   light and projection matrix
  Hi,I am writing a software renderer (4 viewports like 3dsmax) for fun. This is a newbie question. When I apply a perspective projection matrix to meshes should I apply it to the light position too? In my program I apply it to the light and it changes the light position. The perspective view just doesn't look correct.Should I just use an ortho projection matrix to move the light to the correct position?thanksJJ   
  Short answer: no.You must transform light position to a space where you do the lighting (tangent, object, world, eye...)   