| 1 | // Instanced thumbnail quads sampled from atlas pages. Output is straight alpha. |
| 2 | |
| 3 | struct Globals { |
| 4 | viewport: vec2<f32>, |
| 5 | _pad: vec2<f32>, |
| 6 | }; |
| 7 | |
| 8 | @group(0) @binding(0) var<uniform> g: Globals; |
| 9 | @group(0) @binding(1) var samp: sampler; |
| 10 | @group(1) @binding(0) var page: texture_2d<f32>; |
| 11 | |
| 12 | struct Instance { |
| 13 | @location(0) rect: vec4<f32>, // x, y, w, h in physical px |
| 14 | @location(1) uv: vec4<f32>, // u, v, du, dv in the page |
| 15 | @location(2) params: vec4<f32>, // x: opacity |
| 16 | }; |
| 17 | |
| 18 | struct VOut { |
| 19 | @builtin(position) pos: vec4<f32>, |
| 20 | @location(0) uv: vec2<f32>, |
| 21 | @location(1) alpha: f32, |
| 22 | }; |
| 23 | |
| 24 | @vertex |
| 25 | fn vs(@builtin(vertex_index) i: u32, inst: Instance) -> VOut { |
| 26 | var corners = array<vec2<f32>, 6>( |
| 27 | vec2(0.0, 0.0), vec2(1.0, 0.0), vec2(0.0, 1.0), |
| 28 | vec2(0.0, 1.0), vec2(1.0, 0.0), vec2(1.0, 1.0), |
| 29 | ); |
| 30 | let c = corners[i]; |
| 31 | let p = inst.rect.xy + c * inst.rect.zw; |
| 32 | var out: VOut; |
| 33 | out.pos = vec4(p.x / g.viewport.x * 2.0 - 1.0, 1.0 - p.y / g.viewport.y * 2.0, 0.0, 1.0); |
| 34 | out.uv = inst.uv.xy + c * inst.uv.zw; |
| 35 | out.alpha = inst.params.x; |
| 36 | return out; |
| 37 | } |
| 38 | |
| 39 | @fragment |
| 40 | fn fs(in: VOut) -> @location(0) vec4<f32> { |
| 41 | let c = textureSample(page, samp, in.uv); |
| 42 | return vec4(c.rgb, c.a * in.alpha); |
| 43 | } |