Raster Road for Mini Micro

rh = 2  // raster height, in real-screen pixels
// create a couple of 1-pixel-high road images,
// with and without lane stripes
w = 600  // full width of road sprite
gfx.line 0, 0, w, 0, "#666666"
gfx.line 0, 0, 20, 0, color.white
gfx.line w-20, 0, w, 0, color.white
roadImg = []
roadImg.push gfx.getImage(0, 0, w, 1)
gfx.line w*0.33-10, 0, w*0.33+10, 0, "#EEEEEE"
gfx.line w*0.66-10, 0, w*0.66+10, 0, "#EEEEEE"
roadImg.push gfx.getImage(0, 0, w, 1)

// And same for grass.  But for this one, we'll just use
// a 4x4 pixel image and stretch it.
gfx.fillRect 0, 0, 4, rh, color.green
grassImg = gfx.getImage(0, 0, 4, rh)

drawBackground = function()
	img = http.get("https://i.pinimg.com/originals/e8/70/1c/e8701c982aaf5a6f9a93aa17a2cffd90.jpg")
	globals.bgWidth = img.width/3
	gfx.clear color.blue, img.width, 640
	gfx.drawImage img, 0, 320-120
end function
clear
drawBackground

// now create a sprite for each row of the screen
sprDisp = display(4)
sprDisp.clear
grass = []
road = []
rasterZ = []   // distance (0-1) of each raster line from the camera
rasterScale = []  // scale of sprites at each raster line
rasterFog = []   // amount of fog to apply at each raster line
setup = function()
	maxi = 320/rh
	for i in range(0, maxi)
		camHeight = 10
		z = camHeight / (320/rh+5 - i)
		rasterZ.push z
		rasterScale.push (1/z) / (1/rasterZ[0])

		if i > maxi/2 then
			rasterFog.push (i-maxi/2) / (maxi/2)
		else
			rasterFog.push 0
		end if

		// grass
		sp = new Sprite
		sp.image = grassImg
		sp.scale = [1024 / grassImg.width, 1]
		sp.x = 480
		sp.y = i*rh
		grass.push sp
		sprDisp.sprites.push sp

		// road
		sp = new Sprite
		sp.image = roadImg[0]
		sp.scale = rh
		sp.x = 480
		sp.y = i*rh
		sp.scale = [1.5 * rasterScale[-1], rh]
		sprDisp.sprites.push sp
		road.push sp

	end for
end function
setup

// Update the road and grass sprites along our raster lines.
tintColors = [color.white, "#DDDDDD"]  // light/dark tint
fogColor = "#EEEEEE"  // fog in the distance
tintLen = 0.1     // how far (in Z) our tint stripes go
stripeLen = 0.06  // how far (in Z) the lane stripes go
updateRoadDisplay = function(zOffset)
	x = 480  // X position of the road, on screen
	dx = 0   // change in x per raster line
	for i in road.indexes
		// calculate total Z along the road
		z = zOffset + rasterZ[i]

		// update road position
		road[i].x = x
		x = x + dx
		dx = dx + segmentCurveRates[i > nextSegY]

		// apply tint and fog
		c = tintColors[z % (tintLen*2) > tintLen]
		if rasterFog[i] then
			road[i].tint = color.lerp(c, fogColor, rasterFog[i])
		else
			road[i].tint = c
		end if
		grass[i].tint = road[i].tint

		// update sprite (for lane stripes)
		strip = z % (stripeLen*2) > stripeLen
		road[i].image = roadImg[strip]
	end for
end function

// Scroll the background left/right as we go around curves.
updateBackground = function()
	globals.heading = heading + segmentCurveRates[0] * 100
	x = heading % bgWidth
	if x < 0 then x = x + bgWidth
	gfx.scrollX = x
end function

// Frames per second (fps) counter
fpsStart = time
fpsFrameCount = 0
updateFpsCounter = function()
	now = time
	globals.fpsFrameCount = fpsFrameCount + 1
	if now - fpsStart > 1 then
		fps = fpsFrameCount / (now - fpsStart)
		text.row = 25; text.column = 59
		print "FPS: " + round(fps) + "  "
		globals.fpsStart = now
		globals.fpsFrameCount = 0
	end if
end function

// define the track as a series of segments;
// for each one, store the curve (+1 = hard right, -1 = hard left)
trackSegments = [0, 0.5, -0.5, 0, 1, 1, 0, 0, 0, -0.5, -1, -1, -0.5]
curveRate = 0.04
segmentCurveRates = [0,0]
heading = 0

// start the next track segment, updating all relevant
// globals (especially segmentCurveRates, which determines
// the current and next curvature of the road)
startTrackSegment = function(n)
	globals.nextSegY = rasterZ.len - 1  // position of next road segment on screen
	globals.curSeg = n
	nextSeg = (curSeg + 1 + trackSegments.len) % trackSegments.len
	segmentCurveRates[0] = trackSegments[curSeg] * curveRate
	segmentCurveRates[1] = trackSegments[nextSeg] * curveRate
	text.row = 25; print "Track Segment: " + n + "  "
end function
startTrackSegment 0

startNextTrackSegment = function()
	startTrackSegment (curSeg + 1 + trackSegments.len) % trackSegments.len
end function

// Initial state
bottomTint = 0
stripLeft = 10
totalDistAlongTrack = 0
speed = 0.01

// Main update function
update = function()
	updateRoadDisplay totalDistAlongTrack
	updateBackground
	globals.totalDistAlongTrack = totalDistAlongTrack + speed
	globals.nextSegY = nextSegY - 200/rh * speed
	if nextSegY < 0 then startNextTrackSegment
	updateFpsCounter
end function

// Main loop
while true
	update
	yield
end while