Abstract: For storing gesture definitions and evaluating expressions that reference the gesture definitions, an expression evaluation engine evaluates the expressions to determine whether movements of a user satisfy the expressions. The expression evaluation engine receives expressions in user or application requests, or the expression evaluation engine may automatically evaluate the expressions when a gesture recognition system receives updated information about tracked body parts of the user. An expression includes a logical operator that relates different conditions to each other, and the different conditions may reference different gestures or other criteria that are based on the tracked body parts of the user. The expression is satisfied when the logical operator is satisfied. If an expression is satisfied, the expression evaluation engine triggers an action associated with a corresponding gesture definition. An example gesture may trigger display and navigation of a pie menu.

Abstract: For storing gesture definitions and evaluating expressions that reference the gesture definitions, an expression evaluation engine evaluates the expressions to determine whether movements of a user satisfy the expressions. The expression evaluation engine receives expressions in user or application requests, or the expression evaluation engine may automatically evaluate the expressions when a gesture recognition system receives updated information about tracked body parts of the user. An expression includes a logical operator that relates different conditions to each other, and the different conditions may reference different gestures or other criteria that are based on the tracked body parts of the user. The expression is satisfied when the logical operator is satisfied. If an expression is satisfied, the expression evaluation engine triggers an action associated with a corresponding gesture definition. An example gesture may trigger display and navigation of a pie menu.