From c6b70419010164539a8f41ad9d8ad70bd5b6ea4b Mon Sep 17 00:00:00 2001 From: skal Date: Tue, 10 Feb 2026 21:22:44 +0100 Subject: fix: Correct UV coordinate computation to match PyTorch linspace MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Critical mismatch: shader used pixel-center coordinates while PyTorch uses pixel-corner coordinates, causing 0.5-pixel offset. PyTorch: linspace(0, 1, H) → [0, 1/(H-1), ..., 1] Shader: (p.xy - 0.5) / (resolution - 1.0) to match Co-Authored-By: Claude Sonnet 4.5 --- training/train_cnn.py | 3 ++- workspaces/main/shaders/cnn/cnn_layer.wgsl | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/training/train_cnn.py b/training/train_cnn.py index 7a2e85a..2b60d15 100755 --- a/training/train_cnn.py +++ b/training/train_cnn.py @@ -169,7 +169,8 @@ def generate_layer_shader(output_path, num_layers, kernel_sizes): f.write(" return vec4(pos[i], 0.0, 1.0);\n") f.write("}\n\n") f.write("@fragment fn fs_main(@builtin(position) p: vec4) -> @location(0) vec4 {\n") - f.write(" let uv = p.xy / uniforms.resolution;\n") + f.write(" // Match PyTorch linspace: pixel_idx / (size - 1), not pixel_center / size\n") + f.write(" let uv = (p.xy - 0.5) / (uniforms.resolution - 1.0);\n") f.write(" let original_raw = textureSample(original_input, smplr, uv);\n") f.write(" let original = (original_raw - 0.5) * 2.0; // Normalize to [-1,1]\n") f.write(" let gray = dot(original.rgb, vec3(0.2126, 0.7152, 0.0722));\n") diff --git a/workspaces/main/shaders/cnn/cnn_layer.wgsl b/workspaces/main/shaders/cnn/cnn_layer.wgsl index 8eccb26..d33a301 100644 --- a/workspaces/main/shaders/cnn/cnn_layer.wgsl +++ b/workspaces/main/shaders/cnn/cnn_layer.wgsl @@ -29,7 +29,8 @@ struct CNNLayerParams { } @fragment fn fs_main(@builtin(position) p: vec4) -> @location(0) vec4 { - let uv = p.xy / uniforms.resolution; + // Match PyTorch linspace: pixel_idx / (size - 1), not pixel_center / size + let uv = (p.xy - 0.5) / (uniforms.resolution - 1.0); let original_raw = textureSample(original_input, smplr, uv); let original = (original_raw - 0.5) * 2.0; // Normalize to [-1,1] let gray = dot(original.rgb, vec3(0.2126, 0.7152, 0.0722)); -- cgit v1.2.3