gemini glow fixes + positioning for window view

assets/shaders/geminiglow.frag

@@ -50,6 +50,18 @@ void main()
     float r = clamp(radius, 0.0, min(rectSize.x, rectSize.y) * 0.5);
     float d = sdRoundBox(p, rectSize * 0.5, r);
 
+    // ~1px antialiasing width
+    float aa = max(fwidth(d), 0.75);
+
+    // Coverage of the shape: 1 inside, 0 outside, soft across the edge
+    float inside = 1.0 - smoothstep(-aa, aa, d);
+
+    // Only skip work when clearly outside and there's no outer glow
+    if (glowSize <= 0.0 && d > aa) {
+        fragColor = vec4(0.0);
+        return;
+    }
+
     float ang = atan(p.y, p.x);
     float a2  = phase * TAU;
     float u = ang / TAU + 0.5 + phase;
@@ -59,20 +71,28 @@ void main()
     float g = 0.0;
     if (d > 0.0) {
         float t = clamp(d / max(glowSize, 0.001), 0.0, 1.0);
-        g = pow(1.0 - t, 3.0);
+        g = (glowSize > 0.0) ? pow(1.0 - t, 3.0) : 0.0;
     } else if (innerGlow > 0.0) {
-        g = exp(d / innerGlow * 3.0);
+        float t = clamp(-d / innerGlow, 0.0, 1.0);
+        g = pow(1.0 - t, 3.0);
     }
 
     float pulse = 0.9 + 0.1 * sin(a2 * 2.0 + ang);
     g *= pulse;
 
+    // Line: inside only, with a soft inner edge AND a soft outer edge
     float line = 0.0;
-    if (lineWidth > 0.0)
-        line = 1.0 - smoothstep(0.0, lineWidth, abs(d));
+    if (lineWidth > 0.0) {
+        float inner = 1.0 - smoothstep(lineWidth - aa, lineWidth + aa, -d);
+        line = inner * inside;
+    }
 
     float a = clamp(g * intensity + line * 0.9, 0.0, 1.0);
 
+    // Antialias the outer silhouette when there is no outer glow
+    if (glowSize <= 0.0)
+        a *= inside;
+
     col = mix(col, vec3(1.0), line * 0.25);
 
     a += (hash(gl_FragCoord.xy) - 0.5) / 255.0;