fix: Move sigmoid activation to call site in CNN layer shader

Conv functions now return raw sum, sigmoid applied at call site.
Matches tanh pattern used for inner layers.

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

1 files changed, 2 insertions, 2 deletions

diff --git a/workspaces/main/shaders/cnn/cnn_layer.wgsl b/workspaces/main/shaders/cnn/cnn_layer.wgsl
index c5f45ec..73816c6 100644
--- a/workspaces/main/shaders/cnn/cnn_layer.wgsl
+++ b/workspaces/main/shaders/cnn/cnn_layer.wgsl
@@ -45,8 +45,8 @@ struct CNNLayerParams {
         result = cnn_tanh(result);  // Keep in [-1,1]
     }
     else if (params.layer_index == 2) {
-        let gray_out = cnn_conv3x3_7to1(txt, smplr, uv, uniforms.resolution, gray, weights_layer2);
-        // gray_out in [0,1] (sigmoid activation)
+        let sum = cnn_conv3x3_7to1(txt, smplr, uv, uniforms.resolution, gray, weights_layer2);
+        let gray_out = 1.0 / (1.0 + exp(-sum));  // Sigmoid activation
         result = vec4<f32>(gray_out, gray_out, gray_out, 1.0);
         return mix(original_raw, result, params.blend_amount); // [0,1]
     }