Author Topic: Retro Virtual Machine v2.0.beta-1.r0 Released for Windows / Linux / MacOs  (Read 10847 times)

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Offline cpcitor

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Not yet, in the next version I will add a option to have a 1:1 output.

Please do. It's useful to perform exact pixel measurement, which is a different thing from visual assessing of shapes.


Currently RVM uses the real Aspect Ratio of a cpc, (if I have not failed in my calculations) because in the analog world pixels are never square  ;)

As a curiosity, if you load the same loading screen on a ZX 48k or 128k you will see that the aspect ratio is not the same (as on real machines).

What RVM currently does is indeed valuable. It allows to prepare graphics that will look good on a real CPC, not subtly squashed without the author being aware.

This is a use case different from the other one, and both are valid.

Can you share the aspect ratio that you consider "canonical"? This is very useful for people doing work that depends on it. For example, precise 2D or 3D drawing, just drawing a big circle that is indeed circular, for one.

Also, the "official" aspect radio is indeed when preparing artful graphics in an editor that supports different DPI in X and Y directions, like gimp.

In the future version also a cpc 6128+ and a gx4000 do not have the same aspect ratio. But I'm going to add an option to disable it and another one to make the window size in integer multiples

Are you saying that the cpc6128+ has a ratio different from the cpc6128? I'm surprised. In that case, what are the number?

Thanks!

« Last Edit: 18:49, 03 February 20 by cpcitor »
Had a CPC since 1985, currently software dev professional, including embedded systems.

I made the first CPC cross-dev environment that auto-installs C compiler and tools: cpc-dev-tool-chain: a portable toolchain for C/ASM development targetting CPC.

Offline jcgamestoy

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Please do. It's useful to perform exact pixel measurement, which is a different thing from visual assessing of shapes.


What RVM currently does is indeed valuable. It allows to prepare graphics that will look good on a real CPC, not subtly squashed without the author being aware.

This is a use case different from the other one, and both are valid.

Can you share the aspect ratio that you consider "canonical"? This is very useful for people doing work that depends on it. For example, precise 2D or 3D drawing, just drawing a big circle that is indeed circular, for one.

Also, the "official" aspect radio is indeed when preparing artful graphics in an editor that supports different DPI in X and Y directions, like gimp.

Are you saying that the cpc6128+ has a ratio different from the cpc6128? I'm surprised. In that case, what are the number?

Thanks!



Yes, of course.


The calculations are done in mode 2 pixels but by simply multiplying them you can extrapolate to mode 1 or 0


In the PAL standard a video line lasts exactly 64us of which 52us are active video.


In these 52us the cpc gateway makes 16 pixels of mode 2 per us which gives a total of 832 pixels


As for the vertical axis the proportion is one to one exact since the cpc makes (normally if we don't modify the timings of the crtc) 312 lines.


The standard PAL has a resolution (well this is theory since in an analogical television it makes sense to speak of lines and not of pixels) of 768x576. As the CPC makes 832 pixels in the time space there is to show 768 the pixels are smaller on the horizontal axis than normal.


So I use a texture (without overscan) of 832x288 and then using the gpu I scale it to an area with relation 4:3. So if we divide 768/832 the pixels of the cpc are about 92% of the width of a PAL pixel



As for CPC6128+, no, it has exactly the same aspect ratio as the classic cpc.


The one that changes is the GX4000 that Amstrad modified the master clock from 40mhz to 39.9mhz to improve the image on televisions: [size=78%]http://www.cpcwiki.eu/index.php?title=Plus&redirect=no#The_GX4000_Games_Console[/size]


Offline roudoudou

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As for CPC6128+, no, it has exactly the same aspect ratio as the classic cpc.
When the Plus monitor is switched ON it can display 270/271 lines but after a few minutes, it can reach 273 visible lines, will you emulate this?  ;D
use RASM, the best assembler ever made :p

I will survive

Offline jcgamestoy

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When the Plus monitor is switched ON it can display 270/271 lines but after a few minutes, it can reach 273 visible lines, will you emulate this?  ;D


I think I can live with this inaccuracy  :D

Offline roudoudou

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I think I can live with this inaccuracy  :D
Feature request, i tried to edit config file to change ROM configuration but everything is ciphered. Will it be possible to have a simple configuration
rom0=file
rom1=file
...
up to 255 (i know the plus is limited to 128 ROM on expansion slot)

use RASM, the best assembler ever made :p

I will survive

Offline jcgamestoy

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Feature request, i tried to edit config file to change ROM configuration but everything is ciphered. Will it be possible to have a simple configuration
rom0=file
rom1=file
...
up to 255 (i know the plus is limited to 128 ROM on expansion slot)


The machine internal format is changing constantly.


Isn't it easier for you to use an XMEM like on a real machine?


Look Here:
https://www.retrovirtualmachine.org/book/usermanual/en/devices/xmem.html

Offline roudoudou

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Isn't it easier for you to use an XMEM like on a real machine?

absolutely not at all because for each ROM i have to open a dialog box, scroll and select (so changing global rom configuration is pain in the 4ss )


But in addition to that,  the XMEM is limited to 32 roms  ;D whereas the CPC is able to handle 256 roms and the Plus 128 roms
use RASM, the best assembler ever made :p

I will survive