--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 = {
          "11-177_20.49.15_VMC_Img_No_1.png",
          "11-177_20.50.03_VMC_Img_No_2.png",
          "11-177_20.50.45_VMC_Img_No_3.png",
          "11-177_20.51.28_VMC_Img_No_4.png",
          "11-177_20.52.11_VMC_Img_No_5.png",
          "11-177_20.52.54_VMC_Img_No_6.png",
          "11-177_20.53.37_VMC_Img_No_7.png",
          "11-177_20.54.20_VMC_Img_No_8.png",
          "11-177_20.55.03_VMC_Img_No_9.png",
          "11-177_20.55.46_VMC_Img_No_10.png",
          "11-177_20.56.29_VMC_Img_No_11.png",
          "11-177_20.57.12_VMC_Img_No_12.png",
          "11-177_20.57.55_VMC_Img_No_13.png",
          "11-177_20.58.37_VMC_Img_No_14.png",
          "11-177_20.59.21_VMC_Img_No_15.png",
          "11-177_21.00.04_VMC_Img_No_16.png",
          "11-177_21.00.47_VMC_Img_No_17.png",
          "11-177_21.01.30_VMC_Img_No_18.png",
          "11-177_21.02.13_VMC_Img_No_19.png",
          "11-177_21.02.56_VMC_Img_No_20.png",
          "11-177_21.03.39_VMC_Img_No_21.png",
          "11-177_21.04.21_VMC_Img_No_22.png",
        }

dates = {
          celestia:utctotdb(2011, 06, 26, 20, 49, 15),
          celestia:utctotdb(2011, 06, 26, 20, 50, 03),
          celestia:utctotdb(2011, 06, 26, 20, 50, 45),
          celestia:utctotdb(2011, 06, 26, 20, 51, 28),
          celestia:utctotdb(2011, 06, 26, 20, 52, 11),
          celestia:utctotdb(2011, 06, 26, 20, 52, 54),
          celestia:utctotdb(2011, 06, 26, 20, 53, 37),
          celestia:utctotdb(2011, 06, 26, 20, 54, 20),
          celestia:utctotdb(2011, 06, 26, 20, 55, 03),
          celestia:utctotdb(2011, 06, 26, 20, 55, 46),
          celestia:utctotdb(2011, 06, 26, 20, 56, 29),
          celestia:utctotdb(2011, 06, 26, 20, 57, 12),
          celestia:utctotdb(2011, 06, 26, 20, 57, 55),
          celestia:utctotdb(2011, 06, 26, 20, 58, 37),
          celestia:utctotdb(2011, 06, 26, 20, 59, 21),
          celestia:utctotdb(2011, 06, 26, 21, 00, 04),
          celestia:utctotdb(2011, 06, 26, 21, 00, 47),
          celestia:utctotdb(2011, 06, 26, 21, 01, 30),
          celestia:utctotdb(2011, 06, 26, 21, 02, 13),
          celestia:utctotdb(2011, 06, 26, 21, 02, 56),
          celestia:utctotdb(2011, 06, 26, 21, 03, 39),
          celestia:utctotdb(2011, 06, 26, 21, 04, 21),
        }

 xarr = {
          -970.296,
          -943.660,
          -920.321,
          -896.397,
          -872.443,
          -848.460,
          -824.448,
          -800.409,
          -776.343,
          -752.251,
          -728.134,
          -703.992,
          -679.825,
          -656.199,
          -631.424,
          -607.190,
          -582.934,
          -558.659,
          -534.364,
          -510.050,
          -485.718,
          -461.936,
        }

 zarr = {
          -10736.814,
          -10755.018,
          -10770.585,
          -10786.173,
          -10801.404,
          -10816.278,
          -10830.791,
          -10844.942,
          -10858.729,
          -10872.151,
          -10885.205,
          -10897.89,
          -10910.204,
          -10921.871,
          -10933.71,
          -10944.898,
          -10955.708,
          -10966.136,
          -10976.18,
          -10985.84,
          -10995.112,
          -11003.793,
        }

 yarr = {
          -8006.955,
          -7957.088,
          -7913.187,
          -7867.983,
          -7822.519,
          -7776.795,
          -7730.813,
          -7684.572,
          -7638.073,
          -7591.317,
          -7544.304,
          -7497.035,
          -7449.511,
          -7402.846,
          -7353.699,
          -7305.412,
          -7256.871,
          -7208.079,
          -7159.034,
          -7109.738,
          -7060.191,
          -7011.555,
        }

obsno = 22
obstring = "26 June 2011"

--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