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ZealousEngine

Tree normals and Blender...

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A long time ago I bought a great pack of trees here.. http://www.loopix-project.com/ However im having trouble with the normals. The trees are the typical 'group of intersecting quads'. Each of the quads have normals that allign with the face of the quad. So as long as the sunlight is hitting the front face, the lighting looks right. But if you shine light on the tree from behind/below, the face is dark (since the backfaces use the same normals as the frontfaces). My question is, with trees like these, how are the normals SUPPOSED to look? Should they allign with the face, and damn the backfaces? Or is there something im missing? Any help appreciated! * He has a free test tree on his website.. http://www.loopix-project.com/downloads/test_tree.zip

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After thinking about it some more, it seems like there are two 'good' ways to set the normals on a 'leaf quad'.

1.) Have the normal for each leaf quad allign parallel with the quad. This way both front and back faces share the same normal. Kinda like most people do with grass.

or

2.) Have each face (front and back) have their own normal allign perpendicular with the quad. Like two planes sandwiched back to back. This way front faces can be lit, while backfaces stay dark.

The trouble is, these loopix trees dont come into blender with either. They have normals for the front face alligned perpendicular to the quad, but those normals are shared with the backfaces (so if the 'front' of a quad is dark, so is the back, even if it SHOULD be lit).

There has to be some way to implement the above methods in blender without having to monkey with these models too much.. but how!?

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I think its just a matter of recomputing the normals. I had the same problem loading that test tree up into different modeling programs. But it was fine when i loaded it into my engine, and i compute all the normals for new meshes at load time. I guess what I do is #2.

Not sure how to recompute vertex normals in blender, but you should be good if you can do that.

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Well ctrl-N will recompute the normals in blender. But the problem is, it only computes normals for one face of the quad. Thus if the quad is facing away from the light, yet the backface is facing the light, the backface will still be dark (looks terrible).

I think the way these normals SHOULD be is like you see grass billboards. Where the normal points straight up (parallel with the quad).

Its just so odd.. I swear in my old graphics engine I was able to import these trees and they looked AMAZING. Now they look horrible in blender and my engine (ogre)...

If anyone is able to fix these normals using blender you will be my hero!

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