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DX7::D3DX Sprite question

Evil · 1999-11-16T19:33:00

I'm playing around with the new D3DX utility library included in DirectX 7. I'm having one small problem I was hoping the gurus here could clear up for me:In the included sample application 'Sprite', there is a demonstration of alpha-blending. However, in that demo, there is no color keyed transparency, so the rotating doughnut is surrounded by a black box. I made a couple of modifications which I thought was going to correct the output: Right before the operations to draw the sprite, I SetColorKey on the source texture. I also SetRenderState to enable color keying. Still no dice - the black bounding box remains. Can anyone tell me what I forgot? I'd really appreciate it. Thanks in advance!

Graphics and GPU Programming Programming

Started by Evil November 16, 1999 07:33 PM

14 comments, last by Evil 24 years, 7 months ago

Evil

122

Author

November 10, 1999 02:06 PM

Anyone have any ideas? It's blatant omissions like these in the Microsoft examples that drive me bonkers.

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E.N.D. - http://listen.to/evil

BacksideSnap

122

November 10, 1999 04:38 PM

I haven't tried working with what you're working with, but in the past I've seen a lot of people leave out one of these steps:

DDCOLORKEY ddck;
ddck.dwColorSpaceHighValue = RGB(0, 0, 0);
ddck.dwColorSpaceLowValue = RGB(0, 0, 0);
lpDDSurface->SetColorKey (DDCKEY_SRCBLT, &ddck);

If you already have transparency working forgive me, I haven't seen your code to know what you have or haven't tried. Once I get the damn DX 7 SDK from MS I'll take a look at it myself.

Evil

122

Author

November 13, 1999 10:21 AM

Yes, in my modification I did properly set the color key as you demonstrate in your post. However, it still doesn't work. I appreciate the attempt to help though.

Any other guru's have a suggestion I can try?

------------------------
E.N.D. - http://listen.to/evil

null_pointer

289

November 13, 1999 11:32 AM

I'm not very familiar with DirectDraw, but I looked in the Index for Color Keys. There is an article there with instructions. Do you have to specify some options when you blit? BltFast supports a color key value, and Blt has several flags about color keying.

Let me know if this helps! I am planning to learn DirectDraw soon...

Josh Neta

122

November 13, 1999 12:02 PM

D3DRENDERSTATE_COLORKEYENABLE
TRUE to enable color-keyed transparency. The default value is FALSE. Use this render state with D3DRENDERSTATE_ALPHABLENDENABLE to implement fine blending control.
Applications should check the D3DDEVCAPS_DRAWPRIMTLVERTEX flag in the D3DDEVICEDESC7 structure to find out whether this render state is supported.
When color-keyed transparency is enabled, only texture surfaces that were created with the DDSD_CKSRCBLT flag are affected. Surfaces that were created without the DDSD_CKSRCBLT flag exhibit color-keyed transparency effects.

Try looking in the docs next time.

Josh

Evil

122

Author

November 13, 1999 10:47 PM

I *DID* read that in the docs. And if you READ my original message, I said I DID use SetRenderState. It STILL doesn't work.

------------------------
E.N.D. - http://listen.to/evil

Evil

122

Author

November 13, 1999 10:50 PM

Null_Pointer: When using the D3DX library, you don't use BLT or BLTFAST. There are new sprite drawing functions in the library. I can achieve the effect fine with blits, I just cant get any of the new DrawSprite functions to do it.

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E.N.D. - http://listen.to/evil

null_pointer

289

November 14, 1999 09:18 AM

Sorry!

Hard to read documentation is one of the reasons I don't use DirectX yet!

Shinkage

595

November 14, 1999 11:16 AM

The renderstate you want is D3DRENDERSTATE_COLORKEYBLENDENABLE. That's what you get from actually looking in the docs. I'll admit though, you have to be familiar with the DirectX documentation to even know where to look.

Evil

122

Author

November 15, 1999 12:29 AM

I did also set COLORKEYBLENDENABLE (and the ALPHATESTENABLE) render states when trying to make it work, but they had no apparent effect either. I've played with every render state that I thought could possibly affect the output, but still no dice.

It's kind of ironic that the operation I want to use is called D3DXDrawSpriteSIMPLE when something as easy as what I want to do is convoluted with half a dozen renderstate flags.

I probably should have just posted the code I added in the first place, but I never seem to be at either of the systems where I made the modifications at the times I get a chance to visit this board. The code I tried looks like this:

DDCOLORKEY m_CK; //= {0x00000000, 0x00000000};
m_CK.dwColorSpaceHighValue = RGB(0,0,0);
m_CK.dwColorSpaceLowValue = RGB(0,0,0);
m_ptex->SetColorKey(DDCKEY_SRCBLT, &m_CK);
m_pd3dDevice->SetRenderState
(D3DRENDERSTATE_ALPHABLENDENABLE, TRUE);
m_pd3dDevice->SetRenderState(D3DRENDERSTATE_ALPHATESTENABLE, TRUE);
m_pd3dDevice->SetRenderState(D3DRENDERSTATE_COLORKEYBLENDENABLE, TRUE);
m_pd3dDevice->SetRenderState(D3DRENDERSTATE_COLORKEYENABLE, TRUE);

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E.N.D. - http://listen.to/evil

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