38 lines
1.3 KiB
JavaScript
38 lines
1.3 KiB
JavaScript
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class SimplePendulum extends p5.Vector {
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constructor(x, y) {
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super(x, y);
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this.角度 = 0;
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this.角速度 = 0;
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this.摆长 = 100;
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this.重锤 = createVector(this.x, this.y + this.摆长);
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}
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update(damping = 0) {
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if (mouseIsPressed) {
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this.重锤 = createVector(mouseX, mouseY);
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this.摆长 = this.dist(this.重锤);
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this.角速度 = 0;
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const 向下矢量 = createVector(0, 1);
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this.角度 = p5.Vector.sub(this.重锤, this).angleBetween(向下矢量);
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} else {
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// 未考虑时间精确性及重力加速度
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this.角速度 -= sin(this.角度) / this.摆长; // -sin(Θ)g/L
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this.角速度 = lerp(this.角速度, 0, damping); // 模拟阻尼
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this.角度 += this.角速度;
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this.重锤.x = this.x + this.摆长 * sin(this.角度);
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this.重锤.y = this.y + this.摆长 * cos(this.角度);
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}
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}
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draw() {
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push();
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fill(128);
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stroke(255);
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strokeWeight(1);
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line(this.x, this.y, this.重锤.x, this.重锤.y);
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circle(this.重锤.x, this.重锤.y, 20);
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circle(this.x, this.y, 4);
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pop();
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}
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}
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