【解决方法】
在iClient3D for Webgl中可以使用 fromAlpha(color, alpha, result) 方法指定透明度创建一个新的颜色值
使用方法参考下方代码
var red = new SuperMap3D.Color(1,0,0,1);
var alpha = 0.5;
var result = new SuperMap3D.Color();
SuperMap3D.Color.fromAlpha(red, alpha, result);
console.log("red",red,"result",result);
//withAlpha
var red = new SuperMap3D.Color(0.8, 0, 0, 1);
var newred = red.withAlpha(0.5)
