praktikum-holons/src/holeg/utility/math/vector/Geometry.java

package holeg.utility.math.vector;

import static holeg.utility.math.Maths.EPSILON;

import holeg.utility.math.Maths;
import java.awt.Rectangle;
import java.util.Optional;

public class Geometry {

  public static Rectangle createRectangleFromCorners(Vec2i corner, Vec2i otherCorner) {
    //Calculate left top corner, width, height
    Vec2i topLeft = new Vec2i(Math.min(corner.getX(), otherCorner.getX()),
        Math.min(corner.getY(), otherCorner.getY()));
    Vec2i bottomRight = new Vec2i(Math.max(corner.getX(), otherCorner.getX()),
        Math.max(corner.getY(), otherCorner.getY()));
    int width = bottomRight.getX() - topLeft.getX();
    int height = bottomRight.getY() - topLeft.getY();
    return new Rectangle(topLeft.getX(), topLeft.getY(), width, height);
  }

  public static Optional<Vec2f> getProjectionOnSegmentIfInRange(Line line, Circle circle) {
    float lineLengthSqr = line.distanceSqr();
    if (lineLengthSqr < EPSILON) {
      if (line.p1.getSquaredDistance(circle.position) < circle.radius * circle.radius) {
        return Optional.of(new Vec2f(line.p1));
      } else {
        return Optional.empty();
      }
    }
    Vec2f p2p1 = line.p2.subtract(line.p1);
    float t = Maths.clamp(Vec2f.dot(circle.position.subtract(line.p1), p2p1) / lineLengthSqr, 0.0f,
        1.0f);
    Vec2f projection = line.p1.add(p2p1.multiply(t));
    if (projection.getSquaredDistance(circle.position) < circle.radius * circle.radius) {
      return Optional.of(projection);
    } else {
      return Optional.empty();
    }
  }

  public static class Circle {

    public Vec2f position;
    public float radius;

    public Circle(Vec2f position, float radius) {
      this.position = position;
      this.radius = radius;
    }
  }

  public static class Line {

    Vec2f p1;
    Vec2f p2;

    public Line(Vec2f p1, Vec2f p2) {
      this.p1 = p1;
      this.p2 = p2;
    }

    float distanceSqr() {
      return p1.getSquaredDistance(p2);
    }
  }
}