diff --git a/app-proto/full-interface/src/inversive.frag b/app-proto/full-interface/src/inversive.frag
index 47743eb..8327f47 100644
--- a/app-proto/full-interface/src/inversive.frag
+++ b/app-proto/full-interface/src/inversive.frag
@@ -71,18 +71,6 @@ struct taggedFrag {
     vec3 normal;
 };
 
-taggedFrag[2] sort(taggedFrag a, taggedFrag b) {
-    taggedFrag[2] result;
-    if (a.pt.z > b.pt.z) {
-        result[0] = a;
-        result[1] = b;
-    } else {
-        result[0] = b;
-        result[1] = a;
-    }
-    return result;
-}
-
 taggedFrag sphere_shading(vecInv v, vec3 pt, vec3 base_color, float highlight, int id) {
     // the expression for normal needs to be checked. it's supposed to give the
     // negative gradient of the lorentz product between the impact point vector
diff --git a/app-proto/inversive-display/src/inversive.frag b/app-proto/inversive-display/src/inversive.frag
index ae3b930..fc2a474 100644
--- a/app-proto/inversive-display/src/inversive.frag
+++ b/app-proto/inversive-display/src/inversive.frag
@@ -70,18 +70,6 @@ struct taggedFrag {
     vec3 normal;
 };
 
-taggedFrag[2] sort(taggedFrag a, taggedFrag b) {
-    taggedFrag[2] result;
-    if (a.pt.z > b.pt.z) {
-        result[0] = a;
-        result[1] = b;
-    } else {
-        result[0] = b;
-        result[1] = a;
-    }
-    return result;
-}
-
 taggedFrag sphere_shading(vecInv v, vec3 pt, vec3 base_color, int id) {
     // the expression for normal needs to be checked. it's supposed to give the
     // negative gradient of the lorentz product between the impact point vector