No, there isn't. The software renderer is actually pretty accurate but it has to rely on linear interpolation between subspans where the hardware can work per pixel. That makes the hardware more accurate...in most cases. But if the software renderer shows these artifacts, it's most likely that some gpu out there will have similar problems too.. Either move the lines away from the terrain until it works fine or, and maybe better, separate the terrain and the lines into two world instances and render with clearing the depth buffer in between.