1//! A shader that samples its emissive texture at screen space positions rather
2//! than UVs.
3//!
4//! This is used for the mirror example: `examples/3d/mirror.rs`.
5
6import bevy_pbr::render::{
7    forward_io::{VertexOutput, FragmentOutput},
8    pbr_bindings::emissive_texture,
9    pbr_fragment::pbr_input_from_standard_material,
10    pbr_functions::{alpha_discard, apply_pbr_lighting, main_pass_post_lighting_processing}
11};
12
13/// This is unused, but it's here to satisfy `ExtendedMaterial` requirements.
14/// See the comment in `ScreenSpaceTextureExtension` in `examples/3d/mirror.rs`
15/// for more information.
16struct ScreenSpaceTextureMaterial {
17    /// An unused value.
18    dummy: f32,
19}
20
21@group(constants::MATERIAL_BIND_GROUP) @binding(100) var<uniform> material: ScreenSpaceTextureMaterial;
22
23@fragment
24fn fragment(in: VertexOutput, @builtin(front_facing) is_front: bool) -> FragmentOutput {
25    var pbr_input = pbr_input_from_standard_material(in, is_front);
26
27    // Use zero alpha to avoid multiplying the emissive by the view exposure.
28    pbr_input.material.emissive = vec4(
29        textureLoad(emissive_texture, vec2<i32>(floor(in.position.xy)), 0).rgb,
30        0.0
31    );
32
33    var out: FragmentOutput;
34    out.color = apply_pbr_lighting(pbr_input);
35    out.color = main_pass_post_lighting_processing(pbr_input, out.color);
36    return out;
37}