fix:make zerocolor edge

shaders/base.frag

@@ -47,6 +47,14 @@ float maxNeighborValue(vec2 uv) {
     return max(max(v00, v10), max(v01, v11));
 }
 
+vec3 colorRampWithZero(float t) {
+    const float zeroW = 0.005;
+    float blend = smoothstep(0.0, zeroW, t);
+    float tRamp = saturate((t - zeroW) / max(1.0 - zeroW, 1e-6));
+    vec3 ramp = colorRamp(tRamp);
+    return mix(uColorZero, ramp, blend);
+}
+
 void main() {
     vec3 N = normalize(vNormal);
     vec3 L = normalize(uLightDir);
@@ -63,7 +71,7 @@ void main() {
     float eps = max(1e-4, 0.001 * (uMaxV - uMinV));
     float force = smoothstep(uMaxV - eps, uMaxV, m);
     t = max(t, force);
-    vec3 base = isZero ? uColorZero : colorRamp(t);
+    vec3 base = isZero ? uColorZero : colorRampWithZero(t);
 
     vec3 col = base * (0.35 + 0.65 * diff);
     col += vec3(1.0) * spec * 0.10;