Find flipped normals in a 3D model
Faces that point inward look black, disappear or light wrongly in engines. Here the back side of every face is painted red, so flipped areas are easy to see.
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No sign-up, no watermark, no daily limits.
Nothing to install
Works in Chrome, Edge, Firefox and Safari on desktop and mobile.
How it works
- 01
Drop a model.
- 02
Look from outside: gray is correct, red is a face seen from behind.
- 03
Switch to Normals to see direction as color, or turn on Double-sided to hide the problem while you fix it.
Questions
Why are some faces red?+
Their winding order is reversed, so the visible side is the back. Flip those faces in your 3D editor, for example Recalculate Normals in Blender.
Red inside a closed object, is that a problem?+
No. The inside of a closed mesh is normally a back side. Only red that you see from outside matters.
Is double-sided a real fix?+
It hides the problem and costs extra rendering. Flipping the faces is the right fix.
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