What makes a great martial arts movie? Sammo Hung, Lau Kar-leung and other Hong Kong action cinema legends have their say

• For legendary director Chang Cheh, the recipe for a good martial arts film is the same as for other genres – plot and characters that move and entertain people
• For others it is real physical action and southern kung fu fighting using fists, not swords. For actress Cheng Pei-pei, knowing dance gave her something extra