Hi, i''ve got bump-mapping working nicely on my terrain engine, but it''s having a serious impact on performance (about half the fps with it on compared to off). I figure that a good way to improve performance is to fade it out over distance - much past a few meters and it''s indistinguishable from filtering glitches anyhow. I can obviously do this quite simply by just checking the distance from the camera to the vertex chunk and if it''s greater than x then disable the bump map for that chunk. The problem with this is that it tends to visibly ''pop'' into existance unless I make x quite large (which kind of negates the benefit). Ideally I''d like to visually handle it the same way as mip-mapping (a smooth fade-in), and although I can achieve this visually by manually editing the mip-map for the bump-map and setting the lower-detail maps to have no distinguishable bump, it doesn''t really solve the performance drain. I can combine the two methods - use a mip-map chain with no-bump at a certain level, and then draw with no bump beyond that point, but this seems like a clumsy and overwrought method. Any other ideas?

No, id Argue that having LOD (Level of Detail) is a great thing... i wouldnt call it clumsy at all... so go with the mip map (says I)
-Dan