Spring RTS Engine

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local glBeginEnd = gl.BeginEnd
local glColor = gl.Color
local glLineWidth = gl.LineWidth
local glVertex = gl.Vertex
local glRect = gl.Rect
local GL_LINES = GL.LINES
-- remember to repositionate everything using gl.Translate where you want before calling this code!
local horizontalDivisions = 10 -- 10 main divisions
local verticalDivisions = 8 -- 8 main divisions
local cellSideSize = 10 -- division size, in pixel ( you should use a number divisible by 5, for subdivisions! )
local horizontalSize = horizontalDivisions * cellSideSize
local verticalSize = verticalDivisions * cellSideSize
local oscopeBackground = glCreateList( function()
	glColor(0.5, 1.0, 0.5, 0.3)
	glLineWidth(1.0)
	glRect( 0, 0, horizontalSize, verticalSize ) -- draw faint green background
	glColor(0.0, 0.5, 0.0, 0.5) --darker grid
	glLineWidth(0.8)
	local horCount = 0
	while( horCount < (horizontalDivisions+1) ) do -- draw vertical lines
		glBeginEnd(GL_LINES, function()
			glVertex( horCount*cellSideSize, 0)
			glVertex( horCount*cellSideSize, verticalSize)
		end)
		horCount = horCount +1
	end
	local verCount = 0
	while( verCount < (verticalDivisions +1) ) do -- draw horizontal lines
		glBeginEnd(GL_LINES, function()
			glVertex( 0, verCount*cellSideSize)
			glVertex( horizontalSize, verCount*cellSideSize)
		end)
		verCount = verCount +1
	end
end)
local horizontalScale = 1
local verticalScale = 1
local centerPosition = verticalDivisions/2 * cellSideSize
local verticalGain = verticalScale*cellSideSize*verticalDivisions/2
local wavestream = { 0.1, 0.5, -0.3, 0.33  } -- index = sample index, content = value normalized between +-1
local kplogo = glCreateList( function()
	glColor(0.9, 1.0, 0.9, 1.0) -- bright line marks
	glLineWidth(1.5)
	--glSmoothing() --perhaps enable smoothing?
	local previousValue = 0
	for x,y in ipairs(wavestream) do
		local currentPos = (x*horizontalScale) % (horizontalSize)
		local previousPos = ((x-1)*horizontalScale) % (horizontalSize)
		if previousPos ~= (horizontalSize-1) then -- don't draw the line connecting end to begin
			glBeginEnd(GL_LINES, function()
				glVertex(previousPos, centerPosition + previousValue*verticalGain) -- draw a segment connecting to the previous sample
				glVertex(currentPos, centerPosition + y*verticalGain)
			end)
		end
		previousValue = y
	end
end)