The Behind and Clear modes

In this exercise I'll demonstrate the behind and clear modes.…Both of which are part of the normal group, but they're not found inside the…Layers panel, instead they're associated with a handful of the Paint and Edit…tools as well as the Fill and Stroke commands.…I'm working inside a file called Big blue marble.pds, found inside the 03_normal folder.…Notice that the marble layer is selected here in the Layers panel and I've gone…ahead and assigned a white stroke, just so we can easily keep track of the…edges of this layer.…I have also set my foreground color to red in advance, I'm going to go ahead and…switch over to the Brush Tool, which I can get by pressing the B key, and armed…with my walk on tablet, I'm going to go ahead and paint a brush stroke over the…Earth like so, and so this is the effect of normal painting on a layer inside a…Photoshop, and notice that the program went ahead and automatically traced the…stroke around the new contours of the layer.…

Now let's say I want to paint exclusively inside the layer, I want to affect…