Type Property

phong

Shading that incorporates ambient, diffuse, and specular properties, where specular highlights are calculated using the Phong formula.

Declaration

static let phong: SCNMaterial.LightingModel

Discussion

The Phong approximation of real-world reflectance calculates the color of a point on a surface using the following formula:

color = ambient * al + diffuse * max(0, dot(N, L)) + specular * pow(max(0, dot(R, E)), shininess)

Some terms refer to the material’s properties: ambient, diffuse, specular, and shininess. The other terms are as follows:

al

The sum of all ambient lights in the scene (a color).

N

The surface normal vector at the point being shaded, as supplied by the geometry’s vertex data, interpolated between vertices, and possibly modified by the material’s normal property.

L

The (normalized) vector from the point being shaded to the light source.

E

The (normalized) vector from the point being shaded to the viewer.

R

The reflection of the light vector L across the normal vector N.