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Normals noob question


Zetha

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Hi,

Why is it necessary to post-compute normals with with nodes like facet or normal? Aren´t the normals always there there in a surface?

And... if a normal is supposed to be perpendicular to a surface, what is happening when you change its direction?

Edited by Zetha
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1. No need to compute normals without a good reason. Some nodes may use existing normals to output nicer results. Notable example is the Voronoi Fracture transferring input normals to outer surface. Other nodes may output worse-looking result with degenerate normals. Notable example is also the Voronoi Fracture: it cannot transfer to inside surface because it didn't exist on the input.

2. If there is no normal attribute on geometry, Houdini will internally compute some for display.

3. If you change direction of the normal, surface will be shaded as if it was perpendicular at that point. That's how normal mapping works.

normal_examples.hipnc

Edited by f1480187
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