1#import bevy_pbr::{
2    pbr_prepass_functions,
3    pbr_bindings,
4    pbr_bindings::material,
5    pbr_types,
6    pbr_functions,
7    pbr_functions::SampleBias,
8    prepass_io,
9    mesh_bindings::mesh,
10    mesh_view_bindings::view,
11}
12
13#import bevy_render::bindless::{bindless_samplers_filtering, bindless_textures_2d}
14
15#ifdef MESHLET_MESH_MATERIAL_PASS
16#import bevy_pbr::meshlet_visibility_buffer_resolve::resolve_vertex_output
17#endif
18
19#ifdef BINDLESS
20#import bevy_pbr::pbr_bindings::material_indices
21#endif  // BINDLESS
22
23#ifdef PREPASS_FRAGMENT
24@fragment
25fn fragment(
26#ifdef MESHLET_MESH_MATERIAL_PASS
27    @builtin(position) frag_coord: vec4<f32>,
28#else
29    in: prepass_io::VertexOutput,
30    @builtin(front_facing) is_front: bool,
31#endif
32) -> prepass_io::FragmentOutput {
33#ifdef MESHLET_MESH_MATERIAL_PASS
34    let in = resolve_vertex_output(frag_coord);
35    let is_front = true;
36#else   // MESHLET_MESH_MATERIAL_PASS
37
38#ifdef BINDLESS
39    let slot = mesh[in.instance_index].material_and_lightmap_bind_group_slot & 0xffffu;
40    let flags = pbr_bindings::material_array[material_indices[slot].material].flags;
41    let uv_transform = pbr_bindings::material_array[material_indices[slot].material].uv_transform;
42#else   // BINDLESS
43    let flags = pbr_bindings::material.flags;
44    let uv_transform = pbr_bindings::material.uv_transform;
45#endif  // BINDLESS
46
47    // If we're in the crossfade section of a visibility range, conditionally
48    // discard the fragment according to the visibility pattern.
49#ifdef VISIBILITY_RANGE_DITHER
50    pbr_functions::visibility_range_dither(in.position, in.visibility_range_dither);
51#endif  // VISIBILITY_RANGE_DITHER
52
53    pbr_prepass_functions::prepass_alpha_discard(in);
54#endif  // MESHLET_MESH_MATERIAL_PASS
55
56    var out: prepass_io::FragmentOutput;
57
58#ifdef UNCLIPPED_DEPTH_ORTHO_EMULATION
59    out.frag_depth = in.unclipped_depth;
60#endif // UNCLIPPED_DEPTH_ORTHO_EMULATION
61
62#ifdef NORMAL_PREPASS
63    // NOTE: Unlit bit not set means == 0 is true, so the true case is if lit
64    if (flags & pbr_types::STANDARD_MATERIAL_FLAGS_UNLIT_BIT) == 0u {
65        let double_sided = (flags & pbr_types::STANDARD_MATERIAL_FLAGS_DOUBLE_SIDED_BIT) != 0u;
66
67        let world_normal = pbr_functions::prepare_world_normal(
68            in.world_normal,
69            double_sided,
70            is_front,
71        );
72
73        var normal = world_normal;
74
75#ifdef VERTEX_UVS
76#ifdef VERTEX_TANGENTS
77#ifdef STANDARD_MATERIAL_NORMAL_MAP
78
79// TODO: Transforming UVs mean we need to apply derivative chain rule for meshlet mesh material pass
80#ifdef STANDARD_MATERIAL_NORMAL_MAP_UV_B
81        let uv = (uv_transform * vec3(in.uv_b, 1.0)).xy;
82#else
83        let uv = (uv_transform * vec3(in.uv, 1.0)).xy;
84#endif
85
86        // Fill in the sample bias so we can sample from textures.
87        var bias: SampleBias;
88#ifdef MESHLET_MESH_MATERIAL_PASS
89        bias.ddx_uv = in.ddx_uv;
90        bias.ddy_uv = in.ddy_uv;
91#else   // MESHLET_MESH_MATERIAL_PASS
92        bias.mip_bias = view.mip_bias;
93#endif  // MESHLET_MESH_MATERIAL_PASS
94
95        let Nt =
96#ifdef MESHLET_MESH_MATERIAL_PASS
97            textureSampleGrad(
98#else   // MESHLET_MESH_MATERIAL_PASS
99            textureSampleBias(
100#endif  // MESHLET_MESH_MATERIAL_PASS
101#ifdef BINDLESS
102                bindless_textures_2d[material_indices[slot].normal_map_texture],
103                bindless_samplers_filtering[material_indices[slot].normal_map_sampler],
104#else   // BINDLESS
105                pbr_bindings::normal_map_texture,
106                pbr_bindings::normal_map_sampler,
107#endif  // BINDLESS
108                uv,
109#ifdef MESHLET_MESH_MATERIAL_PASS
110                bias.ddx_uv,
111                bias.ddy_uv,
112#else   // MESHLET_MESH_MATERIAL_PASS
113                bias.mip_bias,
114#endif  // MESHLET_MESH_MATERIAL_PASS
115            ).rgb;
116        let TBN = pbr_functions::calculate_tbn_mikktspace(normal, in.world_tangent);
117
118        normal = pbr_functions::apply_normal_mapping(
119            flags,
120            TBN,
121            double_sided,
122            is_front,
123            Nt,
124        );
125
126#endif  // STANDARD_MATERIAL_NORMAL_MAP
127#endif  // VERTEX_TANGENTS
128#endif  // VERTEX_UVS
129
130        out.normal = vec4(normal * 0.5 + vec3(0.5), 1.0);
131    } else {
132        out.normal = vec4(in.world_normal * 0.5 + vec3(0.5), 1.0);
133    }
134#endif // NORMAL_PREPASS
135
136#ifdef MOTION_VECTOR_PREPASS
137#ifdef MESHLET_MESH_MATERIAL_PASS
138    out.motion_vector = in.motion_vector;
139#else
140    out.motion_vector = pbr_prepass_functions::calculate_motion_vector(in.world_position, in.previous_world_position);
141#endif
142#endif
143
144    return out;
145}
146#else
147@fragment
148fn fragment(in: prepass_io::VertexOutput) {
149    pbr_prepass_functions::prepass_alpha_discard(in);
150}
151#endif // PREPASS_FRAGMENT