227 lines
7.9 KiB
C#
227 lines
7.9 KiB
C#
// -----------------------------------------------------------------------
|
|
// <copyright file="IntersectionHelper.cs" company="">
|
|
// Triangle.NET code by Christian Woltering, http://triangle.codeplex.com/
|
|
// </copyright>
|
|
// -----------------------------------------------------------------------
|
|
|
|
namespace UnityEngine.U2D.Animation.TriangleNet
|
|
.Tools
|
|
{
|
|
using Animation.TriangleNet.Geometry;
|
|
|
|
internal static class IntersectionHelper
|
|
{
|
|
/// <summary>
|
|
/// Compute intersection of two segments.
|
|
/// </summary>
|
|
/// <param name="p0">Segment 1 start point.</param>
|
|
/// <param name="p1">Segment 1 end point.</param>
|
|
/// <param name="q0">Segment 2 start point.</param>
|
|
/// <param name="q1">Segment 2 end point.</param>
|
|
/// <param name="c0">The intersection point.</param>
|
|
/// <remarks>
|
|
/// This is a special case of segment intersection. Since the calling algorithm assures
|
|
/// that a valid intersection exists, there's no need to check for any special cases.
|
|
/// </remarks>
|
|
internal static void IntersectSegments(Point p0, Point p1, Point q0, Point q1, ref Point c0)
|
|
{
|
|
double ux = p1.x - p0.x;
|
|
double uy = p1.y - p0.y;
|
|
double vx = q1.x - q0.x;
|
|
double vy = q1.y - q0.y;
|
|
double wx = p0.x - q0.x;
|
|
double wy = p0.y - q0.y;
|
|
|
|
double d = (ux * vy - uy * vx);
|
|
double s = (vx * wy - vy * wx) / d;
|
|
|
|
// Intersection point
|
|
c0.x = p0.X + s * ux;
|
|
c0.y = p0.Y + s * uy;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Intersect segment with a bounding box.
|
|
/// </summary>
|
|
/// <param name="rect">The clip rectangle.</param>
|
|
/// <param name="p0">Segment endpoint.</param>
|
|
/// <param name="p1">Segment endpoint.</param>
|
|
/// <param name="c0">The new location of p0.</param>
|
|
/// <param name="c1">The new location of p1.</param>
|
|
/// <returns>Returns true, if segment is clipped.</returns>
|
|
/// <remarks>
|
|
/// Based on Liang-Barsky function by Daniel White:
|
|
/// http://www.skytopia.com/project/articles/compsci/clipping.html
|
|
/// </remarks>
|
|
internal static bool LiangBarsky(Rectangle rect, Point p0, Point p1, ref Point c0, ref Point c1)
|
|
{
|
|
// Define the x/y clipping values for the border.
|
|
double xmin = rect.Left;
|
|
double xmax = rect.Right;
|
|
double ymin = rect.Bottom;
|
|
double ymax = rect.Top;
|
|
|
|
// Define the start and end points of the line.
|
|
double x0 = p0.X;
|
|
double y0 = p0.Y;
|
|
double x1 = p1.X;
|
|
double y1 = p1.Y;
|
|
|
|
double t0 = 0.0;
|
|
double t1 = 1.0;
|
|
|
|
double dx = x1 - x0;
|
|
double dy = y1 - y0;
|
|
|
|
double p = 0.0, q = 0.0, r;
|
|
|
|
for (int edge = 0; edge < 4; edge++)
|
|
{
|
|
// Traverse through left, right, bottom, top edges.
|
|
if (edge == 0) { p = -dx; q = -(xmin - x0); }
|
|
if (edge == 1) { p = dx; q = (xmax - x0); }
|
|
if (edge == 2) { p = -dy; q = -(ymin - y0); }
|
|
if (edge == 3) { p = dy; q = (ymax - y0); }
|
|
r = q / p;
|
|
if (p == 0 && q < 0) return false; // Don't draw line at all. (parallel line outside)
|
|
if (p < 0)
|
|
{
|
|
if (r > t1) return false; // Don't draw line at all.
|
|
else if (r > t0) t0 = r; // Line is clipped!
|
|
}
|
|
else if (p > 0)
|
|
{
|
|
if (r < t0) return false; // Don't draw line at all.
|
|
else if (r < t1) t1 = r; // Line is clipped!
|
|
}
|
|
}
|
|
|
|
c0.X = x0 + t0 * dx;
|
|
c0.Y = y0 + t0 * dy;
|
|
c1.X = x0 + t1 * dx;
|
|
c1.Y = y0 + t1 * dy;
|
|
|
|
return true; // (clipped) line is drawn
|
|
}
|
|
|
|
/// <summary>
|
|
/// Intersect a ray with a bounding box.
|
|
/// </summary>
|
|
/// <param name="rect">The clip rectangle.</param>
|
|
/// <param name="p0">The ray startpoint (inside the box).</param>
|
|
/// <param name="p1">Any point in ray direction (NOT the direction vector).</param>
|
|
/// <param name="c1">The intersection point.</param>
|
|
/// <returns>Returns false, if startpoint is outside the box.</returns>
|
|
internal static bool BoxRayIntersection(Rectangle rect, Point p0, Point p1, ref Point c1)
|
|
{
|
|
return BoxRayIntersection(rect, p0, p1.x - p0.x, p1.y - p0.y, ref c1);
|
|
}
|
|
|
|
/// <summary>
|
|
/// Intersect a ray with a bounding box.
|
|
/// </summary>
|
|
/// <param name="rect">The clip rectangle.</param>
|
|
/// <param name="p">The ray startpoint (inside the box).</param>
|
|
/// <param name="dx">X direction.</param>
|
|
/// <param name="dy">Y direction.</param>
|
|
/// <returns>Returns false, if startpoint is outside the box.</returns>
|
|
internal static Point BoxRayIntersection(Rectangle rect, Point p, double dx, double dy)
|
|
{
|
|
var intersection = new Point();
|
|
|
|
if (BoxRayIntersection(rect, p, dx, dy, ref intersection))
|
|
{
|
|
return intersection;
|
|
}
|
|
|
|
return null;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Intersect a ray with a bounding box.
|
|
/// </summary>
|
|
/// <param name="rect">The clip rectangle.</param>
|
|
/// <param name="p">The ray startpoint (inside the box).</param>
|
|
/// <param name="dx">X direction.</param>
|
|
/// <param name="dy">Y direction.</param>
|
|
/// <param name="c">The intersection point.</param>
|
|
/// <returns>Returns false, if startpoint is outside the box.</returns>
|
|
internal static bool BoxRayIntersection(Rectangle rect, Point p, double dx, double dy, ref Point c)
|
|
{
|
|
double x = p.X;
|
|
double y = p.Y;
|
|
|
|
double t1, x1, y1, t2, x2, y2;
|
|
|
|
// Bounding box
|
|
double xmin = rect.Left;
|
|
double xmax = rect.Right;
|
|
double ymin = rect.Bottom;
|
|
double ymax = rect.Top;
|
|
|
|
// Check if point is inside the bounds
|
|
if (x < xmin || x > xmax || y < ymin || y > ymax)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
// Calculate the cut through the vertical boundaries
|
|
if (dx < 0)
|
|
{
|
|
// Line going to the left: intersect with x = minX
|
|
t1 = (xmin - x) / dx;
|
|
x1 = xmin;
|
|
y1 = y + t1 * dy;
|
|
}
|
|
else if (dx > 0)
|
|
{
|
|
// Line going to the right: intersect with x = maxX
|
|
t1 = (xmax - x) / dx;
|
|
x1 = xmax;
|
|
y1 = y + t1 * dy;
|
|
}
|
|
else
|
|
{
|
|
// Line going straight up or down: no intersection possible
|
|
t1 = double.MaxValue;
|
|
x1 = y1 = 0;
|
|
}
|
|
|
|
// Calculate the cut through upper and lower boundaries
|
|
if (dy < 0)
|
|
{
|
|
// Line going downwards: intersect with y = minY
|
|
t2 = (ymin - y) / dy;
|
|
x2 = x + t2 * dx;
|
|
y2 = ymin;
|
|
}
|
|
else if (dy > 0)
|
|
{
|
|
// Line going upwards: intersect with y = maxY
|
|
t2 = (ymax - y) / dy;
|
|
x2 = x + t2 * dx;
|
|
y2 = ymax;
|
|
}
|
|
else
|
|
{
|
|
// Horizontal line: no intersection possible
|
|
t2 = double.MaxValue;
|
|
x2 = y2 = 0;
|
|
}
|
|
|
|
if (t1 < t2)
|
|
{
|
|
c.x = x1;
|
|
c.y = y1;
|
|
}
|
|
else
|
|
{
|
|
c.x = x2;
|
|
c.y = y2;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
}
|
|
}
|