diff options
Diffstat (limited to 'world.scm')
| -rw-r--r-- | world.scm | 19 |
1 files changed, 19 insertions, 0 deletions
@@ -56,4 +56,23 @@ (scene-entities-set! scene (filter pred (scene-entities scene))) scene) + + ;; Center camera on entity. Clamps to >= 0 on both axes. + ;; viewport-w and viewport-h are the game window dimensions (pixels). + (define (camera-follow! camera entity viewport-w viewport-h) + (camera-x-set! camera (max 0 (- (entity-ref entity #:x 0) (/ viewport-w 2)))) + (camera-y-set! camera (max 0 (- (entity-ref entity #:y 0) (/ viewport-h 2))))) + + ;; Returns the first entity in scene whose #:tags list contains tag, or #f. + (define (scene-find-tagged scene tag) + (let loop ((entities (scene-entities scene))) + (cond + ((null? entities) #f) + ((member tag (entity-ref (car entities) #:tags '())) (car entities)) + (else (loop (cdr entities)))))) + + ;; Returns all entities in scene whose #:tags list contains tag. + (define (scene-find-all-tagged scene tag) + (filter (lambda (e) (member tag (entity-ref e #:tags '()))) + (scene-entities scene))) ) |