-- File: PadGraphicsImpl.mesa
-- Last edited by Bier on December 18, 1982 1:29 am
-- Author: Eric Bier on August 6, 1982 12:30 pm
-- Contents: Simple 2d graphics package for the scratchpad

DIRECTORY
	Graphics,
	PadGraphics,
	Matrix3d,
	RealFns,
	SVDraw,
	SVPolygon2d,
	SVVector2d;

PadGraphicsImpl: PROGRAM
	IMPORTS Graphics, RealFns, SVDraw, SVVector2d
	EXPORTS PadGraphics =

BEGIN

Path: TYPE = SVPolygon2d.Path;
Point2d: TYPE = Matrix3d.Point2d;
Polygon: TYPE = SVPolygon2d.Polygon;
Vector2d: TYPE = SVVector2d.Vector2d;

squareSide: REAL _ 6.0;

ScreenToPad: PUBLIC PROC [screenPoint: Point2d, origin: Point2d, scalar: REAL _ 1] RETURNS [padPoint: Point2d] = {
	-- origin is the pad origin in screen coordintates
	padPoint[1] _ screenPoint[1] - origin[1];
	padPoint[2] _ screenPoint[2] - origin[2];
	padPoint _ SVVector2d.Scale[padPoint, 1/scalar];
	};
	
PadToScreen: PUBLIC PROC [padPoint: Point2d, origin: Point2d, scalar: REAL _ 1] RETURNS [screenPoint: Point2d] = {
	padPoint _ SVVector2d.Scale[padPoint, scalar];
	screenPoint[1] _ padPoint[1] + origin[1];
	screenPoint[2] _ padPoint[2] + origin[2];
	};

MoveTo: PUBLIC PROC [dc: Graphics.Context, padPoint: Point2d, origin: Point2d] = {
	screenPoint: Point2d;
	screenPoint _ PadToScreen[padPoint, origin];
	Graphics.SetCP[dc, screenPoint[1], screenPoint[2]];
	};
DrawTo: PUBLIC PROC [dc: Graphics.Context, padPoint: Point2d, origin: Point2d] = {
	screenPoint: Point2d;
	screenPoint _ PadToScreen[padPoint, origin];
	Graphics.DrawTo[dc, screenPoint[1], screenPoint[2]];
	};
MirrorMoveTo: PUBLIC PROC [dc: Graphics.Context, padPoint: Point2d, origin: Point2d] = {
	screenPoint: Point2d;
	padPoint[1] _ -padPoint[1];
	screenPoint _ PadToScreen[padPoint, origin];
	Graphics.SetCP[dc, screenPoint[1], screenPoint[2]];
	};
MirrorDrawTo: PUBLIC PROC [dc: Graphics.Context, padPoint: Point2d, origin: Point2d] = {
	screenPoint: Point2d;
	padPoint[1] _ -padPoint[1];
	screenPoint _ PadToScreen[padPoint, origin];
	Graphics.DrawTo[dc, screenPoint[1], screenPoint[2]];
	};
	
DrawPathNeighborHood: PUBLIC PROC [dc: Graphics.Context, path: Path, index: NAT, origin: Point2d] = {
	-- draw three points and 2 edges corresponding to the neighborhood of path[index];
	-- path is in pad coordinates.
	-- if index is one of the two ends of the path then draw 2 points and 1 edge.
	DrawSquare[dc, squareSide, path[index], origin];
	IF index>0 THEN {
		MoveTo[dc, path[index-1], origin];
		DrawTo[dc, path[index], origin];
		};
	IF index<path.len-1 THEN {
		MoveTo[dc, path[index+1], origin];
		DrawTo[dc, path[index], origin];
		};
	};
	
MirrorDrawPathNeighborHood: PUBLIC PROC [dc: Graphics.Context, path: Path, index: NAT, origin: Point2d] = {
	-- draw three points and 2 edges corresponding to the neighborhood of path[index];
	-- path is in pad coordinates.
	-- if index is one of the two ends of the path then draw 2 points and 1 edge.
	MirrorDrawSquare[dc, squareSide, path[index], origin];
	IF index>0 THEN {
		MirrorMoveTo[dc, path[index-1], origin];
		MirrorDrawTo[dc, path[index], origin];
		};
	IF index<path.len-1 THEN {
		MirrorMoveTo[dc, path[index+1], origin];
		MirrorDrawTo[dc, path[index], origin];
		};
	};
	
DrawPolyNeighborHood: PUBLIC PROC [dc: Graphics.Context, poly: Polygon, index: NAT, origin: Point2d] = {
	-- draw three points and 2 edges corresponding to the neighborhood of poly[index];
	-- poly is in pad coordinates.
	-- poly.len = 2 then draw both points and the edge joining them.
	-- if poly.len = 1 then just draw a point.
	indexPlusOne, indexMinusOne: NAT;
	indexPlusOne _ IF index = poly.len-1 THEN 0 ELSE index + 1;
	indexMinusOne _ IF index = 0 THEN poly.len-1 ELSE index - 1;
	DrawSquare[dc, squareSide, poly[index], origin];
	IF poly.len = 1 THEN RETURN;
	MoveTo[dc, poly[indexPlusOne], origin];
	DrawTo[dc, poly[index], origin];
	IF poly.len = 2 THEN RETURN;
	MoveTo[dc, poly[indexMinusOne], origin];
	DrawTo[dc, poly[index], origin];
	};
	
MirrorDrawPolyNeighborHood: PUBLIC PROC [dc: Graphics.Context, poly: Polygon, index: NAT, origin: Point2d] = {
	-- draw three points and 2 edges corresponding to the neighborhood of poly[index];
	-- poly is in pad coordinates.
	-- poly.len = 2 then draw both points and the edge joining them.
	-- if poly.len = 1 then just draw a point.
	indexPlusOne, indexMinusOne: NAT;
	indexPlusOne _ IF index = poly.len-1 THEN 0 ELSE index + 1;
	indexMinusOne _ IF index = 0 THEN poly.len-1 ELSE index - 1;
	MirrorDrawSquare[dc, squareSide, poly[index], origin];
	IF poly.len = 1 THEN RETURN;
	MirrorMoveTo[dc, poly[indexPlusOne], origin];
	MirrorDrawTo[dc, poly[index], origin];
	IF poly.len = 2 THEN RETURN;
	MirrorMoveTo[dc, poly[indexMinusOne], origin];
	MirrorDrawTo[dc, poly[index], origin];
	};

DrawPath: PUBLIC PROC [dc: Graphics.Context, path: Path, origin: Point2d, scalar: REAL _ 1] = {
	-- poly is in Pad coordinates
	-- transform each point to screen coordinates and draw using Graphics.
	outline: Graphics.Path _ Graphics.NewPath[path.len];
	screenPoint: Point2d;
	IF path.len <= 1 THEN RETURN;
	screenPoint _ PadToScreen[path[0], origin, scalar];
	Graphics.MoveTo[outline, screenPoint[1], screenPoint[2]];
	FOR i: NAT IN [1..path.len) DO
		screenPoint _ PadToScreen[path[i], origin, scalar];
		Graphics.LineTo[outline, screenPoint[1], screenPoint[2]];
	ENDLOOP;
	Graphics.DrawStroke[dc, outline, 2, FALSE, round];
	};
	
DrawPolygon: PUBLIC PROC [dc: Graphics.Context, poly: Polygon, origin: Point2d, scalar: REAL _ 1] = {
	-- poly is in Pad coordinates
	-- transform each point to screen coordinates and draw using Graphics.
	screenPoint0, screenPoint1, screenPoint2: Point2d;
	IF poly.len <= 1 THEN RETURN;
	screenPoint0 _ screenPoint1 _ PadToScreen[poly[0], origin, scalar];
	FOR i: NAT IN [1..poly.len) DO
		screenPoint2 _ PadToScreen[poly[i], origin, scalar];
		SVDraw.LineSandwich[dc, screenPoint1[1], screenPoint1[2], screenPoint2[1], screenPoint2[2]];
		screenPoint1 _ screenPoint2;
	ENDLOOP;
	SVDraw.LineSandwich[dc, screenPoint1[1], screenPoint1[2], screenPoint0[1], screenPoint0[2]];
	};
	
CrossHairs: PUBLIC PROC [dc: Graphics.Context, origin: Point2d] = {
	leftPoint, rightPoint, topPoint, bottomPoint, screenPoint: Point2d;
	leftPoint _ [-1000, 0];
	rightPoint _ [1000, 0];
	topPoint _ [0, 1000];
	bottomPoint _ [0, -1000];
	screenPoint _ PadToScreen[leftPoint, origin];
	Graphics.SetCP[dc, screenPoint[1], screenPoint[2]];
	screenPoint _ PadToScreen[rightPoint, origin];
	Graphics.DrawTo[dc, screenPoint[1], screenPoint[2]];
	screenPoint _ PadToScreen[topPoint, origin];
	Graphics.SetCP[dc, screenPoint[1], screenPoint[2]];
	screenPoint _ PadToScreen[bottomPoint, origin];
	Graphics.DrawTo[dc, screenPoint[1], screenPoint[2]];
	};
	
DrawSquare: PUBLIC PROC [dc: Graphics.Context, side: REAL, center: Point2d, origin: Point2d] = {
	delta: REAL _ side/2.0;
	screenPoint: Point2d;
	square: Graphics.Path _ Graphics.NewPath[4];
	screenPoint _ PadToScreen[[center[1]-delta, center[2]-delta], origin];
	Graphics.MoveTo[square, screenPoint[1], screenPoint[2]];
	screenPoint _ PadToScreen[[center[1]-delta, center[2]+delta], origin];
	Graphics.LineTo[square, screenPoint[1], screenPoint[2]];
	screenPoint _ PadToScreen[[center[1]+delta, center[2]+delta], origin];
	Graphics.LineTo[square, screenPoint[1], screenPoint[2]];
	screenPoint _ PadToScreen[[center[1]+delta, center[2]-delta], origin];
	Graphics.LineTo[square, screenPoint[1], screenPoint[2]];
	Graphics.DrawStroke[dc, square, 1, TRUE];
	};
	
MirrorDrawSquare: PUBLIC PROC [dc: Graphics.Context, side: REAL, center: Point2d, origin: Point2d] = {
	delta: REAL _ side/2.0;
	screenPoint: Point2d;
	square: Graphics.Path _ Graphics.NewPath[4];
	center[1] _ -center[1];
	screenPoint _ PadToScreen[[center[1]-delta, center[2]-delta], origin];
	Graphics.MoveTo[square, screenPoint[1], screenPoint[2]];
	screenPoint _ PadToScreen[[center[1]-delta, center[2]+delta], origin];
	Graphics.LineTo[square, screenPoint[1], screenPoint[2]];
	screenPoint _ PadToScreen[[center[1]+delta, center[2]+delta], origin];
	Graphics.LineTo[square, screenPoint[1], screenPoint[2]];
	screenPoint _ PadToScreen[[center[1]+delta, center[2]-delta], origin];
	Graphics.LineTo[square, screenPoint[1], screenPoint[2]];
	Graphics.DrawStroke[dc, square, 1, TRUE];
	};

Draw2dVector: PUBLIC PROC [dc: Graphics.Context, vec: Vector2d, at: Point2d, origin: Point2d] = {
	unitVec, vec50: Vector2d;
	mag: REAL;
	mag _ RealFns.SqRt[vec[1]*vec[1] + vec[2]*vec[2]];
	unitVec[1] _ vec[1]/mag;
	unitVec[2] _ vec[2]/mag;
	vec50[1] _ unitVec[1]*50;
	vec50[2] _ unitVec[2]*50;
	MoveTo[dc, at, origin];
	DrawTo[dc, [at[1]+vec50[1], at[2]+vec50[2]], origin];
	};	-- end of Draw2dVector
	
END.
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