OpenGL Discussion and Help Forums - Math and Algorithms http://www.opengl.org/discussion_boards/ Discussion about 3D math and linear algebra that is essential as a background to OpenGL coding en Wed, 22 May 2013 05:39:28 GMT vBulletin 60 http://www.opengl.org/discussion_boards/images/misc/rss.png OpenGL Discussion and Help Forums - Math and Algorithms http://www.opengl.org/discussion_boards/ Smoothing the dges of a polygon http://www.opengl.org/discussion_boards/showthread.php/181739-Smoothing-the-dges-of-a-polygon?goto=newpost Mon, 20 May 2013 19:57:45 GMT Attachment 1032 (http://www.opengl.org/discussion_boards/attachment.php?attachmentid=1032) Hello every body, I have a polygon consisting of 26... Click image for larger version.  Name: boundary.jpg  Views: 61  Size: 5.8 KB  ID: 1032

Hello every body, I have a polygon consisting of 26 points as shown in the figure. i would just like to smoothen the edges. Could you suggest me some simple way to do it? Thanks in advance.
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]]> Math and Algorithms jenny_wui http://www.opengl.org/discussion_boards/showthread.php/181739-Smoothing-the-dges-of-a-polygon Finding the convex hull of a set of points http://www.opengl.org/discussion_boards/showthread.php/181716-Finding-the-convex-hull-of-a-set-of-points?goto=newpost Thu, 16 May 2013 19:06:25 GMT Hello every body, I need to find the convex hull of a set of points. Could any one help me how that can be done. Lastly, I need to find the boundary... Hello every body, I need to find the convex hull of a set of points. Could any one help me how that can be done. Lastly, I need to find the boundary of the convex hull. Thanks. ]]> Math and Algorithms jenny_wui http://www.opengl.org/discussion_boards/showthread.php/181716-Finding-the-convex-hull-of-a-set-of-points Determing facet winding http://www.opengl.org/discussion_boards/showthread.php/181595-Determing-facet-winding?goto=newpost Wed, 01 May 2013 16:09:45 GMT We normally use clockwise windings for our facet models. However, we have some models that have a mixture of CW and CCW facets so that the backward... We normally use clockwise windings for our facet models. However, we have some models that have a mixture of CW and CCW facets so that the backward facets appear dark when displayed in OpenGL.

I was trying to find a way to determine which facets are backwards so that I can fix them in the models. My first idea was to simply do a cross product of all of the facets and check the direction of the normal. If it is negative then I reverse the facet direction. But then I realized that CW facets on the opposite size of the model will always come back negative, since they actually face away from the user. The only other idea I can come up with to to manually render the model from six sides to determines which facets should point towards the user. But even this could cause problems, like how much resolution do I need and what if a facet is perpendicular.

Before I go too far down this road I was wondering if you have any suggestions. Maybe there is a simple solution that I'm not thinking about.

Thank you,

Jim ]]> Math and Algorithms JRGlide http://www.opengl.org/discussion_boards/showthread.php/181595-Determing-facet-winding