interpolate_point4d()

void interpolate_point4d	(	POINT4D *	A,
		POINT4D *	B,
		POINT4D *	I,
		double	F
	)

Find interpolation point I between point A and point B so that the len(AI) == len(AB)*F and I falls on AB segment.

Example:

F=0.5 : A-—I-—B F=1 : A------—B==I F=0 : A==I------—B F=.2 : A-I----—B

Definition at line 680 of file lwgeom_api.c.

References lwerror(), POINT4D::m, POINT4D::x, POINT4D::y, and POINT4D::z.

Referenced by LWGEOM_line_interpolate_point(), and ptarray_substring().

{
#if PARANOIA_LEVEL > 0
        double absF=fabs(F);
        if ( absF < 0 || absF > 1 )
        {
                lwerror("interpolate_point4d: invalid F (%g)", F);
        }
#endif
        I->x=A->x+((B->x-A->x)*F);
        I->y=A->y+((B->y-A->y)*F);
        I->z=A->z+((B->z-A->z)*F);
        I->m=A->m+((B->m-A->m)*F);
}

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