Full volume rendering

1. Under the menu item with title ‘Volume Rendering’, create pull-down submenus with titles ‘Full Volume Rendering’. When it is selected, your program will use the transfer function values to generate result images. 2. You will need to implement Phong shading by yourself. Please initialize an appropriate light source position and intensity. For the colors with shading, make sure you don’t exceed 1.0 in each R,G,B. If you do, which can happen if you set ka+kd+ks>1.0, just clamp to 1.0. 3. You will need 4 transfer functions, one for each red, green, blue, and alpha (RGBA). For this purpose, use the extern global 4-element array transFunc in Application.cpp. It will hold the red, green, blue, and alpha transfer functions for your volume renderer. Now you have an array with four instances of a 256-member array, i.e., element k of the 2nd volume transfer function (the one for green) is transFunc[1][k]. Each transfer function will be drawn in a different color. You can set these colors in the extern array of floats, transFuncColor[4][3]. You can set the first triple (the one for red) to {1.0, 0.0, 0.0}, and the one for green, blue, and alpha to {0.0, 1.0, 0.0}, {0.0, 0.0, 1.0} and {1.0, 1.0, 1.0}, respectively. There are two more extern variables: maxTransFunc and activeTransFunc. The former is set to 4 when you do volume rendering. The latter variable tells the EditorWindow what transfer function is to be edited at a time. You may want to use 4 radio buttons for each of them to indicate what is currently selected. The value of activeTransFunc must be set in the callbacks of the radio buttons. (You can also use menuItems instead of radio buttons for this purpose.) Only compute gradients and shade when the opacity is greater than some small value, like 0.1. For most datasets, densities of less than 30 do not return meaningful structures, just noise. When you choose the transfer function, you may set the opacity for densities < 30 to 0. This means you need to pull the alpha transfer function to 0 at densities you don’t want to consider. You may utilize the histogram to find out at what density ranges meaningful structures are.