View Full Version : TPicture to OpenGL Texture

20-06-2003, 02:42 PM
Hi all,

i was woundering if it is possible to extract data from TPicture and use it in OpenGL? any ideas??

Thanx for any help

24-06-2003, 05:25 PM
My answer is "it's probably possible." I can't say that I know off-hand, but when it comes down to it, TBitmap is just a bunch of pixels, which is what OpenGL likes ;). One problem would be ordering of colours (bgr versus rgb) -- dunno if that would factor into things, since I've not investigated the matter myself. You might have to manually swap the order (not a big deal, but not exactly handy for speed), though maybe not.

First of all, the TPicture.Bitmap property will get you a TBitmap. You might try something along the lines of the following: set the bitmap's pixel format to a known value so that it's not pfDevice (e.g. MyPic.Bitmap.PixelFormat := pf32Bit). Then, you can take a look at the scanline property of the picture's bitmap and pass it to the relevant function(s) in OpenGL using the address of scanline[0]^[0] or scanline[bmpheight - 1]^[0] (not sure which is appropriate). Will the padding-to-dword for each scanline affect things? Who knows! ;)

If you don't care much about speed, the simple solution would be to create a dynamic array of byte, size it appropriately, then do some blockreads for the bitmap's scanlines.

Can you tell that I don't use the VCL much with OpenGL? :)

Try the usual (http://www.delphi3d.net) suspects (http://www.sulaco.co.za) to see if they have any examples. Hopefully someone with more knowledge will chime in here.

25-06-2003, 03:01 AM
Thanks for your idea, i found something on the web with the same idea, and am now adding it in :twisted:
heres the link http://www.delphifr.com/article.aspx?Val=2218
Its in french, but most of it is easily worked out.

Just one last question about this though, i've got a feeling that TPicture wont store the alpha channel for TGA files, im using the GraphicEx library to read them, and im not sure how i can dig out the alpha channel or if it stores it?? do you have any idea about this??

Thanks for your help..