SonED2 Level Editor

The Level Editor is used for editing the layout of normal gameplay levels. Levels are built by placing "Chunks" onto the level grid with the cursor. "Chunks" can be either 256 or 128 pixels in both width and height depending on the target game, and are built from 16x16 "Blocks", which are built from 8x8 Tiles. They can all be built and modified from within the Tile Editor, or they may be imported from an image file.

Levels are composed of two planes: Plane A (Foreground) and Plane B (Background, and in some cases, special moving floors). These planes are further divided into "High" and "Low" portions by settings within the 16x16 Blocks.

The Level Editor may be used to edit Plane A, Plane B, or its own "clipboard" plane. The clipboard plane receives imported plane layout data, but may also be drawn to manually as with Planes A and B. This data may then be pasted onto Plane A or B at any location.

The following features are available in this editor:

• Status
  
• Drawing to the Level
  
• Pasting from the Clipboard
  
• Toggling "Loop" Tile
  
• Selecting or "Grabbing" a Chunk
  
• Moving Around the Level
  
• Resizing the Level
  
• Switching Between Planes and Other Editing Modes
  
• Altering Scroll Speed
  
• Viewing Controls
  
• Split-Screen Mode Compatibility
  
  Status
  
  
  The Status Display appears at the upper-left corner of the editor and displays certain level and editor information.
  
  This display may be toggled off and back on by pressing "Tab".
  
  
  

  Screen Position	-	The X and Y world position of the top-left corner of the screen, shown in hex as with the in-game debug modes
  Cursor Position	-	The X and Y layout position being pointed to by the cursor, followed by its byte position within the data when the map layout is expressed as a linear (1D) array
  Plane Size	-	The Width and Height of the plane currently selected for editing, measured in Chunks, shown in hex
  Current Chunk	-	The currently-selected Chunk. This Chunk is displayed as the cursor, and will be inserted into the level when "drawing"
  Chunk at Cursor	-	The ID of the Chunk that is currently placed at the level position under the cursor
  Solid ???	-	This entry describes which of the two solidity paths is being drawn over the level, and whether or not the corresponding angle values are shown
  Objects ???	-	This entry describes how the objects are currently being displayed relative to the high/low planes of the level
  Scroll Speed	-	The number of pixels that the screen will move when the arrow keys are used for scrolling

  
  
  Drawing to the Level
  
  
  To draw the currently-selected Chunk onto the currently-selected level plane, left-click the desired location, or hold the left mouse button and drag across the desired area
  
  
  Pasting from the clipboard
  
  
  To paste the contents of the clipboard onto the currently-selected level plane, move the cursor to the upper-left corner of the desired area, then hold Ctrl and press P
  
  
  Toggling "Loop" Tile
  
  
  In games that do not support a two-path level collision system, such as Sonic 1 and Sonic CD, "loops" are kept track of by an array stored in the program that holds two Chunk IDs per zone, specifying which two Chunks can act as "loops". "Loop" Chunks in these game types should be stored once with solidity traveling up the right side, and should be immediately followed by a visually identical copy with solidity traveling down the left side. The Chunk must also be "flagged" within the level layout. To do this, hover over the Chunk and press Spacebar. When a Chunk is "flagged", its ID shown by the "Chunk at Cursor" status element will be followed by the word "(Loop)". If the game's loop Chunk ID array must be modified, the ID that should be entered into the array is the Chunk's real ID plus 0x80 (128). None of this applies to games that use a two-path level collision system, as those games use special objects to trigger collision changes instead
  
  
  Selecting or "Grabbing" a Chunk
  
  
  To select a Chunk for drawing, use the A and Z keys or the mouse wheel to cycle through the list, right-click the map to "pick up" the Chunk that is under the cursor's current position, or use the "Chunk Selector" in the Tile Editor
  
  
  Moving Around the Level
  
  
  To scroll around the level area, use the Arrow Keys to scroll by the "scroll value", or use the scrollbars surrounding the window. When holding CTRL, moving the mouse pointer to the edges of the screen will also scroll
  
  
  Resizing the Level
  
  
  Holding Ctrl while pressing the arrow keys will change the level size. Left and Down increase Width and Height, Right and Up decrease Width and Height. (This is level data size, not gameplay boundary size. The in-game boundaries are determined by another array, and are usually modified by program code during gameplay)
  
  
  Switching Between Planes and Other Editing Modes
  
  
  The "Editors" menu has options to switch to any of the other editing modes available to a project using this editor. The following keys also have the same effect:
  
  

  L	-	Level Editor Plane A (foreground)
  P	-	Level Editor Plane B (background)
  K	-	Level Editor Clipboard
  O	-	Object Editor

  
  
  Altering Scroll Speed
  
  
  The H and N keys increase and decrease the number of pixels that the screen will scroll when using the arrow keys or moving the mouse to the screen edges while holding CTRL
  
  
  Viewing Controls
  
  
  The following keys affect other viewing options:
  
  

  Q	-	Disable Solidity viewing
  W	-	Display Solidity Path 0 Over Level
  E	-	Display Solidity Path 1 Over Level (for games that support two-path collision)
  R	-	Toggle angle view when viewing solidity path
  T	-	Change object viewing status: Disabled Below High Plane (Game View, some objects "hidden" by the foreground) Above High Plane (All objects on top, total visibility)
  Y	-	Toggles the "Low" plane on or off
  U	-	Toggles the "High" plane on or off

Split-Screen Mode Compatibility

Sonic the Hedgehog 2 features a split-screen competition mode that makes use of the Megadrive/Genesis's "interlace mode" to double the screen's vertical resolution. While using this mode, the system switches from using 8x8 Tiles to 8x16 Tiles, so 16x16 Blocks must be set up in the following way:

Within both columns of a 16x16 Block, the two 8x8 Tile entries must be set to the same palette row and the same drawing priority. Not following this rule will cause the graphics to display improperly, because the Block now effectively has two 8x16 Tile entries instead of four 8x8 Tile entries. In effect, this means that the game will only be reading the settings for the two 8x8 Tile entries on the upper row, and applying them to the two entries on the bottom row (Ex: The properties of the lower-left Tile entry must be set equal to the properties of the upper-left Tile entry for them to be displayed as they were designed, because while in "interlace mode", those two Tiles become one double-height Tile, and only the settings for the upper-left Tile entry will be read and applied). These two settings cannot be compensated for through automated conversion; care must be taken to follow this rule while initially designing the level graphics and layout

Using this option will, however, automatically re-arrange and duplicate the Tiles as needed to construct a full set of proper 8x16 Tiles and compensate for lower-row Tile entries using different draw direction settings than the entry immediately above them

Because of the nature of this video mode, performing this conversion can sometimes dramatically increase the number of 8x8 Tiles. This can't be helped, as while this creates many duplicate 8x8 Tiles, all of the tiles are actually unique when regarded as 8x16, and are necessary to render the level the way it was designed. Care should be taken to reduce the number of 8x8 Tiles that are used in the initial production of the level so that this process doesn't generate too many to be used in-game

To perform this conversion, select the "Make Level 2P Compat" option in the "Editor" menu. If any Block settings errors are detected, they will be noted through the message system

In terms of the original, unmodified game programs, this mode is only available in Sonic 2 (Sonic 3 uses normal resolution with smaller graphics). The option is available at all times in the Level Editor, but it is not designed to handle "Tile Paging", and so, the conversion will not be performed when there is more than one 8x8 Tiles page