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View Full Version : Does order of triangles matter?



varieux
10-16-2010, 01:02 PM
Hi all,

I have a model that consists of large numbers of triangles.
Some of these triangles are too large (for selection purposes), so I decided to break the bigger ones down into smaller ones if the area is above a threshold.

That works, however there is a discoloration problem now. The smaller (broken down) triangles are often dark gray instead of white. I am also adding any new triangles to the end of my array, rather than inserting them at the point of the original. So I am wonder, does the order in which triangles are presented to OpenGL matter?

My other thought was that this is a problem of normal vectors pointing inward instead of outward but I have not yet looked into that...

Thanks.

mhagain
10-16-2010, 01:28 PM
Not in the kind of scenario you're talking about, no it doesn't matter. You can quickly check your normals theory be enabling two-sided lighting:

glLightModeli(GL_LIGHT_MODEL_TWO_SIDE, GL_TRUE);

varieux
10-17-2010, 06:54 PM
That didn't fix it, so something else is going on here.