I had this Issue recently and its been driving me insane. Ive resorted to building the basic framework of the model, exporting it from sketchup 2014 to sketchup 8 to use the .x exporter (3dRad), loading it in Entity workshop (1st check) if it loads fine, I save it in there and load the model in fpsc (2nd check) if it passes both checks I go back to Sketchup 2014 and save what Ive got so far, then model the next section and repeat the entire process.
If at any point it fails a check I revert to the last known saved version (the last version that passed both checks) and remodel the section that failed.
its an incredibly frustrating and time consuming process but I have noticed a couple of things.
1. I have to draw faces in a specific way, example if I have a wall and want to model a painting on it by simply drawing two rectangles ( a large one with a smaller one inside and then extrude the 'frame') then I HAVE TO draw the exterior one first then draw the interior one, If I do it the other way around it generates a free floating face, inside the current face but no longer connected to it. This is one factor that seems to cause a failed import.
2. It only seems to happen when Im modelling an interior. In order to optimize my game Im building the levels in their entirity inside sketchup, and when building a model thats large open plan it seems to create problems. Take a closed box, you model it and texture the outside, and the insides largely unused, however building a level is akin to building on the interior of the box and that seems to cause me issues too.
It seems somewhat random and arbitrary and Im not entirely sure if theres an easy fix but my method, as long winded and time consuming as it is seems to work best at least for me, that way I never have to remodel an ENTIRE level, just the section that most recently didnt work, and usually I repeat this process every half hour so its never more than 30 minutes work.
Hope this helps
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