Author Topic: Can't Get Jo_VDP2 to Work Properly  (Read 72 times)

SaturnTeam

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Can't Get Jo_VDP2 to Work Properly
« on: November 15, 2017, 07:56:08 pm »
I am hoping someone can point me in the right direction. I've researched the Jo_VDP2 entries and associated files. I can get my project to appear in Yabause as 480p, but there are a number of problems. I'm not clear as to how to fully implement this. Can I do this without using the Sega code found in the FPS demo, in the C and header files? Based on the engine code I've looked at, it seems like I should be able to. Yabause says that VDP2 is being used. However, I'm getting black artifacts all over the screen. I can't figure out how to use a TGA bitmap at 1024x512, without it being too large of a file. If I export it from the map editor, it's over 1MB, no matter what the image is. If I try to import a TGA that's 16-bit from a different program, Yabause just gives me a blue screen. I tried converting the BG to a C file, but that crashed Yabause. Do I need to use a tile set background? Even then, wouldn't the total image need to be under 512KB? In Yabause, the 480p works if the background is the normal resolution, but it gets displayed 4x in 4 separate tiles. The polygon/sprite layer is mostly hidden behind the black artifacts that appear to be on the NBG0 layer. If I disable the NGB0 layer display in Yabause, most of the screen clears up. I'm also not clear on what Yabause is doing with the interlacing. I believe it has trouble with that, but I had difficulty finding info on that. I'll be grateful for any help. Thanks.
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mindslight

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Re: Can't Get Jo_VDP2 to Work Properly
« Reply #1 on: November 15, 2017, 10:32:25 pm »
Hi,

resolution doesn't work today in Jo Engine

SaturnTeam

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Re: Can't Get Jo_VDP2 to Work Properly
« Reply #2 on: November 15, 2017, 10:49:23 pm »
Okay. Thanks. That saves me from spending more time trying to use the engine's VDP2 code. I'll have to implement it the old fashioned way.
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XL2

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Re: Can't Get Jo_VDP2 to Work Properly
« Reply #3 on: November 16, 2017, 01:19:04 am »
480i resolution works by using 8 bits color data instead of 16 bits when you write to the framebuffer. You also need to coordinate the NBG0 and NBG1 so that they display the same thing, with one line offset. You also cannot use gouraud shading with it. It's just a pain and it's not worth it. You can try 352x480 instead, which, while half the horizontal resolution, comes at no cost except it's interlaced instead of progressive.

SaturnTeam

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Re: Can't Get Jo_VDP2 to Work Properly
« Reply #4 on: November 16, 2017, 02:09:47 am »
Okay. Thanks. I'll keep at it. I know that Dead or Alive used 704x480, so it's not impossible. I'll figure it out.
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XL2

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Re: Can't Get Jo_VDP2 to Work Properly
« Reply #5 on: November 16, 2017, 03:13:45 am »
Nobody says it's impossible, it's just a pain. You only have a 256 kb draw framebuffer and a 256 kb display framebuffer, so if you do the maths you will figure that it's impossible to use 16 bits data.
« Last Edit: November 16, 2017, 03:18:11 am by XL2 »

SaturnTeam

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Re: Can't Get Jo_VDP2 to Work Properly
« Reply #6 on: November 16, 2017, 04:25:25 am »
That's a good point. Of course, with DOA, there's not as much going on. It's confined to a fighting platform/ring. There's no expansive world.
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