//
// Arrow
//
public static HashSet <Triangle2> Arrow(MyVector2 p1, MyVector2 p2, float lineWidth, float arrowSize)
{
HashSet <Triangle2> arrowTriangles = new HashSet <Triangle2>();
//An arrow consists of two parts: the pointy part and the rectangular part
//First we have to see if we can fit the parts
MyVector2 lineDir = p2 - p1;
float lineLength = MyVector2.Magnitude(lineDir);
if (lineLength < arrowSize)
{
Debug.Log("Cant make arrow because line is too short");
return(null);
}
//Make the arrow tip
MyVector2 lineDirNormalized = MyVector2.Normalize(lineDir);
MyVector2 arrowBottom = p2 - lineDirNormalized * arrowSize;
MyVector2 lineNormal = MyVector2.Normalize(new MyVector2(lineDirNormalized.y, -lineDirNormalized.x));
MyVector2 arrowBottom_R = arrowBottom + lineNormal * arrowSize * 0.5f;
MyVector2 arrowBottom_L = arrowBottom - lineNormal * arrowSize * 0.5f;
Triangle2 arrowTipTriangle = new Triangle2(p2, arrowBottom_R, arrowBottom_L);
arrowTriangles.Add(arrowTipTriangle);
//Make the arrow rectangle
float halfWidth = lineWidth * 0.5f;
MyVector2 p1_T = p1 + lineNormal * halfWidth;
MyVector2 p1_B = p1 - lineNormal * halfWidth;
MyVector2 p2_T = arrowBottom + lineNormal * halfWidth;
MyVector2 p2_B = arrowBottom - lineNormal * halfWidth;
HashSet <Triangle2> rectangle = LineSegment(p1_T, p1_B, p2_T, p2_B);
foreach (Triangle2 t in rectangle)
{
arrowTriangles.Add(t);
}
return(arrowTriangles);
}
//Calculate the angle between the vectors if we are going from p1-p2-p3
//Return +180 if "small" or -180 if "large"
//public static float CalculateAngleBetweenVectors(MyVector2 p1, MyVector2 p2, MyVector2 p3)
//{
// MyVector2 from = p1 - p2;
// MyVector2 to = p3 - p2;
// float angle = Vector2.SignedAngle(from, to);
// return angle;
//}
//Create a supertriangle that contains all other points
//According to the book "Geometric tools for computer graphics" a reasonably sized triangle
//is one that contains a circle that contains the axis-aligned bounding rectangle of the points
//Is currently not used anywhere because our points are normalized to the range 0-1
//and then we can make a supertriangle by just setting its size to 100
public static Triangle2 GenerateSupertriangle(HashSet <MyVector2> points)
{
//Step 1. Create a AABB around the points
AABB2 aabb = new AABB2(new List <MyVector2>(points));
MyVector2 TL = new MyVector2(aabb.minX, aabb.maxY);
MyVector2 TR = new MyVector2(aabb.maxX, aabb.maxY);
MyVector2 BR = new MyVector2(aabb.maxX, aabb.minY);
//Step2. Find the inscribed circle - the smallest circle that surrounds the AABB
MyVector2 circleCenter = (TL + BR) * 0.5f;
float circleRadius = MyVector2.Magnitude(circleCenter - TR);
//Step 3. Create the smallest triangle that surrounds the circle
//All edges of this triangle have the same length
float halfSideLenghth = circleRadius / Mathf.Tan(30f * Mathf.Deg2Rad);
//The center position of the bottom-edge
MyVector2 t_B = new MyVector2(circleCenter.x, circleCenter.y - circleRadius);
MyVector2 t_BL = new MyVector2(t_B.x - halfSideLenghth, t_B.y);
MyVector2 t_BR = new MyVector2(t_B.x + halfSideLenghth, t_B.y);
//The height from the bottom edge to the top vertex
float triangleHeight = halfSideLenghth * Mathf.Tan(60f * Mathf.Deg2Rad);
MyVector2 t_T = new MyVector2(circleCenter.x, t_B.y + triangleHeight);
//The final triangle
Triangle2 superTriangle = new Triangle2(t_BR, t_BL, t_T);
return(superTriangle);
}
