virtual void irr::video::IVideoDriver::setFog  (  SColor  color = SColor(0, 255, 255, 255),  
  bool  linearFog = true,  
  f32  start = 50.0f,  
  f32  end = 100.0f,  
  f32  density = 0.01f,  
  bool  pixelFog = false,  
  bool  rangeFog = false 
 )  [pure virtual]

Sets the fog mode.

These are global values attached to each 3d object rendered, which has the fog flag enabled in its material.

Parameters:
color,: Color of the fog
linearFog,: Set this to true for linear fog, otherwise exponential fog is applied.
start,: Only used in linear fog mode (linearFog=true). Specifies where fog starts.
end,: Only used in linear fog mode (linearFog=true). Specifies where fog ends.
density,: Only used in expotential fog mode (linearFog=false). Must be a value between 0 and 1.
pixelFog,: Set this to false for vertex fog, and true if you want pixel fog.
rangeFog,: Set this to true to enable range-based vertex fog. The distance from the viewer is used to compute the fog, not the z-coordinate. This is better, but slower. This is only available with D3D and vertex fog.

Avec ça, tu devrais avoir tout ce qu'il te faut

Concrètement, tu vas jouer sur la distance du brouillard à la caméra et la densité pour réaliser l'effet que tu souhaites.