returns 1.0 for x==0.0 (unlike glsl)

implements Perez's model for sky luminance

check if a utf8 string contains a prefix which is the utf16 string; if so return length of matching utf8 string

true if vertex v is in front of face f

returns the new scene if one is requested

calculates local space positions given a set of particles and rigid indices

compacts all constraints into linear arrays

creates distance constraints between particles within some radius

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returns the new scene if one is selected