diff --git a/modules/hex_wave.frag b/modules/hex_wave.frag
index bfd884d..f296fc3 100644
--- a/modules/hex_wave.frag
+++ b/modules/hex_wave.frag
@@ -14,10 +14,10 @@ layout(std140, binding = 0) uniform buf {
     vec4 uC2;
 };
 
-float sdHexFlat(vec2 p, float r) {
-    const vec3 k = vec3(0.5, 0.8660254, 0.5773503);
+float sdHexagon(vec2 p, float r) {
+    const vec3 k = vec3(-0.866025404, 0.5, 0.577350269);
     p = abs(p);
-    p -= 2.0 * min(dot(k.yx, p), 0.0) * k.yx;
+    p -= 2.0 * min(dot(k.xy, p), 0.0) * k.xy;
     p -= vec2(clamp(p.x, -k.z * r, k.z * r), r);
     return length(p) * sign(p.y);
 }
@@ -42,7 +42,7 @@ void main() {
     float inradius = baseR * (1.0 + 0.35 * wf);
 
     vec2 p = frag - center;
-    float d = sdHexFlat(p, inradius);
+    float d = sdHexagon(p.yx, inradius);  // swap for flat-top
     if (d > 0.0) {
         fragColor = vec4(0.0);
         return;