1#import bevy_sprite::{
2    mesh2d_vertex_output::VertexOutput,
3    mesh2d_view_bindings::view,
4}
5
6#ifdef TONEMAP_IN_SHADER
7#import bevy_core_pipeline::tonemapping
8#endif
9
10struct ColorMaterial {
11    color: vec4<f32>,
12    uv_transform: mat3x3<f32>,
13    // 'flags' is a bit field indicating various options. u32 is 32 bits so we have up to 32 options.
14    flags: u32,
15    alpha_cutoff: f32,
16};
17
18const COLOR_MATERIAL_FLAGS_TEXTURE_BIT: u32              = 1u;
19const COLOR_MATERIAL_FLAGS_ALPHA_MODE_RESERVED_BITS: u32 = 3221225472u; // (0b11u32 << 30)
20const COLOR_MATERIAL_FLAGS_ALPHA_MODE_OPAQUE: u32        = 0u;          // (0u32 << 30)
21const COLOR_MATERIAL_FLAGS_ALPHA_MODE_MASK: u32          = 1073741824u; // (1u32 << 30)
22const COLOR_MATERIAL_FLAGS_ALPHA_MODE_BLEND: u32         = 2147483648u; // (2u32 << 30)
23
24@group(#{MATERIAL_BIND_GROUP}) @binding(0) var<uniform> material: ColorMaterial;
25@group(#{MATERIAL_BIND_GROUP}) @binding(1) var texture: texture_2d<f32>;
26@group(#{MATERIAL_BIND_GROUP}) @binding(2) var texture_sampler: sampler;
27
28@fragment
29fn fragment(
30    mesh: VertexOutput,
31) -> @location(0) vec4<f32> {
32    var output_color: vec4<f32> = material.color;
33
34#ifdef VERTEX_COLORS
35    output_color = output_color * mesh.color;
36#endif
37
38    let uv = (material.uv_transform * vec3(mesh.uv, 1.0)).xy;
39
40    if ((material.flags & COLOR_MATERIAL_FLAGS_TEXTURE_BIT) != 0u) {
41        output_color = output_color * textureSample(texture, texture_sampler, uv);
42    }
43
44    output_color = alpha_discard(material, output_color);
45
46#ifdef TONEMAP_IN_SHADER
47    output_color = tonemapping::tone_mapping(output_color, view.color_grading);
48#endif
49    return output_color;
50}
51
52fn alpha_discard(material: ColorMaterial, output_color: vec4<f32>) -> vec4<f32> {
53    var color = output_color;
54    let alpha_mode = material.flags & COLOR_MATERIAL_FLAGS_ALPHA_MODE_RESERVED_BITS;
55    if alpha_mode == COLOR_MATERIAL_FLAGS_ALPHA_MODE_OPAQUE {
56        // NOTE: If rendering as opaque, alpha should be ignored so set to 1.0
57        color.a = 1.0;
58    }
59#ifdef MAY_DISCARD
60    else if alpha_mode == COLOR_MATERIAL_FLAGS_ALPHA_MODE_MASK {
61       if color.a >= material.alpha_cutoff {
62            // NOTE: If rendering as masked alpha and >= the cutoff, render as fully opaque
63            color.a = 1.0;
64        } else {
65            // NOTE: output_color.a < in.material.alpha_cutoff should not be rendered
66            discard;
67        }
68    }
69#endif // MAY_DISCARD
70
71    return color;
72}