Edit: there is a version more suitable for Gimp 2.10 further down this thread.
A slightly more realistic effect than a plain "bump map" (even if there is still some bump-mapping). The idea is to combine bump-mapping for a nice 3D effect on the edges with a drop-shadow to give it more "depth" than is achievable with bump-mapping alone.
This requires manipulation in the Layers list, so keep it open (Ctr-L):
- Create the text in black with the text tool, and maybe adjust the canvas size around it
- Duplicate the text layer (icon at bottom of Layers list)
- Add a new layer filled with white (name it "BumpMap")
- In the Layers list, drag it under the top copy of the text layer
- Select the top copy of the text layer and Layer>Merge down. You will obtain a layer with your text on white.
- Filter>Blur>Gaussian blur and apply a blur of about 1/4 of the character thickness
- Create the "surface" by adding a new layer (call it "Bottom") and filling it with the required color (you can also use a slight radial gradient)
- Duplicate that layer and rename the copy to "Top" (double-click the name to edit it, [enter] when done)
- With "Top" selected: Filters>Map>BumpMap. In the "Map" selector,select the "BumpMap" layer, keep all defaults, and [OK]. Your top ayer should now have the text engraved in it.
- Right-click the initial text layer, and select Alpha to selection (you should have the "marching ants" running along the text outline)
- Make sure the Top layer is selected and hit [Delete] (or Edit>Clear). This will remove a good deal of the shadows.
- Select>None
- Filters>Light and shadows>Drop shadow:
- Offsets: use about a third of the character thickness,
- Blur radius: use roughly a half of the character thickness
- Opacity 60% is OK.
- Offsets: use about a third of the character thickness,
- This creates a a new "Drop shadow" layer between top and bottom, and you can adjust the opacity with the "Opacity" slider at the top of the layers list and the offsets by moving it with the Move tool (set to "Move the active layer")
You can also apply this technique with a texture, in which case the process isn't very different:
- Open your texture image
- Add the text layer
- Position/crop both layers
- Create the bumpmap layer as above
- Duplicate the texture layer
- Apply bumpmap to top layer
- Punch out the text on the top layer
- Apply drop shadow to top layer
- Possibly shift the bottom layer a bit so that the pattern on it is slightly offset