  Many biological active agents respond to gradients of environmental cues by
redirecting their motion. Besides the well-studied prominent examples such as
photo- and chemotaxis, there has been considerable recent interest in
topotaxis, i.e.\ the ability to sense and follow topographic environmental
cues. We numerically investigate the topotaxis of active agents moving in
regular arrays of circular pillars. While a trivial topotaxis is achievable
through a spatial gradient of obstacle density, here we show that imposing a
gradient in the characteristics of agent-obstacle interaction can lead to an
effective topotaxis in an environment with a spatially uniform density of
obstacles. As a proof of concept, we demonstrate how a gradient in the angle of
sliding around pillars -- as e.g.\ observed in bacterial dynamics near surfaces
-- breaks the spatial symmetry and biases the direction of motion. We provide
an explanation for this phenomenon based on effective reflection at the
imaginary interface between pillars with different sliding angles. Our results
are of technological importance for design of efficient taxis devices.
