Improve drawing

src/pipelines/brush/brush.wgsl

@@ -0,0 +1,23 @@
+struct VertexOutput {
+  @builtin(position) position : vec4<f32>,
+  @location(0) uv : vec2<f32>
+}
+
+@vertex
+fn vertex(
+  @location(0) uv : vec2<f32>
+) -> VertexOutput {
+  let position = uv * 2.0 - 1.0;
+  return VertexOutput(vec4(position, 0.0, 1.0), uv);
+}
+
+struct Settings {
+  size : vec2<f32>
+};
+
+@group(0) @binding(0) var<uniform> settings : Settings;
+
+@fragment
+fn fragment(@location(0) uv: vec2<f32>) -> @location(0) vec4<f32> {
+  return vec4(1, settings.size.x  * 0, 0, 1);
+}