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我正在使用 Till Nagel 的代码来投影世界地图，然后根据纬度和经度坐标绘制数据。但现在我要检索鼠标位置的纬度和经度坐标。通过给出 mouseX 和 mouseY，它应该返回地图上的经度和纬度。有人可以帮忙吗？下面是我使用的代码：

/**
 * Utility class to convert between geo-locations and Cartesian screen coordinates.
 * Can be used with a bounding box defining the map section.
 *
 * (c) 2011 Till Nagel, tillnagel.com
 */
public class MercatorMap {

  public static final float DEFAULT_TOP_LATITUDE = 80;
  public static final float DEFAULT_BOTTOM_LATITUDE = -80;
  public static final float DEFAULT_LEFT_LONGITUDE = -180;
  public static final float DEFAULT_RIGHT_LONGITUDE = 180;

  /** Horizontal dimension of this map, in pixels. */
  protected float mapScreenWidth;
  /** Vertical dimension of this map, in pixels. */
  protected float mapScreenHeight;

  /** Northern border of this map, in degrees. */
  protected float topLatitude;
  /** Southern border of this map, in degrees. */
  protected float bottomLatitude;
  /** Western border of this map, in degrees. */
  protected float leftLongitude;
  /** Eastern border of this map, in degrees. */
  protected float rightLongitude;

  private float topLatitudeRelative;
  private float bottomLatitudeRelative;
  private float leftLongitudeRadians;
  private float rightLongitudeRadians;

  public MercatorMap(float mapScreenWidth, float mapScreenHeight) {
    this(mapScreenWidth, mapScreenHeight, DEFAULT_TOP_LATITUDE, DEFAULT_BOTTOM_LATITUDE, DEFAULT_LEFT_LONGITUDE, DEFAULT_RIGHT_LONGITUDE);
  }

  /**
   * Creates a new MercatorMap with dimensions and bounding box to convert between geo-locations and screen coordinates.
   *
   * @param mapScreenWidth Horizontal dimension of this map, in pixels.
   * @param mapScreenHeight Vertical dimension of this map, in pixels.
   * @param topLatitude Northern border of this map, in degrees.
   * @param bottomLatitude Southern border of this map, in degrees.
   * @param leftLongitude Western border of this map, in degrees.
   * @param rightLongitude Eastern border of this map, in degrees.
   */
  public MercatorMap(float mapScreenWidth, float mapScreenHeight, float topLatitude, float bottomLatitude, float leftLongitude, float rightLongitude) {
    this.mapScreenWidth = mapScreenWidth;
    this.mapScreenHeight = mapScreenHeight;
    this.topLatitude = topLatitude;
    this.bottomLatitude = bottomLatitude;
    this.leftLongitude = leftLongitude;
    this.rightLongitude = rightLongitude;
    this.topLatitudeRelative = getScreenYRelative(topLatitude);
    this.bottomLatitudeRelative = getScreenYRelative(bottomLatitude);
    this.leftLongitudeRadians = getRadians(leftLongitude);
    this.rightLongitudeRadians = getRadians(rightLongitude);
  }

  /**
   * Projects the geo location to Cartesian coordinates, using the Mercator projection.
   *
   * @param geoLocation Geo location with (latitude, longitude) in degrees.
   * @returns The screen coordinates with (x, y).
   */
  public PVector getScreenLocation(PVector geoLocation) {
    float latitudeInDegrees = geoLocation.x;
    float longitudeInDegrees = geoLocation.y;
    return new PVector(getScreenX(longitudeInDegrees), getScreenY(latitudeInDegrees));

  }


  private float getScreenYRelative(float latitudeInDegrees) {
    return log(tan(latitudeInDegrees / 360f * PI + PI / 4));
  }

  protected float getScreenY(float latitudeInDegrees) {
    return mapScreenHeight * (getScreenYRelative(latitudeInDegrees) - topLatitudeRelative) / (bottomLatitudeRelative - topLatitudeRelative);
  }

  private float getRadians(float deg) {
    return deg * PI / 180;
  }


  protected float getScreenX(float longitudeInDegrees) {
    float longitudeInRadians = getRadians(longitudeInDegrees);
    return mapScreenWidth * (longitudeInRadians - leftLongitudeRadians) / (rightLongitudeRadians - leftLongitudeRadians);
  }
}
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1 回答 1

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void setup(){
  size(500, 500);
}

void draw(){
  PVector p = getLatLong(mouseX, mouseY);
  println("longitude: " + p.x + ", latitude: " + p.y); 
}

PVector getLatLong(int x, int y){
  return new PVector(
    map(x, 0, width-1, -180, 180),
    map(y, 0, height-1, 90, -90));
}
于 2013-07-01T10:48:37.427 回答