Question

我正在尝试通过使用3d点（Vector 3D http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/geom/Vector3D.html）填充查找表来优化3D演示，稍后我将访问该表。

这些3D点将在3D空间中定义随机且可循环的路径。

有谁知道实现这一目标的方法？

我正在考虑修改Greensock Bezier补间以在3d空间中创建一个bezier，然后以某种方式获取生成的补间的xyz值。

Answer 1

好的，你需要做两件事：

从多个片段
创建一个自定义补间函数，将您的对象作为目标，将bezier循环作为路径和总循环时间。

立方贝塞尔曲线的一个片段总是需要4个顶点，一个完整的循环必须包含至少2个段，因此您需要随机创建至少7个顶点。顶点的数量始终为3 * NumberOfSegments + 1，但我们将仅存储3 * NumberOfSegments，因为第一个顶点将等于最后一个顶点

最简单的情况（2个段，6个顶点）：

...
private function generateRandomPoints():Vector<Vector3D>
{
    var resultingVector:Vector<Vector3D> = new Vector<Vector3D>();
    for(var i:int = 0; i < 6; i++)
    {
        var x:Number = Math.random() * 10;
        var y:Number = Math.random() * 10;
        var z:Number = Math.random() * 10;
        var currentPoint3D:Vector3D = new Vector3D(x, y, z);
        resultingVector.push(currentPoint3D);
    }
    return resultingVector;
}
...

现在，当我们有了路径时，我们可以解析它以获得这种补间效果。您可以在每次需要新坐标时调用此函数（但您需要将初始时间存储在某处），或者创建一个可以为您处理所有内容的tweener对象。我将展示最基本的例子 - 自主功能：

public static function getNextCoordinates(loopStartTime:int, totalLoopTime:int, path:Vector.<Vector3D>):Vector3D
    {
        var resultingPoint:Vector3D = new Vector3D();
        var passedTime:int = getTimer() - loopStartTime;

        //Total passed ratio
        var passedRatio:Number = passedTime / totalLoopTime;
        var totalSegments:int = path.length / 3;

        var totalTimePerSegment:Number = totalLoopTime / totalSegments;

        //So it can loop forever
        while (passedRatio > 1)
        {
            passedRatio -= 1;
        }
        //Let's find our current bezier curve segment number
        var currentSegment:int = Math.floor( passedRatio * totalSegments);
        var currentSegmentRatio:Number = (passedTime - currentSegment * totalTimePerSegment) / totalTimePerSegment;
        //It can be optimized here
        while (currentSegmentRatio > 1)
        {
            currentSegmentRatio -= 1;
        }

        var startingIndex:int = currentSegment * 3;
        //our four path vertices
        var point0:Vector3D = path[startingIndex];
        var point1:Vector3D = path[startingIndex + 1];
        var point2:Vector3D = path[startingIndex + 2];

        //if it's a last segment, we need to "connect" to the first vertex
        if (startingIndex + 3 >= path.length)
        {
            var point3:Vector3D = path[0];
        }
        else
        {
            point3 = path[startingIndex + 3];
        }
        //At last, we find our coordinates
        var tempRatio:Number = 1 - currentSegmentRatio;
        resultingPoint.x = tempRatio * tempRatio * tempRatio * point0.x + 3 * tempRatio * tempRatio * currentSegmentRatio * point1.x + 3 * tempRatio * currentSegmentRatio * currentSegmentRatio * point2.x + currentSegmentRatio * currentSegmentRatio * currentSegmentRatio * point3.x;
        resultingPoint.y = tempRatio * tempRatio * tempRatio * point0.y + 3 * tempRatio * tempRatio * currentSegmentRatio * point1.y + 3 * tempRatio * currentSegmentRatio * currentSegmentRatio * point2.y + currentSegmentRatio * currentSegmentRatio * currentSegmentRatio * point3.y;
        resultingPoint.z = tempRatio * tempRatio * tempRatio * point0.z + 3 * tempRatio * tempRatio * currentSegmentRatio * point1.z + 3 * tempRatio * currentSegmentRatio * currentSegmentRatio * point2.z + currentSegmentRatio * currentSegmentRatio * currentSegmentRatio * point3.z;

        return resultingPoint;
    }

您可以将此函数扩展为补间对象的一部分。我已经在2D空间中对它进行了测试，它完美地沿着随机多段贝塞尔曲线循环精灵的运动

干杯！

AS3-在3D空间中创建可循环的随机路径

1 个答案: