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The Titlescreen Kernel


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#201 Lillapojkenpćön OFFLINE  

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Posted Tue Jan 24, 2017 1:33 AM

1.6 looks great, rock steady.

When I go from the titlescreen to the game the score jumps one pixel to the left, same in 1.5. I've modified both score fonts the same way, six pixel wide numbers with one row of nothing on each side, how do i fix it?


Edited by Lillapojkenpćön, Tue Jan 24, 2017 1:33 AM.


#202 RevEng ONLINE  

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Posted Wed Jan 25, 2017 9:41 AM

If I recall correctly, I designed the title-screen score minikernel to be dead-center, so it would align nicely with the other graphics.

The bB standard kernel displays the kernel off-center. (this to give it some extra cycles where it needs it, which allows it to display playfield bars on either side of the score.) This is where the alignment shift is coming from. It shouldn't be an issue with the standard kernel.

The title-screen score minikernel would needs some surgery to reposition the score off-center, to match the standard kernel. When I get a chance, I'll see if I can add this as an option.

#203 kdgarris OFFLINE  

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Posted Sun May 14, 2017 9:43 AM

I've given the titlescreen kernel a try for the first time, and I've been successful at displaying a bitmap with the 48x2 kernel. However, it has a background color that is dark, but isn't completely black like the rest of the screen. Is there any way to make the background pure black?

 

Screenshot_20170514_072555.png



#204 RevEng ONLINE  

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Posted Sun May 14, 2017 3:36 PM

I've given the titlescreen kernel a try for the first time, and I've been successful at displaying a bitmap with the 48x2 kernel. However, it has a background color that is dark, but isn't completely black like the rest of the screen. Is there any way to make the background pure black?


The overall color can be set in titlescreen/titlescreen_color.asm, but it defaults to black.

Maybe you're comparing the black background to the blanking color? Blanking is darker than the blackest black an NTSC 2600 can produce.

#205 kdgarris OFFLINE  

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Posted Sun May 14, 2017 5:24 PM

That may well be it.  In that case, is there a way to set the rest of the screen to the same color so that the images don't appear is obvious rectangles?  It seems like I must be missing something obvious, since the screenshots I see don't show this color contrast at all.

 

Another question - does anyone have a command line utility that works like the ImgToCode Windows app?  If not, would anyone be interested in one?  I was thinking about writing a simple one for my own convenience that could work on Mac/Linux, and I would be happy to share the results if anyone would find it useful as well.



#206 RevEng ONLINE  

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Posted Sun May 14, 2017 6:24 PM

The overall screen color can be set in titlescreen/titlescreen_color.asm. Of if you prefer something dynamic, you can dim a "titlescreencolor" variable, and set it to the color you want.

I'm not actually seeing any contrast between blacks in your screenshot. On both my computer and phone, it appears all to be uniformly black.

I think a cross-platform command-line utility like ImgToCode would be great!

#207 kdgarris OFFLINE  

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Posted Sun May 14, 2017 7:36 PM

I can see it clearly in two emulators, but maybe I should try it on real hardware before deciding if it's a real issue.  I suppose I can make a taller bitmap that fills all of the vertical space as a workaround if so, so that it appears to be more uniform.



#208 kdgarris OFFLINE  

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Posted Mon May 15, 2017 6:45 AM

After more experimenting, it looks like the problem must be with my bitmap specifically.  When I replaced my 48x2 with the "Yoshi" one from example 4, I didn't get the weird color as image background.  When I did the reverse substituting my bitmap for the Yoshi one in example 4, I did still get the weird background color for my bitmap, but not for any of the others.  I visually exaimed by converted bitmap and compared it visually to the working Yoshi one, but I couldn't find any problems.  Any thoughts?

 

Mind you, this isn't vitally important, since I could always start from scratch with a new image if need be, since this one is more of a placeholder, but the mystery of it is bugging me.  Attached is the compiled example 4 with my image substituted for the Yoshi one, and the problematic converted image itself.

 

Attached File  ex4-color_by_flicker.bas.bin   16KB   7 downloads

 

Attached File  48x2_1_image.asm   3.66KB   7 downloads



#209 kdgarris OFFLINE  

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Posted Tue May 16, 2017 12:18 PM

Well, I never figured out the cause of my issue, but I don't much care since I have something that looks much nicer now that I've started fresh.  I love this kernel! :)  This screenshot doesn't do it justice, since I think it only captures one frame of the flicker?

 

 

Screenshot_20170516-141333.jpg

 

 



#210 kdgarris OFFLINE  

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Posted Sun Jun 25, 2017 6:38 PM

Is it at all possible to combine the titlescreen with a starfield effect?  If so, what objects (if any) are not used by the titlescreen kernel to use for this?  I made a stab at it with the ball, but it didn't show up when I tried it.  Or is it not possible to have an effect that covers the whole screen like that while the titlescreen kernel is active?

 

I'll confess that I don't understand that wizardry and black magic that the titlescreen kernel uses, so it's hard for me to make an educated guess on this one.  :-)



#211 RevEng ONLINE  

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Posted Sun Jun 25, 2017 7:18 PM

Each of the minikernels in the titlescreen kernel hit HMOVE at some point. This resets the effect, so a clean full-screen starfield effect wouldn't be possible.

For the horizontal strip that any particular minikernel would occupy, it's possible that the effect could be added into the assembly code, but it would take a fair bit of surgery.

#212 kdgarris OFFLINE  

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Posted Mon Jun 26, 2017 7:48 AM

It sounds like it would be more trouble than it would be worth, since for an individual titlescreen minikernel, I could draw my own stars with a bitmap that would look much better, anyway.  I suspected that having a screen-wide effect wouldn't be possible, but I just wanted to make sure.  :-)



#213 Gemintronic OFFLINE  

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Posted Mon Jun 26, 2017 7:51 AM

You'd have to incorporate the starfield effect into whatever titlescreen mini kernel you're using at the time otherwise you'd be flickering between them.  This would mean having enough assembly savvy to not only integrate two disparate graphic kernels but make sure there's enough time for both of them.



#214 RevEng ONLINE  

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Posted Mon Jun 26, 2017 9:25 AM

I think the fact it would be limited to each horizontal strip, and also limited to full screen width, limits the visual usefulness. It also would likely require more memory (IIRC I'm already using the object x and y coordinates, though I may be wrong)

Agreed its probably not worth the effort.




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