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Act solid only when hit from above

This commit is contained in:
Tony Garnock-Jones 2015-10-27 14:26:55 -04:00
parent b87f1e1da2
commit 7b03d90b23
1 changed files with 13 additions and 7 deletions
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20
examples/platformer/main.rkt
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@ -445,6 +445,9 @@
(define (segment-intersection-time p0 r q0 q1) (define (segment-intersection-time p0 r q0 q1)
;; See http://stackoverflow.com/a/565282/169231 ;; See http://stackoverflow.com/a/565282/169231
;; Enhanced to consider the direction of impact with the segment,
;; too: only returns an intersection when the vector of motion is
;; at an obtuse angle to the normal of the segment.
(define s (v- q1 q0)) (define s (v- q1 q0))
(define rxs (vcross2 r s)) (define rxs (vcross2 r s))
(cond [(< (abs rxs) 0.005) #f] ;; zeroish; lines are parallel (and maybe collinear) (cond [(< (abs rxs) 0.005) #f] ;; zeroish; lines are parallel (and maybe collinear)
@ -456,7 +459,10 @@
(let* ((q-pxr (vcross2 q-p r)) (let* ((q-pxr (vcross2 q-p r))
(u (/ q-pxr rxs))) (u (/ q-pxr rxs)))
(and (< 0 u 1) (and (< 0 u 1)
(- t 0.001))))])) (let* ((q-norm
(vnormalize (vector (vector-ref s 1) (- (vector-ref s 0))))))
(and (not (positive? (vdot r q-norm)))
(- t 0.001))))))]))
(define (three-corners top-left size) (define (three-corners top-left size)
(match-define (vector w h) size) (match-define (vector w h) size)
@ -474,9 +480,10 @@
(apply min (apply min
(for/list [(p (in-list (list top-left top-right bottom-right bottom-left)))] (for/list [(p (in-list (list top-left top-right bottom-right bottom-left)))]
(min (or (segment-intersection-time p r solid-top-left solid-top-right) 1) (min (or (segment-intersection-time p r solid-top-left solid-top-right) 1)
(or (segment-intersection-time p r solid-top-left solid-bottom-left) 1) ;; TODO: some means of specifying *which edges* should appear solid.
(or (segment-intersection-time p r solid-top-right solid-bottom-right) 1) #;(or (segment-intersection-time p r solid-top-right solid-bottom-right) 1)
(or (segment-intersection-time p r solid-bottom-left solid-bottom-right) 1))))) #;(or (segment-intersection-time p r solid-bottom-right solid-bottom-left) 1)
#;(or (segment-intersection-time p r solid-bottom-left solid-top-left) 1)))))
(v+ top-left (v* r t))) (v+ top-left (v* r t)))
(define (clip-movement-by-solids s p0 p1 size) (define (clip-movement-by-solids s p0 p1 size)
@ -496,10 +503,9 @@
(for/or [(p (in-list (list top-left top-right bottom-right bottom-left)))] (for/or [(p (in-list (list top-left top-right bottom-right bottom-left)))]
(or (or
(and (segment-intersection-time p r touchable-top-left touchable-top-right) 'top) (and (segment-intersection-time p r touchable-top-left touchable-top-right) 'top)
(and (segment-intersection-time p r touchable-top-left touchable-bottom-left) 'left)
(and (segment-intersection-time p r touchable-top-right touchable-bottom-right) 'right) (and (segment-intersection-time p r touchable-top-right touchable-bottom-right) 'right)
(and (segment-intersection-time p r touchable-bottom-left touchable-bottom-right) (and (segment-intersection-time p r touchable-bottom-right touchable-bottom-left) 'bottom)
'bottom)))) (and (segment-intersection-time p r touchable-bottom-left touchable-top-left) 'left))))
(let () (let ()
(match-define (vector left top) top-left) (match-define (vector left top) top-left)
(match-define (vector touchable-left touchable-top) touchable-top-left) (match-define (vector touchable-left touchable-top) touchable-top-left)