This　work　is　part　of　a　project　＂full　life　cycle　automation　of　computer　animation　generation＂.　Among　various　animation　planning　tasks,　it　is　crucial　to　plan　the　moving　traces　of　avatars.　Our　previous　animation　generation　software　＜　Swan　＞　includes　a　path　planning　module.　However,　that　module　generates　only　a　2D　plan　path.　In　this　paper,　we　introduce　a　recent　work　of　3D　path　planning.　Considering　the　possibility　that　inadequate　3D　environments　may　request　the　avatars　to　undertake　special　posture　while　traversing　the　environment,　we　combine　path　planning　with　posture　planning　in　automatic　3D　traverse.　Other　contributions　of　this　paper　include:　development　a　2D　mathematical　model　for　3D　real　environment　and　an　algorithm　transforming　the　latter　to　the　former;　a　new　principle　of　constraint　based　avatar　sensitive　path　determination;　design　a　calculus　for　calculating　constraint　oriented　cost　calculation　based　on　spatial　movement　complexity　of　motion　graph　clips.