switch(FEAT_, SELF, generation4) ... switch(FEAT_, SELF, generation3) ... switch(FEAT_, SELF, generation2) ... switch(FEAT_, SELF, generation1) ... #define YEAR_GEN2 1930 #define YEAR_GEN3 1960 #define YEAR_GEN4 1990 // upgrade gen3->gen4, using probability 1 in 4 random_switch(FEAT_, SELF, randup4, bitmask(TRIGGER_VEHICLE_SERVICE)){ 4:generation3; } // upgrade gen3->gen4 available? switch(FEAT_, SELF, testup4, current_year){ 0..(YEAR_GEN4-1):generation3; default:randup4; } // at least gen3, already upgraded to gen4? random_switch(FEAT_, SELF, maybegen4){ dependent: randup4; 3:testup4; 1:generation4; } // upgrade gen2->gen3, using probability 1 in 4 random_switch(FEAT_, SELF, randup3, bitmask(TRIGGER_VEHICLE_SERVICE)){ 4:generation2; } // upgrade gen2->gen3 available? switch(FEAT_, SELF, testup3, current_year){ 0..(YEAR_GEN3-1):generation2; default:randup3; } // at least gen2, already upgraded to gen3? random_switch(FEAT_, SELF, maybegen3){ dependent: randup3; 3:testup3; 1:maybegen4; } // upgrade gen1->gen2, using probability 1 in 4 random_switch(FEAT_, SELF, randup2, bitmask(TRIGGER_VEHICLE_SERVICE)){ 4:generation1; } // upgrade gen1->gen2 available? switch(FEAT_, SELF, testup2, current_year){ 0..(YEAR_GEN2-1):generation1; default:randup2; } // at least gen1, already upgraded to gen2? random_switch(FEAT_, SELF, maybegen2){ dependent: randup2; 3:testup2; 1:maybegen3; } // default generation by build-year switch(FEAT_, SELF, main_graphics, build_year){ 0..(YEAR_GEN2-1): maybegen2 YEAR_GEN2..(YEAR_GEN3-1): maybegen3 YEAR_GEN3..(YEAR_GEN4-1): maybegen4 default: generation4; }