Celestia

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-- ---------------------------------------------------------------------------------------
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-- This file demonstrates the 'celestia:overlay' command
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-- The command allows you to display an image in the format BMP, JPG, PNG, which must be
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-- Pre-located in the "images" folder or its sub-folders of the Celestia main directory.
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-- Supports image scaling, transparency and positioning.
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-- Script author: Vincent (June 2006, contact: vince.gian@free.fr)
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-- Modified by: Sergey Leonov aka Leserg <leserg@ua.fm>
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--
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--  This command accepts 6 arguments:
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--
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--  celestia:overlay ( float [duration], float [xoffset], float [yoffset], float [alpha], str [filename], int [fitscreen] )
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--
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--  duration  - Determines the duration of the image display.
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--              If not specified, the default time is 3 seconds.
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--
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--  xoffset   - Determines the placement of the image horizontally
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--              relative to the center of the working area of the Celestia window.
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--              If not specified,  the default value is 0.0.
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--              Valid values are in the range from -1 to 1 relative to the center of the Celestia window:
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--	             > if xoffset = -1 -> The image is placed in the center of the left edge
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--                 Celestia window => You will only see the right half of the image;
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--	             > if xoffset = 1 -> The image is placed in the center of the right edge
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--                 Celestia window => You will only see the left half of the image;
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--
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--  yoffset   - Determines the placement of the image vertically
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--              relative to the center of the working area of the Celestia window.
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--              If not specified,  the default value is 0.0.
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--              Valid values are in the range from -1 to 1 relative to the center of the Celestia window:
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--	             > if yoffset = -1 -> The image is placed in the center of the bottom edge
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--                 of Celestia window => You will only see the upper half of the image;
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--	             > if yoffset = 1 -> The image is placed in the center of the upper edge
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--                 of Celestia window => You will only see the bottom half of the image;
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-- 	             > if xoffset = 0.0 and yoffset = 0.0 -> The image is centered.
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--
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--  alpha     - Determines the transparency of the image on the screen.
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--              If not specified,  the default value is 1.0
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--              Valid values are in the range from 0.0 to 1.0
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--               > if alpha = 0.0 -> The image is completely transparent (ie invisible);
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--               > if alpha = 1.0 -> The image is opaque (i.e., fully visible).
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--
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--  filename  - Specifies the name of the image file to display.
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--              The search for files is relative to the "images" subfolder,
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--              which should be located in the Celestia main directory.
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--              Thus, all the images for display using the script command must be in the
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--              "images" folder or its subfolders.
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--
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--  fitscreen - Determines the image zoom mode:
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--               > if fitscreen = 0 -> The image will be shown in the original size;
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--               > if fitscreen = 1 -> The image will be scaled by the Celestia window.
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--              If not specified,  the default value is 0.
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--  --------------------------------------------------------------------------------------
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celestia:print ( "Welcome!\n\nYou start a script with examples of displaying the image on the screen.", 5.0, -1, -1, 3, 5 )
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wait (5)
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-- ======< Example 1 >======
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-- In the center of the Celestia window, display the image file "image.jpg". Time 6 seconds.
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-- Set the transparency level to 0.7. The parameter 'fitscreen' is used with default value,
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-- so do not specify it.
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celestia:overlay ( 6, 0, 0, 0.7, "image.jpg" )
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wait(1)
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celestia:print ( "The image is placed in the center of the window.", 4.0, -1, -1, 3, 5 )
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wait(4)
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wait(2)
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-- ======< Example 2 >======
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-- We will deduce on the center an image file "image.jpg" and we will deploy it on all window Celestia.
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-- Set the transparency level to 0.5. Time 6 seconds.
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celestia:overlay ( 6, 0, 0, 0.5, "image.jpg", 1 )
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wait(1)
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celestia:print ( "The image is maximized on the whole window.", 4.0, -1, -1, 3, 5 )
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wait(4)
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wait(2)
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-- ======< Example 3 >======
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-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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-- Now we will display the image sequentially at the corners of the Celestia window.
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-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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-- The original width of the image in pixels
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image_width = 512
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-- The original height of the image in pixels
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image_height = 256
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-- Determine the width and height for the working area of the Celestia window
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screen_width, screen_height = celestia:getscreendimension()
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xoffset_left = (image_width/screen_width) - 1
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-- (xoffset_right = - xoffset_left).
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xoffset_right = 1 - (image_width/screen_width)
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yoffset_bottom = (image_height/screen_height) - 1
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-- (yoffset_top = - yoffset_bottom).
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yoffset_top = 1 - (image_height/screen_height)
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celestia:print ( "Now the image will be shown at the corners of the window.", 5.0, -1, -1, 3, 5 )
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wait(6)
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celestia:overlay (3, xoffset_left, yoffset_bottom, 0.5, "image.jpg")
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wait(3)
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celestia:overlay (3, xoffset_left, yoffset_top, 0.5, "image.jpg")
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wait(3)
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celestia:overlay (3, xoffset_right, yoffset_top, 0.5, "image.jpg")
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wait(3)
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celestia:overlay (3, xoffset_right, yoffset_bottom, 0.5, "image.jpg")
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wait(3)
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wait(1)
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-- ======< Example 4 >======
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-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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--   Now the image will move around the screen with the 'ping-pong' effect.
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-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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x_pos = 0
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y_pos = 0
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x_mod = 0.05
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y_mod = 0.05
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script_running = true
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celestia:print ( "Now the image will move around the screen.", 5.0, -1, -1, 3, 5 )
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wait(5)
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wait(1)
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-- Define the keystroke processing function
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function celestia_keyboard_callback(str)
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		script_running = false
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end
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-- Enable event handling by keystrokes
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celestia:requestkeyboard(true)
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-- Run the execution of the loop, which will work until you press any key on the keyboard.
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while script_running do
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	image_width = 512
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	image_height = 256
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	screen_width, screen_height = celestia:getscreendimension()
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	xoffset_left = (image_width/screen_width) - 1
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	xoffset_right = - xoffset_left
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	yoffset_bottom = (image_height/screen_height) - 1
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	yoffset_top = - yoffset_bottom
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	if x_pos <  xoffset_left then
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		x_pos = xoffset_left
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		x_mod = 0.02
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	end
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	if x_pos >  xoffset_right then
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		x_pos = xoffset_right
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		x_mod = -0.02
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	end
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	if y_pos <  yoffset_bottom then
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		y_pos = yoffset_bottom
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		y_mod = 0.02
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	end
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	if y_pos >  yoffset_top then
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		y_pos = yoffset_top
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		y_mod = -0.02
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	end
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-- Display the image on the screen, according to the calculated coordinates.
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	celestia:overlay (0.01, x_pos, y_pos, 0.5, "image.jpg")
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-- Calculate the new coordinates of the image.
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	x_pos = x_pos + x_mod
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	y_pos = y_pos + y_mod
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	celestia:print("Press any key to end the script ...", 0.5, -1, -1, 2, 4)
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	wait (0.01)
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end
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