Light Direction is 'the opposite direction of light', right?
BryceSummers
@PandaX the light direction is the direction of the line that goes through the incoming light source's position and the point on the surface. There are two possible directions which are negation of each other.
Similarly the surface normal is a direction that is orthogonal to the local plane that approximates the point on the surface in the tangent direction. There are two possible normal directions.
Here the calculation should be done using a choice of a light direction vector and a surface normal vector whose dot product is no less than 0, because every surface that is not parallel to the light with have a non trivial irradience value assuming the light source is not occluded.
Light Direction is 'the opposite direction of light', right?
@PandaX the light direction is the direction of the line that goes through the incoming light source's position and the point on the surface. There are two possible directions which are negation of each other.
Similarly the surface normal is a direction that is orthogonal to the local plane that approximates the point on the surface in the tangent direction. There are two possible normal directions.
Here the calculation should be done using a choice of a light direction vector and a surface normal vector whose dot product is no less than 0, because every surface that is not parallel to the light with have a non trivial irradience value assuming the light source is not occluded.