Demo of how a 3rd person camera works in PICO-8

thirdperson.p8

pico-8 cartridge // http://www.pico-8.com
version 29
__lua__
--------------------------------
-- 3rd person camera demo     --
--                            --    
-- (c) 2021 alanna kelly      --
--                            --
--                            --
--this work is licensed under --
--the terms of the mit        --
--license.                    --
--for a copy, see             --
--https://choosealicense.com/l--
--icenses/mit/                -- 
--                            --
--https://alannakelly.ie      --
--------------------------------

-- player
player={
	x=64,
	y=64,
	h=0.25
}

-- camera
cam={
	rho=30, -- distance to player
	theta=.75
}

function _update()
 -- arrows move player
	if (btn(2)) forward()
	if (btn(3)) backward()
	if (btn(0)) player.h += 0.01
	if (btn(1)) player.h -= 0.01

 -- use [s] and [f] to orbit camera
	if (btn(0,1)) cam.theta -= .01
	if (btn(1,1)) cam.theta += .01	
	
	-- use [e] and [d] to change camera distance
	if (btn(2,1)) cam.rho -= .5
	if (btn(3,1)) cam.rho += .5	

end

function forward()
	player.x += cos(player.h)
	player.y += sin(player.h)
end

function backward()
	player.x -= cos(player.h)
	player.y -= sin(player.h)
end

function update_cam() 
	
end

function _draw()
 cls()
 
 print("3rd person camera demo")
 print("⬆️⬇️⬅️➡️ moves player")
 print("edsf moves camera")
 
 -- draw player
 local px = player.x
 local py = player.y
 
 -- draw player
 spr(1,px-4,py-4)
 -- draw player heading
 line(px,py,px+cos(player.h)*10,py+sin(player.h)*10,11)

	-- the look at vector
	local cvx = cos(cam.theta)
	local cvy = sin(cam.theta) 
	
	-- polar to world coordinates
 local cx = px + (cam.rho * cvx)
 local cy = py + (cam.rho * cvy)  
 
 -- draw camera
 spr(2,cx-4,cy-4)
 -- draw camera look at vector
 line(cx,cy,cx-cvx*10,cy-cvy*10)
end
__gfx__
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