# What is the equation for flat shading?

Is there an equation for flat shading?

To my understanding, it is this:

$$I = I_a \times K_a + F_{att} \times I_l \times (K_d \times (N \times L))$$

Final intensity = ambient reflection x ambient reflection coefficient + (attenuation x incident light intensity x (diffusive reflection coefficient x (surface normal x Light intensity))

However, I have only found one source for this equation (my lecture slides).

Are there any other sources to confirm this is the equation for flat shading? I can't find one.

• The (surface normal x Light intensity) / diffuse part, shouldn't that be N.L * lightColour * diffuseColour ? Commented Mar 17, 2017 at 7:56
• I didn't add a divide anywhere in the equation. It is lightIntensity*(diffusive reflection coefficient * (N.L))
– S.A
Commented Mar 17, 2017 at 8:33
• @PaulHK Is it possible you could give a reference to where you found the equation for flat shading?
– S.A
Commented Mar 17, 2017 at 8:56
• OpenGL's fixed function pipeline, I found a decent reference here > cs.cmu.edu/afs/cs/academic/class/15462-s09/www/lec/02/… Commented Mar 17, 2017 at 9:33
• This equation doesn't consider flat or smooth shading, that is down to you to use either a fixed normal per triangle or interpolated vertex normals. Commented Mar 17, 2017 at 9:34