DD Image darkening

[git]

Hi,

Is it possible to blit an image to screen with DD/BltFast (fullscreen), and also darken it to a certain amount? Is there an easy way to do this?

-Git

[Sastraxi]

Well you could make a black surface (bltcolorfill it) and then alphablend them together w/microsoft's alphablend function.

[Jotaf98]

Nah, I think that function only works in Win98 (not sure). You should use something more reliable, like a custom DLL

Look for vbDABL, it's the best one in my opinion. You can find it in any search engine I think, if not, reply here and I'll e-mail it to you.

[PsychoMark]

That DLL won't work without MMX, and my own pc doesn't have MMC


If you really want control and speed, plus some other nice things like rotation, you could also use Direct3D:

Direct3D -> 2D, Rotation
Direct3D -> 2D, Faking Light (the darkening you're looking for)
Direct3D -> 2D, Alpha Blending


Those are samples I've uploaded to PSC when I started using Direct3D for 2D graphics...

[Jotaf98]

Yeah, that's cool. The only reason why it's not THAT widely used, is that it only works decently with a hardware accelerator... of course you could add the option to turn off those effects, but maybe having a "backup plan" would be better

I've heard ASM is really fast. Maybe faster than C++. But which one do you think would be easier to make a special effects DLL?

[PsychoMark]

I don't know ASM, but I started learning C++ and Delphi recently. Delphi is easier, but I think C++ is a little faster (haven't really tested the Delphi DLL, but the C++ DLL was 900% faster than VB!!!!). AFAIK, ASM is a little faster than C++, but I never even tried to understand it...

Btw, the test I performed was between a C++ DLL, and a VB ActiveX DLL, both doing array manipulation to change pictures (without lookup tables)... there's an example at http://www.vbexplorer.com/directx4vb/ (Code -> General VB Gaming -> C++ DLL), which I used as a base for my code, not too difficult really...

[Jotaf98]

Hey PsychoMark, thanks for the link! I've been looking for that for AGES!!! And it's easier than I thought

Also, why did that DLL work only with MMX, and is it THAT fast?

[PsychoMark]

It uses MMX because of some 64-bit buffers or something. I don't know much about it, but it's explained at the DirectX4VB site...

Don't know how fast it is; my P133 doesn't have MMX, so even though I have a P550 which does support it, I forgot about it ASAP (didn't want to force the user to have MMX)...

[git]

Hmm...is there any way to do it with Direct X/Draw 7? I'd prefer not to use DX8 or D3D (my entire program is written in DD7), but I guess I might not have a choice.

-Git

[PsychoMark]

For your problem, there are generally 3 ways:

- create some slow VB code
- create a C++ DLL which handles it
- use Direct3D

[Jotaf98]

Don't worry, I'm doing it the DLL way right now, all you gotta do is wait

I'll use the same code to generate the lookup tables as in another special effects module I made, for BitBlt games. To have a look at it, look for "Special Effects for BitBlt", somewhere in this forum. But this time it's gonna be for DDraw

[PsychoMark]

You can amazing things with the DirectDraw GetLockedArray function and a C++ DLL, that's for sure.... I almost can't wait to see your DLL Jotaf98

Also, if you make the DLL accept an array, you can use it for both the DD GetLockedArray call and you can apply it to normal PictureBoxes (I've got a sample program here which get's an array from a picture for fast manipulation, somewhat like the GetLockedArray thing, which is pretty fast, a lot faster then Get/SetPixel anyways). Now wouldn't that be nice

[Jotaf98]

The DLL is coming a long good, I've done it in VB and it works very well, so all I need to do now is translate it into C++.

The DLL will manipulate ARRAYS, not surfaces! You can use it with anything you want, as long as it's 24-bits, NO MATTER IF IT'S RGB OR BGR. Also, the lookup tables will be built-in, so all you have to do is write a simple blting function that handles cut edges (I'll provide one, so don't worry)