CNN v2: Change feature #6 from sin(10*x) to sin(20*y)

Update positional encoding to use vertical coordinate at higher frequency.

Changes:
- train_cnn_v2.py: sin10_x → sin20_y (computed from uv_y)
- cnn_v2_static.wgsl: sin10_x → sin20_y (computed from uv_y)
- index.html: sin10_x → sin20_y (STATIC_SHADER)
- CNN_V2.md: Update feature descriptions and examples
- CNN_V2_BINARY_FORMAT.md: Update static features documentation

Feature vector: [p0, p1, p2, p3, uv_x, uv_y, sin20_y, bias]

Rationale: Higher frequency (20 vs 10) + vertical axis provides better
spatial discrimination for position encoding.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/workspaces/main/shaders/cnn_v2/cnn_v2_static.wgsl b/workspaces/main/shaders/cnn_v2/cnn_v2_static.wgsl
index 29acddd..7039d96 100644
--- a/workspaces/main/shaders/cnn_v2/cnn_v2_static.wgsl
+++ b/workspaces/main/shaders/cnn_v2/cnn_v2_static.wgsl
@@ -1,5 +1,5 @@
 // CNN v2 Static Features Compute Shader
-// Generates 8D parametric features: [p0, p1, p2, p3, uv.x, uv.y, sin10_x, bias]
+// Generates 8D parametric features: [p0, p1, p2, p3, uv.x, uv.y, sin20_y, bias]
 // p0-p3: Parametric features from specified mip level (0=mip0, 1=mip1, 2=mip2, 3=mip3)
 // Note: Input image RGBD (mip0) fed separately to Layer 0
 //
@@ -51,18 +51,18 @@ fn main(@builtin(global_invocation_id) id: vec3<u32>) {
   let uv_y = 1.0 - (f32(coord.y) / f32(dims.y));
 
   // Multi-frequency position encoding
-  let sin10_x = sin(10.0 * uv_x);
+  let sin20_y = sin(20.0 * uv_y);
 
   // Bias dimension (always 1.0)
   let bias = 1.0;
 
   // Pack 8×f16 into 4×u32 (rgba32uint)
-  // [p0, p1, p2, p3, uv_x, uv_y, sin10_x, bias]
+  // [p0, p1, p2, p3, uv_x, uv_y, sin20_y, bias]
   let packed = vec4<u32>(
     pack2x16float(vec2<f32>(p0, p1)),
     pack2x16float(vec2<f32>(p2, p3)),
     pack2x16float(vec2<f32>(uv_x, uv_y)),
-    pack2x16float(vec2<f32>(sin10_x, bias))
+    pack2x16float(vec2<f32>(sin20_y, bias))
   );
 
   textureStore(output_tex, coord, packed);