VRAM Windows

VRAM Windows

A composite is a copy of an area of video memory (VRAM). It puts entries one after another and uses them as one tile source. Getting Started makes a simple composite. This page shows the other features.

Start from the project you made in Getting Started.

1. A window is what video memory holds

1. Select Level tiles.

2. Right-click ▸ Edit….

At, Tile and Bytes give the start and the size of each piece.

While a level runs, the game copies more tiles into VRAM: the frames of the ?-block, coin and water animations, from GFX33. They replace tiles $40 to $7F of this window. To show them, a composite can use part of an entry: a byte range. A byte range counts unpacked bytes, so it can use part of a compressed sheet.

The dialog can move or remove ranges. It cannot make new ones. Add source… adds a whole entry. To add a range, edit the project file. Each piece of a composite is one line in its pieces list. This piece is 4 tiles of entry 7, starting at tile 192 (3bpp, 24 bytes a tile):

{ "entry_index": 7, "offset": 4608, "length": 96 }

2. A gap, held open

Each VRAM slot is 128 tiles. On the THE END screen, the second sprite slot holds GFX30, which is only 64 tiles. A blank piece fills the rest of the slot, so the sheets after it stay in the correct place.

1. Carve these four sheets. Select the ROM in Files, then File ▸ New Slice…. Set Compression to LZ2 improved and leave Length blank.

Name	Offset
GFX2C	$5D7B9
GFX30	$5F3BB
GFX2D	$5E006
GFX0E	$4DDCB

2. File ▸ New Composite View…. Name it THE END sprites.
3. In Add source…, pick GFX2C, then GFX30.
4. Click Add blank.
5. Set the Bytes of the blank to 1536. This is 64 tiles of 3bpp, 24 bytes a tile.
6. Add GFX2D and GFX0E.

7. Click OK. Set Rows to 32.

3. A map through a window

The Tiles setting of Background stamps is the Level tiles window.

Open the Tile Source tab and click a cell. A ring shows the tile that the cell uses. The tile shows in the palette row of the cell.

To open the tile source, click the ring button next to Tiles. To go back: Navigate ▸ Back (Alt+Left).

4. Editing through a window

When you draw on a composite, celPix edits the entry that the tile comes from. Here, the tile comes from GFX1B.

GFX1B is marked ●: it has the unsaved change.

Drawing on a blank piece has no effect.

You can also draw on a map in Pixel Mode. celPix edits the sheet through the window.