Jump to content
  • Advertisement
Sign in to follow this  
john_t

Bitmasking

This topic is 4820 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

I've been doing some 2D programming lately working with surfaces (IDirect3DSurface9*). I've been loading these surfaces in from bitmap (.bmp) files using the D3DXLoadSurfaceFromFile call, and blitting these surfaces to the backbuffer with StretchRect. This has all worked fine, except that I can't figure out how to mask bits and as a result all of my images have black boxes surrounding them. The D3DLoadSurfaceFromFile has a parameter--ColorKey--that looks like what I want. I'm passing ColorKey D3DCOLOR_ARGB(255, 0, 0, 0), which should replace opaque black with transparent black, but the black box is still there. Does StretchRect not use alpha values? Or am I going about this masking in the wrong manner?

Share this post


Link to post
Share on other sites
Advertisement
Colorkey should be a color, the alpha channel should have no effect IIRC. I ussually use hot pink 255r, 0g, 255b. Also its called a masked blit. bitmasking is another subject.

Share this post


Link to post
Share on other sites
Quote:
Original post by Boku San
Got my hopes up and everything...

I wanted to explain bitmasking [cool]. Oh well.

If you know what you're talking about, explain it here: NeXe [smile]


Anyway, for the original poster... classic mistake - two common reasons:

1. Check your texture has an alpha component, in your D3DFMT_, make sure that you have an "A" something... e.g. D3FMT_A8R8G8B8 instead of D3FMT_X8R8G8B8.

2. Make sure that you're enabling alpha blending. You have to set three render states:
D3DRS_SRCBLEND = D3DBLEND_SRCALPHA
D3DRS_DESTBLEND = D3DBLEND_INVSRCALPHA
D3DRS_ALPHABLENDENABLE = TRUE

hth
Jack

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!