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# X marks the spot?

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I wrote a small landscape editing program, with the help from this forum and others. When I use it to draw an 'X' into the mesh, raising the vertices to a specified height, the diagonal to the left shows up as spikes, whereas the diagonal going to the right shows up as spikes+embedded wall when either smooth-shaded or texture-shaded. The mesh is drawn out as quads btw. I thought I had it wrong, then I tried the same thing in anim8or (www.anim8or.com), and it does the exact same thing. Going one way, the diagonal is a row of spikes, the other way it is spikes + what looks like a wall or the spikes are connected together or something. After subdividing it looks ok tho. What is going on here? I fseek, therefore I fam. [edited by - drarem on November 19, 2002 12:47:56 PM]

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This is due to the way triangles are oriented in a mesh of quads. Quads are drawn like this:
|---||\  || \ ||  \||---|

(excuse the artwork...)

If you view it in wireframe, you''ll see why this happens - one way you get triangles raised all the way along, the other you just get an edge.

At least, I think that''s what''s happening.

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