diff --git a/src/drawables/shapes/circle.ts b/src/drawables/shapes/circle.ts
index d3e945d..937bc65 100644
--- a/src/drawables/shapes/circle.ts
+++ b/src/drawables/shapes/circle.ts
@@ -9,17 +9,15 @@ export class Circle extends Drawable {
           uniform vec2 circleCenters[CIRCLE_COUNT];
           uniform float circleRadii[CIRCLE_COUNT];
 
-          void circleMinDistance(inout float minDistance, inout float color) {
-              float myMinDistance = maxMinDistance;
-              for (int i = 0; i < CIRCLE_COUNT; i++) {
-                  float dist = distance(circleCenters[i], position) - circleRadii[i];
-                  myMinDistance = min(myMinDistance, dist);
-              }
-              minDistance = min(minDistance, myMinDistance);
-              color = mix(1.0 / {paletteSize}, color, step(
-                distanceNdcPixelSize + SURFACE_OFFSET, 
-                myMinDistance
-              ));
+          float circleMinDistance(vec2 target, out float colorIndex) {
+            colorIndex = 2.0;
+            float minDistance = 1000.0;
+            for (int i = 0; i < CIRCLE_COUNT; i++) {
+              float dist = distance(circleCenters[i], target) - circleRadii[i];
+              minDistance = min(minDistance, dist);
+            }
+
+            return minDistance;
           }
         `,
       distanceFunctionName: 'circleMinDistance',
diff --git a/src/drawables/shapes/inverted-tunnel.ts b/src/drawables/shapes/inverted-tunnel.ts
index 8d3ccad..9f65925 100644
--- a/src/drawables/shapes/inverted-tunnel.ts
+++ b/src/drawables/shapes/inverted-tunnel.ts
@@ -12,12 +12,13 @@ export class InvertedTunnel extends Drawable {
         uniform vec2 toFromDeltas[INVERTED_TUNNEL_COUNT];
         uniform float fromRadii[INVERTED_TUNNEL_COUNT];
         uniform float toRadii[INVERTED_TUNNEL_COUNT];
-      
-        void invertedTunnelMinDistance(inout float minDistance, inout float color) {
-          float myMinDistance = -minDistance;
+
+        float invertedTunnelMinDistance(vec2 target, out float colorIndex) {
+          float minDistance = 1000.0;
+
           for (int i = 0; i < INVERTED_TUNNEL_COUNT; i++) {
-            vec2 targetFromDelta = position - froms[i];
-            
+            vec2 targetFromDelta = target - froms[i];
+
             float h = clamp(
                 dot(targetFromDelta, toFromDeltas[i])
               / dot(toFromDeltas[i], toFromDeltas[i]),
@@ -30,14 +31,10 @@ export class InvertedTunnel extends Drawable {
               targetFromDelta, toFromDeltas[i] * h
             );
 
-            myMinDistance = min(myMinDistance, currentDistance);
+            minDistance = min(minDistance, currentDistance);
           }
-  
-          color = mix(0.0, color, step(
-            distanceNdcPixelSize + SURFACE_OFFSET,
-            -myMinDistance
-          ));
-          minDistance = -myMinDistance;
+
+          return -minDistance;
         }
       `,
       distanceFunctionName: 'invertedTunnelMinDistance',
diff --git a/src/drawables/shapes/tunnel.ts b/src/drawables/shapes/tunnel.ts
index ee2f435..3656581 100644
--- a/src/drawables/shapes/tunnel.ts
+++ b/src/drawables/shapes/tunnel.ts
@@ -12,11 +12,13 @@ export class Tunnel extends Drawable {
         uniform vec2 toFromDeltas[TUNNEL_COUNT];
         uniform float fromRadii[TUNNEL_COUNT];
         uniform float toRadii[TUNNEL_COUNT];
-      
-        void tunnelMinDistance(inout float minDistance, inout float color) {
-          float myMinDistance = minDistance;
+
+        float tunnelMinDistance(vec2 target, out float colorIndex) {
+          colorIndex = 1.0;
+
+          float minDistance = 1000.0;
           for (int i = 0; i < TUNNEL_COUNT; i++) {
-            vec2 targetFromDelta = position - froms[i];
+            vec2 targetFromDelta = target - froms[i];
             
             float h = clamp(
                 dot(targetFromDelta, toFromDeltas[i])
@@ -29,15 +31,11 @@ export class Tunnel extends Drawable {
             ) + distance(
               targetFromDelta, toFromDeltas[i] * h
             );
-    
-            myMinDistance = min(myMinDistance, currentDistance);
+
+            minDistance = min(minDistance, currentDistance);
           }
-    
-          color = mix(2.0 / {paletteSize}, color, step(
-            distanceNdcPixelSize + SURFACE_OFFSET,
-            myMinDistance
-          ));
-          minDistance = min(minDistance, myMinDistance);
+
+          return minDistance;
         }
       `,
       distanceFunctionName: 'tunnelMinDistance',
diff --git a/src/graphics/graphics-library/program/uniform-array-autoscaling-program.ts b/src/graphics/graphics-library/program/uniform-array-autoscaling-program.ts
index 3e67f40..f7e6e93 100644
--- a/src/graphics/graphics-library/program/uniform-array-autoscaling-program.ts
+++ b/src/graphics/graphics-library/program/uniform-array-autoscaling-program.ts
@@ -135,7 +135,22 @@ export class UniformArrayAutoScalingProgram implements IProgram {
           return '';
         }
 
-        return `${descriptors[i].sdf!.distanceFunctionName}(minDistance, color);`;
+        return `
+          #ifndef NOT_EMPTY
+          #define NOT_EMPTY
+          #endif
+
+          objectMinDistance = ${
+            descriptors[i].sdf!.distanceFunctionName
+          }(position, objectColor);
+
+          color = mix(objectColor / {paletteSize}, color, step(
+            distanceNdcPixelSize + SURFACE_OFFSET, 
+            objectMinDistance
+          ));
+
+          minDistance = min(minDistance, objectMinDistance);
+        `;
       })
       .join('\n');
   }
diff --git a/src/graphics/rendering/shaders/distance-fs-100.glsl b/src/graphics/rendering/shaders/distance-fs-100.glsl
index e1ed46e..ae51453 100644
--- a/src/graphics/rendering/shaders/distance-fs-100.glsl
+++ b/src/graphics/rendering/shaders/distance-fs-100.glsl
@@ -13,10 +13,16 @@ varying vec2 position;
 {declarations}
 
 void main() {
-    float minDistance = maxMinDistance;
+    float minDistance = abs(maxMinDistance);
     float color = 0.0;
 
+    float objectMinDistance, objectColor;
+
     {functionCalls}
+    
+    #ifndef NOT_EMPTY
+    minDistance = maxMinDistance;
+    #endif
 
     // minDistance / 2.0: NDC to UV scale
     gl_FragColor = vec4(minDistance / 2.0, color, 0.0, 0.0);
diff --git a/src/graphics/rendering/shaders/distance-fs.glsl b/src/graphics/rendering/shaders/distance-fs.glsl
index 4e058d1..59234e7 100644
--- a/src/graphics/rendering/shaders/distance-fs.glsl
+++ b/src/graphics/rendering/shaders/distance-fs.glsl
@@ -15,11 +15,17 @@ in vec2 position;
 out vec2 fragmentColor;
 
 void main() {
-    float minDistance = maxMinDistance;
+    float minDistance = abs(maxMinDistance);
     float color = 0.0;
 
+    float objectMinDistance, objectColor;
+
     {functionCalls}
 
+    #ifndef NOT_EMPTY
+    minDistance = maxMinDistance;
+    #endif
+
     // minDistance / 2.0: NDC to UV scale
     fragmentColor = vec2(minDistance / 2.0, color);
 }