If a SKSpriteNode has a texture with alpha that's not rectangular, and no outline/border, does the touch area of the SPSpriteNode reduce to the area of only opaque pixels and ignore the completely transparent pixels?
Or is the SKSpriteNode's rectangular size, regardless of texture transparency, the touch area?
Yes and no believe it or not, touch area is based on the frame property of your node, This is the minimal visible boxed area of your sprite. So if you have a Sprite that is 32x32, but inside you have a visible circle of diameter 16, then your touch area is a 16x16 square that surrounds the circle