如果你想围绕一个枢轴旋转一个矩形,那么你可以这样绘制矩形,矩形的中心位于位置 (0, 0):
let rect_w = (w-20);
rect(-rect_w/2, -rect_w/2, rect_w, rect_w);
Rotate (rotate()) 围绕 (0, 0) 的矩形,也是矩形的中心:
rotate(angle);
翻译 (translate()) 将矩形移动到最终位置:
let tx = x+10 + rect_w / 2;
let ty = y+10 + rect_w / 2;
translate(tx, ty);
必须保存矩阵堆栈(push())在此操作之前并恢复(pop()) 后。对当前模型矩阵的操作必须以相反的顺序执行:
e.g.
this.innerSquare = function () {
noFill();
stroke(150, 0, 255);
let ts = millis()/1000.0;
let angle = radians(ts*2.0*Math.PI*5.0); // or "frameCount"
let rect_w = (w-20);
let tx = x+10 + rect_w / 2;
let ty = y+10 + rect_w / 2;
push();
translate(tx, ty);
rotate(angle);
rect(-rect_w/2, -rect_w/2, rect_w, rect_w);
pop();
}
请参阅示例,其中我将建议的更改应用于您的原始代码:
var cols, rows;
var w = 50;
var grid = [];
function setup() {
createCanvas(400, 400);
// load the col / row vars with values that dynamically read from the canvas.
cols = floor(width/w);
rows = floor(height/w);
// load the the array with generic row and column values
for (var j = 0; j < rows; j++){
for (var i = 0; i < cols; i++){
// And for each, create an object instance based on the Shape class.
var shape = new Shape(i,j);
grid.push(shape);
}
}
}
function draw() {
background(51);
//frameRate(2);
// draw grid (outer squares)
for (var i = 0; i < grid.length; i++) {
grid[i].outerGrid();
}
// draw inner squares
for (var i = 0; i < grid.length; i++) {
grid[i].innerSquare();
}
}
function Shape(i, j) {
this.i = i;
this.j = j;
var x = this.i*w;
var y = this.j*w;
this.outerGrid = function () {
push();
stroke(200, 0, 255);
noFill();
rect(x, y, w, w);
translate(x, y);
pop();
}
this.innerSquare = function () {
noFill();
stroke(150, 0, 255);
let ts = millis()/1000.0;
let angle = radians(ts*2.0*Math.PI*5.0);
let rect_w = (w-20);
let tx = x+10 + rect_w / 2;
let ty = y+10 + rect_w / 2;
push();
translate(tx, ty);
rotate(angle);
rect(-rect_w/2, -rect_w/2, rect_w, rect_w);
pop();
}
}
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