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pbr shader cleanup (#10105)
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# Objective

cleanup some pbr shader code. improve shader stage io consistency and
make pbr.wgsl (probably many people's first foray into bevy shader code)
a little more human-readable. also fix a couple of small issues with
deferred rendering.

## Solution

mesh_vertex_output: 
- rename to forward_io (to align with prepass_io)
- rename `MeshVertexOutput` to `VertexOutput` (to align with prepass_io)
- move `Vertex` from mesh.wgsl into here (to align with prepass_io)

prepass_io: 
- remove `FragmentInput`, use `VertexOutput` directly (to align with
forward_io)
- rename `VertexOutput::clip_position` to `position` (to align with
forward_io)

pbr.wgsl:
- restructure so we don't need `#ifdefs` on the actual entrypoint, use
VertexOutput and FragmentOutput in all cases and use #ifdefs to import
the right struct definitions.
- rearrange to make the flow clearer
- move alpha_discard up from `pbr_functions::pbr` to avoid needing to
call it on some branches and not others
- add a bunch of comments

deferred_lighting:
- move ssao into the `!unlit` block to reflect forward behaviour
correctly
- fix compile error with deferred + premultiply_alpha

## Migration Guide

in custom material shaders:
- `pbr_functions::pbr` no longer calls to
`pbr_functions::alpha_discard`. if you were using the `pbr` function in
a custom shader with alpha mask mode you now also need to call
alpha_discard manually
- rename imports of `bevy_pbr::mesh_vertex_output` to
`bevy_pbr::forward_io`
- rename instances of `MeshVertexOutput` to `VertexOutput`

in custom material prepass shaders:
- rename instances of `VertexOutput::clip_position` to
`VertexOutput::position`
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robtfm authored Oct 13, 2023
1 parent 26ecfcf commit 979c409
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Showing 26 changed files with 173 additions and 202 deletions.
4 changes: 2 additions & 2 deletions assets/shaders/animate_shader.wgsl
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
// The time since startup data is in the globals binding which is part of the mesh_view_bindings import
#import bevy_pbr::mesh_view_bindings globals
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput

fn oklab_to_linear_srgb(c: vec3<f32>) -> vec3<f32> {
let L = c.x;
Expand All @@ -23,7 +23,7 @@ fn oklab_to_linear_srgb(c: vec3<f32>) -> vec3<f32> {
}

@fragment
fn fragment(in: MeshVertexOutput) -> @location(0) vec4<f32> {
fn fragment(in: VertexOutput) -> @location(0) vec4<f32> {
let speed = 2.0;
// The globals binding contains various global values like time
// which is the time since startup in seconds
Expand Down
4 changes: 2 additions & 2 deletions assets/shaders/array_texture.wgsl
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput
#import bevy_pbr::mesh_view_bindings view
#import bevy_pbr::pbr_types STANDARD_MATERIAL_FLAGS_DOUBLE_SIDED_BIT, PbrInput, pbr_input_new
#import bevy_core_pipeline::tonemapping tone_mapping
Expand All @@ -10,7 +10,7 @@
@fragment
fn fragment(
@builtin(front_facing) is_front: bool,
mesh: MeshVertexOutput,
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
let layer = i32(mesh.world_position.x) & 0x3;

Expand Down
4 changes: 2 additions & 2 deletions assets/shaders/cubemap_unlit.wgsl
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput

#ifdef CUBEMAP_ARRAY
@group(1) @binding(0) var base_color_texture: texture_cube_array<f32>;
Expand All @@ -10,7 +10,7 @@

@fragment
fn fragment(
mesh: MeshVertexOutput,
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
let fragment_position_view_lh = mesh.world_position.xyz * vec3<f32>(1.0, 1.0, -1.0);
return textureSample(
Expand Down
4 changes: 2 additions & 2 deletions assets/shaders/custom_material.wgsl
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput
// we can import items from shader modules in the assets folder with a quoted path
#import "shaders/custom_material_import.wgsl" COLOR_MULTIPLIER

Expand All @@ -12,7 +12,7 @@ struct CustomMaterial {

@fragment
fn fragment(
mesh: MeshVertexOutput,
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
return material.color * textureSample(base_color_texture, base_color_sampler, mesh.uv) * COLOR_MULTIPLIER;
}
4 changes: 2 additions & 2 deletions assets/shaders/custom_material_screenspace_texture.wgsl
Original file line number Diff line number Diff line change
@@ -1,13 +1,13 @@
#import bevy_pbr::mesh_view_bindings view
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput
#import bevy_pbr::utils coords_to_viewport_uv

@group(1) @binding(0) var texture: texture_2d<f32>;
@group(1) @binding(1) var texture_sampler: sampler;

@fragment
fn fragment(
mesh: MeshVertexOutput,
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
let viewport_uv = coords_to_viewport_uv(mesh.position.xy, view.viewport);
let color = textureSample(texture, texture_sampler, viewport_uv);
Expand Down
4 changes: 2 additions & 2 deletions assets/shaders/fallback_image_test.wgsl
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
#import bevy_pbr::mesh_view_bindings
#import bevy_pbr::mesh_bindings
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput

@group(1) @binding(0) var test_texture_1d: texture_1d<f32>;
@group(1) @binding(1) var test_texture_1d_sampler: sampler;
Expand All @@ -21,4 +21,4 @@
@group(1) @binding(11) var test_texture_3d_sampler: sampler;

@fragment
fn fragment(in: MeshVertexOutput) {}
fn fragment(in: VertexOutput) {}
4 changes: 2 additions & 2 deletions assets/shaders/line_material.wgsl
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput

struct LineMaterial {
color: vec4<f32>,
Expand All @@ -8,7 +8,7 @@ struct LineMaterial {

@fragment
fn fragment(
mesh: MeshVertexOutput,
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
return material.color;
}
4 changes: 2 additions & 2 deletions assets/shaders/shader_defs.wgsl
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput

struct CustomMaterial {
color: vec4<f32>,
Expand All @@ -8,7 +8,7 @@ struct CustomMaterial {

@fragment
fn fragment(
mesh: MeshVertexOutput,
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
#ifdef IS_RED
return vec4<f32>(1.0, 0.0, 0.0, 1.0);
Expand Down
4 changes: 2 additions & 2 deletions assets/shaders/show_prepass.wgsl
Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
#import bevy_pbr::mesh_types
#import bevy_pbr::mesh_view_bindings globals
#import bevy_pbr::prepass_utils
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput

struct ShowPrepassSettings {
show_depth: u32,
Expand All @@ -17,7 +17,7 @@ fn fragment(
#ifdef MULTISAMPLED
@builtin(sample_index) sample_index: u32,
#endif
mesh: MeshVertexOutput,
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
#ifndef MULTISAMPLED
let sample_index = 0u;
Expand Down
4 changes: 2 additions & 2 deletions assets/shaders/texture_binding_array.wgsl
Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput

@group(1) @binding(0) var textures: binding_array<texture_2d<f32>>;
@group(1) @binding(1) var nearest_sampler: sampler;
Expand All @@ -7,7 +7,7 @@

@fragment
fn fragment(
mesh: MeshVertexOutput,
mesh: VertexOutput,
) -> @location(0) vec4<f32> {
// Select the texture to sample from using non-uniform uv coordinates
let coords = clamp(vec2<u32>(mesh.uv * 4.0), vec2<u32>(0u), vec2<u32>(3u));
Expand Down
4 changes: 2 additions & 2 deletions assets/shaders/tonemapping_test_patterns.wgsl
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
#import bevy_pbr::mesh_view_bindings
#import bevy_pbr::mesh_bindings
#import bevy_pbr::mesh_vertex_output MeshVertexOutput
#import bevy_pbr::forward_io VertexOutput
#import bevy_pbr::utils PI

#ifdef TONEMAP_IN_SHADER
Expand Down Expand Up @@ -43,7 +43,7 @@ fn continuous_hue(uv: vec2<f32>) -> vec3<f32> {

@fragment
fn fragment(
in: MeshVertexOutput,
in: VertexOutput,
) -> @location(0) vec4<f32> {
var uv = in.uv;
var out = vec3(0.0);
Expand Down
16 changes: 7 additions & 9 deletions crates/bevy_pbr/src/deferred/deferred_lighting.wgsl
Original file line number Diff line number Diff line change
Expand Up @@ -56,14 +56,15 @@ fn fragment(in: FullscreenVertexOutput) -> @location(0) vec4<f32> {
var pbr_input = pbr_input_from_deferred_gbuffer(frag_coord, deferred_data);
var output_color = vec4(0.0);

#ifdef SCREEN_SPACE_AMBIENT_OCCLUSION
let ssao = textureLoad(screen_space_ambient_occlusion_texture, vec2<i32>(in.position.xy), 0i).r;
let ssao_multibounce = gtao_multibounce(ssao, pbr_input.material.base_color.rgb);
pbr_input.occlusion = min(pbr_input.occlusion, ssao_multibounce);
#endif // SCREEN_SPACE_AMBIENT_OCCLUSION

// NOTE: Unlit bit not set means == 0 is true, so the true case is if lit
if ((pbr_input.material.flags & STANDARD_MATERIAL_FLAGS_UNLIT_BIT) == 0u) {

#ifdef SCREEN_SPACE_AMBIENT_OCCLUSION
let ssao = textureLoad(screen_space_ambient_occlusion_texture, vec2<i32>(in.position.xy), 0i).r;
let ssao_multibounce = gtao_multibounce(ssao, pbr_input.material.base_color.rgb);
pbr_input.occlusion = min(pbr_input.occlusion, ssao_multibounce);
#endif // SCREEN_SPACE_AMBIENT_OCCLUSION

output_color = pbr_functions::pbr(pbr_input);
} else {
output_color = pbr_input.material.base_color;
Expand All @@ -85,9 +86,6 @@ fn fragment(in: FullscreenVertexOutput) -> @location(0) vec4<f32> {
output_rgb = powsafe(output_rgb, 2.2);
output_color = vec4(output_rgb, output_color.a);
#endif
#endif
#ifdef PREMULTIPLY_ALPHA
output_color = pbr_functions::premultiply_alpha(material.flags, output_color);
#endif

return output_color;
Expand Down
10 changes: 5 additions & 5 deletions crates/bevy_pbr/src/prepass/prepass.wgsl
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
#import bevy_pbr::prepass_bindings
#import bevy_pbr::mesh_functions
#import bevy_pbr::prepass_io Vertex, VertexOutput, FragmentInput, FragmentOutput
#import bevy_pbr::prepass_io Vertex, VertexOutput, FragmentOutput
#import bevy_pbr::skinning
#import bevy_pbr::morph
#import bevy_pbr::mesh_bindings mesh
Expand Down Expand Up @@ -50,10 +50,10 @@ fn vertex(vertex_no_morph: Vertex) -> VertexOutput {
var model = bevy_pbr::mesh_functions::get_model_matrix(vertex_no_morph.instance_index);
#endif // SKINNED

out.clip_position = bevy_pbr::mesh_functions::mesh_position_local_to_clip(model, vec4(vertex.position, 1.0));
out.position = bevy_pbr::mesh_functions::mesh_position_local_to_clip(model, vec4(vertex.position, 1.0));
#ifdef DEPTH_CLAMP_ORTHO
out.clip_position_unclamped = out.clip_position;
out.clip_position.z = min(out.clip_position.z, 1.0);
out.clip_position_unclamped = out.position;
out.position.z = min(out.position.z, 1.0);
#endif // DEPTH_CLAMP_ORTHO

#ifdef VERTEX_UVS
Expand Down Expand Up @@ -111,7 +111,7 @@ fn vertex(vertex_no_morph: Vertex) -> VertexOutput {

#ifdef PREPASS_FRAGMENT
@fragment
fn fragment(in: FragmentInput) -> FragmentOutput {
fn fragment(in: VertexOutput) -> FragmentOutput {
var out: FragmentOutput;

#ifdef NORMAL_PREPASS
Expand Down
34 changes: 3 additions & 31 deletions crates/bevy_pbr/src/prepass/prepass_io.wgsl
Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,9 @@ struct Vertex {
}

struct VertexOutput {
@builtin(position) clip_position: vec4<f32>,
// This is `clip position` when the struct is used as a vertex stage output
// and `frag coord` when used as a fragment stage input
@builtin(position) position: vec4<f32>,

#ifdef VERTEX_UVS
@location(0) uv: vec2<f32>,
Expand Down Expand Up @@ -62,36 +64,6 @@ struct VertexOutput {
#endif
}

struct FragmentInput {
@builtin(position) position: vec4<f32>,
#ifdef VERTEX_UVS
@location(0) uv: vec2<f32>,
#endif // VERTEX_UVS

#ifdef NORMAL_PREPASS_OR_DEFERRED_PREPASS
@location(1) world_normal: vec3<f32>,
#ifdef VERTEX_TANGENTS
@location(2) world_tangent: vec4<f32>,
#endif
#endif // NORMAL_PREPASS_OR_DEFERRED_PREPASS

@location(3) world_position: vec4<f32>,
#ifdef MOTION_VECTOR_PREPASS
@location(4) previous_world_position: vec4<f32>,
#endif // MOTION_VECTOR_PREPASS

#ifdef DEPTH_CLAMP_ORTHO
@location(5) clip_position_unclamped: vec4<f32>,
#endif // DEPTH_CLAMP_ORTHO
#ifdef VERTEX_OUTPUT_INSTANCE_INDEX
@location(6) instance_index: u32,
#endif

#ifdef VERTEX_COLORS
@location(7) color: vec4<f32>,
#endif
};

#ifdef PREPASS_FRAGMENT
struct FragmentOutput {
#ifdef NORMAL_PREPASS
Expand Down
52 changes: 52 additions & 0 deletions crates/bevy_pbr/src/render/forward_io.wgsl
Original file line number Diff line number Diff line change
@@ -0,0 +1,52 @@
#define_import_path bevy_pbr::forward_io

struct Vertex {
@builtin(instance_index) instance_index: u32,
#ifdef VERTEX_POSITIONS
@location(0) position: vec3<f32>,
#endif
#ifdef VERTEX_NORMALS
@location(1) normal: vec3<f32>,
#endif
#ifdef VERTEX_UVS
@location(2) uv: vec2<f32>,
#endif
// (Alternate UVs are at location 3, but they're currently unused here.)
#ifdef VERTEX_TANGENTS
@location(4) tangent: vec4<f32>,
#endif
#ifdef VERTEX_COLORS
@location(5) color: vec4<f32>,
#endif
#ifdef SKINNED
@location(6) joint_indices: vec4<u32>,
@location(7) joint_weights: vec4<f32>,
#endif
#ifdef MORPH_TARGETS
@builtin(vertex_index) index: u32,
#endif
};

struct VertexOutput {
// This is `clip position` when the struct is used as a vertex stage output
// and `frag coord` when used as a fragment stage input
@builtin(position) position: vec4<f32>,
@location(0) world_position: vec4<f32>,
@location(1) world_normal: vec3<f32>,
#ifdef VERTEX_UVS
@location(2) uv: vec2<f32>,
#endif
#ifdef VERTEX_TANGENTS
@location(3) world_tangent: vec4<f32>,
#endif
#ifdef VERTEX_COLORS
@location(4) color: vec4<f32>,
#endif
#ifdef VERTEX_OUTPUT_INSTANCE_INDEX
@location(5) @interpolate(flat) instance_index: u32,
#endif
}

struct FragmentOutput {
@location(0) color: vec4<f32>,
}
9 changes: 2 additions & 7 deletions crates/bevy_pbr/src/render/mesh.rs
Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@ use super::skin::SkinIndices;
#[derive(Default)]
pub struct MeshRenderPlugin;

pub const MESH_VERTEX_OUTPUT: Handle<Shader> = Handle::weak_from_u128(2645551199423808407);
pub const FORWARD_IO_HANDLE: Handle<Shader> = Handle::weak_from_u128(2645551199423808407);
pub const MESH_VIEW_TYPES_HANDLE: Handle<Shader> = Handle::weak_from_u128(8140454348013264787);
pub const MESH_VIEW_BINDINGS_HANDLE: Handle<Shader> = Handle::weak_from_u128(9076678235888822571);
pub const MESH_TYPES_HANDLE: Handle<Shader> = Handle::weak_from_u128(2506024101911992377);
Expand All @@ -74,12 +74,7 @@ pub const MORPH_HANDLE: Handle<Shader> = Handle::weak_from_u128(9709828135876073

impl Plugin for MeshRenderPlugin {
fn build(&self, app: &mut bevy_app::App) {
load_internal_asset!(
app,
MESH_VERTEX_OUTPUT,
"mesh_vertex_output.wgsl",
Shader::from_wgsl
);
load_internal_asset!(app, FORWARD_IO_HANDLE, "forward_io.wgsl", Shader::from_wgsl);
load_internal_asset!(
app,
MESH_VIEW_TYPES_HANDLE,
Expand Down
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