bevy/assets/shaders/extended_material.wgsl
robtfm c99351f7c2
allow extensions to StandardMaterial (#7820)
# Objective

allow extending `Material`s (including the built in `StandardMaterial`)
with custom vertex/fragment shaders and additional data, to easily get
pbr lighting with custom modifications, or otherwise extend a base
material.

# Solution

- added `ExtendedMaterial<B: Material, E: MaterialExtension>` which
contains a base material and a user-defined extension.
- added example `extended_material` showing how to use it
- modified AsBindGroup to have "unprepared" functions that return raw
resources / layout entries so that the extended material can combine
them

note: doesn't currently work with array resources, as i can't figure out
how to make the OwnedBindingResource::get_binding() work, as wgpu
requires a `&'a[&'a TextureView]` and i have a `Vec<TextureView>`.

# Migration Guide

manual implementations of `AsBindGroup` will need to be adjusted, the
changes are pretty straightforward and can be seen in the diff for e.g.
the `texture_binding_array` example.

---------

Co-authored-by: Robert Swain <robert.swain@gmail.com>
2023-10-17 21:28:08 +00:00

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2.0 KiB
WebGPU Shading Language

#import bevy_pbr::pbr_fragment pbr_input_from_standard_material
#import bevy_pbr::pbr_functions alpha_discard
#ifdef PREPASS_PIPELINE
#import bevy_pbr::prepass_io VertexOutput, FragmentOutput
#import bevy_pbr::pbr_deferred_functions deferred_output
#else
#import bevy_pbr::forward_io VertexOutput, FragmentOutput
#import bevy_pbr::pbr_functions apply_pbr_lighting, main_pass_post_lighting_processing
#endif
struct MyExtendedMaterial {
quantize_steps: u32,
}
@group(1) @binding(100)
var<uniform> my_extended_material: MyExtendedMaterial;
@fragment
fn fragment(
in: VertexOutput,
@builtin(front_facing) is_front: bool,
) -> FragmentOutput {
// generate a PbrInput struct from the StandardMaterial bindings
var pbr_input = pbr_input_from_standard_material(in, is_front);
// we can optionally modify the input before lighting and alpha_discard is applied
pbr_input.material.base_color.b = pbr_input.material.base_color.r;
// alpha discard
pbr_input.material.base_color = alpha_discard(pbr_input.material, pbr_input.material.base_color);
#ifdef PREPASS_PIPELINE
// in deferred mode we can't modify anything after that, as lighting is run in a separate fullscreen shader.
let out = deferred_output(in, pbr_input);
#else
var out: FragmentOutput;
// apply lighting
out.color = apply_pbr_lighting(pbr_input);
// we can optionally modify the lit color before post-processing is applied
out.color = vec4<f32>(vec4<u32>(out.color * f32(my_extended_material.quantize_steps))) / f32(my_extended_material.quantize_steps);
// apply in-shader post processing (fog, alpha-premultiply, and also tonemapping, debanding if the camera is non-hdr)
// note this does not include fullscreen postprocessing effects like bloom.
out.color = main_pass_post_lighting_processing(pbr_input, out.color);
// we can optionally modify the final result here
out.color = out.color * 2.0;
#endif
return out;
}