I am attempting to create a GLSL shader for simple, per-fragment directional light. So far, after following many tutorials, I have continually ran into the issue: my light is specified in world coordinates, however, the shader treats the light's position as being in eye space, thus, the light direction changes when I move the camera. My question is, how to I transform a directional light position such as (50, 50, 50, 0) into eye space, or, would doing things this way be the incorrect approach to the problem?