Texturing and Shading - Learn OpenGL ES: For Mobile Game and Graphics Development - page 211

Figure 5-9 . Blender: obtaining the center of object
Note In the source code for this chapter, inside the Blender folder,
you will find Blender files named pointLight* . You can open
these files to see how you can add a point light source. Instead of us-
ing a sphere as a light source object, I have used an Icosphere mesh,
which can be easily added using the Add menu (from the Info win-
dow). I have used this object in both VERTEX POINT LIGHTING
and FRAGMENT POINT LIGHTING applications.In these applic-
ations, I have demonstrated lighting/shading effects using a point
light source. This application contains the Tank and Light objects,
where the Light object is an Icosphere added from Blender.
▪ Because the normal vector ( N ) is in eye-space (to get points and
vectors in eye-space, they must be transformed using their re-
spective MV matrices), you must also transform the S vector into
eye-space, so it becomes possible to take their dot product. For
this, make sure the current vertex position and the light source po-
sition are transformed using their respective MV matrices. In most
graphical applications, the light source is usually fixed. However
in the application I have provided for demonstrating lighting/