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Oliver_zx

Reading texture data

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Oliver_zx    518
Hello all,

I have troubles understanding how to read data from a locked texture. What im trying todo is to parse through an image of b/w texels to retrieve some informations. For testing that i created a 3x1 bmp file containing 2 black and 1 white (b,b,w) texel.(RGB, 8bit channels, 24bit depth)

So what i'm doing here is to create a texture out of that file and lock it. For my tests i directly access the pBits area of the locked rect. Yet they are not as expected.
As far as i know each texel will be represented by 4 bytes (b,g,r,a) on the locked memory area.

By that I would have expected a result like this:

First two black:
pbits[0] = 0
pbits[1] = 0
pbits[2] = 0
pbits[3] = 255
pbits[4] = 0
pbits[5] = 0
pbits[6] = 0
pbits[7] = 255

Last white:
pbits[8] = 255
pbits[9] = 255
pbits[10] = 255
pbits[11] = 255


Yet i receive something like this:
pbits[0] = 43
pbits[1] = 43
pbits[2] = 43
pbits[3] = 0
pbits[4] = 0
pbits[5] = 0
pbits[6] = 0
pbits[7] = 0
pbits[8] = 96
pbits[9] = 96
pbits[10] = 96
pbits[11] = 0


When i have only two pixel using black and white it does work however. Can someone help me finding out what i'm doing wrong here ? The pitch should not be important here as i only test the first 3 pixels, right ?!


Here a code snipped without all the checking stuff around:
[code]
IDirect3DTexture9* tex;
D3DXCreateTextureFromFile(g_device, "pixelTest.bmp", &tex);
D3DLOCKED_RECT lRect;
ZeroMemory(&lRect, sizeof(D3DLOCKED_RECT));

tex->LockRect(0, &lRect, NULL, NULL);
int iPitch = lRect.Pitch;
BYTE* pPBits = static_cast<BYTE*>(lRect.pBits);
[/code]


Any help would be highly appreciated - this thing costs me some hours already :unsure:


Thanks alot,
Oliver

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Oliver_zx    518
ok, it does work when using D3DXCreateTextureFromFileEx. Even with a very default'ish one...

[code]
D3DXCreateTextureFromFileEx(g_device, "pixelTest.bmp", NULL, NULL, NULL, NULL, D3DFMT_UNKNOWN, D3DPOOL_MANAGED, D3DX_FILTER_NONE, D3DX_DEFAULT, NULL, NULL, NULL, &tex);
[/code]

The default Filter parameter D3DX_FILTER_TRIANGLE | D3DX_FILTER_DITHER was the reason for the color adjustments during the load.


Thanks anyway!

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