44 lines
1.0 KiB
GDScript
44 lines
1.0 KiB
GDScript
class_name SpringDamper
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extends Object
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# Based on: allenchou.net/2015/04/game-math-precise-control-over-numeric-springing/
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var omega
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var zeta
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var v:Variant = null
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# Called when the node enters the scene tree for the first time.
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func _ready():
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pass # Replace with function body.
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func _init(v0:Variant, osc_freq:float = 4, osc_red:float = 0.003, osc_red_h:float = 0.003):
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assert (osc_red > 0.001 and osc_red < 0.999)
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omega = osc_freq * 2 * PI
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zeta = log(1.0 - osc_red) / (-omega * osc_red_h)
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v = v0
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func calc(x, xt, h:float):
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var f = 1.0 + 2.0 * h * zeta * omega
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var oo = omega * omega
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var hoo = oo * h
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var hhoo = hoo * h
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var det_inv = 1.0 / (f + hhoo)
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var det_x = f * x + h * v + hhoo * xt
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var det_v = v + hoo * (xt - x)
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x = det_x * det_inv
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v = det_v * det_inv
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return x
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func calc_clamped_speed(x, xt, h:float, s_max:float):
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var x_old = x
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var x_new = calc(x, xt, h)
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var vel_new = (x_new - x_old) / h
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var speed_new = vel_new.length()
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if speed_new > s_max:
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vel_new = (vel_new / speed_new) * s_max
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x = x_old + vel_new * h
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return x
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