I'm implementing a simple Lamberitan BRDF in GLSL, using a point light source. My fragment shader simply returns
light_colour * 1.0/PI * cosine, which should model a fully diffuse white material.
However, it looks rather dark... If I have a point light with colour (1,1,1), and no attenuation with distance, the maximum brightness of the material (at normal incidence) will be 1/3 (dark grey).
Is this just because I am using a physically incorrect point light with zero size? Is there any "correct" value for the light colour in this case, if I want the surface to be white at its brightest parts?