1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
|
#include "CurveIntersection.h"
#include "LineUtilities.h"
bool implicitLine(const _Line& line, double& slope, double& axisIntercept) {
_Point delta;
tangent(line, delta);
bool moreHorizontal = fabs(delta.x) > fabs(delta.y);
if (moreHorizontal) {
slope = delta.y / delta.x;
axisIntercept = line[0].y - slope * line[0].x;
} else {
slope = delta.x / delta.y;
axisIntercept = line[0].x - slope * line[0].y;
}
return moreHorizontal;
}
int reduceOrder(const _Line& line, _Line& reduced) {
reduced[0] = line[0];
int different = line[0] != line[1];
reduced[1] = line[different];
return 1 + different;
}
void sub_divide(const _Line& line, double t1, double t2, _Line& dst) {
_Point delta;
tangent(line, delta);
dst[0].x = line[0].x - t1 * delta.x;
dst[0].y = line[0].y - t1 * delta.y;
dst[1].x = line[0].x - t2 * delta.x;
dst[1].y = line[0].y - t2 * delta.y;
}
// may have this below somewhere else already:
// copying here because I thought it was clever
// Copyright 2001, softSurfer (www.softsurfer.com)
// This code may be freely used and modified for any purpose
// providing that this copyright notice is included with it.
// SoftSurfer makes no warranty for this code, and cannot be held
// liable for any real or imagined damage resulting from its use.
// Users of this code must verify correctness for their application.
// Assume that a class is already given for the object:
// Point with coordinates {float x, y;}
//===================================================================
// isLeft(): tests if a point is Left|On|Right of an infinite line.
// Input: three points P0, P1, and P2
// Return: >0 for P2 left of the line through P0 and P1
// =0 for P2 on the line
// <0 for P2 right of the line
// See: the January 2001 Algorithm on Area of Triangles
float isLeft( _Point P0, _Point P1, _Point P2 )
{
return (P1.x - P0.x)*(P2.y - P0.y) - (P2.x - P0.x)*(P1.y - P0.y);
}
|
