Development: Earthbound

Earthbound backgrounds are drawn using either one or two layers. In the following example, I’ll be talking about Starman’s background, which uses two layers.

BG3 layer is used as the base, with a tilemap consisting of a pattern of circles that changes colour every 60-frames. The wavy motion is done using a simple sine pattern raster effect, pretty standard stuff here so I won’t dive into it further. The more interesting scanline effect is potentially done by using HDMA to sample the tilemap image in two different spots, giving the illusion that there are two autonomous images, separated by each scanline.

BG4 layer is displayed overtop BG3, with a nifty static square-and-triangle tilemap. Unlike the previous layer, this one does not change it’s palette and only uses a simple raster effect, so again, pretty standard stuff.

The resulting effect of mixing these two layers is the beautiful and groovy backgrounds that have become a staple in the Mother series.