Using Instancing to Efficiently Render Carbon Nanotubes

In this paper, we present an effcient way to visualize Super Carbon Nanotubes (SCNTs). SCNTs are complex, hierarchical structures and their models easily consist of more than 1 million atoms. Our SCNTs are modeled as graphs of uniform nodes and egdes. We show that OpenGL instancing is a very suitable technique for rendering such large graphs, because they only consist of two different types of geometry. Our visualizer software exploits this property and we demonstrate that it allows to render the tubes in a fashion that is time- and space-effective. We implemented auto-tuning of the model to the underlying graphics card through adaptive mesh-resolution-choices. We also designed and implemented our own shading programs in the OpenGL Shading Language (GLSL) to realize a sufficient but performant and configurable lighting computation. This allows us to render big models even on laptop GPUs and to cope with models that consist of 150 million triangles, which is still a challenging amount for most of today's graphics cards.