Tree visualization and specular mappingDecember 6, 2013 - 2:20 pm by Joss Whittle C/C++ Graphics PhD University
Previously I’ve debugged my KD-trees only by looking at archaic console printouts where at best each descending node in the structure is tabbed a couple of spaces further in from it’s parent.
However, seeing as I’m currently building a new renderer it seemed apt to build in a method for visualizing the generated trees. This was pretty simple to add in, if a preprocessor flag
__AABB_EDGE__ is defined at compile time then during tree traversal additional code will run which does a simple UV coordinate calculation for the Axis Aligned-Bounding Box; if the UV is close enough to the edge of the box then the current pixel is abandoned and set to plain blue. The result is quite interesting to view and because of the power of the C++ preprocessor when it is disabled it effectively doesn’t exist in the compiled executable, meaning it has no effect on performance.
I have also been playing with specular and normal mapping. It was trivial to add due to the design of the shader class this time. In the case of specular mapping the max value of each RGB tuple is taken as the value for the map on the [0,1] range; this is then used to linearly scale the specular exponent of the shader which is used to calculate the glossy reflection for surfaces with an exponent > 0. Below a checker-board texture was used to scale a specular exponent of 128 into regions of 0 and 128 over the surface of the teapot.