diff --git a/sample/stencilMask/index.html b/sample/stencilMask/index.html
index 6957e09f..28a283ea 100644
--- a/sample/stencilMask/index.html
+++ b/sample/stencilMask/index.html
@@ -3,7 +3,7 @@
   <head>
     <meta charset="utf-8">
     <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
-    <title>webgpu-samples: instancedCube</title>
+    <title>webgpu-samples: stencilMask</title>
     <style>
       :root {
         color-scheme: light dark;
diff --git a/sample/stencilMask/main.ts b/sample/stencilMask/main.ts
index 692ad04a..4d8dd360 100644
--- a/sample/stencilMask/main.ts
+++ b/sample/stencilMask/main.ts
@@ -398,7 +398,7 @@ const tmpMat4Scene1 = mat4.create();
 // Update the transformation matrix data for each instance.
 function updateTransformationMatrix() {
   const nowScene0 = Date.now() / 1000;
-  const nowScene1 = nowScene0 + 100.0;
+  const nowScene1 = nowScene0 * 2;
 
   let m = 0,
     i = 0;
diff --git a/sample/stencilMask/meta.ts b/sample/stencilMask/meta.ts
index eeb81e63..7cddc6ec 100644
--- a/sample/stencilMask/meta.ts
+++ b/sample/stencilMask/meta.ts
@@ -7,7 +7,7 @@ export default {
     // Ts files
     { path: 'main.ts' },
     // Stencil Mask shaders
-    { path: 'fullscreenQuad.vert.wgsl' },
+    { path: 'positionQuad.vert.wgsl' },
     { path: 'sdf.frag.wgsl' },
     // Instanced Cube verts
     { path: '../instancedCube/instanced.vert.wgsl' },
diff --git a/sample/stencilMask/fullscreenQuad.vert.wgsl b/sample/stencilMask/positionQuad.wgsl
similarity index 88%
rename from sample/stencilMask/fullscreenQuad.vert.wgsl
rename to sample/stencilMask/positionQuad.wgsl
index b2330043..630fe00c 100644
--- a/sample/stencilMask/fullscreenQuad.vert.wgsl
+++ b/sample/stencilMask/positionQuad.wgsl
@@ -1,6 +1,6 @@
 struct VertexOutput {
   @builtin(position) Position : vec4f,
-  @location(0) fragUV : vec2f,
+  @location(0) v_uv : vec2f,
 }
 
 struct Uniforms {
@@ -38,13 +38,15 @@ fn vertexMain(@builtin(vertex_index) VertexIndex : u32) -> VertexOutput {
   let mask_offset = vec2f(uniforms.offset_x, uniforms.offset_y);
   // scale_to_canvas is effectively a transformation that takes our quad positions from NDC space to canvas space.
   let scale_to_canvas = vec2<f32>(uniforms.scale_to_canvas_x, uniforms.scale_to_canvas_y);
+  // Position in canvas space
   let posCS = pos[VertexIndex] * scale_to_canvas;
+  // offset of position based on mouse cursor input in canvas space
   let offsetCS = mask_offset * scale_to_canvas;
   output.Position = vec4(
     posCS * uniforms.radius_scale + offsetCS, 
     0.0, 
     1.0
   );
-  output.fragUV = uv[VertexIndex];
+  output.v_uv = uv[VertexIndex];
   return output;
 }
