Why exactly does having multiple normals on a vertex give an edge split effect? From my understanding, smoothness comes from the fact that we're interpolating values within each triangle after computing brightness using the vertices? So why would adding more normals as the professor suggests create an edge split?

stexus

To be clear, I understand that we have some sort of threshold for the normals on the model in the far left, but I don't understand why that necessarily results in sharp edges if we're still interpolating values.

Staffjamesfobrien

Triangles A and B share an edge. If the vertices of the edge each have a single normal then A and B would get the same color result for those vertices. The result is that the edge is the same for both triangles. But if A uses one pair of normals when computing color and B used another then they would have different colors where they meet at the edge.

Why exactly does having multiple normals on a vertex give an edge split effect? From my understanding, smoothness comes from the fact that we're interpolating values within each triangle after computing brightness using the vertices? So why would adding more normals as the professor suggests create an edge split?

To be clear, I understand that we have some sort of threshold for the normals on the model in the far left, but I don't understand why that necessarily results in sharp edges

ifwe're still interpolating values.Triangles A and B share an edge. If the vertices of the edge each have a single normal then A and B would get the same color result for those vertices. The result is that the edge is the same for both triangles. But if A uses one pair of normals when computing color and B used another then they would have different colors where they meet at the edge.