I have a car model that has normal problem. This question has been asked many times in the forum, I believe.
Some faces of the car model are disappeared. I tried recalculated normal outside, but it does not help.
If I set “Doubled Sided” off in blender, I can see blender shows exactly the same problem as in panda.
If I manually flip normal for these missing polygons, panda can see the missing faces again, but blender, render in solid mode, the faces become missing.
What can I do in blender in order to make the blender rendering match the panda rendering (without setTwoSided in Panda) ?
It could be that your model has a negative scale.
In object mode, hit N and make sure there is no negative scale set. Instead, apply any negative scale in edit mode. (Afterwards, flip or recalculate the normals outside again)
I also met this problem once, and this error persisted no matter how I recalculated normals. I am not sure, but suspect it could happen because vertices (for some strange reason) were exported from Blender in clockwise order (while they must be counterclockwise). Again, I am not sure, and the problem definitely requires more investigation.