What is Diffuse Light?
A diffuse reflection is the reflection of light by a surface such that the incident light is scattered at many angles instead of one angle. Diffuse lighting occurs when the light is scattered by centers beneath the surface as shown in the picture. A non-shiny surface would have a very high diffuse value. The amount of diffuse lighting emitted by the surface is controlled by the lambetian reflectance, given by lambert’s cosine law.
Most of the surfaces in the real world are diffuse by nature. The main exceptions include particularly shiny surfaces such as mirrors and metals.
Calculating Diffuse Light
I am using the following equation to calculate the diffuse light
(g_LightColor * (saturate(dot(normalize(g_LightRotation), normalize(i_normals)))) + ambientLight)
Where g_LightColor is the color of the directional light, g_LightRotation is the forward direction of the light. These two values are passed from the application in the per frame constant buffer. i_normals is the value of the normal of that fragment. The normal of a surface is defined as the vector that is perpendicular to the surface.
In the below video you can see that I am simulating a warning light beacon.