Can't select a Backbuffer in A8R8G8B8, shows NONE

This drives me crazy. I already installed the latest ATI driver and latest DirectX Runtime 9c. Uninstalled everything, installed again… If I’m opening a EX9 Renderer in the Inspector and select A8R8G8B8 for Backbuffer, I can’t select a Backbuffer Format. It just shows NONE. Selection X8R8G8B8, I can choose one. Anyone having similar problems. Any idea? Thank you a lot in advance for help… Ah, running Win7 64bit, ATI 4670 Graphics on a Dell Studio XPS.

Ah, here is a screenshot of the inspector: 1_0.png
Anyone any ideas?

bad news for you, you can’t have a backbuffer when you have a format that includes transparency. At least that’s my understanding. Change to a different format without an A in it and you’ll find your backbuffer is back.

what would be the reason to use an alpha channeled backbuffer format? are you sure you need that? i have no idea what it could be used for.

If you looking for transparent bground set your render bgr to alpha 0

O.K. thanks for your replies. Indeed I’m not sure, if I’m having a real problem here. I discovered it in one of the workshops (transformation) rotating the moon around the earth and my (and only my) moon was not hidden behind the earth. Next step was trying to switch on a depth-buffer in the renderer and I couldn’t select one until I changed to X8R8G8B8 for back buffer format. Meanwhile I tried on 3 different computers with different operating systems and configurations (but all with some kind of ATI graphics) and it’s everywhere the same. So I guess it could be the ‘normal’ behavior.

Can anyone tell me, if it reacts the same in his environment and I was just too stupid to get an alpha texture transparent at the same time using a depth buffer? CAn anybody select a depth buffer and A8R8G8B8 at the same time and with which configuration (graphic card, system,dx-version)

Thanks in advance…

Here a picture of the problem in the project: 6.png
As you can see in the red circle, there is no alpha. It depends on the order the system drawing the billboards (halo_dot.bmp) and because the backbuffer does not have alpha (because I can’t select A8… if I want a depth buffer) it seems, that it can’t be tested for alpha while drawing the billboards.

If you want to have a look for yourself: Here is the patch: (11.6 kB)

i’d still argue your problem is not connected to the backbuffers format. X8R8G8B8 is the default and i never had to change that.

the halodot.bmp you are using there has no alpha channel. instead you could use the Halo.fx with a Grid (EX9) to get real transparency.

also it is a lot of text but if interested in an understanding of the actual problem involved you may want to read this about Transparency.

Thank you joreg, I guess you are right. I just was so confused in the workshop that my system behaves different to all the others by default. Good to know, that X8R8G8B8 is the usual default. I never checked the transparency of the halo_dot.bmp and just guessed, that it is 32bit with alpha. So I will do my homework now and read the f…g manual ;-)