OpenGL rendering

mesh is constructed by recursing in an octree (only stores bounding boxes and field intensities, there is a custom memory allocator for the nodes so rather large trees can be generated without mem alloc penalty)

recursion takes into account visibility and metaballs bounding spheres, it stops inside the volume (negative metaballs are not handled yet)

metaballs field values calculation is writen in asm (~10% performance gain)

"highly" optimized bounding boxes view frustum culling (used ideas from Ulf Assarsson and Tomas Möller, "Optimized View Frustum Culling Algorithms," (http://www.ce.chalmers.se/staff/uffe/) : implemented frustum planes masking, temporal coherency (easy one but did not gave good results on the allways changing octree), and tests on n-p vertices)

mesh is generated using marching cubes algorithm