PDA

View Full Version : wrong lighting with Vertex Arrays



steve_j
03-22-2005, 07:41 AM
Hi!

I am now using vertex arrays for drawing terrain. The terrain is rendered with a LOD algorithm and uses GL_TRIANGLE_FAN. The triangles are drawn normally but the lighting is wrong. I noticed that the lighting is only below the terrain. So, when I move below the terrain, I see a correct lighting of the inverse terrain. The vertex calculation didn't change from earlier implementations where I used glBegin/End and explicitely used Normal3fv. The vertex array is as big as the normals array. Each vertex has a normal. I also tried to change glFrontFace, but with no effect. So, has anyone a hint what I've done wrong?

thanks,
Steve

03-24-2005, 04:32 PM
I'm not exactly sure what ur saying and i'm not that great with lighting, but maybe you might have the light position on the wrong side of the terrain. That's all I can think of. Like I said i'm not that great.

shinpaughp
03-24-2005, 06:07 PM
Is your winding clockwise or counterclockwise or are your normals pointing below the surface? The default winding is counterclockwise (right-hand rule). You can change the winding using glFrontFace( GL_CW ) to reverse this or you can change your algorithm to travel counterclockwise. ANd, also verify your light position as the previous poster suggested.