Illustrative Rendering in

L∑i=1View-dependent Terms[ c k max( f ( vˆ⋅ rˆ) kf k ( v r ) )] spec, ˆ ⋅ ˆk rim+ ( nˆ⋅uˆ) f k a( vˆ)iss• Multiple Phong terms per light• k rimbroad, constant exponent• k specexponent (constant or texture)• f sartist tuned Fresnel term• f rrim Fresnel term, (1-(n·v)) 4• k rrim mask texture• k sspecular mask texture• Dedicated rim lighting• a(v) Directional ambient evaluated with v• k rsame rim mask• f rsame rim Fresnel• n·u term that makes rim highlights tend tocome from above (u is up vector)irrirr© 2007 Valve Corporation. All Rights Reserved.