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Fede-lasse

Member

Registered: 2008-07-18

Posts: 4

Ghost outlines for some ... GM bug? DX bug? GPU bug?

Hi. This is my first topic here on GMLjoint.com. I have this bug in my program that manipulates with the output bitmaps, which is a little annoying. My program's called Profile Generator. It is a program to make sideview profiles of a man.
It can be found here: http://gmc.yoyogames.com/index.php?showtopic=386950

I recently added hats to it, but there appears to be a problem when they overlap the top of the character's head. Try the program, and equip the first hat onto the character (The flat one. Note, that the hat sprite itself has another color as transparent color, so the issue isn't about the hat itself). Now, press Space to save the profile to a bitmap file. Note, that the program uses the normal screen_save_part() function. Now, go into MSPaint and fill the flat hat with the color red on the VERY top, and on the lowest spot (One pixel above the lowest on the hat). Notice, this white ghost outline that forms the rest of the head, appears! If you're lazy, then look at this instead:

Since the ears overlap the flat hat, this outline appears on the ears, too.

I have no idea why this happens, since all the face parts are mere objects placed together with their sprite indexes as each several face part, like the nose, libs or ears. Same goes for the hat. Also, as this is highly unusual, I thought it belonged in the "bugs section" here on GMLjoint.com, since the GMC doesn't have one

xot

Administrator

Registered: 2007-08-18

Posts: 1,240

Re: Ghost outlines for some ... GM bug? DX bug? GPU bug?

I'm unable to duplicate the problem.

[Image deleted by the ImageShack gods]

I think it must be a GPU or graphics driver issue, possibly arising out of the (annoying) edge preprocessing GM does to sprites that have a transparency color. When GM switched to Direct3D, many systems underwent changes that, for some people, result in fringing or gaps between adjacent images.

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Abusing forum power since 1986.

Fede-lasse

Member

Registered: 2008-07-18

Posts: 4

Re: Ghost outlines for some ... GM bug? DX bug? GPU bug?

God, how unlucky you can be. Well, should I mark this "Not a GM bug" or something, then? Or does anyone else wanna test?

xot

Administrator

Registered: 2007-08-18

Posts: 1,240

Re: Ghost outlines for some ... GM bug? DX bug? GPU bug?

What make and model graphics card are you using? Up to date drivers? Driver version? DirectX version?

Also, maybe try non-transparent sprites, and set the alpha at runtime. Be sure to try a 1-bit alpha channel, that is, pure black and white with no gray.

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Abusing forum power since 1986.

Fede-lasse

Member

Registered: 2008-07-18

Posts: 4

Re: Ghost outlines for some ... GM bug? DX bug? GPU bug?

Sorry for taking a hundred years on replying. I'm currently vacation, so I do only sometimes get a computer with Internet near me.

What make and model graphics card are you using? Up to date drivers? Driver version?

I'm still on vacation, but all I remember is that it's NVidia as the graphics card.

DirectX version?

I'm pretty sure it's 9.0c or whatever it's called.

Also, maybe try non-transparent sprites, and set the alpha at runtime.

What do you mean by setting the alpha?

Be sure to try a 1-bit alpha channel, that is, pure black and white with no gray.

It is pure black and white, where white is the transparent color and black the outlines' color.

Last edited by Fede-lasse (2008-08-29 14:11:18)

xot

Administrator

Registered: 2007-08-18

Posts: 1,240

Re: Ghost outlines for some ... GM bug? DX bug? GPU bug?

By setting the alpha, I mean start with a non-transparent sprite and add an alpha channel to it at run time using sprite_set_alpha_from_sprite(). That requires you to make alpha channel sprites to go with your regular colored sprites. I believe for alpha sprites, black is fully transparent, white is fully opaque, and gray is somewhere in between. As a further test, I'm recommending alpha sprites that have no gray, only full black or full white, ie. 1-bit transparency.

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Abusing forum power since 1986.