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Mipmaps with D3DX??

Started by Void Jun 22, 2000 at 5:10 AM 9 replies 1.1k views

Original Post

Jun 22, 2000 at 5:10 AM

Hi, Does any know how to generate mipmaps using the D3DX library. I use the D3DXCreateTextureFromFile function. The docs says it will auto generate the mipmaps if the h/w supports it. I checked the Dx Caps Viewer and it seems to support it.. but the mipmap count from the function returns ZERO.. Do I have to explicitly create a chain of texture using D3DXCreateTexture first and then loading the bitmap data in?? Thanks.. ..

Gandalf

Jun 22, 2000 at 5:15 AM

Take a look at the MipMap example in DirectX SDK 7. Very good tutorial.

Gandalf the White

Void

Jun 22, 2000 at 8:42 PM

That''s the problem.. I did look at that sample..

I''m trying to avoid traversing the surface chain and bltting every (progressively smaller) bitmap to each mipmap surface..

I was thinking in terms of auto mipmap generation like OpenGL using the aux library ..Juz wondering how the d3dx library would help me there..

..

Verminaard

Jun 23, 2000 at 5:40 AM

sorry, the above post is from me.

Void

Jun 25, 2000 at 9:44 PM

Verminaard:

Do you check the "#_mipmap" parameter you passed in?? (That is the actual number of mipmaps generated from the D3DXCreateTextureFromFile function call)

The call sets that parameter to 0 on my machine. The hresult succeeds and the "flags" paramater DOES NOT return D3DX_TEXTURE_NOMIPMAP..( the mipmap creation is not supported flag)

That is the queer part..

..

Verminaard

Jun 26, 2000 at 2:08 AM

So you mean after the call num_mipmap contains the actual number created by 3d3x? I''m not sure what the return value is, but I can visibly see the mipmap working. Are you sure d3dx isn''t creating mipmaps (just from looking at the picture)?

Void

Jun 26, 2000 at 2:46 AM

quote:
Original post by Verminaard

I can visibly see the mipmap working. Are you sure d3dx isn''t creating mipmaps (just from looking at the picture)?

You can visibly see the mipmaps working?? How is that possible unless you use a different image for each smaller mipmap like the Dx7 sample..

As for the num_mipmap parameter, this is from the d3dx Create Texture doc

    
IDirectDrawSurface7 *m_ptex;
    m_pd3dDevice = m_pd3dx->GetD3DDevice();
 
    hr = D3DXCreateTextureFromFile(
            m_pd3dDevice,
            NULL,                   // dwFlags

            NULL,                   // auto-width

            NULL,                   // auto-height

            NULL,                   // auto-surface type

            NULL,                   // pointer to Palette

            &m_ptex,                // returned pointer to texture

            NULL,                   // returned number of mipmaps

            "texture.bmp",          // file name for texture

            D3DX_FT_DEFAULT);       // default scaling

From the comments there, I assume it would return the number of mipmaps generated.. or else why would it take a pointer..

Could you please check the return value and get back to me??..

..

Verminaard

Jun 27, 2000 at 3:55 AM

sorry, thats from me. this is like the post that never dies.

Void

Jun 27, 2000 at 4:57 AM

You are probably right.. I placed two textures side by side and it does seems to blur with the mipmapped one..

Guess I was over paranoid.. the width and height are references cause they will return the adjusted values so the documentation led me to believe it will return the actual mipmaps generated..

Wish the source for the d3dx lib is available so we don''t have to guess but sadly it is not a supported library..

Thanks there.. I was on the verge of discarding the d3dx lib and writing my own loader..

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