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抱歉，帖子很长，但我想尽可能详细

所以我正在创建一个带有几个自定义ig.Class实例的插件。一个是 Vector 实现：Vec2然后我有一个粒子类：

Particle = ig.Class.extend({
    pos: null,
    last: null,
    init: function (pos) {
        this.pos = new Vec2().mutableSet(pos.x, pos.y);
        this.last = this.pos;
    },
    draw: function (ctx) {
        ctx.beginPath();
        ctx.arc(this.pos.x, this.pos.y, 2, 0, 2 * Math.PI);
        ctx.fillStyle = "#2dad8f";
        ctx.fill();
    }
});

接下来我在另一个类中有这个轮胎功能：

tire: function (origin, radius, segments, spokeStiffness, treadStiffness) {
        var stride = (2 * Math.PI) / segments;

        var composite = new Composite();

        // particles
        for (var i = 0; i < segments; i++) {
            var theta = i * stride;
            composite.particles.push(new Particle(new Vec2(origin.x + Math.cos(theta) * radius, origin.y + Math.sin(theta) * radius)));
        }
        var center = new Particle(origin);
        composite.particles.push(center);
        // constraints
        for (i = 0; i < segments; i++) {
            composite.constraints.push(new DistanceConstraint(composite.particles[i], composite.particles[(i + 1) % segments], treadStiffness));
            composite.constraints.push(new DistanceConstraint(composite.particles[i], center, spokeStiffness))
            composite.constraints.push(new DistanceConstraint(composite.particles[i], composite.particles[(i + 5) % segments], treadStiffness));
        }

        this.composites.push(composite);
        return composite;
    }

最后是与轮胎函数在同一类中的更新函数：

update: function (step) {
        for (var c in this.composites) {
            for (var i in this.composites[c].particles) {
                var particles = this.composites[c].particles;
                // calculate velocity
                var velocity = particles[i].pos.sub(particles[i].last).scale(this.friction);

                // ground friction
                if (particles[i].pos.y >= this.height - 1 && velocity.length2() > 0.000001) {
                    var m = velocity.length();
                    velocity.x /= m;
                    velocity.y /= m;
                    velocity.mutableScale(m * this.groundFriction);
                }

                // save last good state
                particles[i].last.mutableSet(particles[i].pos);

                // gravity
                particles[i].pos.mutableAdd(this.gravity);

                // inertia  
                particles[i].pos.mutableAdd(velocity);
            }
        }
        // relax
        var stepCoef = 1 / step;
        for (var c in this.composites) {
            var constraints = this.composites[c].constraints;
            for (var i = 0; i < step; ++i) {
                for (var j in constraints) {
                    constraints[j].relax(stepCoef);
                }
            }
        }

        // bounds checking
        for (var c in this.composites) {
            var particles = this.composites[c].particles;
            for (var i in particles) {
                this.bounds(particles[i]);
            }
        }
    }

我得到的错误是在更新函数的这一行：var velocity = particles[i].pos.sub(particles[i].last).scale(this.friction);特别是错误是说它不能调用sub未定义的方法。我将上面的轮胎方法更改为如下所示，以便可以对其进行调试：

tire: function (origin, radius, segments, spokeStiffness, treadStiffness) {
        var stride = (2 * Math.PI) / segments;

        var composite = new Composite();

        // particles
        for (var i = 0; i < segments; i++) {
            var theta = i * stride;
            var x = origin.x + Math.cos(theta) * radius;
            var y = origin.y + Math.sin(theta) * radius;
            var pos = new Vec2(x, y);
            console.log(pos);
            var particle = new Particle(pos);
            composite.particles.push(particle);
        }
        var center = new Particle(origin);
        composite.particles.push(center);
        // constraints
        for (i = 0; i < segments; i++) {
            composite.constraints.push(new DistanceConstraint(composite.particles[i], composite.particles[(i + 1) % segments], treadStiffness));
            composite.constraints.push(new DistanceConstraint(composite.particles[i], center, spokeStiffness))
            composite.constraints.push(new DistanceConstraint(composite.particles[i], composite.particles[(i + 5) % segments], treadStiffness));
        }

        this.composites.push(composite);
        return composite;
    }

当我记录pos变量时，我得到正确的值输出到控制台，但是如果仍然得到错误。我唯一能想到的是，pos在方法中创建变量的位置tire与在Particle构造函数中传递和分配变量之间的某个位置，它会丢失其值并导致粒子具有pos.x / pos.yNaN 值，我可以在记录时看到varparticles高于错误行 ( var velocity = particles[i].pos.sub(particles[i].last).scale(this.friction);)。我真的不知道出了什么问题我尝试更改Particle构造函数的参数pos分配以通过多种方式分配它（通过Vec2.mutableSet()方法和直接设置。但无论我做什么，它仍然会导致粒子的 NaN 值。

谁能看到我不是的东西？谢谢

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1 回答 1

1

想通了，有一个正在加载的 javascript 文件覆盖了Particle该类。用 javascript 文件删除了脚本标签，一切都很好

于 2013-05-29T17:42:08.547 回答