Deathchase Like Game - Beebchase

[ChrisB]

Deathchase seems to be one of those games that gets talked about a lot in terms of conversion. The game was never something that I played or was aware of back in the day however I've started to look at doing something deathchase-like. This won't be a conversion - more a heavily inspired game. The mechanics seem quite simple the only real work here appears to be plotting the 3d tree effect so I've been playing around with this. Don't know if it's going to come to fruition yet although it looks to be feasible.

This is a very early (and very flickery) prototype as a proof of concept.

https://youtu.be/H4Rfd0asKPo

This is a shrunk Mode 5 (play area is 128x160) and the intention is to palette switch for the horizon and double buffer (possibly with the score board being shared via vertical rupture) Should leave plenty of room for the limited graphics. Of course none of this is in place which is why it flickers so much...

[RobC]

This looks really good and it would be great to see Deathchase on the Beeb

Single buffering the score panel sounds like a good idea. Have you thought about just using the screen wraparound rather than rupture to achieve this?

The panel just needs to be at your chosen wraparound address with the first screen buffer directly before it and the second screen buffer directly before 0x8000. You then point CRTC registers 12 and 13 at the required buffer and set the wraparound to the panel address.

It should save having a timer for the rupture. (Just don't use the details in the AUG for the screen wraparound as they are wrong - I think the NAUG is correct though!)

[fizgog]

You are like a machine, there is no stopping you

Looking good

[ChrisB]

The panel just needs to be at your chosen wraparound address with the first screen buffer directly before it and the second screen buffer directly before 0x8000. You then point CRTC registers 12 and 13 at the required buffer and set the wraparound to the panel address.

Ooh - clever. Just a matter of deciding how bigger "hole" you want/need for the code between the end of the scoreboard and buffer 2. With the screen wrap at 3000 I might even be able to fit code in as a single block.

[RobC]

Just a matter of deciding how bigger "hole" you want/need for the code between the end of the scoreboard and buffer 2.

Yes - exactly. Rupture gives you more flexibility but has a greater overhead.

[ChrisB]

Minor update now with double buffering and "leaves" on the trees. At the moment I've gone with &3000 as the wrap point and extended the scoreboard to 4 lines.

The version above had 3 vsync waits to reduce flicker. This one is running at "full speed" with just one wait to prevent tearing however the tree plot is just a simplistic block fill so this will slow considerably as I'm intending to add "texture" to the trees. There is also no other game logic present.


https://youtu.be/4Raiet-bKWE

[ChrisB]

Updates now with texture for the trees and a scoreboard. There are wrap issues for the plotting that leads to trees appearing on the wrong side and the scoreboard corruption. I've slowed this version down with 3 vsync waits between frames which I think gives a reasonable amount of speed.


https://youtu.be/O5QFl2U1w9U

[ChrisB]

Added clipping for the trees at the edges of the screen so the scoreboard doesn't corrupt. Attached is an SSD with the current state. Z/X for left/right and K/M to increase/decrease the density of the trees. Next is some rounding at the bottom of the trees and some interrupt/palette work.

BeebChase.ssd

(3.75 KiB) Downloaded 34 times

[Cybershark]

Woo! It's like the speeder bike chase from Return of the Jedi

[ChrisB]

Added some palette switching which needs a rework as it's not allowing the OS space afterwards however as a proof of concept I'm quite happy. Makes MODE 5 a bit more colourful in any case. (Extra sprites added as a test only...) I don't have quite enough colours for a blue and yellow bike. Options are

• Blue bikes - White shots, planes and helicopters
• Blue & Yellow bikes - Yellow shots. White helicopters/tanks with landed ones possibly having some "colour clash"
• Blue and white bikes - white shots, helicopters & Tanks.

Where "Blue", "Yellow" and "White" can be any of the beeb colours.

I could also apply multiple colours to the bike sprites (so for example white with blue rider or blue with white rider to make them different). Depends on how closely I want to stick to the original.

Any thoughts?

deathchase3.png (4.9 KiB) Viewed 3864 times

Also - rounded tree bases.

[ChrisB]

New SSD image attached.
This has a better interrupt routine that seems fairly solid (the colours don't move/flicker as far as I can see). This also means the frame rate is constant (12fps...)
Keyboard routines are still placeholder and subject to auto repeat. Also added a masked sprite plot routine that's used to plot the handlebars (unmoving for the moment) and two placeholder bikes that respond to the direction you're moving in.

I've taken the bike graphics more or less from the original but the pixel aspect was thinner so they are a bit chunky at the moment.

BeebChase.ssd

(5.75 KiB) Downloaded 36 times

11+KB free

[fizgog]

Looking very smooth and polished, never seen or played the spectrum version so had to go off and watch a YouTube video

This version looks better in my opinion

[ChrisB]

Time for another update. This time I've added:

• Pointed tree tops and rounded leaf bases
• K/M now increases/decreases speed
• Animated Bikes that move around and respond to player inputs (There are some problems here that need working through)
• Animated handlebars
• Re-worked input routine that no longer suffers from auto repeat.
• WIP scoreboard.
• Edit: Also tree height variance.

BeebChase.ssd

(6.25 KiB) Downloaded 32 times

[ChrisB]

Good progress today. Changes this time:

• Bike movement corrected/refined
• Added photon bolt (Press L to fire when at full speed)
• Bikes can be destroyed
• Added Range indicator

Any comments about how this "feels" would be appreciated.

BeebChase.ssd

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For interest here are the colour changes that take place during each frame - with the final result on the left and the "raw" image on the right.
Colour 3 is always white and doesn't change.

[ChrisB]

Another update today - this now feels like a game.

• Scoreboard with scores
• Improved bike hit detection
• Photon bolt is blocked by trees
• Day/night cycle
• Level progression (6 levels then super speed mode...)

BeebChase.ssd

(7.5 KiB) Downloaded 36 times

Todo:

• Explosions for bike hits
• Bonus tank/chopper animation & hit
• Player death and highscores
• Sound
• Quality of life (pause, sound on/off, loader, re-definable keys)

[fizgog]

Just given the lates build a try, I must admit though I haven't a clue what you re supposed to do as I had never heard of the game for the speccy.

I did manage to shoot the 2 blue bikes, after the second one the sky flashed magenta and then went to black (I m guessing that's night time)

I did notice on the night level there is a slight flicker between the green ground and the black sky - I'm guessing to do with the palettes swap?

Other than that it feels very smooth.

[Cybershark]

Amazing to see the speed that this is progressing at!

[ChrisB]

New version this morning:

• Inter level text prompts.
• Explosions when bikes destroyed

BeebChase.ssd

(8.5 KiB) Downloaded 30 times

The flickering in the colours needs looking at. At the moment I have the OS routines in place (Was looking to use them for sound as space isn't a premium).

[ChrisB]

Getting closer:

• Added tree collision detection and death routine
• Added Game Over and Highscore Update
• Attempted to reduce flicker - feedback appreciated

BeebChase.ssd

(8.75 KiB) Downloaded 30 times

[RobC]

Looking great - it's come on so quickly! Really great work

The palette switching looks fine in BeebEm although I've not tried it on real hardware. B-Em didn't seem to like it though but I might be using an old version.

[ChrisB]

Last gameplay feature added...

• Added helicopter/tank logic replacing the placeholder sprites. At the moment they are - to my mind- to easy to shoot - so I will probably reduce the hitbox size.
• Added clouds and moon. I realise these are not in the original but as I was working on the vehicle code these were easy to add.

BeebChase.ssd

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beebchase.png (5.44 KiB) Viewed 3131 times

Next I need to work out if I can reduce the flickering any more - or whether I need to take over the interrupts completely (and have to do my own sound).

[fizgog]

Chris,

Ive just tried the latest version and its looking fantastic

Also tried it on jsbeeb and the palette switch flicker is no longer there like it was on an earlier release

Keep up the good work, looks like it's not far off from being finished.


*** Update ***

Works fine in BeebEm on Windows using Mac Parallels

Just tried in on B-EM v-8f73f4c (not sure what the latest version is?) using Mac Parallels
and get the following: -

[ChrisB]

I believe have identified what's causing the flicker - OS Keyboard routines being called at "random" times in the frame appear to cause interrupts to go missing. Moving them to somewhere just after the vsync should prevent the issue.

Regarding b-em I have versio0n 09cfa9 and this works fine - as does real hardware - so I think you're seeing a bug with the emulator there.

[ChrisB]

Time for another update.

• Added BASIC intro program and title screen - keys are now redefinable and initial cloud positions are random.
• Moved input routines to (as far as I can tell) remove the last of the flashing.
• Reduced the hit box on the bonus objects to make them slightly harder.

BeebChase.ssd

(11.75 KiB) Downloaded 28 times

Sound still to do.

[fizgog]

Whilst looking for laserzone info on the Dragon, I came across this site

http://archive.worldofdragon.org/index ... Deathchase

Never new 3d death chase also came out on the Dragon


*Edit

Just noticed it’s a 2009 game

[ChrisB]

Now with sound! Also corrected an issue with the moon plotting. Made the close trees move slightly straighter so they will appear to dodge out of the way slightly less. Introduced a small delay changing speeds which will also help the sound on/off switch.

This is very close to release so feedback is appreciated.

BeebChase.ssd

(12 KiB) Downloaded 29 times

Todo:
Sound on/off toggle.

I am wondering about the bikes and whether the graphics needs tweaking either to make two distinct bikes or to add some colour to the sprites.

[fizgog]

Working perfectly and the sound effects always seem to make it a more enjoyable experience

RE: Blue bikes, sometimes less is more I quite like them, but I'm guessing you could dither one to make it look like another colour, I'm guessing you have blue, white and red to play with (don't think green would work)

[ChrisB]

Here's a version with a second dithered colour for the second bike. Of the colours I think this one works best. I've also added some colour to the bonus sprites. Thoughts appreciated.

BeebChase.ssd

(12.25 KiB) Downloaded 23 times

[ChrisB]

Here is Release Candidate 1. Please let me know of any comments.

Final tweaks this version:

• F0 can be used to enable and disable sound.
• Slight sprite colour tweaks
• Increased tree density slightly in first sector
• Corrected minor graphical bug where the bottom of the first tree drawn used a bike sprite (uninitialised data)

BeebChase.ssd

(12.25 KiB) Downloaded 46 times

[nicolagiacobbe]

Really nice. Why don't you write here something about the gauntlet you found while developing the game? I bet would result in an interesting read, to say the least.