// Label rendering: per-quad vertex buffer (4 verts × N glyphs), each
// vertex carries pos + atlas UV. Fragment samples the R8 atlas and
// uses the alpha as a coverage mask over the uniform tint colour.
struct Viewport {
size: vec2<f32>,
_pad: vec2<f32>,
};
struct LabelTint {
color: vec4<f32>,
};
@group(0) @binding(0) var<uniform> view: Viewport;
@group(0) @binding(1) var<uniform> tint: LabelTint;
@group(0) @binding(2) var atlas: texture_2d<f32>;
@group(0) @binding(3) var atlas_samp: sampler;
struct VertexIn {
@location(0) pos: vec2<f32>,
@location(1) uv: vec2<f32>,
};
struct VertexOut {
@builtin(position) clip: vec4<f32>,
@location(0) uv: vec2<f32>,
};
@vertex
fn vs_main(v: VertexIn) -> VertexOut {
let ndc = vec2<f32>(
(v.pos.x / view.size.x) * 2.0 - 1.0,
1.0 - (v.pos.y / view.size.y) * 2.0,
);
var out: VertexOut;
out.clip = vec4<f32>(ndc, 0.0, 1.0);
out.uv = v.uv;
return out;
}
@fragment
fn fs_main(v: VertexOut) -> @location(0) vec4<f32> {
let mask = textureSample(atlas, atlas_samp, v.uv).r;
return vec4<f32>(tint.color.rgb, tint.color.a * mask);
}