 
     vec2 difftexcoord;
     if (isdifference != NODIFFERENCE) {
-        if (/*radius2 >= 1. ||*/ diffrotatedHitPoint.z <= 0.) {
+        if (/*radius2 >= 1. ||*/ diffRotatedHitPoint.z <= 0.) {
             hitPoint = vec3(up1.x, up1.y, intersectPlane(cameraDifference[1], up1, onDisk));
-            diffrotatedHitPoint = rotate_vector_inverse(cameraDifference[1], hitPoint);
-            diffrotatedHitPoint = apply_center(diffrotatedHitPoint, crval[1], crotaQuat[1]);
+            diffRotatedHitPoint  = rotate_vector_inverse(cameraDifference[1], hitPoint);
+            diffCenteredHitPoint = apply_center(diffRotatedHitPoint, crval[1], crotaQuat[1]);
         }
 
-        difftexcoord = differencerect.zw * vec2(diffrotatedHitPoint.x - differencerect.x, -diffrotatedHitPoint.y - differencerect.y);
+        difftexcoord = differencerect.zw * vec2(diffCenteredHitPoint.x - differencerect.x, -diffCenteredHitPoint.y - differencerect.y);
         clamp_coord(difftexcoord);
 
-        float diffrotatedHitPointRad = length(diffrotatedHitPoint.xy);
-        if (diffrotatedHitPointRad > radii[1] || diffrotatedHitPointRad < radii[0]) {
+        float diffRotatedHitPointRad = length(diffRotatedHitPoint.xy);
+        if (diffRotatedHitPointRad > radii[1] || diffRotatedHitPointRad < radii[0]) {
             discard;
         }
     }

    bool onDisk = radius2 <= 1.;

    float factor;
    vec3 hitPoint = vec3(0.), rotatedHitPoint = vec3(0.), diffrotatedHitPoint = vec3(0.);

    if (onDisk) {
        hitPoint = vec3(up1.x, up1.y, sqrt(1. - radius2));
        rotatedHitPoint     = differential(deltaT[0], rotate_vector_inverse(cameraDifference[0], hitPoint));
        rotatedHitPoint     = apply_center(rotatedHitPoint, crval[0], crotaQuat[0]);

        diffrotatedHitPoint = differential(deltaT[1], rotate_vector_inverse(cameraDifference[1], hitPoint));
        diffrotatedHitPoint = apply_center(diffrotatedHitPoint, crval[1], crotaQuat[1]);

        factor = 1.;
        gl_FragDepth = 0.5 - hitPoint.z * CLIP_SCALE_NARROW;

        if (length(rotatedHitPoint) <= 1.) // differential: central disk
            discard;

        centeredHitPoint = apply_center(rotatedHitPoint, crval[0], crotaQuat[0]);

        if (calculateDepth != 0) // intersecting Euhforia planes
            gl_FragDepth = 0.5 - hitPoint.z * CLIP_SCALE_WIDE;
    }

    if (sector[0] != 0.) {
        float theta = atan(centeredHitPoint.y, centeredHitPoint.x);
        if (theta < sector[1] || theta > sector[2])
            discard;
    }

    vec2 texcoord = rect.zw * vec2(centeredHitPoint.x - rect.x, -centeredHitPoint.y - rect.y);
    clamp_coord(texcoord);

    float geometryFlatDist = abs(dot(rotatedHitPoint.xy, cutOffDirection));
