text rendering

src/shaders/text.wgsl

@@ -0,0 +1,45 @@
+struct Uniforms
+{
+    view_proj: mat4x4<f32>,
+}
+
+@group(0) @binding(0)
+var<uniform> u: Uniforms;
+
+@group(0) @binding(1)
+var glyph_atlas: texture_2d<f32>;
+
+@group(0) @binding(2)
+var glyph_sampler: sampler;
+
+struct VertexIn
+{
+    @location(0) position: vec3<f32>,
+    @location(1) uv:       vec2<f32>,
+}
+
+struct VertexOut
+{
+    @builtin(position) clip_pos: vec4<f32>,
+    @location(0)       uv:       vec2<f32>,
+}
+
+@vertex
+fn vs_main(in: VertexIn) -> VertexOut
+{
+    var out: VertexOut;
+    out.clip_pos = u.view_proj * vec4<f32>(in.position, 1.0);
+    out.uv       = in.uv;
+    return out;
+}
+
+@fragment
+fn fs_main(in: VertexOut) -> @location(0) vec4<f32>
+{
+    let coverage = textureSample(glyph_atlas, glyph_sampler, in.uv).r;
+    if coverage < 0.5
+    {
+        discard;
+    }
+    return vec4<f32>(1.0, 1.0, 1.0, 1.0);
+}