Udało mi się tylko nie rozumiem tego "1.6. In the Material Editor, make sure the popcorn map is open. Click on “Bitmap”, and select Mask from the Map Browser. Choose “Keep old map as sub-map” in the “Replace Map” dialog. In the new Mask material, your popcorn map is set as Map, so drag that do the Mask slot, and choose “Swap”.
1.7. Click the Map slot, and choose Gradient Ramp from the Map Browser. Set Gradient Type to Radial. Right-click the left flag, choose “Edit properties” and change the color from black to white, right-click the center flag and choose “Delete”, and right-click the right flag and choose “Edit properties”."