-- 2D physics with no 3D at all:  crates drawn as sprites fall and pile up in overlay coordinates.
-- Runs on any machine, GPU or not (try it with SDL_GPU_DRIVER=nothing).
local font   = fontLoad("Singe/FreeSansBold.ttf", 24)
local box    = spriteLoad("testScripts/crate.png")
local frames = 0
local width, height = overlayGetWidth(), overlayGetHeight()

fontSelect(font)
physicsSet2D(true)
physicsSetGravity(0, 900, 0)          -- Pixels per second squared; overlay Y runs down.

-- The floor and walls, static, sized in pixels.
local floor = nodeNew()
nodeSetPosition(floor, width / 2, height - 10, 0)
bodyNew(floor, BODY_STATIC, SHAPE_BOX, width, 20, 50)
local leftWall = nodeNew()
nodeSetPosition(leftWall, -10, height / 2, 0)
bodyNew(leftWall, BODY_STATIC, SHAPE_BOX, 20, height, 50)
local rightWall = nodeNew()
nodeSetPosition(rightWall, width + 10, height / 2, 0)
bodyNew(rightWall, BODY_STATIC, SHAPE_BOX, 20, height, 50)

-- A slope the crates tumble off.
local slope = nodeNew()
nodeSetPosition(slope, width * 0.3, height * 0.55, 0)
nodeSetRotation(slope, 0, 0, 20)
bodyNew(slope, BODY_STATIC, SHAPE_BOX, width * 0.45, 12, 50)

local size   = spriteGetWidth(box)
local crates = {}
local function drop(i)
	local crate = nodeNew()
	nodeSetPosition(crate, width * 0.15 + (i % 5) * size * 0.6, -size * (1 + i * 0.5), 0)
	nodeSetRotation(crate, 0, 0, i * 13)
	bodyNew(crate, BODY_DYNAMIC, SHAPE_BOX, size, size, 50)
	bodySetMass(crate, 1)
	bodySetFriction(crate, 0.6)
	bodySetBounce(crate, 0.2)
	crates[#crates + 1] = crate
end
for i = 1, 14 do
	drop(i)
end

local resting = 0
function onCollision(a, b, x, y, z, speed)
end

function onOverlayUpdate()
	frames = frames + 1
	overlayClear()
	resting = 0
	for _, crate in ipairs(crates) do
		local x, y = nodeGetPosition(crate)
		local _, _, angle = nodeGetRotation(crate)
		spriteRotate(box, angle)
		spriteDraw(box, x, y, true)
		if bodyIsResting(crate) then
			resting = resting + 1
		end
	end
	fontPrint(10, 8, string.format("2D physics, frame %d, %d of %d resting", frames, resting, #crates))
	if frames == 40 or frames == 100 or frames == 220 then
		singeScreenshot()
	end
	if frames == 240 then
		singeQuit()
	end
	return OVERLAY_UPDATED
end