMISSION`.
- Fixed performance regression caused by the introduction of
transmission, by gating transmission shader logic behind the newly
introduced shader defs;
- Renamed ~~`STANDARDMATERIAL_NORMAL_MAP`~~ to
`STANDARD_MATERIAL_NORMAL_MAP` for consistency;

## Migration Guide

- If you were using `#ifdef STANDARDMATERIAL_NORMAL_MAP` on your shader
code, make sure to update the name to `STANDARD_MATERIAL_NORMAL_MAP`;
(with an underscore between `STANDARD` and `MATERIAL`)
2024-02-02 15:01:56 +00:00

56 lines
1.7 KiB
WebGPU Shading Language

#import bevy_pbr::{
forward_io::VertexOutput,
mesh_view_bindings::view,
pbr_types::{STANDARD_MATERIAL_FLAGS_DOUBLE_SIDED_BIT, PbrInput, pbr_input_new},
pbr_functions as fns,
}
#import bevy_core_pipeline::tonemapping::tone_mapping
@group(2) @binding(0) var my_array_texture: texture_2d_array<f32>;
@group(2) @binding(1) var my_array_texture_sampler: sampler;
@fragment
fn fragment(
@builtin(front_facing) is_front: bool,
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
let layer = i32(mesh.world_position.x) & 0x3;
// Prepare a 'processed' StandardMaterial by sampling all textures to resolve
// the material members
var pbr_input: PbrInput = pbr_input_new();
pbr_input.material.base_color = textureSample(my_array_texture, my_array_texture_sampler, mesh.uv, layer);
#ifdef VERTEX_COLORS
pbr_input.material.base_color = pbr_input.material.base_color * mesh.color;
#endif
let double_sided = (pbr_input.material.flags & STANDARD_MATERIAL_FLAGS_DOUBLE_SIDED_BIT) != 0u;
pbr_input.frag_coord = mesh.position;
pbr_input.world_position = mesh.world_position;
pbr_input.world_normal = fns::prepare_world_normal(
mesh.world_normal,
double_sided,
is_front,
);
pbr_input.is_orthographic = view.projection[3].w == 1.0;
pbr_input.N = fns::apply_normal_mapping(
pbr_input.material.flags,
mesh.world_normal,
double_sided,
is_front,
#ifdef VERTEX_TANGENTS
#ifdef STANDARD_MATERIAL_NORMAL_MAP
mesh.world_tangent,
#endif
#endif
mesh.uv,
view.mip_bias,
);
pbr_input.V = fns::calculate_view(mesh.world_position, pbr_input.is_orthographic);
return tone_mapping(fns::apply_pbr_lighting(pbr_input), view.color_grading);
}