Rotate part of a map

Fri, 23 Aug 2024 00:07:58 UTC

While making a top-down map for my game, I needed to arrange some of its parts to fit better together, which required rotating some sections. Since PICO-8 does not provide a way to rotate a map selection, I wrote a simple utility function to do that.

This function rotates a square section of the map clockwise.
MX and MY are the map X and Y coordinates of the upper left corner, and MS is the length of the square side - 1 (e.g. to rotate an 8x8 square, set MS=7)

Notes:

Make sure that you do not modify the map in any way before you call the rotate function, or the in-memory changes will be written to the cart
Uncomment the second CSTORE (or edit the to edit the lower portion of the map
This function is not optimized and is not intended for frequent use (unless you are making some gravity-based platformer, I suppose...)

-- rotate a square section 
-- of a map clockwise
function rotate_map(mx,my,ms)
	-- read tiles
	local tiles={}
	for x=0,ms do
		tiles[x]={}
		for y=0,ms do
			tiles[x][y]=
				mget(mx+x,my+y)
		end
	end
	-- write tiles
	for x=0,ms do
		for y=0,ms do
			local tx=y
			local ty=mx+ms-x
			mset(mx+x,my+y,tiles[tx][ty])
		end
	end
	cstore(0x2000,0x2000,0x1000)
	-- to edit extended map, uncomment
	--cstore(0x1000,0x1000,0x1000)
end

Dark Streets Tech Demo 1

Fri, 01 Mar 2024 01:17:10 UTC

Dark Streets Tech Demo 1

by yaky

[Click to Play]

Dark Streets Tech Demo 1

Hi all! Dark Streets is a first-person shooter, mechanically most similar to Wolfenstein 3D or Blake Stone, but also inspired by Doom, Blood, and Ion Fury. I have been slowly developing this game in my free time over the last year and a half. I referenced LoDev and a paper by Amanatides and Woo for some of the raycasting steps, but the rest of the code and graphics are mine. Enjoy a small preview!

Raycasting renderer

Since the setting of the game is a city, I specifically wanted to write a renderer that could draw tall buildings, short objects, doors, and interiors. I think I am pretty close.

Pretty performant: Everything below takes up only 50-60% of CPU, unless you go crazy with geometry and distances.
Fixed camera height: This makes walls look better. Originally, I had variable camera height and headbob, but that made textures a bit too jagged.Might reconsider based on performance later.
Variable brightness: Based on distance, using draw palettes.
Floor textures: Pretty basic, using horizontal TLINE
Multiple floors! Normally, I see raycasters render just one floor (Caped Feline Arena and Anarch are notable exceptions), so this is a bit unusual, and it allows more interesting designs.
Ceilings. Although texture-less, ceilings are rendered separately from the sky, and allow for features such as archways, underpasses, and building interiors.
Animated doors: They are also rendered halfway on the tile to stand out from the walls.
Z-buffer and clipped sprites: This piece is not very efficient yet, but works pretty well.

Gameplay

You can walk around, open doors, pick up and fire weapons (but can't defeat the enemies yet).

Variety of objects: Solid obstacles, ceiling decor (can be walked under), floor decor (cannot be walked through, but can be shot over)
Five weapons: Infinite pistol, shotgun, Gatling gun, flamethrower, and a rocket launcher (unfinished).
One large level, hoping to keep it like that for final game. Might not be possible with number of objects per level.
Health and weapon pickups.
Weapon switching: When picking up a new weapon and when running out of ammo.
Enemies: Basic move-aim-fire behavior, in beginning stages.

Known issues

Looking through open doors is slow. This is due to calculations on which vertical slice must be rendered for the door on each ray.
Adding many objects will slow the game down a lot, due to many visibility and collision calculations.

Thanks

Big thanks to other PICO-8 first-person games for motivation:

Trial of the Sorcerer
Caped Feline Arena
Star Beast
Whiplash Taxi Co

yaky [Lexaloffle Blog Feed]

Rotate part of a map

Dark Streets Tech Demo 1

Dark Streets Tech Demo 1

Raycasting renderer

Gameplay

Known issues

Thanks