Figure 10

Comparison of Phong vertex and fragment shaders to OpenGL's built-in lighting. (A) A close up view of a small portion of the c-Jun homodimer [PDB:1JUN], a leucine zipper protein [39], is shown as a space filling (spheres) style display. Lighting calculations were performed using the phong.vert and phong.frag shaders in the ProteinShader shaders directory. (B) The same view as in (A), except that OpenGL's built-in lighting was activated by temporarily removing the phong.frag file from the shaders directory and restarting the program (a dialog box warns the user that the Phong shaders could not be compiled, and OpenGL's built-in lighting is used as a backup). (C) Several proteins were used to compare the frames per second that could be rendered during an animation of a space filling style display while using OpenGL's built-in lighting (white bars) or Phong shaders (black bars). (D) Phong lighting is used on a tubes style display of the same protein as in (A). (E) The same view as (D), except that OpenGL's built-in lighting is used. (F) The same comparisons as in (C), except that a tubes style display is used. See Table 3 for the sizes of the test proteins and notes on the computer used for performance testing.