My vertex shader code for simple diffuse light is the following: vfconn OUT; OUT.HPos = mul(ModelViewProj, IN.position); OUT.Col0=IN.position*saturate( dot(IN.norm, normalize(litepos-IN.position)) ); OUT.texcoord=IN.texcoord; return OUT; And the results: The radius of the lit area both increases with increasing x,y or z coords of the light (a rectangle on the x/y plane is lit) I checked my vertices, normals and light position to be correct. Any idea whats wrong? thank you in advance! "Knowledge is no more expensive than ignorance, and at least as satisfying." -Barrin [edited by - orbano on January 11, 2004 6:34:09 AM]

Well for starters - You havent normalised your normal.
If you dont make sure that all the vectors u use are normalised - bad things tend to happen

Hope that helps
[edit]

also - do u mean for lighting to also be a function of position?

IN.position*saturate( dot(IN.norm, normalize(litepos-IN.position)) );

*regular* diffuse lighting would be:-

saturate(dot(normalize(NORMAL),normalize(Lightvector)));

where Lightvector is (as u correctly did) LightPosition (litepos)- Vertex Position (IN.position)

[edited by - Dh_UK on January 11, 2004 9:32:08 PM]

thank you! my vertex shader was just fine (ive been doing such stuff in SW for long). this morning i woke up with the solution: I created my surface normals with absoltue coordinates, not vertex-relative, so they were vertex+[0,0,1] (plane on x/y). Now i set them simply to 0,0,1 and everything is fine! Going for specular highlight!

"Knowledge is no more expensive than ignorance, and at least as satisfying." -Barrin