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_view_bindings::view,
10}
11
12#ifdef MESHLET_MESH_MATERIAL_PASS
13#import bevy_pbr::meshlet_visibility_buffer_resolve::resolve_vertex_output
14#endif
15
16#ifdef PREPASS_FRAGMENT
17@fragment
18fn fragment(
19#ifdef MESHLET_MESH_MATERIAL_PASS
20    @builtin(position) frag_coord: vec4<f32>,
21#else
22    in: prepass_io::VertexOutput,
23    @builtin(front_facing) is_front: bool,
24#endif
25) -> prepass_io::FragmentOutput {
26#ifdef MESHLET_MESH_MATERIAL_PASS
27    let in = resolve_vertex_output(frag_coord);
28    let is_front = true;
29#else
30    pbr_prepass_functions::prepass_alpha_discard(in);
31#endif
32
33    var out: prepass_io::FragmentOutput;
34
35#ifdef DEPTH_CLAMP_ORTHO
36    out.frag_depth = in.clip_position_unclamped.z;
37#endif // DEPTH_CLAMP_ORTHO
38
39#ifdef NORMAL_PREPASS
40    // NOTE: Unlit bit not set means == 0 is true, so the true case is if lit
41    if (material.flags & pbr_types::STANDARD_MATERIAL_FLAGS_UNLIT_BIT) == 0u {
42        let double_sided = (material.flags & pbr_types::STANDARD_MATERIAL_FLAGS_DOUBLE_SIDED_BIT) != 0u;
43
44        let world_normal = pbr_functions::prepare_world_normal(
45            in.world_normal,
46            double_sided,
47            is_front,
48        );
49
50        var normal = world_normal;
51
52#ifdef VERTEX_UVS
53#ifdef VERTEX_TANGENTS
54#ifdef STANDARD_MATERIAL_NORMAL_MAP
55
56// TODO: Transforming UVs mean we need to apply derivative chain rule for meshlet mesh material pass
57#ifdef STANDARD_MATERIAL_NORMAL_MAP_UV_B
58        let uv = (material.uv_transform * vec3(in.uv_b, 1.0)).xy;
59#else
60        let uv = (material.uv_transform * vec3(in.uv, 1.0)).xy;
61#endif
62
63        // Fill in the sample bias so we can sample from textures.
64        var bias: SampleBias;
65#ifdef MESHLET_MESH_MATERIAL_PASS
66        bias.ddx_uv = in.ddx_uv;
67        bias.ddy_uv = in.ddy_uv;
68#else   // MESHLET_MESH_MATERIAL_PASS
69        bias.mip_bias = view.mip_bias;
70#endif  // MESHLET_MESH_MATERIAL_PASS
71
72        let Nt = pbr_functions::sample_texture(
73            pbr_bindings::normal_map_texture,
74            pbr_bindings::normal_map_sampler,
75            uv,
76            bias,
77        ).rgb;
78        let TBN = pbr_functions::calculate_tbn_mikktspace(normal, in.world_tangent);
79
80        normal = pbr_functions::apply_normal_mapping(
81            material.flags,
82            TBN,
83            double_sided,
84            is_front,
85            Nt,
86        );
87
88#endif  // STANDARD_MATERIAL_NORMAL_MAP
89#endif  // VERTEX_TANGENTS
90#endif  // VERTEX_UVS
91
92        out.normal = vec4(normal * 0.5 + vec3(0.5), 1.0);
93    } else {
94        out.normal = vec4(in.world_normal * 0.5 + vec3(0.5), 1.0);
95    }
96#endif // NORMAL_PREPASS
97
98#ifdef MOTION_VECTOR_PREPASS
99#ifdef MESHLET_MESH_MATERIAL_PASS
100    out.motion_vector = in.motion_vector;
101#else
102    out.motion_vector = pbr_prepass_functions::calculate_motion_vector(in.world_position, in.previous_world_position);
103#endif
104#endif
105
106    return out;
107}
108#else
109@fragment
110fn fragment(in: prepass_io::VertexOutput) {
111    pbr_prepass_functions::prepass_alpha_discard(in);
112}
113#endif // PREPASS_FRAGMENT