--m.stone February 19, 1980  5:20 PM

SplineDefs: DEFINITIONS =
BEGIN
X: INTEGER = 1;
Y: INTEGER = 2;
NDIM: INTEGER = Y;
--points in object space
FPCoords: TYPE = ARRAY [X..NDIM] OF REAL;
--points in screen space
ScrPt: TYPE = ARRAY [X..NDIM] OF INTEGER;
Coeffs: TYPE = RECORD
	[t3: FPCoords,
	 t2: FPCoords,
	 t1: FPCoords,
	 t0: FPCoords];

SplineType: TYPE = 
--global splines
	{naturalUM,cyclicUM,naturalAL,cyclicAL,
--special case cubic curves
	bezier,bsplineInterp,
--local splines
	bspline,crspline};	

TooFewKnots: SIGNAL[numknots: INTEGER] ;
UnknownSpline: SIGNAL[splineType: SplineType] ;
UnmatchedEnds: SIGNAL ;
NoInitSplines: SIGNAL ;

InitSplines: PROCEDURE[
	alloc: PROCEDURE[nwords: CARDINAL] RETURNS[POINTER],
	free: PROCEDURE[POINTER TO UNSPECIFIED]];

FreeCoeffs: PROCEDURE[coeffs: DESCRIPTOR FOR ARRAY OF Coeffs];

MakeSpline: PROCEDURE
	[knots: DESCRIPTOR FOR ARRAY OF FPCoords, splineType: SplineType]
	RETURNS [DESCRIPTOR FOR ARRAY OF Coeffs]; 

DisplayCubic: PROCEDURE
	[coeffs: POINTER TO Coeffs, 
	MoveTo: PROCEDURE[ScrPt], 
	DrawTo: PROCEDURE[ScrPt]];

END.