diff options
| -rw-r--r-- | 2d/actions.scm | 26 |
1 files changed, 15 insertions, 11 deletions
diff --git a/2d/actions.scm b/2d/actions.scm index dfd747a..58d2ba9 100644 --- a/2d/actions.scm +++ b/2d/actions.scm @@ -56,17 +56,20 @@ (proc action-proc)) (define (make-action proc duration) - "Returns a new action object. Throws an error if duration is 0." + "Create a new action object that takes DURATION updates to +complete. PROC is a procedure that takes a value in the range [0, 1] +as its only argument. An error is thrown if DURATION is 0." (if (zero? duration) (throw 'action-duration-zero) (%make-action proc duration))) (define (step-action action t) - "Run action proc with given delta t" + "Apply ACTION procedure to the time delta, T." ((action-proc action) t)) (define (perform-action action) - "Perform the given action." + "Execute ACTION. `perform-action` must be called from within a +coroutine, as it yields back to the agenda after each step." (let ((duration (action-duration action))) (define (step time) (if (= duration time) @@ -78,11 +81,12 @@ (step 1))) (define (schedule-action action) - "Schedules a coroutine to run the given action." + "Schedules a coroutine in the current agenda that will perform +ACTION on the next update." (agenda-schedule (colambda () (perform-action action)))) (define (action-cons a1 a2) - "Returns an action that performs a1 first, followed by a2." + "Return an action that performs A1 first, followed by A2." (define (real-cons) (let* ((duration (+ (action-duration a1) (action-duration a2))) (t1 (/ (action-duration a1) duration)) @@ -97,13 +101,13 @@ (if a2 (real-cons) a1)) (define (action-list . actions) - "Returns an action that executes actions in sequence." + "Return an action that performs every action in the list ACTIONS." (if (null? actions) #f (action-cons (car actions) (apply action-list (cdr actions))))) (define (action-parallel . actions) - "Perform the given actions in parallel." + "Perform every action in the list ACTIONS in parallel." (let ((max-duration (reduce max 0 (map action-duration actions)))) ;; Add idle action to each action to fill the time ;; difference between the action's duration and the @@ -120,7 +124,7 @@ max-duration)))) (define (action-repeat n action) - "Repeat an action n times." + "Return an action that will perform ACTION N times." (apply action-list (make-list n action))) ;;; @@ -128,12 +132,12 @@ ;;; (define (idle duration) - "Do nothing." + "Return an action that does nothing." (make-action (lambda (t) #t) duration)) (define (lerp proc start end duration) - "Linearly interpolate a number from start to end. Calls proc with the -interpolated value every frame." + "Linearly interpolate a number from START to END that takes DURATION +updates. Apply PROC to the linearly interpolated at each step." (let ((delta (- end start))) (make-action (lambda (t) |