Qt Quick Particles 示例 - 发射器

这是在 QML 粒子系统中使用 Emitters 的示例集。

这是有关在粒子系统中使用发射器的 QML 小范例集。每个示例都是一个强调特定类型或特征的小 QML 文件。

运动速度（Velocity from motion）主要通过移动发射器来产生强烈的粒子运动效果：

Emitter {
    id: trailsNormal
    system: sys1

    emitRate: 500
    lifeSpan: 2000

    y: mouseArea.pressed ? mouseArea.mouseY : circle.cy
    x: mouseArea.pressed ? mouseArea.mouseX : circle.cx

    velocity: PointDirection {xVariation: 4; yVariation: 4;}
    acceleration: PointDirection {xVariation: 10; yVariation: 10;}
    velocityFromMovement: 8

    size: 8
    sizeVariation: 4
}

爆裂和脉冲在两个相同的发射器上调用爆裂和脉冲方法。

    if (root.lastWasPulse) {
        burstEmitter.burst(500);
        root.lastWasPulse = false;
    } else {
        pulseEmitter.pulse(500);
        root.lastWasPulse = true;
    }

请注意，burst 的参数是要发射的粒子数量，而 pulse 的参数是要发射的毫秒数。这两种方法的行为略有不同，在本例中很容易看到。

自定义发射器连接到 emitParticles 信号，以便在发射粒子时对粒子数据设置任意值；

onEmitParticles: (particles) => {
    for (var i=0; i<particles.length; i++) {
        let particle = particles[i];
        particle.startSize = Math.max(02,Math.min(492,Math.tan(particle.t/2)*24));
        let theta = Math.floor(Math.random() * 6.0);
        particle.red = theta == 0 || theta == 1 || theta == 2 ? 0.2 : 1;
        particle.green = theta == 2 || theta == 3 || theta == 4 ? 0.2 : 1;
        particle.blue = theta == 4 || theta == 5 || theta == 0 ? 0.2 : 1;
        theta /= 6.0;
        theta *= 2.0*Math.PI;
        theta += sys.convert(sys.petalRotation);//Convert from degrees to radians
        particle.initialVX = sys.petalLength * Math.cos(theta);
        particle.initialVY = sys.petalLength * Math.sin(theta);
        particle.initialAX = particle.initialVX * -0.5;
        particle.initialAY = particle.initialVY * -0.5;
    }
}

这用于发射六个旋转辐条中的曲线粒子。

Emit mask 在发射器上设置图像掩码，以发射出任意形状的粒子。

shape: MaskShape {
    source: "images/starfish_mask.png"
}

最大发射量每次发射的粒子数量不超过一定数量。通过这个例子可以很容易地看到达到上限时会发生什么。

形状和方向 "会从一个未填充的椭圆形中发射粒子，使用一个TargetDirection

shape: EllipseShape {fill: false}
velocity: TargetDirection {
    targetX: root.width/2
    targetY: root.height/2
    proportionalMagnitude: true
    magnitude: 0.5
}

这将使粒子以相应的速度向椭圆中心移动，并在向中心移动的过程中保持椭圆的轮廓。

TrailEmitter 使用该类型添加烟雾粒子，以跟踪场景中的火粒子。

onEmitParticles: (particles) => {
    for (var i=0; i<particles.length; i++) {
        let particle = particles[i];
        particle.startSize = Math.max(02,Math.min(492,Math.tan(particle.t/2)*24));
        let theta = Math.floor(Math.random() * 6.0);
        particle.red = theta == 0 || theta == 1 || theta == 2 ? 0.2 : 1;
        particle.green = theta == 2 || theta == 3 || theta == 4 ? 0.2 : 1;
        particle.blue = theta == 4 || theta == 5 || theta == 0 ? 0.2 : 1;
        theta /= 6.0;
        theta *= 2.0*Math.PI;
        theta += sys.convert(sys.petalRotation);//Convert from degrees to radians
        particle.initialVX = sys.petalLength * Math.cos(theta);
        particle.initialVY = sys.petalLength * Math.sin(theta);
        particle.initialAX = particle.initialVX * -0.5;
        particle.initialAY = particle.initialVY * -0.5;
    }
}

示例项目 @ code.qt.io

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