Go Penguin WIP platformer for MSX 1

From my point of view it is an excellent job for these reasons:
- Smooth Scroll on Msx1 in multicolor mode
- Multicolor sprites
- Pentaro movement
- At the moment, no sprite flicker

Just a few tips:
- In testing, forget the keyboard and try to play with just the joystick (This allows for a kind of Arcade game when placed in a cabinet)
- Insert different levels maybe with password at the end of a level (this also allows on FPGA to have a kind of save state)
-At the moment I don't have audio on my computer, but I hope there is a tune, or that a nice tune has been added

Thanks again for your job

Nice improvent! I'll post some commets/tips as sone as I've some time.

For now I can say that sometimes the game crashes. It happens when I switch fast between moving left and right, combined with z-key pressed. This screen appears:

Player can view left and right, but will not move. After a jump the game becomes normal again (takes a second, at first player lands on the pink line).

Instead of crashing there is sometimes a litte flickering.

It's all hard to reproduce but it happened to me a few times in WEBMsx.

EDIT: Ok, I managed to reproduce and make a little videoclip.

I have a suggestion too: even if in a middle of a jump or if you jump in the opposite direction you are faced the penguin should turn in the jump direction (so it should turn several times, and fast, when ascending/descending

About the corruotes screeen bug found by Pbk71:

I can only do assumptions here, but I suppose that you copy nametable values from a RAM buffer and due to some mistake there were copied a lot of full or empty chars wich foreground (if fullfilled) or background (if empty) color is set to 0 (transparent, so border/last background color) and so we see border colors there too.
I don't know when you do copy from RAM to VRAM nametable but maybe vram addresses are changed during ISR messing that copy?
The penguin seems stuck because probably your collision detection routine doesn't include those bordercolor characters..

Hi there!

I just watched a video and the scrolling look really impressive! All together it looks like you've got a solid foundation on a platformer engine.

I've noticed something though, and that's how rigidly the characters tend to jump in a lot of MSX games. It appears to me that he's jumping up and down at a set speed, probably in whole pixels. I'd like to share the approach I used for jumping characters in the past, and as far as I'm aware, this is how it's typically done for NES programmers.

I would have an X and Y position as well as an X and Y velocity for each object. You'll need 3 bytes for each position, as one byte will be screen position, one byte will be pixel position, and one byte will be sub-pixel position. Velocity will be two bytes, one for pixels and one for sub-pixels.

It looks to me like the jump now is being executed by basically adding a set number to the position every frame. We can make a smooth jump with sub-pixels and velocity.

I don't ever directly add to the value of an object's position, I modify its velocity.

Every frame, object X velocity is added to X position, and Y velocity is added to Y position. Then I do background collision and eject my object from solid titles and reset velocity to 0 if necessary.

There's also a routine for gravity, which adds to the Y velocity of every (gravity-affected) object, every frame. This will bring your character down, so falling becomes automatic. Gravity is always increasing your Y velocity, but Y velocity gets set back to 0 every time an object is ejected from a background tile on the Y axis.

All of the velocity variables need to have a maximum speed that is checked every frame. if it's too high, reset it to the maximum. You don't want this to be any higher than your smallest collision detection area.

Once this is set up, how do you make your character jump? Easy! Just give them a negative velocity that results in a jump speed you like. Gravity will naturally turn that into a smooth curve, and then reset velocity to 0 once they hit ground. You can set a jump flag if necessary so you can change the character's sprite or trigger other behaviors.

Please let me know if any of that was confusing!