Hi,
Christian Sam wrote:
Hi J.P.
Thank you for taking the time in helping me. i have two questions
regarding your recommendations.
I think most people would nowadays advise to just specify normals
per vertex and not try to use normals per face (slow path).
- does this mean: if a normals-indexarray hasn't the same amount of
entries like the vertex-indexarray (like in the case i'm planning to
do) the rendering will be done with glBegin/glEnd calls instead of
the faster alternatives (displaylists, indexed arrays, etc.)
- i have never heard the phrase "slow path", but this does not sounds
good ;-) does this mean the consequences mentioned above?
yes and yes, graphics cards are good at eating attributes per vertex. If
you do a search for "slow path" here
http://news.gmane.org/gmane.comp.graphics.openscenegraph.user
you'll find some discussions.
jp
E.g. primitive 1 = vertex_array_shared + normal_array1 +
drawelements primitive 2 = vertex_array_shared + normal_array2 +
drawelements
i' m a opengl/osg beginner, so i hope i got you right - you mean that
instead of defining one primitive (triangle_strip, drawElements) that
defines a roof-geometry, i define several primitives (triangle_strip,
drawElements) with same vertices and indices, but different assigned
normalarrays) for the same roof-geometry. (there would still be a
need of normals array 3, for the normals of vertex 4 and 5, pointing
north) this will result in two exact overlying, seperate
triangle_strips so no difference will be noticed, [Image:
http://www.spatiality.at/osg/roof.jpg ]
but wouldn't their faces z-fighting?
Best regards, christian sam
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