6.2.4 Highlights

These are bright spots which appear when light coming directly from a light source reflects off a smooth surface. This can be simulated by

	finish { ... phong P phong_size S [metallic] ... }

where $0\leq P\leq 1$ specifies the amount by which the light is saturated by the surface color (1 means complete saturation). The phong_size $S$ is inverse proportional to the size of the highlight.

The formula for the corresponding light intensity is

$$I_p := \frac1{S}*I_d*\cos(\th )^n,$$

for some exponent $n$.

An alternative method (which is better on low viewing angles) is

	finish { ... specular P roughness R [metallic] ... }

where $0\leq P\leq 1$ specifies the amount by which the light is saturated by the surface color. (1 is complete saturation). The roughness $R$ is proportional to the size of the highlight.

The optional keyword metallic gives the object a more metallic appearance.