-- File: SV2d.mesa
-- Last edited by Bier on December 18, 1982 1:01 am
-- Author: Eric Bier on August 20, 1982 11:39 am
-- Contents: Definitions of data structures used to represent two dimensional entities, and procedures to support them. Part of the Solidviews Three Dimensional Illustrator.

SV2d: DEFINITIONS =
BEGIN

Point2d: TYPE = ARRAY[1..2] OF REAL;

-- Not currently used
Ray2d: TYPE = REF Ray2dObj;
Ray2dObj: TYPE = RECORD [
 p, qMinusP: Point2d];
 
maxPolyEdges: NAT = 20;

-- Not currently used
Classif2d: TYPE = REF Classif2dObj;
Classif2dObj: TYPE = RECORD [
 count: NAT,
 params: ParamArray,
 classifs: ClassifArray,
 edges: EdgeArray];
 
-- Not currently used
ParamArray: TYPE = ARRAY [1..maxPolyEdges] OF REAL;
ClassifArray: TYPE = ARRAY [1..maxPolyEdges+1] OF InOutOn;
InOutOn: TYPE = {in, out, on};
EdgeArray: TYPE = ARRAY [1..maxPolyEdges] OF Edge;
 Edge: TYPE = RECORD[v1, v2: Point2d];
 
-- Polygons and Paths

Polygon: TYPE = REF PolygonObj;
PolygonObj: TYPE = RECORD [
 len: NAT, seq: SEQUENCE maxVerts: NAT OF Point2d];
 
Path: TYPE = REF PathObj;
PathObj: TYPE = RECORD [
 len: NAT, seq: SEQUENCE maxVerts: NAT OF Point2d];

TrigPolygon: TYPE = REF TrigPolygonObj;
TrigPolygonObj: TYPE = RECORD [
 len: NAT, seq: SEQUENCE maxVerts: NAT OF TrigLineSeg];
 
-- not currently used
Intersection: TYPE = REF IntersectionObj;
IntersectionObj: TYPE = RECORD [
 t: REAL,
 edge: Edge];
IntersectionRec: TYPE = REF IntersectionRecObj;
IntersectionRecObj: TYPE = RECORD [
 array: ARRAY [1..maxPolyEdges] OF Intersection,
 len: NAT];
 
-- a possible substitute for TrigLineSeg
LineSeg: TYPE = REF LineSegObj;
LineSegObj: TYPE = RECORD [
 p1, p2: Point2d,
 slope: REAL,
 xInt, yInt: REAL,
 isVert: BOOL
 ];
 
TrigLineSeg: TYPE = REF TrigLineSegObj;
 -- a TrigLine with endpoints pLo and pHi.
 -- pLo has lower y than pHi or the same y and lower x.
TrigLineSegObj: TYPE = RECORD [
 line: TrigLine,
 pLo, pHi: Point2d,
 pLoIsFirst: BOOL]; -- are [pLo, pHi] in the same order as [v1, v2] (the segment endpoints as they are given to CreateTrigLineSeg)?

TrigLine: TYPE = REF TrigLineObj;
TrigLineObj: TYPE = RECORD [
 -- line equation of the form: y*cos(theta) - x*sin(theta) -d = 0;
 -- where theta is the angle which the line makes with the x axis and d is the distance from the line to the origin.
 c: REAL, -- cos(theta)
 s: REAL, -- sin(theta)
 theta: REAL, -- angle in (-pi..pi]
 d: REAL, -- distance from line to origin
 slope: REAL, -- slope and yInt are redundant information but they come almost for free.
 yInt: REAL
 ];
 
END.