实现原理：series中包含两个普通的柱状图bar，其宽度各占一半且设置间距barGap为0，再添加一个象形柱状图pictorialBar，symbol设为菱形diamond，调整其位置大小层级等数据以达到覆盖在柱状图顶部的立体效果。

运行效果：

代码：

function getEcharts3DBar () {
    let yAxisData = ['标题1', '标题2', '标题3', '标题4', '标题5', '标题6'];
    let seriesData = [5, 36, 10, 20, 15, 25];
    var barWidth = 30, constData = [], showData = [];
    seriesData.forEach(item => {
      if (item) {
          constData.push(1);
          showData.push(item);
      } else {
          constData.push(0);
          showData.push(
           {
              value: 1,
              itemStyle: {
                normal: {
                  borderColor: "rgba(0,0,0,0)",
                  borderWidth: 2,
                  color: "rgba(0,0,0,0)",
                },
              },
           }
          );
      }
    });
    return {
        xAxis: {
            type: 'value',
            splitLine: {
              lineStyle: {
                color: '#3AA8E2'
              }
            }
        },
        yAxis: {
            type: 'category',
            data: yAxisData,
            axisLine: { show: false },
            axisTick: { show: false }
        },
        series: [
            {
	            name: '数据',
	            type: "bar",
	            barWidth: barWidth / 2,
	            barGap: "0%",
	            data: seriesData,
	            color: '#57F1FF',
	            label: {
	              show: true,
	              position: 'right',
	              offset: [barWidth / 3, barWidth / 3]
	            }
            },
            {
	            name: '数据',
	            type: "bar",
	            barWidth: barWidth / 2,
	            data: seriesData,
	            color: '#0090B4',
            },
            {
	            z: 3,
	            name: '数据',
	            type: "pictorialBar",
	            symbolPosition: "end",
	            data: showData,
	            symbol: "diamond",
	            symbolOffset: ["50%", "0%"],
	            symbolSize: [barWidth / 2, barWidth],
	            color: '#017592'
            },
        ],
    };
}
option = getEcharts3DBar();