#pragma once
#include <vector>
#include <cmath>
#include "Vector2.hpp"
namespace IntersectionFunctions
{
struct IntersectionObject
{
std::vector<Vector2> points;
void InsertSolution(float x, float y)
{
points.push_back(Vector2(x, y));
}
void InsertSolution(Vector2 v)
{
points.push_back(v);
}
int NumberOfSolutions()
{
return points.size();
}
};
// Circle to Circle
IntersectionObject CircleToCircleIntersection(Vector2 circlePosition1, float radius1,
Vector2 circlePosition2, float radius2)
{
IntersectionObject result;
float a, distSq, dist, h;
Vector2 d, r, v2;
// d is the vertical and horizontal distances between the circle centers
d = circlePosition1 - circlePosition2;
//distance squared between the circles
distSq = d.LengthSq();
// Check for equality and infinite intersections exist
if (distSq == 0 && radius1 == radius2)
{
return result;
}
//Check for solvability
if (distSq > (radius1 + radius2) * (radius1 + radius2))
{
// no solution. circles do not intersect
return result;
}
if (distSq < abs(radius1 - radius2) * abs(radius1 - radius2))
{
// no solution. one circle is contained in the other
return result;
}
if (distSq == (radius1 + radius2) * (radius1 + radius2))
{
//one solution
result.InsertSolution((circlePosition1 - circlePosition2) / (radius1 + radius2) * radius1 + circlePosition1);
return result;
}
dist = sqrt(distSq);
// 'point 2' is the point where the line through the circle
// intersection points crosses the line between the circle
// centers.
// Determine the distance from point 0 to point 2
a = ((radius1 * radius1) - (radius2 * radius2) + distSq) / (2.0f * dist);
// Determine the coordinates of point 2
v2 = circlePosition1 + d * (a / dist);
// Determine the distance from point 2 to either of the intersection points
h = sqrt((radius1 * radius1) - (a * a));
// Now determine the offsets of the intersection points from point 2
r = d * (h / dist);
r = r.Normal();
// Determine the absolute intersection points
result.InsertSolution(v2 + r);
result.InsertSolution(v2 - r);
return result;
}
// Used only within this namespace
int PrivateLineToCircleIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 circlePosition, float radius,
Vector2 & solution1, Vector2 & solution2)
{
// Vector from point 1 to point 2
Vector2 vertex1to2 = vertex2 - vertex1;
// Vector from point 1 to the circle's center
Vector2 circleToVertex1 = circlePosition - vertex1;
float dot = vertex1to2.Dot(circleToVertex1);
Vector2 proj1 = vertex1to2 * (dot / vertex1to2.LengthSq());
Vector2 midpt = vertex1 + proj1;
Vector2 circleToMidpt = midpt - circlePosition;
float distSqToCenter = circleToMidpt.LengthSq();
if (distSqToCenter > radius * radius) return 0;
if (distSqToCenter == radius * radius)
{
solution1 = midpt;
return 1;
}
float distToIntersection;
if (distSqToCenter == 0)
{
distToIntersection = radius;
}
else
{
distToIntersection = sqrt(radius * radius - distSqToCenter);
}
vertex1to2 = vertex1to2.Normalize();
vertex1to2 *= distToIntersection;
solution1 = midpt + vertex1to2;
solution2 = midpt - vertex1to2;
return 2;
}
//Line to Circle
IntersectionObject LineToCircleIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 circlePosition, float radius)
{
IntersectionObject result;
Vector2 solution1, solution2;
switch(PrivateLineToCircleIntersection(vertex1, vertex2, circlePosition, radius, solution1, solution2))
{
case 2:
result.InsertSolution(solution2);
case 1:
result.InsertSolution(solution1);
break;
}
return result;
}
// Circle to Line
IntersectionObject CircleToLineIntersection(Vector2 circlePosition, float radius,
Vector2 vertex1, Vector2 vertex2)
{
return LineToCircleIntersection(vertex1, vertex2, circlePosition, radius);
}
// LineSegment to Circle
IntersectionObject LineSegmentToCircleIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 circlePosition, float radius)
{
IntersectionObject result;
Vector2 solution1, solution2;
Vector2 vertex1to2 = vertex2 - vertex1;
Vector2 vertex1ToSolution1, vertex2ToSolution1, vertex1ToSolution2, vertex2ToSolution2;
switch(PrivateLineToCircleIntersection(vertex1, vertex2, circlePosition, radius, solution1, solution2))
{
case 2:
vertex1ToSolution2 = solution2 - vertex1;
vertex2ToSolution2 = solution2 - vertex2;
if (vertex1ToSolution2.Dot(vertex1to2) > 0 &&
vertex2ToSolution2.Dot(vertex1to2) < 0)
{
result.InsertSolution(solution2);
}
case 1:
vertex1ToSolution1 = solution1 - vertex1;
vertex2ToSolution1 = solution1 - vertex2;
if (vertex1ToSolution1.Dot(vertex1to2) > 0 &&
vertex2ToSolution1.Dot(vertex1to2) < 0)
{
result.InsertSolution(solution1);
}
break;
}
return result;
}
// Circle to LineSegment
IntersectionObject CircleToLineSegmentIntersection(Vector2 circlePosition, float radius,
Vector2 vertex1, Vector2 vertex2)
{
return LineSegmentToCircleIntersection(vertex1, vertex2, circlePosition, radius);
}
// Ray to Circle
IntersectionObject RayToCircleIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 circlePosition, float radius)
{
IntersectionObject result;
Vector2 solution1, solution2;
Vector2 vertex1to2 = vertex2 - vertex1;
Vector2 vertex1ToSolution1, vertex1ToSolution2;
switch(PrivateLineToCircleIntersection(vertex1, vertex2, circlePosition, radius, solution1, solution2))
{
case 2:
vertex1ToSolution2 = solution2 - vertex1;
if (vertex1ToSolution2.Dot(vertex1to2) > 0)
{
result.InsertSolution(solution2);
}
case 1:
vertex1ToSolution1 = solution1 - vertex1;
if (vertex1ToSolution1.Dot(vertex1to2) > 0)
{
result.InsertSolution(solution1);
}
break;
}
return result;
}
// Circle to Ray
IntersectionObject CircleToRayIntersection(Vector2 circlePosition, float radius,
Vector2 vertex1, Vector2 vertex2)
{
return RayToCircleIntersection(vertex1, vertex2, circlePosition, radius);
}
// Used only within this namespace
bool PrivateLineToLineIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4, float & r, float & s)
{
float d;
//Make sure the lines aren't parallel
Vector2 vertex1to2 = vertex2 - vertex1;
Vector2 vertex3to4 = vertex4 - vertex3;
//if (vertex1to2.x * -vertex3to4.y + vertex1to2.y * vertex3to4.x != 0)
//{
if(vertex1to2.y / vertex1to2.x != vertex3to4.y / vertex3to4.x)
{
d = vertex1to2.x * vertex3to4.y - vertex1to2.y * vertex3to4.x;
if (d != 0)
{
Vector2 vertex3to1 = vertex1 - vertex3;
r = (vertex3to1.y * vertex3to4.x - vertex3to1.x * vertex3to4.y) / d;
s = (vertex3to1.y * vertex1to2.x - vertex3to1.x * vertex1to2.y) / d;
return true;
}
}
return false;
}
// Line to Line
IntersectionObject LineToLineIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4)
{
IntersectionObject result;
float r, s;
if(PrivateLineToLineIntersection(vertex1, vertex2, vertex3, vertex4, r, s))
{
result.InsertSolution(vertex1 + (vertex2 - vertex1) * r);
}
return result;
}
// LineSegment to LineSegment
IntersectionObject LineSegmentToLineSegmentIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4)
{
IntersectionObject result;
float r, s;
if(PrivateLineToLineIntersection(vertex1, vertex2, vertex3, vertex4, r, s))
{
if (r >= 0 && r <= 1)
{
if (s >= 0 && s <= 1)
{
result.InsertSolution(vertex1 + (vertex2 - vertex1) * r);
}
}
}
return result;
}
// LineSegment to Line
IntersectionObject LineSegmentToLineIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4)
{
IntersectionObject result;
float r, s;
if(PrivateLineToLineIntersection(vertex1, vertex2, vertex3, vertex4, r, s))
{
if (r >= 0 && r <= 1)
{
result.InsertSolution(vertex1 + (vertex2 - vertex1) * r);
}
}
return result;
}
// Line to LineSement
IntersectionObject LineToLineSegmentIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4)
{
return LineSegmentToLineIntersection(vertex3, vertex4, vertex1, vertex2);
}
// Ray to LineSegment
IntersectionObject RayToLineSegmentIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4)
{
IntersectionObject result;
float r, s;
if(PrivateLineToLineIntersection(vertex1, vertex2, vertex3, vertex4, r, s))
{
if (r >= 0)
{
if (s >= 0 && s <= 1)
{
result.InsertSolution(vertex1 + (vertex2 - vertex1) * r);
}
}
}
return result;
}
// LineSegment to Ray
IntersectionObject LineSegmentToRayIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4)
{
return RayToLineSegmentIntersection(vertex3, vertex4, vertex1, vertex2);
}
// Ray to Line
IntersectionObject RayToLineIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4)
{
IntersectionObject result;
float r, s;
if(PrivateLineToLineIntersection(vertex1, vertex2, vertex3, vertex4, r, s))
{
if (r >= 0)
{
result.InsertSolution(vertex1 + (vertex2 - vertex1) * r);
}
}
return result;
}
// Line to Ray
IntersectionObject LineToRayIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4)
{
return RayToLineIntersection(vertex3, vertex4, vertex1, vertex2);
}
// Ray to Ray
IntersectionObject RayToRayIntersection(Vector2 vertex1, Vector2 vertex2,
Vector2 vertex3, Vector2 vertex4)
{
IntersectionObject result;
float r, s;
if(PrivateLineToLineIntersection(vertex1, vertex2, vertex3, vertex4, r, s))
{
if (r >= 0)
{
if (s >= 0)
{
result.InsertSolution(vertex1 + (vertex2 - vertex1) * r);
}
}
}
return result;
}
}