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javascript - 与 console.log 相比，dist() 返回不同的结果

问题描述

我正在制作一个程序来创建和移动一些点，然后每个点都连接到离它最近的 x 个点。我的问题是线是在错误的地方创建的，或者不是所有的都是奇怪的。这是我的代码：

var numPoints = 10;
var connections = 3;
var points = [];
var noiseT = [];

function setup() {
  createCanvas(displayWidth, displayHeight);
  // creating points and settings for the random movement
  for (var i = 0; i < numPoints; i++) {
    var tempNoiseX = random(-50, 50);
    var tempNoiseY = random(-50, 50);
    var tempNoiseXplus = random(-0.002, 0.002);
    var tempNoiseYplus = random(-0.002, 0.002);
    noiseT.push([tempNoiseX, tempNoiseY, tempNoiseXplus, tempNoiseYplus]);
    var tempX = width * noise(noiseT[i][0]);
    var tempY = height * noise(noiseT[i][1]);
    points.push([tempX, tempY]);
  }
  frameRate(60);
  stroke(0,0,255);
  background(0);
}

function draw() {
  background(0);

  // moving the points
  for (var i = 0; i < numPoints; i++) {
    points[i][0] = width * noise(noiseT[i][0]) * 1.2;
    points[i][1] = height * noise(noiseT[i][1]) * 1.2;
  }

  // calculate the distance between all the points
  for (var i = 0; i < points.length; i++) {
    var distance = {};
    for (var j = 0; j < numPoints; j++) {
      var startX = points[i][0];
      var startY = points[i][1];
      var endX = points[j][0];
      var endY = points[j][1];
      var tempDistance = dist(startX, startX, endX, endY);
      distance[tempDistance] = [endX, endY];
    }

    var tempKeys = Object.values(Object.keys(distance)).sort(function(a, b) {
      return a - b
    });
    // drawing lines
    for (var c = 0; c < connections; c++) {
      line(points[i][0], points[i][1], distance[tempKeys[c]][0], distance[tempKeys[c]][1]);
    }
  }

  // adding noise
  for (var i = 0; i < noiseT.length; i++) {
    noiseT[i][0] += noiseT[i][2];
    noiseT[i][1] += noiseT[i][3];
  }
  // cehcking the borders
  for (var i = 0; i < points.length; i++) {
    if (points[i][0] >= width) {
      points[i][0] = width;
    } else if (points[i][0] <= 0) {
      points[i][0] = 0;
    }
    if (points[i][1] >= height) {
      points[i][1] = height;
    } else if (points[i][1] <= 0) {
      points[i][1] = 0;
    }
  }
}
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我已经尝试在不同的点制作线条以及制作它们的方式，所有这些都会导致相同的问题。（顺便把代码缩小了很多）

标签： javascriptprocessingp5.js

解决方案

您的代码中有一个错字dist(startX, startX, endX, endY)，startX是两次，但startY丢失了。它一定要是：

var tempDistance = dist(startX, startY, endX, endY);

列表中的第一个点是点本身，因为它的距离为 0。所以最接近的 3 个点，除了点本身是索引为 1、2 和 3 的点：

for (var c = 1; c <= connections; c++) {
  line(points[i][0], points[i][1], distance[tempKeys[c]][0], distance[tempKeys[c]][1]);
}


var numPoints = 10;
var connections = 3;
var points = [];
var noiseT = [];

function setup() {
  createCanvas(innerWidth, innerHeight);
  // creating points and settings for the random movement
  for (var i = 0; i < numPoints; i++) {
    var tempNoiseX = random(-50, 50);
    var tempNoiseY = random(-50, 50);
    var tempNoiseXplus = random(-0.002, 0.002);
    var tempNoiseYplus = random(-0.002, 0.002);
    noiseT.push([tempNoiseX, tempNoiseY, tempNoiseXplus, tempNoiseYplus]);
    var tempX = width * noise(noiseT[i][0]);
    var tempY = height * noise(noiseT[i][1]);
    points.push([tempX, tempY]);
  }
  frameRate(60);
  stroke(0,0,255);
  background(0);
}

function draw() {
  background(0);

  // moving the points
  for (var i = 0; i < numPoints; i++) {
    points[i][0] = width * noise(noiseT[i][0]) * 1.2;
    points[i][1] = height * noise(noiseT[i][1]) * 1.2;
  }

  // calculate the distance between all the points
  for (var i = 0; i < points.length; i++) {
    var distance = {};
    for (var j = 0; j < numPoints; j++) {
      var startX = points[i][0];
      var startY = points[i][1];
      var endX = points[j][0];
      var endY = points[j][1];
      var tempDistance = dist(startX, startY, endX, endY);
      distance[tempDistance] = [endX, endY];
    }

    var tempKeys = Object.values(Object.keys(distance)).sort(function(a, b) {
      return a - b
    });
    // drawing lines
    for (var c = 1; c <= connections; c++) {
      line(points[i][0], points[i][1], distance[tempKeys[c]][0], distance[tempKeys[c]][1]);
    }
  }

  // adding noise
  for (var i = 0; i < noiseT.length; i++) {
    noiseT[i][0] += noiseT[i][2];
    noiseT[i][1] += noiseT[i][3];
  }
  // cehcking the borders
  for (var i = 0; i < points.length; i++) {
    if (points[i][0] >= width) {
      points[i][0] = width;
    } else if (points[i][0] <= 0) {
      points[i][0] = 0;
    }
    if (points[i][1] >= height) {
      points[i][1] = height;
    } else if (points[i][1] <= 0) {
      points[i][1] = 0;
    }
  }
}
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