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Samurai Jack

Exact available Video Ram? Texture size?

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Greetings! I was wondering how could i achieve something like this: temp = save_video_mem_state loadtexture with mipmaps ram_required = temp - video_mem_state I saw something like GEtAvailableTexture mem but it is too unprecize. Any ideas how I could determine texture size with mipmaps?

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I saw something like GetAvailableTexture mem but it is too unprecize.

I know what you mean by "unprecise" but in truth, it is a correct value. Texture memory can also include AGP memory, whilst you might not *want* to use it, it is there to be used if necessary.

Any ideas how I could determine texture size with mipmaps?

It's not actually that complicated. Work out how many bits-per-pixel you're using (e.g. D3DFMT_A8R8G8B8 = 32bit/pixel) multiplied by the height/width of the texture, and recursively do this for each mip-map level you generate.

Technically you'd want to examine the pitch of the texture - but iirc for 2^n texture sizes this doesn't factor in. Also, the header required to describe the texture is negligeable.

As an example... a 128x64 texture in a 32bit mode:

128x64x4 = 32768
64x32x4 = 8192
32x16x4 = 2048
16x8x4 = 512
8x4x4 = 128
4x2x4 = 32
2x1x4 = 8

TOTAL = 43688 (~43kb)

Obviously, the above example is a full chain (setting '0' as the parameter in calls to D3DXCreateTextureFromFileEx..), you'd want to limit the above calculation...

//this code is untested/off the top of my head
//it should calculate memory usage for a complete mip-map chain,
//it shouldn't be too hard to modify it to calculate 'n' mip-map levels..
DWORD CalcTexMemUsage(int iWidth, int iHeight, int iBitsPerPixel)
DWORD dwThisLevel = (iWidth * iHeight * (iBitsPerPixel / 8));

if( ( iWidth == 1 ) || ( iHeight == 1 ) )
return dwThisLevel;
return dwThisLevel + CalcTexMemUsage(iWidth / 2, iHeight / 2, iBitsPerPixel);


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Thank you for the reply.
I'm aware how to compute pixels and bitdepth, I didn't post my request correct.

I was wondering if DirectX supports any method/functions with LPD3DXTEXTURE9 whith computes souch things automaticaly? How can i figure out how many lods are supported in my texture? How can I read out the bitdepth? If I try to access widtht & height it throws me an error!

Thank you for any suggestion.

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You can get the surface description for a given mip-map level quite easily:

I don't know of this LPD3DXTEXTURE9 you mention, so I'll assume you just meant IDirect3DTexture9 / LPDIRECT3DTEXTURE9

IDirect3DTexture9::GetLevelCount() will tell you how many levels have been generated.

You can then use this as the basis for a loop to cycle through each level:

IDirect3DTexture9::GetLevelDesc() takes in the loop index and a pointer to a D3DSURFACE_DESC. You can then use the Width, Height and Format fields of this struct to get the information you want.

I'm not aware of a built in function that'll decode a D3DFORMAT from it's constant down to the number of bits/bytes of space it occupies; but it's fairly easy to write one as a switch-case function to cover the formats you're expecting to encounter...

Put all the stuff in my two posts together and you could easily write a little function that takes in a loaded texture and computes how much memory it takes up and any other related mip-map information you want.


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