Improve color handling approach

src/graphics/rendering/shaders/distance-fs-100.glsl

@@ -6,17 +6,23 @@ uniform float maxMinDistance;
 uniform float distanceNdcPixelSize;
 varying vec2 position;
 
+uniform sampler2D palette;
+
+vec4 readFromPalette(int index) {
+  return texture2D(palette, vec2((float(index) + 0.5) / {paletteSize}, 0.5));
+}
+
+
 {macroDefinitions}
 
 {declarations}
 
 void main() {
-    float minDistance = maxMinDistance;
-    float color = 0.0;
-
-    float objectMinDistance, objectColor;
+    float minDistance = maxMinDistance, objectMinDistance;
+    vec4 color = {backgroundColor};
+    vec4 objectColor;
 
     {functionCalls}
     
-    gl_FragColor = vec4(minDistance * 8.0, color, 0.0, 1.0);
+    gl_FragColor = vec4(color.rgb, minDistance * 8.0);
 }