Newbie Projekt - running water light

I have a COB WS2814 RGB-NW strip with 91 segments of WLED. Everything works very well so far. I would now like a certain effect to switch on the light, which I cannot achieve despite hours of trying. I want the light to turn on from the center to the sides with the Running Water or Horse Race (I don’t know exactly what it’s called) and turn off backwards from the sides to the center. I have divided the strip into 2 segments 0-48 & 48-91.
I found this API code somewhere: {“mainseg”:1,“seg”:[{“id”:0,“grp”:1,“spc”:0,“of”:0,“on”:true,“frz”:false,“bri”:255,“cct”:127,“col”:[[255,255,255],[0,0,0],[0,0,0]],“fx”:98,“sx”:21,“ix”:100,“pal”:0,“sel”:true,“rev”:true,“mi”:false}]}
However, only half of this works and the white is not the NW of the stripe but a composite.
Does anyone have an idea or template that I could use?