If you can isolate the area as a selection then try filling with a gradient.
Draw a basic foreground to background gradient in the selection, set the Shape to Shaped (angular)
Click on the gradient line to make a stop and drag to near one end. Each half aso has a center point drag these to one end as well.
Draw a basic foreground to background gradient in the selection, set the Shape to Shaped (angular)
Click on the gradient line to make a stop and drag to near one end. Each half aso has a center point drag these to one end as well.