Unmodified Doom 3 uses the Blinn-Phong shading model, which is an approximation of the more computationally expensive Phong shading model. Both images are using a fixed exponent of 16.0f, however it's possible to adjust the exponent based on material type in both shading models. Currently, this is not done.
A higher exponent produces a tight specular highlight (for example chrome metal) while a lower exponent will produce a broader highlight (for example matte paint or skin tones.)
Please note that some tuning of the exponent may be required for the Phong model due differences in lighting calculation.
|Doom 3: Blinn-Phong (16.0f)|
|Doom 3: Phong (16.0f)|
|Doom 3: Phong (4.0f)|