math - 放大鼠标指向的位置

Question

我正在编写太阳系符号，我需要能够放大/缩小鼠标指向的位置。到目前为止，我所做的是移动行星并放大/缩小点 (0, 0) 所在的位置。

这是我的代码:

主类

Planeta sun = new Planeta(color(235, 225, 52), 0, 696000, 0, 0);
Planeta mercury = new Planeta(color(166, 142, 88), 57909170, 2439, 0, 87.989);
Planeta venus = new Planeta(color(250, 193, 50), 108208926, 6052, 0, 224.701);

color stroke = color(70, 70, 70, 70);

int sx, sy;
int centerX, centerY;
static float m1 = 1000;
public static float magn = 1/m1;

void setup() {
  fullScreen();
  background(0);
  sx = width/2;
  sy = height/2;
  ellipseMode(RADIUS);
  stroke(stroke);
  strokeWeight(3);
  centerX = width/2;
  centerY = height/2;
}

void draw() {
  magn = 1/m1;
  background(0);
  translate(sx, sy);

  sun.drawOrbit();
  sun.drawPlanet();

  mercury.drawOrbit();    
  mercury.drawPlanet();

  venus.drawOrbit();
  venus.drawPlanet();


  if(mousePressed) {
    float wx = mouseX - pmouseX;
    float wy = mouseY - pmouseY;

    sx += wx;
    sy += wy; 
  }
}

void mouseWheel(MouseEvent event) {
  float e = float(event.getCount())*m1/3;
  if(m1+e > 0.2) {
    m1 += e;
  }
}

二等舱

class Planeta {
  color c;
  float distance;
  float radius;
  float angle;
  float orbit_time;

  Planeta(color kolor, float dystans, float promien, float kat, float czas) {
    this.c = kolor;
    this.distance = dystans/100;
    this.radius = promien/100;
    this.angle = kat;
    this.orbit_time = czas;
  }

  public PVector getPos() {
    float x = this.distance*sin(this.angle);
    float y = this.distance*cos(this.angle);
    return new PVector(x, y);
  }


  public void drawOrbit() {
    noFill();
    circle(0, 0, this.distance*magn);
  }

  public void drawPlanet() {
    fill(this.c);
    PVector pos = getPos();
    circle(pos.x*magn, pos.y*magn, this.radius*magn);
  }
}

sx 和 sy 用于平移，centerX 和 centerY 是常数，magn 和 m1 用于缩放。

所以移动行星就像一个魅力，但我不知道如何放大/缩小到我的鼠标所在的位置。我在谷歌上搜索过代码，没有任何效果。

我感谢每一个帮助。

Answer 1

我建议使用浮点变量进行翻译，以提高准确性:

float sx, sy;

您必须根据比例因子的变化来更改翻译。
计算比例因子的相对变化:

float fromM = m1;
float toM = m1 + e;
float scaleRel = fromM / toM;

计算从鼠标光标到当前翻译的距离:

float dx = mouseX - sx;
float dy = mouseY - sy;

根据鼠标光标到当前平移的距离( dx 、 dy )和相对比例的增量( 1 - scaleRel )更改平移:

sx += dx * (1.0-scaleRel);
sy += dy * (1.0-scaleRel);

例如:

void mouseWheel(MouseEvent event) {
    float e = float(event.getCount())*m1/3;
    if(m1+e > 0.2) {
        float fromM = m1;
        float toM = m1 + e;
        float scaleRel = fromM / toM;
        float dx = mouseX - sx;
        float dy = mouseY - sy;
        sx += dx * (1.0-scaleRel);
        sy += dy * (1.0-scaleRel);
        m1 = toM;
    }
}