--First stop time
celestia:settimescale(0)

--Then get variables containing Mars, the observer and the Celestia co-ord->km conversion factors
mars = celestia:find("Mars")
obs = celestia:getobserver()
km_per_mly=9466411.842
mly_per_km=1.0 / km_per_mly

--Clear render flags & labels
celestia:hide("orbits", "constellations", "boundaries", "markers", "grid")
celestia:hidelabel("planets", "moons", "spacecraft", "asteroids", "comets", "constellations", "stars", "galaxies", "locations")

--Preload Mars textures
mars:preloadtexture()

--Create arrays with the TASC generated MEX locations for each image
names = {
          "10-176_11.23.55_VMC_Img_No_1.png",
          "10-176_11.24.42_VMC_Img_No_2.png",
          "10-176_11.25.24_VMC_Img_No_3.png",
          "10-176_11.26.07_VMC_Img_No_4.png",
          "10-176_11.26.50_VMC_Img_No_5.png",
          "10-176_11.27.33_VMC_Img_No_6.png",
          "10-176_11.28.16_VMC_Img_No_7.png",
          "10-176_11.28.59_VMC_Img_No_8.png",
          "10-176_11.29.42_VMC_Img_No_9.png",
          "10-176_11.30.25_VMC_Img_No_10.png",
          "10-176_11.31.08_VMC_Img_No_11.png",
          "10-176_11.31.51_VMC_Img_No_12.png",
          "10-176_11.32.34_VMC_Img_No_13.png",
          "10-176_11.33.17_VMC_Img_No_14.png",
          "10-176_11.34.00_VMC_Img_No_15.png",
          "10-176_11.34.43_VMC_Img_No_16.png",
          "10-176_11.35.25_VMC_Img_No_17.png",
          "10-176_11.36.09_VMC_Img_No_18.png",
          "10-176_11.36.52_VMC_Img_No_19.png",
          "10-176_11.37.35_VMC_Img_No_20.png",
          "10-176_11.38.18_VMC_Img_No_21.png",
          "10-176_11.39.01_VMC_Img_No_22.png",
        }

dates = {
          celestia:utctotdb(2010, 06, 25, 11, 23, 55),
          celestia:utctotdb(2010, 06, 25, 11, 24, 42),
          celestia:utctotdb(2010, 06, 25, 11, 25, 24),
          celestia:utctotdb(2010, 06, 25, 11, 26, 07),
          celestia:utctotdb(2010, 06, 25, 11, 26, 50),
          celestia:utctotdb(2010, 06, 25, 11, 27, 33),
          celestia:utctotdb(2010, 06, 25, 11, 28, 16),
          celestia:utctotdb(2010, 06, 25, 11, 28, 59),
          celestia:utctotdb(2010, 06, 25, 11, 29, 42),
          celestia:utctotdb(2010, 06, 25, 11, 30, 25),
          celestia:utctotdb(2010, 06, 25, 11, 31, 08),
          celestia:utctotdb(2010, 06, 25, 11, 31, 51),
          celestia:utctotdb(2010, 06, 25, 11, 32, 34),
          celestia:utctotdb(2010, 06, 25, 11, 33, 17),
          celestia:utctotdb(2010, 06, 25, 11, 34, 00),
          celestia:utctotdb(2010, 06, 25, 11, 34, 43),
          celestia:utctotdb(2010, 06, 25, 11, 35, 25),
          celestia:utctotdb(2010, 06, 25, 11, 36, 09),
          celestia:utctotdb(2010, 06, 25, 11, 36, 52),
          celestia:utctotdb(2010, 06, 25, 11, 37, 35),
          celestia:utctotdb(2010, 06, 25, 11, 38, 18),
          celestia:utctotdb(2010, 06, 25, 11, 39, 01),
        }

 xarr = {
          4539.657,
          4533.151,
          4527.176,
          4520.903,
          4514.471,
          4507.884,
          4501.140,
          4494.242,
          4487.190,
          4479.986,
          4472.629,
          4465.121,
          4457.462,
          4449.654,
          4441.698,
          4433.593,
          4425.536,
          4416.944,
          4408.401,
          4399.714,
          4390.882,
          4381.908,
        }

 zarr = {
          11229.04,
          11274.871,
          11315.426,
          11356.556,
          11397.29,
          11437.629,
          11477.573,
          11517.123,
          11556.278,
          11595.04,
          11633.409,
          11671.384,
          11708.966,
          11746.156,
          11782.953,
          11819.359,
          11854.539,
          11890.994,
          11926.224,
          11961.064,
          11995.512,
          12029.57,
        }

 yarr = {
          4963.105,
          4923.308,
          4887.568,
          4850.810,
          4813.882,
          4776.787,
          4739.527,
          4702.104,
          4664.520,
          4626.777,
          4588.878,
          4550.822,
          4512.614,
          4474.254,
          4435.745,
          4397.088,
          4359.189,
          4319.338,
          4280.249,
          4241.020,
          4201.652,
          4162.147,
        }

obsno = 22
obstring = "25 June 2010"

--Set the initial time
celestia:settime(dates[1]);

--Go to Mars then write title
obs:track(mars)
celestia:flash("European Space Agency\nMars Express Visual Monitoring Camera\nObservation "..obstring, 15)
obs:goto(mars,5)
obs:goto((mars:getposition() + celestia:newvector(xarr[1], yarr[1], zarr[1]) * (mly_per_km)),5)
wait(10)
celestia:flash("Press 'M' for next image, 'N' for previous image.\nUse left and right arrow keys to rotate the\nplanet to the same orientation as the image.", 10)
wait(10)
celestia:showlabel("locations", "moons", "spacecraft")

--Create a function that goes to a given image number
gotoimage = function(imgno)
	
	celestia:settime(dates[imgno])
		
	obs:setposition(mars:getposition() + celestia:newvector(xarr[imgno], yarr[imgno], zarr[imgno]) * (mly_per_km))
		
	celestia:select(mars)
	
	obs:track(mars)
	
	celestia:flash(names[imgno], 60)	

end

--Create a function that will go to the next image in the series
next = function(goto)

	if (count + 1)>obsno then
		count = 1
	else
		count = count + 1
	end
	
	gotoimage(count)
end

--Create a function that will go to the previous image in the series
last = function()
	
	if (count - 1)<1 then
		count = obsno
	else
		count = count - 1
	end
  
    gotoimage(count)
end

--Create a counter holding the position of the current image
count = 1

--Set the position to the first image
gotoimage(count)

--Add the necessary keyboard callback code
keymap = { n = last, m = next }

celestia_keyboard_callback = function(key) 
     f = keymap[key]
     if f then 
        f() 
        return true
     end
        return false
end

celestia:requestkeyboard(true)
repeat
     wait(10)
until false