update

shader/bg.frag

@@ -9,9 +9,9 @@ uniform bool uLightMode;
 
 float gridLine(float stepPx) {
     vec2 coord = gl_FragCoord.xy;
-    vec2 q = coord / stepPx;
-
-    vec2 q = abs(fract(q - 0.5) - 0.5) / fwidth(stepPx);
+    vec2 q = coord / max(stepPx, 1.0);
+    vec2 fw = max(fwidth(q), vec2(1e-6));
+    q = abs(fract(q - 0.5) - 0.5) / fw;
     float line = 1.0 - min(min(q.x, q.y), 1.0);
 
     return line;
@@ -21,27 +21,24 @@ void main() {
     vec2 viewport = max(uViewport, vec2(1.0));
     vec2 uv = gl_FragCoord.xy / viewport;
 
-    vec3 topCol, botCol, majCol, minCol;
-    float majStrength, minStrength;
-    float vignettePow, vignetteStrength;
+    vec3 topCol, botCol;
+    float majorStrength, minorStrength;
 
     topCol = vec3(0.99, 0.99, 1.00);
     botCol = vec3(0.94, 0.95, 0.98);
 
-    minorCol = vec3(0.80, 0.82, 0.87);
-    majorCol = vec3(0.70, 0.73, 0.80);
+    vec3 minorCol = vec3(0.80, 0.82, 0.87);
+    vec3 majorCol = vec3(0.70, 0.73, 0.80);
 
-    minorStrength = 0.22;
-    majorStrength = 0.35;
-    vignettePow = 0.12;
-    vignetteStrength = 0.35;
+    minorStrength = 0.28;
+    majorStrength = 0.45;
 
     vec3 col = mix(botCol, topCol, uv.y);
     float minor = gridLine(max(uMinorStep, 1.0));
     float major = gridLine(max(uMajorStep, 1.0));
 
-    col = mix(col, minorCol, minStrength * minor);
-    col = mix(col, majorCol, majStrength * major);
+    col = mix(col, minorCol, minorStrength * minor);
+    col = mix(col, majorCol, majorStrength * major);
 
     vec2 p = uv * 2.0 - 1.0;
     float v = clamp(1.0 - dot(p, p) * 0.12 , 0.0, 1.0);