1 files changed, 41 insertions, 2 deletions
diff --git a/flowy/src/shader.wgsl b/flowy/src/shader.wgsl
index 1597ff6..bfa4176 100644
--- a/flowy/src/shader.wgsl
+++ b/flowy/src/shader.wgsl
@@ -1,11 +1,50 @@
 
 @group(0) @binding(0) var output: texture_storage_2d<bgra8unorm, write>;
 @group(0) @binding(1) var texa: texture_2d<f32>;
+@group(0) @binding(2) var texb: texture_2d<f32>;
 
+const SDIST: i32 = 4;
+
+const NN: vec2<i32> = vec2(-1,-1);
+const NP: vec2<i32> = vec2(-1,1);
+const PN: vec2<i32> = vec2(1,-1);
+const PP: vec2<i32> = vec2(1,1);
 
 @compute @workgroup_size(1) fn main(@builtin(global_invocation_id) global_id: vec3<u32>) {
-    let p = textureLoad(texa, global_id.xy, 0);
-    textureStore(output, global_id.xy, p);
+    let uv = vec2<i32>(global_id.xy);
+    let orig = textureLoad(texa, uv, 0);
+    let orignn = textureLoad(texa, uv+NN, 0);
+    let orignp = textureLoad(texa, uv+NP, 0);
+    let origpn = textureLoad(texa, uv+PN, 0);
+    let origpp = textureLoad(texa, uv+PP, 0);
+
+    var best_sim = 1000.;
+    var best_coord = vec2(0,0);
+    for (var x = -SDIST; x <= SDIST; x++) {
+    for (var y = -SDIST; y <= SDIST; y++) {
+        let ov = uv + vec2(x,y);
+        let samp = textureLoad(texb, ov, 0);
+        let sampnn = textureLoad(texb, ov+NN, 0);
+        let sampnp = textureLoad(texb, ov+NP, 0);
+        let samppn = textureLoad(texb, ov+PN, 0);
+        let samppp = textureLoad(texb, ov+PP, 0);
+        let d = distance(samp.rgb, orig.rgb)
+            + distance(sampnn.rgb, orignn.rgb)
+            + distance(sampnp.rgb, orignp.rgb)
+            + distance(samppn.rgb, origpn.rgb)
+            + distance(samppp.rgb, origpp.rgb);
+        if d < best_sim {
+            best_sim = d;
+            best_coord = vec2(x,y);
+        }
+    }}
+
+    let col = vec4(colormap_vec(vec2<f32>(best_coord) / f32(SDIST)), 1.);
+
+    textureStore(output, global_id.xy, col);
 }
 
+fn colormap_vec(v: vec2<f32>) -> vec3<f32> {
+    return vec3(v.y, v.x - 0.5 * v.y, -v.x - 0.5 * v.y);
+}