--m.stone February 19, 1980  5:20 PM
-- Last Edited by: Stone, March 15, 1983 3:26 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];
     
CoeffsSequence: TYPE = REF CoeffsSequenceRec;
CoeffsSequenceRec: TYPE = RECORD[element: SEQUENCE length:NAT OF Coeffs];
KnotSequence: TYPE = REF KnotSequenceRec;
KnotSequenceRec: TYPE = RECORD[element: SEQUENCE length:NAT OF 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 ;

MakeSpline: PROCEDURE
    [knots: KnotSequence, splineType: SplineType] RETURNS [CoeffsSequence]; 

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

END.