# OpenGL Handrolled mipmaps

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Hi,

I have terrain that I want to display with a grid.  I thought multitexturing would be a good way to apply the grid (basically, have one texture that is a square outline), but I run into problems when zooming the camera out because of minification.  I want the grid lines to be a consistent width no matter the zoom.

I thought the solution would be to build my own mipmaps in a graphics editor so the texture contains each LOD.  I did something similar in OpenGL a while ago, but I'm not having any luck finding out how to do it in DX.  Can someone point me to where I can (if it's possible) implement this?

Also, if this is possible:  My base texture is 256x256 and when the camera is fully zoomed out the texture size would be 16x16.  Would I just stub out the remaining LODs or just leave them out entirely?

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I want the grid lines to be a consistent width no matter the zoom.

You could instead draw the terrain with line primitives, although then you'll have jaggies.

I thought the solution would be to build my own mipmaps in a graphics editor so the texture contains each LOD.  I did something similar in OpenGL a while ago, but I'm not having any luck finding out how to do it in DX.  Can someone point me to where I can (if it's possible) implement this?

If you're using photoshop, there is an nvidia plugin that allows you to specify the mipmaps and save as a .dds file.

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If you're using photoshop, there is an nvidia plugin that allows you to specify the mipmaps and save as a .dds file.

Note also that you can save .dds as RGBA without compression, which you'll probably want to do - dds is just a container format.

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