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javascript - 空白屏幕 - Matter.js

转载 作者：行者123 更新时间：2023-12-04 10:34:45 24 4
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问题.js -

这是 one of the demo来自matter.js。它返回一个空白屏幕。我尝试了几种方法，并在这方面花费了数小时和数小时，但仍然无法弄清楚这里出了什么问题。

我检查了括号、语法和错别字，但它仍然返回一个空白屏幕。

我已经检查过 matter.js 在后台正确加载。

有人可以指出这里的错误吗？

<script>
window.addEventListener('load', function() {

//Fetch our canvas
var canvas = document.getElementById('world22');

    var Engine = Matter.Engine,
        Render = Matter.Render,
        Runner = Matter.Runner,
        Composites = Matter.Composites,
        Events = Matter.Events,
        Constraint = Matter.Constraint,
        MouseConstraint = Matter.MouseConstraint,
        Mouse = Matter.Mouse,
        World = Matter.World,
        Bodies = Matter.Bodies;

    // create engine
    var engine = Engine.create(),
        world = engine.world;

    // create renderer
    var render = Render.create({
        // element: document.body,
        canvas: canvas,
        engine: engine,
        options: {
            width: 800,
            height: 600,
            showAngleIndicator: true,
        }
    });

    Render.run(render);

    // create runner
    var runner = Runner.create();
    Runner.run(runner, engine);

    // add bodies
    var ground = Bodies.rectangle(395, 600, 815, 50, { isStatic: true }),
        rockOptions = { density: 0.004 },
        rock = Bodies.polygon(170, 450, 8, 20, rockOptions),
        anchor = { x: 170, y: 450 },
        elastic = Constraint.create({ 
            pointA: anchor, 
            bodyB: rock, 
            stiffness: 0.05
        });

    var pyramid = Composites.pyramid(500, 300, 9, 10, 0, 0, function(x, y) {
        return Bodies.rectangle(x, y, 25, 40);
    });

    var ground2 = Bodies.rectangle(610, 250, 200, 20, { isStatic: true });

    var pyramid2 = Composites.pyramid(550, 0, 5, 10, 0, 0, function(x, y) {
        return Bodies.rectangle(x, y, 25, 40);
    });

    World.add(engine.world, [ground, pyramid, ground2, pyramid2, rock, elastic]);

    Events.on(engine, 'afterUpdate', function() {
        if (mouseConstraint.mouse.button === -1 && (rock.position.x > 190 
 rock.position.y < 430)) {
            rock = Bodies.polygon(170, 450, 7, 20, rockOptions);
            World.add(engine.world, rock);
            elastic.bodyB = rock;
        }
    });

    // add mouse control
    var mouse = Mouse.create(render.canvas),
        mouseConstraint = MouseConstraint.create(engine, {
            mouse: mouse,
            constraint: {
                stiffness: 0.2,
                render: {
                    visible: false
                }
            }
        });

    World.add(world, mouseConstraint);

    // keep the mouse in sync with rendering
    render.mouse = mouse;

    // fit the render viewport to the scene
    Render.lookAt(render, {
        min: { x: 0, y: 0 },
        max: { x: 800, y: 600 }
    });


        });
  </script>

<canvas id="world22"></canvas>

最佳答案

修复:

(1) 更改您的 world22元素来自 canvas到 div ，或任何其他合适的元素。显然，matter.js 会在容器中创建它自己的 Canvas ，因此不能对 Canvas 内的 Canvas 做任何事情。

(2) 缺少||在您的情况下，此处导致语法错误，介于 rock.position.x > 190 rock.position.y < 430 之间.不知道在粘贴到 SO 时这是否成为一个错字。

(3) 使用属性element在创建渲染时指定容器元素时。不要使用 canvas: canvas .使用 element: canvas .关于这里Render.create({ ... });
这是修改后的源代码。我想你可以放心地忽略我是如何包含 matt.js 脚本的。我不知道版本是否重要，并假设您拥有最新版本。

<!doctype html>
<html>
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/matter-js/0.14.2/matter.js"></script>
<script>
window.addEventListener('load', function() {

	//Fetch our canvas
	var canvas = document.getElementById('world22');

    var Engine = Matter.Engine,
        Render = Matter.Render,
        Runner = Matter.Runner,
        Composites = Matter.Composites,
        Events = Matter.Events,
        Constraint = Matter.Constraint,
        MouseConstraint = Matter.MouseConstraint,
        Mouse = Matter.Mouse,
        World = Matter.World,
        Bodies = Matter.Bodies;

    // create engine
    var engine = Engine.create(),
        world = engine.world;

    // create renderer
    var render = Render.create({
        element: canvas,
        engine: engine,
        options: {
            width: 800,
            height: 600,
            showAngleIndicator: true,
        }
    });

    Render.run(render);

    // create runner
    var runner = Runner.create();
    Runner.run(runner, engine);

    // add bodies
    var ground = Bodies.rectangle(395, 600, 815, 50, { isStatic: true }),
        rockOptions = { density: 0.004 },
        rock = Bodies.polygon(170, 450, 8, 20, rockOptions),
        anchor = { x: 170, y: 450 },
        elastic = Constraint.create({ 
            pointA: anchor, 
            bodyB: rock, 
            stiffness: 0.05
        });

    var pyramid = Composites.pyramid(500, 300, 9, 10, 0, 0, function(x, y) {
        return Bodies.rectangle(x, y, 25, 40);
    });

    var ground2 = Bodies.rectangle(610, 250, 200, 20, { isStatic: true });

    var pyramid2 = Composites.pyramid(550, 0, 5, 10, 0, 0, function(x, y) {
        return Bodies.rectangle(x, y, 25, 40);
    });

    World.add(engine.world, [ground, pyramid, ground2, pyramid2, rock, elastic]);

    Events.on(engine, 'afterUpdate', function() {
        if (mouseConstraint.mouse.button === -1 && (rock.position.x > 190 || 
 rock.position.y < 430)) {
            rock = Bodies.polygon(170, 450, 7, 20, rockOptions);
            World.add(engine.world, rock);
            elastic.bodyB = rock;
        }
    });

    // add mouse control
    var mouse = Mouse.create(render.canvas),
        mouseConstraint = MouseConstraint.create(engine, {
            mouse: mouse,
            constraint: {
                stiffness: 0.2,
                render: {
                    visible: false
                }
            }
        });

    World.add(world, mouseConstraint);

    // keep the mouse in sync with rendering
    render.mouse = mouse;

    // fit the render viewport to the scene
    Render.lookAt(render, {
        min: { x: 0, y: 0 },
        max: { x: 800, y: 600 }
    });


});
</script>


</head>
<body>
<div id="world22"></div>
</body>
<html>


我通过引用此处提供的最小示例进行调试 https://github.com/liabru/matter-js/wiki/Getting-started ....

起初我没有 catch canvas问题，但后来我使用浏览器开发工具并检查了 world22 元素。另一个 Canvas 是嵌套的，所以我就是这样知道的。

关于javascript - 空白屏幕 - Matter.js，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/60236612/

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