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I am making a racing game, and on the small test track I created, when I play it, the cars sometimes just randomly hit something on the track.enter image description here

I tried changing it to wireframe and found that blender had put in some edges for some reason. enter image description here

Why did it create these edges? Is there any way to stop blender from doing this? This is what it looks like before you play the game. enter image description here

Jude Nelson
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1 Answers1

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That's the result of Triangulation of NGons in the game engine, it doesn't effect the original geometry.

enter image description here

in game mode

enter image description here

Back out of Game Engine, the geometry is not changed. If it bothers you the solution is to make the geometry without NGons in the first place. This means cutting up the NGon into triangles or quadrangles. A fast way to convert an NGon to the elementary polygon types is:

Ngon to Tris

  • in edit mode

  • select the ngon

  • press Ctrl+t (this creates Triangles)

    should generate something like this enter image description here

Tris to Quads

  • With a set of Triangles selected press Alt + j , and blender will try to make quads from the geometry.

Sometimes it isn't possible to convert all selected Triangles into a set of Quads. invariably there will be times when the algorithm leaves a few Triangles, even though geometrically it would be possible to neatly Quadify all selected geometry. This is not a bug (really, we could argue about this), but rather a limitation in the algorithm.

this might produce geometry like this:

enter image description here

The algorithms that do this don't have the benefit of our eyes and brains, to make the best decisions. Sometimes you have to do the tessellation yourself

enter image description here

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zeffii
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  • Please add a solution if you can (recommended way to fill with quads, tris) – J Sargent May 10 '15 at 17:49
  • zeffii, I tried this and it only created more of those lines. Is there any other solution? – Jude Nelson May 10 '15 at 20:40
  • those "lines" are edges, internal to your Ngons (do you know what an Ngon is?) . Those lines are really there, because all surfaces (that we're talking about) are made from triangles or quads in the end. The best you can do is to control the geometry yourself if it bothers you, and avoid Ngons. That means picking three or 4 vertices and pressing F to fill them, instead of a massive edge loop of 20 vertices. – zeffii May 10 '15 at 21:07
  • that's what it looks like if you start the game engine while viewing the scene in wireframe mode, it allows you to see how geometry is represented "under the hood", it's a feature not a mistake. – zeffii May 11 '15 at 05:13