Where the heightmap is shifted to, can be adjusted with the Direction vector. The brighter parts of the shading is located at the direction pointer.

The shape of the shading is dependent on the employed Heightmap. While the effect in Image 1 was produced with the solid Mask Modes rectangle and ellipse, the birdshots in Image 3 resulted from some gradient ellipses. The Source Texture ("Use Texture/Source" mode) was utilitized for Image 2.

Adjust the contrast of the shading with the Amplify value.