mirror of
https://github.com/open-goal/jak-project
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water111
96 lines
4.8 KiB
Common Lisp
96 lines
4.8 KiB
Common Lisp
;;-*-Lisp-*-
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(in-package goal)
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(bundles "ENGINE.CGO" "GAME.CGO")
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(require "engine/math/vector.gc")
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(require "engine/physics/trajectory-h.gc")
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(require "engine/debug/debug-h.gc")
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;; DECOMP BEGINS
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(defmethod eval-position! ((this trajectory) (elapsed-time float) (result vector))
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"Evaluate position after elapsed-time game-time ticks into result. Vertical motion includes
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one half gravity times time squared; evaluation is not clamped to the solved flight duration."
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(vector-copy! result (-> this initial-position))
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(+! (-> result x) (* elapsed-time (-> this initial-velocity x)))
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(+! (-> result y) (* elapsed-time (-> this initial-velocity y)))
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(+! (-> result z) (* elapsed-time (-> this initial-velocity z)))
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(+! (-> result y) (* (/ elapsed-time 2) elapsed-time (-> this gravity)))
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result)
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(defmethod eval-velocity! ((this trajectory) (elapsed-time float) (result vector))
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"Evaluate velocity after elapsed-time game-time ticks into result. Only the vertical
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component changes under gravity."
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(vector-copy! result (-> this initial-velocity))
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(+! (-> result y) (* elapsed-time (-> this gravity)))
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result)
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(defmethod setup-from-to-duration! ((this trajectory) (start vector) (destination vector) (duration float) (gravity float))
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"Solve the initial velocity that moves from start to destination in duration game-time ticks
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under constant vertical gravity. Store the supplied duration; callers must provide a positive,
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nonzero duration."
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(vector-copy! (-> this initial-position) start)
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(set! (-> this gravity) gravity)
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(set! (-> this time) duration)
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(let ((xz-speed (/ (vector-vector-xz-distance destination start) duration)))
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(vector-! (-> this initial-velocity) destination start)
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(vector-xz-normalize! (-> this initial-velocity) xz-speed))
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(set! (-> this initial-velocity y)
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(- (/ (- (-> destination y) (-> start y)) duration) (* (/ duration 2) (-> this gravity))))
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0
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(none))
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(defmethod setup-from-to-xz-vel! ((this trajectory) (start vector) (destination vector) (xz-speed float) (gravity float))
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"Solve a trajectory from start to destination at the requested nonzero horizontal speed
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under constant vertical gravity. Horizontal distance divided by xz-speed determines the duration."
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(let ((duration (/ (vector-vector-xz-distance destination start) xz-speed)))
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(setup-from-to-duration! this start destination duration gravity))
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0
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(none))
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(defmethod setup-from-to-y-vel! ((this trajectory) (start vector) (destination vector) (initial-y-velocity float) (gravity float))
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"Solve a trajectory from start to destination with initial-y-velocity and constant vertical
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gravity. Use the later real time at which the vertical equation reaches the destination; when no
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real root exists, use a 900-tick fallback duration."
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(let ((discriminant (- (square initial-y-velocity) (* 2.0 (- (-> start y) (-> destination y)) gravity)))
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(duration 900.0))
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(when (>= discriminant 0.0)
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(let ((sqrt-discriminant (sqrtf discriminant)))
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(set! duration
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(fmax (/ (- (- initial-y-velocity) sqrt-discriminant) gravity) (/ (+ (- initial-y-velocity) sqrt-discriminant) gravity)))))
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(setup-from-to-duration! this start destination duration gravity))
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0
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(none))
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(defmethod setup-from-to-height! ((this trajectory) (start vector) (destination vector) (apex-height float) (gravity float))
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"Solve a trajectory from start to destination whose apex is apex-height above the higher
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endpoint. Derive the required initial vertical velocity, using 4096 when that square-root input is
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not positive, then solve the corresponding flight duration."
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(let* ((apex-y (+ apex-height (fmax (-> start y) (-> destination y))))
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(initial-y-speed-squared (* 2.0 (- (-> start y) apex-y) gravity))
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(initial-y-velocity 4096.0))
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(if (< 0.0 initial-y-speed-squared) (set! initial-y-velocity (sqrtf initial-y-speed-squared)))
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(setup-from-to-y-vel! this start destination initial-y-velocity gravity))
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0
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(none))
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(defmethod debug-draw! ((this trajectory))
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"Draw the solved flight as ten translucent red line segments from time zero through the
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stored duration, without depth testing."
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(let ((previous-position (new 'stack-no-clear 'vector))
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(position (new 'stack-no-clear 'vector))
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(num-segments 10))
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(vector-copy! position (-> this initial-position))
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(dotimes (i num-segments)
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(vector-copy! previous-position position)
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(let ((sample-time (* (-> this time) (/ (+ 1.0 (the float i)) (the float num-segments)))))
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(eval-position! this sample-time position))
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(add-debug-line #t
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(bucket-id debug-no-zbuf)
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previous-position
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position
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(new 'static 'rgba :r #xff :a #x80)
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#f
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(the-as rgba -1))))
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0
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(none))
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