Hi Stuart, > De: Stuart Buchanan > > On Wed, May 23, 2012 at 2:38 PM, Björn Kesten wrote: > > Would trimming down building variety help? > > Unfortunately not. Individual buildings aren't instantiations > of a small number of objects, as the random vegetation is. > > Instead, a huge group of buildings are a single OSG object, > which limits the OSG overhead and means they are very > efficient to render.
There is an OpenGL feature that is available in OSG : you can instantiate the same geometry multiple times. You prepare the geometry once and when adding the primitive set (IIRC) you specify an optional number of instances. The vertex shader is call the number of instance specified times with a predefined uniform gl_InstanceID set from 1 to n. Of course, as you don't want your geometry draw n times at the same place, you have to compute the placement of objects inside the vertex shader using gl_InstanceID. Either you compute placement with an algorithm inside the shader, or you provide a matrix array uniform that you can index with gl_InstanceID. see http://www.opengl.org/wiki/Vertex_Specification#Instancing for a less nebulous explanation ;) Regards, -Fred ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
