bevy/crates/bevy_pbr/src/prepass/prepass_bindings.rs

use bevy_core_pipeline::prepass::ViewPrepassTextures;
use bevy_render::render_resource::{
    binding_types::{
        texture_2d, texture_2d_multisampled, texture_depth_2d, texture_depth_2d_multisampled,
    },
    BindGroupLayoutEntryBuilder, TextureAspect, TextureSampleType, TextureView,
    TextureViewDescriptor,
};
use bevy_utils::default;

use crate::MeshPipelineViewLayoutKey;

pub fn get_bind_group_layout_entries(
    layout_key: MeshPipelineViewLayoutKey,
) -> [Option<BindGroupLayoutEntryBuilder>; 4] {
    let mut entries: [Option<BindGroupLayoutEntryBuilder>; 4] = [None; 4];

    let multisampled = layout_key.contains(MeshPipelineViewLayoutKey::MULTISAMPLED);

    if layout_key.contains(MeshPipelineViewLayoutKey::DEPTH_PREPASS) {
        // Depth texture
        entries[0] = if multisampled {
            Some(texture_depth_2d_multisampled())
        } else {
            Some(texture_depth_2d())
        };
    }

    if layout_key.contains(MeshPipelineViewLayoutKey::NORMAL_PREPASS) {
        // Normal texture
        entries[1] = if multisampled {
            Some(texture_2d_multisampled(TextureSampleType::Float {
                filterable: false,
            }))
        } else {
            Some(texture_2d(TextureSampleType::Float { filterable: false }))
        };
    }

    if layout_key.contains(MeshPipelineViewLayoutKey::MOTION_VECTOR_PREPASS) {
        // Motion Vectors texture
        entries[2] = if multisampled {
            Some(texture_2d_multisampled(TextureSampleType::Float {
                filterable: false,
            }))
        } else {
            Some(texture_2d(TextureSampleType::Float { filterable: false }))
        };
    }

    if layout_key.contains(MeshPipelineViewLayoutKey::DEFERRED_PREPASS) {
        // Deferred texture
        entries[3] = Some(texture_2d(TextureSampleType::Uint));
    }

    entries
}

pub fn get_bindings(prepass_textures: Option<&ViewPrepassTextures>) -> [Option<TextureView>; 4] {
    let depth_desc = TextureViewDescriptor {
        label: Some("prepass_depth"),
        aspect: TextureAspect::DepthOnly,
        ..default()
    };
    let depth_view = prepass_textures
        .and_then(|x| x.depth.as_ref())
        .map(|texture| texture.texture.create_view(&depth_desc));

    let normal_view = prepass_textures
        .and_then(|x| x.normal.as_ref())
        .map(|texture| texture.default_view.clone());

    let motion_vectors_view = prepass_textures
        .and_then(|x| x.motion_vectors.as_ref())
        .map(|texture| texture.default_view.clone());

    let deferred_view = prepass_textures
        .and_then(|x| x.deferred.as_ref())
        .map(|texture| texture.default_view.clone());

    [depth_view, normal_view, motion_vectors_view, deferred_view]
}