从Javascript代码中删除鼠标控件

Question

我有一大段代码，可以绘制由鼠标控制的羽毛似的设计。这是使用鼠标按下和mouseX，mouseY。

我希望代码在不涉及鼠标的情况下运行并绘制羽毛（即打开画布并让羽毛自动在屏幕上绘制）。

完整代码如下：

var points = [];
var painting = false;
var strokeNumber = 0;

var scl = 6;
var cols, rows;
var inc = 0.1;
var zOff = 0;
var particles = [];
var flowField = [];
var saturation = [];

function setup() {
  createCanvas(windowWidth, windowHeight);
  // createCanvas(400, 400);

  pixelDensity(5);
  background(0);

  cols = floor(width / scl);
  rows = floor(height / scl);

  flowField = Array(cols * rows);
  saturation = Array(width * height).fill(0);
  greateForceField();

}

function mousePressed() {
  painting = true;
  strokeNumber++;
}

function mouseReleased() {
  painting = false;
}

function updateForceField(){
  var v = createVector(mouseX, mouseY);
  var vPrev = createVector(pmouseX, pmouseY);
  v.sub(vPrev);
  v.setMag(1);
  var i = floor(mouseX / scl);
  var j = floor(mouseY / scl);
  var index =  i * rows + j;
  flowField[index] = v;
}

function showForceField(){
  for(var i = 0; i < cols; i++){
    for(var j = 0; j < rows; j++){
      var index = i * rows + j;
      var v = flowField[index];
      stroke(0,50);
      strokeWeight(1);
      push();      
      translate(i * scl, j * scl);
      rotate(v.heading());
      line(0,0,scl,0);
      pop();
    }    
  }
}

function greateForceField(){
  var xOff = 0;
  for(var i = 0; i < cols; i++){
    var yOff = 0;
    for(var j = 0; j < rows; j++){
      yOff += inc; 
      var angle = noise(xOff, yOff, zOff) * TWO_PI;
      var v = p5.Vector.fromAngle(angle);
      v.setMag(.1);
      var index = i * rows + j;
      flowField[index] = v;
    }
    xOff += inc;
  }
  // zOff += inc * 0.1;
}

function draw() {
  // background(255);
  // showForceField();

  if(painting){
    updateForceField();

    var idx = mouseY * width + mouseX;
    if(saturation[idx] < 10){
      var r = 1+sqrt(sq(mouseX-pmouseX)+sq(mouseY-pmouseY));
      for(var a = 0; a < 100; a++){
        var particle = new Particle(mouseX+random()*r*cos(random(TWO_PI)), mouseY+random()*r*sin(random(TWO_PI)));
        particles.push(particle);
      }
      saturation[idx] ++;
    }
  }

  particles.filter(particle => particle.spread > 0).map(particle => {
    particle.update();
    particle.show();
    // particle.edges();
    particle.follow();
  })

  particles.map((particle, idx) => {
    if(particle.spread <= 0){
      particles.splice(idx,1);
    }
  });

}

function Particle(x,y){  
  this.pos = createVector(x,y);
  // this.color = color(245, 225, 50);
  // this.color = color(145, 225, 192);
  this.color = color(255);
  this.spread = 127;
  this.spreadInc = this.spread/100;

  this.prevPos = this.pos.copy();
  this.vel = p5.Vector.random2D();
  this.acc = createVector(0,0);
  this.maxSpeed = 2;

  this.update = function(){
    this.spread -= this.spreadInc;
    this.vel.add(this.acc);
    this.vel.limit(this.maxSpeed);
    this.pos.add(this.vel);
    this.acc.mult(0);
  }

  this.applyForce = function(force){
    this.acc.add(force);
  }

  this.follow = function(){
    var i = floor(this.pos.x / scl);
    var j = floor(this.pos.y / scl);
    var index =  i * rows + j;
    var force = flowField[index];
    this.applyForce(force);    
  }

  this.show = function(){
    stroke(red(this.color),green(this.color),blue(this.color),this.spread);
    strokeWeight(.3*this.spread/127);
    // point(this.pos.x, this.pos.y);
    line(this.pos.x, this.pos.y, this.prevPos.x, this.prevPos.y);
    this.updatePrev();
  }

  this.updatePrev = function(){
    this.prevPos = this.pos.copy();
  }

  this.edges = function(){
    if(this.pos.x > width) {
      this.pos.x = 0;
      this.updatePrev();
    }
    if(this.pos.x < 0){
      this.pos.x = width;
      this.updatePrev();
    }
    if(this.pos.y > height){
      this.pos.y = 0;
      this.updatePrev();
    }
    if(this.pos.y < 0) {
      this.pos.y = height;
      this.updatePrev();
    }

  }
}

Answer 1

使用4个变量current_x，current_y，prev_x和prev_y代替mosueX，mouseY，pmouseX和pmouseY。

var current_x=0, current_y=0, prev_x=0, prev_y=0;

function updateForceField(){
    var v = createVector(current_x, current_y);
    var vPrev = createVector(prev_x, prev_y);
    v.sub(vPrev);
    v.setMag(1);
    var i = floor(current_x / scl);
    var j = floor(current_y / scl);
    var index =  i * rows + j;
    flowField[index] = v;
}

代替状态painting，请使用时间间隔。可以从内置变量deltaTime中获取2帧之间的时间（以毫秒为单位）。通过随机值设置x和y位置。例如：

var interval = 200; // 200 milliseconds
var sum_time = 0;

function draw() {

    sum_time += deltaTime;
    if(sum_time > interval){
        sum_time = 0;

        current_x = Math.floor(random(width));
        current_y = Math.floor(random(height));
        updateForceField();
        prev_x = current_x;
        prev_y = current_y; 

        var idx = current_y * width + current_x;
        if(saturation[idx] < 10){
            var r = 1+sqrt(sq(current_x-prev_x)+sq(current_y-prev_y));
            for(var a = 0; a < 100; a++){
                var particle = new Particle(current_x+random()*r*cos(random(TWO_PI)), current_y+random()*r*sin(random(TWO_PI)));
                particles.push(particle);
            }
            saturation[idx] ++;
        }
    }

    // [...]
}

请参见示例：

var points = [];
var painting = false;
var strokeNumber = 0;

var scl = 6;
var cols, rows;
var inc = 0.1;
var zOff = 0;
var particles = [];
var flowField = [];
var saturation = [];

function setup() {
  //createCanvas(windowWidth, windowHeight);
  createCanvas(500, 200);

  pixelDensity(5);
  background(0);

  cols = floor(width / scl);
  rows = floor(height / scl);

  flowField = Array(cols * rows);
  saturation = Array(width * height).fill(0);
  greateForceField();

}

function mousePressed() {
  painting = true;
  strokeNumber++;
}

function mouseReleased() {
  painting = false;
}

var current_x=0, current_y=0, prev_x=0, prev_y=0;

function updateForceField(){
    var v = createVector(current_x, current_y);
    var vPrev = createVector(prev_x, prev_y);
    v.sub(vPrev);
    v.setMag(1);
    var i = floor(current_x / scl);
    var j = floor(current_y / scl);
    var index =  i * rows + j;
    flowField[index] = v;
}

function showForceField(){
  for(var i = 0; i < cols; i++){
    for(var j = 0; j < rows; j++){
      var index = i * rows + j;
      var v = flowField[index];
      stroke(0,50);
      strokeWeight(1);
      push();      
      translate(i * scl, j * scl);
      rotate(v.heading());
      line(0,0,scl,0);
      pop();
    }    
  }
}

function greateForceField(){
  var xOff = 0;
  for(var i = 0; i < cols; i++){
    var yOff = 0;
    for(var j = 0; j < rows; j++){
      yOff += inc; 
      var angle = noise(xOff, yOff, zOff) * TWO_PI;
      var v = p5.Vector.fromAngle(angle);
      v.setMag(.1);
      var index = i * rows + j;
      flowField[index] = v;
    }
    xOff += inc;
  }
  // zOff += inc * 0.1;
}

var interval = 200; // 200 milliseconds
var sum_time = 0;

function draw() {
    // background(255);
    // showForceField();

    sum_time += deltaTime;
    if(sum_time > interval){
        sum_time = 0;

        current_x = Math.floor(random(width));
        current_y = Math.floor(random(height));
        updateForceField();
        prev_x = current_x;
        prev_y = current_y; 

        var idx = current_y * width + current_x;
        if(saturation[idx] < 10){
            var r = 1+sqrt(sq(current_x-prev_x)+sq(current_y-prev_y));
            for(var a = 0; a < 100; a++){
                var particle = new Particle(current_x+random()*r*cos(random(TWO_PI)), current_y+random()*r*sin(random(TWO_PI)));
                particles.push(particle);
            }
            saturation[idx] ++;
        }
    }

    particles.filter(particle => particle.spread > 0).map(particle => {
        particle.update();
        particle.show();
        // particle.edges();
        particle.follow();
    })

    particles.map((particle, idx) => {
        if(particle.spread <= 0){
            particles.splice(idx,1);
        }
    });
}

function Particle(x,y){  
  this.pos = createVector(x,y);
  // this.color = color(245, 225, 50);
  // this.color = color(145, 225, 192);
  this.color = color(255);
  this.spread = 127;
  this.spreadInc = this.spread/100;

  this.prevPos = this.pos.copy();
  this.vel = p5.Vector.random2D();
  this.acc = createVector(0,0);
  this.maxSpeed = 2;

  this.update = function(){
    this.spread -= this.spreadInc;
    this.vel.add(this.acc);
    this.vel.limit(this.maxSpeed);
    this.pos.add(this.vel);
    this.acc.mult(0);
  }

  this.applyForce = function(force){
    this.acc.add(force);
  }

  this.follow = function(){
    var i = floor(this.pos.x / scl);
    var j = floor(this.pos.y / scl);
    var index =  i * rows + j;
    var force = flowField[index];
    this.applyForce(force);    
  }

  this.show = function(){
    stroke(red(this.color),green(this.color),blue(this.color),this.spread);
    strokeWeight(.3*this.spread/127);
    // point(this.pos.x, this.pos.y);
    line(this.pos.x, this.pos.y, this.prevPos.x, this.prevPos.y);
    this.updatePrev();
  }

  this.updatePrev = function(){
    this.prevPos = this.pos.copy();
  }

  this.edges = function(){
    if(this.pos.x > width) {
      this.pos.x = 0;
      this.updatePrev();
    }
    if(this.pos.x < 0){
      this.pos.x = width;
      this.updatePrev();
    }
    if(this.pos.y > height){
      this.pos.y = 0;
      this.updatePrev();
    }
    if(this.pos.y < 0) {
      this.pos.y = height;
      this.updatePrev();
    }

  }
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/p5.js/0.9.0/p5.js"></script>