It is called LColorf, and it is a typedef for LVecBase4f, which is the generic Panda3D class for four-component floating-point values (such as vectors and colours). The 'f' stands for 'float'; there is also an LColord typedef available.
This was a change in Panda3D 1.8.0. Before 1.8.0, it was called Colorf (without the leading L). Presumably, the sample programs you downloaded were designed for an earlier version. You may change the relevant sample program to use LColorf, or you may choose to add the following before including these headers:
#if PANDA_NUMERIC_VERSION >= 1008000
#define Colorf LColorf
#endif
(Alternatively, you could use a typedef if that is what you prefer.)
For the record, the appropriate header file to include to make the LColorf symbol available is luse.h
. You should not include panda_glext.h
, it is only used by the OpenGL renderer.