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-rw-r--r--2d/actions.scm26
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)