Spring RTS Engine

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...

local function writeBmp(data, filename)
	local file = assert(io.open(filename,'w'), "Unable to save to "..filename)
	-- bitmap file header
	file:write("BM") -- windows bitmap header
	file:write(le.uint32(0)) -- filesize, only useful for compressed bitmaps
	file:write(le.uint16(0)) -- reserved1, always 0
	file:write(le.uint16(0)) -- reserved2, always 0
	file:write(le.uint32(54)) -- offset into file of data
	-- bitmap info header
	file:write(le.uint32(40)) -- size of bitmap info header
	file:write(le.uint32(heightMapX + 1)) -- width (colums)
	file:write(le.uint32(heightMapY + 1)) -- height (rows)
	file:write(le.uint16(1)) -- number of planes
	file:write(le.uint16(32)) -- bits per pixel
	file:write(le.uint32(0)) -- compression type
	file:write(le.uint32(0)) -- size of image data (only necessary if compressed)
	file:write(le.uint32(0)) -- horizontal pixels per meter
	file:write(le.uint32(0)) -- vertical pixels per meter
	file:write(le.uint32(0)) -- number of colours used
	file:write(le.uint32(0)) -- important colours

	-- bmps are upside down
	for row = heightMapY, 0, -1 do
		for col = 0, heightMapX, 1 do
			file:write(le.uint8(data[row][col] or 0):rep(4))
		end
	end

	file:close()
	Spring.Echo("Exported to " .. filename)
end


function widget:TextCommand(command)
	if (string.find(command, 'exportheightmap') == 1) then
		local minHeight, maxHeight = Spring.GetGroundExtremes()
		local heightDif = (maxHeight - minHeight)
		local imageData = {}

		print("min height: " .. tostring(minHeight) .. ", max height: " .. tostring(maxHeight))

		-- save the image data
		for row = 0, heightMapY, 1 do
			imageData[row] = {}

			for col = 0, heightMapX, 1 do
				local pixelHeight = GetGroundHeight(col * 8, row * 8)
				local pixelColor = floor(((pixelHeight - minHeight) / heightDif) * 255)
				imageData[row][col] = pixelColor
			end
		end

		local filename = ("screenshots\\" .. string.lower(string.gsub(Game.mapName, ".smf", "_")) .. "heightmap.bmp")

		writeBmp(imageData, filename)
		Spring.Echo("Map Height - Min: " .. floor(minHeight) .. ", Max: " .. floor(maxHeight))

	end
end