1#define_import_path bevy_pbr::pbr_prepass_functions
2
3#import bevy_render::bindless::{bindless_samplers_filtering, bindless_textures_2d}
4
5#import bevy_pbr::{
6    prepass_io::VertexOutput,
7    prepass_bindings::previous_view_uniforms,
8    mesh_bindings::mesh,
9    mesh_view_bindings::view,
10    pbr_bindings,
11    pbr_types,
12}
13
14#ifdef BINDLESS
15#import bevy_pbr::pbr_bindings::material_indices
16#endif  // BINDLESS
17
18// Cutoff used for the premultiplied alpha modes BLEND, ADD, and ALPHA_TO_COVERAGE.
19const PREMULTIPLIED_ALPHA_CUTOFF = 0.05;
20
21// We can use a simplified version of alpha_discard() here since we only need to handle the alpha_cutoff
22fn prepass_alpha_discard(in: VertexOutput) {
23
24#ifdef MAY_DISCARD
25#ifdef BINDLESS
26    let slot = mesh[in.instance_index].material_and_lightmap_bind_group_slot & 0xffffu;
27    var output_color: vec4<f32> = pbr_bindings::material_array[material_indices[slot].material].base_color;
28    let flags = pbr_bindings::material_array[material_indices[slot].material].flags;
29#else   // BINDLESS
30    var output_color: vec4<f32> = pbr_bindings::material.base_color;
31    let flags = pbr_bindings::material.flags;
32#endif  // BINDLESS
33
34#ifdef VERTEX_UVS
35#ifdef STANDARD_MATERIAL_BASE_COLOR_UV_B
36    var uv = in.uv_b;
37#else   // STANDARD_MATERIAL_BASE_COLOR_UV_B
38    var uv = in.uv;
39#endif  // STANDARD_MATERIAL_BASE_COLOR_UV_B
40
41#ifdef BINDLESS
42    let uv_transform = pbr_bindings::material_array[material_indices[slot].material].uv_transform;
43#else   // BINDLESS
44    let uv_transform = pbr_bindings::material.uv_transform;
45#endif  // BINDLESS
46
47    uv = (uv_transform * vec3(uv, 1.0)).xy;
48    if (flags & pbr_types::STANDARD_MATERIAL_FLAGS_BASE_COLOR_TEXTURE_BIT) != 0u {
49        output_color = output_color * textureSampleBias(
50#ifdef BINDLESS
51            bindless_textures_2d[material_indices[slot].base_color_texture],
52            bindless_samplers_filtering[material_indices[slot].base_color_sampler],
53#else   // BINDLESS
54            pbr_bindings::base_color_texture,
55            pbr_bindings::base_color_sampler,
56#endif  // BINDLESS
57            uv,
58            view.mip_bias
59        );
60    }
61#endif // VERTEX_UVS
62
63    let alpha_mode = flags & pbr_types::STANDARD_MATERIAL_FLAGS_ALPHA_MODE_RESERVED_BITS;
64    if alpha_mode == pbr_types::STANDARD_MATERIAL_FLAGS_ALPHA_MODE_MASK {
65#ifdef BINDLESS
66        let alpha_cutoff = pbr_bindings::material_array[material_indices[slot].material].alpha_cutoff;
67#else   // BINDLESS
68        let alpha_cutoff = pbr_bindings::material.alpha_cutoff;
69#endif  // BINDLESS
70        if output_color.a < alpha_cutoff {
71            discard;
72        }
73    } else if (alpha_mode == pbr_types::STANDARD_MATERIAL_FLAGS_ALPHA_MODE_BLEND ||
74            alpha_mode == pbr_types::STANDARD_MATERIAL_FLAGS_ALPHA_MODE_ADD ||
75            alpha_mode == pbr_types::STANDARD_MATERIAL_FLAGS_ALPHA_MODE_ALPHA_TO_COVERAGE) {
76        if output_color.a < PREMULTIPLIED_ALPHA_CUTOFF {
77            discard;
78        }
79    } else if alpha_mode == pbr_types::STANDARD_MATERIAL_FLAGS_ALPHA_MODE_PREMULTIPLIED {
80        if all(output_color < vec4(PREMULTIPLIED_ALPHA_CUTOFF)) {
81            discard;
82        }
83    }
84
85#endif // MAY_DISCARD
86}
87
88#ifdef MOTION_VECTOR_PREPASS
89fn calculate_motion_vector(world_position: vec4<f32>, previous_world_position: vec4<f32>) -> vec2<f32> {
90    let clip_position_t = view.unjittered_clip_from_world * world_position;
91    let clip_position = clip_position_t.xy / clip_position_t.w;
92    let previous_clip_position_t = previous_view_uniforms.clip_from_world * previous_world_position;
93    let previous_clip_position = previous_clip_position_t.xy / previous_clip_position_t.w;
94    // These motion vectors are used as offsets to UV positions and are stored
95    // in the range -1,1 to allow offsetting from the one corner to the
96    // diagonally-opposite corner in UV coordinates, in either direction.
97    // A difference between diagonally-opposite corners of clip space is in the
98    // range -2,2, so this needs to be scaled by 0.5. And the V direction goes
99    // down where clip space y goes up, so y needs to be flipped.
100    return (clip_position - previous_clip_position) * vec2(0.5, -0.5);
101}
102#endif // MOTION_VECTOR_PREPASS