Hi, all maybe this is a old topic , but I can't find answer in lots of forum, so I have to ask for help .
I write a terrain engine mostly like interlocking terrain; there are 32x32 tiles for whole terrain, and 17x17 vertexs for one tile. every tile has one vertexarray, I use osg to realize it. all terrain is treated as one geode. and one drawable represents one tile.so I have one geode, and 1024 drawables.( I'm not sure if the structure is good ). but I met problem now: when see terrain on the fly,(all tiles are show in eye-views), the draw time is much more than on the ground(a few tiles are show); ofcourse, it should be certainly because of culling. now I want to reduce draw time on the fly. I think that maybe more draw calls make draw time high because one tile represent one drawable(one draw call, is that right?). and more worse: tile is dealed by LOD. when tile' lod level is lowest, it only has few vertices and indices, it could be very inefficient when one draw call only for the tile under the situation. should I batch several tile' vertexs into vertexarray?? but what to do this in osg-node-system, and it should be influence to culling?? anyone can explain how to do banlance between batch and cull in tiled terrain system ? thianks in advance. of course, it 's my thought about high draw time on the fly is because more draw calls( i'm not sure if 32x32=1024 draw calls are high?). my another thought about bad performance on the fly is that my lod tile'vertexarry is big. I don't design: lod3 vertexarray3 indicearray3 lod2 vertexarray2 indicearray2 lod1 vertexarray1 indicearray1 ( numbers of vertexarray: vertexarray3>vertexarray2>vertexarry1, decrease by lod level), I design simply: lod3 vertexarry indicearry3 lod2 vertexarry indicearry2 lod1 vertexarry indicearry1 every tile in different lod level has same vertexarray( most high vertex varry), it make me only dirty inidices varray every frame, but even if in lowest lod level, draw call still send lots of vertices(is that right?). now I'm not sure what real reason make high draw time on the fly view? 1: more draw calls in one frame 2. more vertices transfer in one frame anybody help, very appreciate! thanks again. Thank you! Cheers, John ------------------ Read this topic online here: http://forum.openscenegraph.org/viewtopic.php?p=42990#42990 _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
