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一段linux下用OpenGL实现的小程序

                Smooth Scrolling
                ----------------

      This is a simple demonstration of ultra
    smooth scrolling, using OpenGL and sub-pixel
      accurate rendering. Map editor included.


The demo works best with retrace syncronized pageflipping,
and on systems that are fast enough to maintain a steady
full frame rate. In works pretty well without retrace sync,
but it isn't nearly as smooth at higher speeds.

Note that interpolation across tile edges is solved in a
most primitive way in this demo; it's built right into the
tile palette. Rather than having the engine do some magic,
I'm just relying on the map to use only "compatible" tiles
together. The net result is that the pixels *outside* a
tile will always match the corresponding pixels of the
surrounding tiles on the map.

Command line switches:
	-sdl		Use SDL 2D for rendering
	-w		Use windowed mode
	-s<scale>	Set scale (Default; SDL: 1, OpenGL: 2)
	-b<bpp>		Use <bpp> bits per pixel mode
			(Default: auto)
	-e		Activate map editor
	-m <name>	Use map file <name>
	-ntf		Disable the "time filter"

Redundant switches:
	-gl		Use OpenGL for rendering (default)
	-f		Use fullscreen mode (default)
	-tf		Enable the "time filter"

Control:
	Arrow keys	Change the scrolling speed.
	SPACE		Stop scrolling instantly.
	ESC		Exit demo.


Using the Map Editor
--------------------
This demo includes a primitive map editor that I used to
create the demo map. The editor works only in SDL mode
(which is selected automatically), and supports higher
resolutions through the -s<scale> switch. The map file
edited is the default map file, or the file specified
using the -m <name> switch.

Editor control:
	F2 or S		Saves the current map, OVERWRITING
			any existing file with the same name
			as that specified as the map name.

	ESC		Exits the editor WITHOUT saving.

	SPACE		Switches between selection mode and
			editing mode.

	CTRL		Enters selection mode, but only for
			as long as the CTRL key is held down.

	Arrow keys	Scroll the map.

	Mouse		Moving the mouse (obviously) moves
			the cursor. An animated marker
			indicates which exact tile is under
			the cursor.

	Mouse buttons
		Selection mode:
			Selects tile for the button clicked.

		Editing mode:
			Pastes tile selected for the clicked
			button.


Have fun!


			//David Olofson <[e-mail]>