PyMOL v1.5 supports the OpenGL shading language (GLSL) for drawing molecules. This improves the speed and real-time rendering of data. The speed increases are on the order of 500–1700% (PyMOL v1.5. features page). Quality of those representations is compared here.
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These images compare the new rendering of sticks and spheres. No image here was ray traced–these are all real-time rendered in PyMOL.
PyMOL ray tracing is slow, but provides the finest quality images. Achieving that quality in real-time is the goal. Consider the following ray-trace image of the surface of an alanine fragment:
Notice how smooth the lighting is around the specular reflection (white patch on the blue surface). Now compare this to the following standard-level quality from PyMOL:
Notice the blotchy pattern of the white light on the surface of the molecule. Notice the lack of depth around the perimeter of the surface. In order to get real-time rendering, these area of quality had to be degraded–but, not any more. Consider the following snapshot what PyMOL v1.5 rendering produces in real-time:
Shader improvements still need to be made to perfect the PyMOL lighting and sense of depth. More on this, soon.