Jump to content
  • Advertisement
Sign in to follow this  
Oliver_zx

Reading texture data

This topic is 2562 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

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:

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);



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


Thanks alot,
Oliver

Share this post


Link to post
Share on other sites
Advertisement
ok, it does work when using D3DXCreateTextureFromFileEx. Even with a very default'ish one...


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


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


Thanks anyway!

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

We are the game development community.

Whether you are an indie, hobbyist, AAA developer, or just trying to learn, GameDev.net is the place for you to learn, share, and connect with the games industry. Learn more About Us or sign up!

Sign me up!