Hi All,
I have spent most of the day and yesterday, tearing my hair hout about OpenGL and Spot lights.

Basically I am using glOrtho to rendering a textured background and some text. That is fine, but now I want to add a spot light that moves over the screen only highlighting only the bits of the back ground where the spotlight is. I know I could do this using a Mask, but I'd like to use proper lighting for this effect. Does anyone know a resource or have some sample code that shows this effect in operation. At the moment I only see light when, the spot cutoff is set to 180...
glLightf( GL_LIGHT0, GL_SPOT_CUTOFF, 180.0 );
My spot exponent does not seem to make any difference regardless of what I set it to. It is currently set to...
glLightf( GL_LIGHT0, GL_SPOT_EXPONENT, 15.0 );
and spot direction is set as follows...
spotDirection[0] := 0.0;
spotDirection[1] := 0.0;
spotDirection[2] := -1.0;
glLightfv( GL_LIGHT0, GL_SPOT_DIRECTION, @spotDirection );


What am I missing??