Emulate a phazer with the mouse

[ColinPitrat]

Detecting the clicked (or hovered ?) pixel and setting the light pen input high when the CRTC reaches it:
http://www.cpcwiki.eu/index.php/Trojan_Light_Phazer

[ColinPitrat]

Similar devices (would be nice for support to be generic enough to emulate any of them):
https://www.cpcwiki.eu/index.php/Amstrad_LP-1_light_pen
http://www.cpcwiki.eu/index.php/Amstrad_Magnum_Phaser

[ColinPitrat]

And another one mentioned in #214:
https://www.cpcwiki.eu/index.php/Gunstick

[Huntsman360]

amstrad cpc has this guns that i know:
Gunstick
Magnum
Trojan
Westphaser

Any possibility to add mouse / actual guns support? i have a sinden lightgun and will be a very nice nostalgia moment

Best regards

[ColinPitrat]

Right, the Westphaser:
https://www.cpcwiki.eu/index.php/Loriciel_Phaser_(West_Phaser)

I'll look into mouse support when time permits. It should work for Sinden lightgun too as it behaves as a mouse.

[Huntsman360]

thanks a lot, i have a arcade machine with retroarch so if you compile it in libretro core for windows i appreciate so much

Sorry for a lot a requests

Edit: sorry refloating this topic, any news about phaser support?

[Huntsman360]

Sorry, any news on lightguns support? i know it's not prioritary but i hope some day

[ColinPitrat]

I gave it a try but couldn't find a clean way to do it.

We'd need to activate the input (Joystick Up, Joystick Down, CRTC Light Pen Input depending on the model emulated) at this place in the code:

caprice32/src/crtc.cpp

Line 1066 in ac440f5

PreRender(); // translate CPC video memory bytes to entries referencing the palette

This would require identify which pixel we're drawing which, interestingly, is not that easy in the current code.
IIRC:

• CRTC.sl_count gives the Y, but maybe with some subtleties (impacted by overscan?)
• CRTC.char_count would give the X (with some calculation) with some approximation (8 pixel)

I'm not 100% sure how well this would work. I'd need a game, or even better a test program to validate it.

I'm not sure if we can do better. This code would need some better documentation which, at this point, means some reverse engineering.

I'll see if I find some time to give it a try in the coming weeks.

[Huntsman360]

thanks a lot.

For a reference, the real hardware when you push trigger gun the game shows white rectangles on shootable objects. If the gun sees this white bright rectangle, then impacts. Every rectangle is shown in order. for example, if you have 3 objects, when you pull the trigger, 3 rectangles appear but not at the same time, if the gun sees one in that frame time, the object is hit.

Maybe you can trace this rectangles too and if the cursor mouse is in on one of them at the proper time it hits

This is high level function, how to implement it i don't know

Sorry my english

[ColinPitrat]

That's not how emulation works :-) I have to emulate what the hardware is doing. The rectangles are drawn by the software running on the CPC.

What I need to do is:

• When the mouse button is clicked, do as if a joystick button was pressed (or for the Magnum, answer on port FBFEh)
• Continuously, when the pixel under the mouse is drawn, set the CRTC Light Pen Input (and reset when not)

My assumption that it's not possible to have a precision to the pixel is confirmed by the technical specifications:
https://www.cpcwiki.eu/index.php/Amstrad_Magnum_Phaser#Technical

The` accuracy is 1 CRTC character (R9 lines in height - normally 8) and 2 bytes horizontally. This is due to the way the CRTC outputs are mapped to memory addresses.

[ColinPitrat]

I started to look into this and the first finding is that it requires specific games to support it.

For example, the Magnum Phazer was sold with 6 games supporting it:
https://cpcrulez.fr/GamesTest/compilation-magnum_light_phaser.htm

This can be found in ROMs where there are many versions and one is identified as the LIGHTGUN one:
https://cpcrulez.fr/GamesTest/operation_wolf.htm

When trying it on Caprice, every other frame is completely white. Not sure whether it's a bug in Caprice or a consequence of not having a Phazer "plugged".

Testing another game ("Mission" on the compilation disk) there's the same huge white rectangle in the whole area where you can shoot every other frame.

IIUC, these white areas should only display when pressing the phazer button?

[Huntsman360]

here in spain we have "gunstick" with games like:

Bestial Warrior
Cosmic Sheriff
El Equipo A
Guillermo Tell
Mike Gunner
Outlaws
Solo
Sootland
Space Smugglers
Target Plus
Trigger

and that i remember, when you press the trigger the white areas flash very quick and in order, and the gun if sees one, send the message to computer that can determine what objet is hit by the frametime gun says it saw a white rectangle

PD: i loaded target plus in retroarch caprice 32, and every time i press the button white squares flashes
PD2: and obviusly this is not pixel perfect like gun-con, if the gun sees the rectangle is a hit
PD3: the only thing to do is determine if the cursor is on the rectangle when it shows up that is when shots and send the info the gun sends to the hard when this ocurs. Other thing is how, jejej

[ColinPitrat]

So, good news is that I have some code that works for one gun (Amstrad Magnum Phazer) with one game from the compilation (Mission) when running in windowed mode.

I know this sounds promising, but it relies on some weird hardcoded values and there's still a lot of things that are not well understood...

In particular, it doesn't work in mode 0 (and probably not in mode 2). It doesn't work in fullscreen (because the mouse coordinates are different in this case). And I'm pretty sure it wouldn't work well with overscan or other weird CRTC parameters.

[Huntsman360]

thanks a lot for the effort

It's more difficult than i thought