Area door/animation graphic (black line/seam) issues

[Sam.]

And @argent77 once again swoops in with the solution to all our problems.  In this case an automated solution that eliminates the dark lines around overlay tiles when converting from palette-based tilesets to PVR(Z)-based tilesets.  His method is different than mine, but objectively his approach is superior.  And he released it before I could finish writing my own tool to do this, so I bow to the master.

[argent77]

On 5/14/2023 at 2:50 AM, Sam. said:

PVRZ files are Z-Lib compressed versions of the PowerVR container file format (PVR).  This file format supports a large number of texture compression algorithms, but the EEs use the Block Compression (BC) aka DXT family of LOSSY texture compression algorithms.  A side effect of the nature of these compression algorithms is that the color of a pixel will “bleed” into the pixels that surround it.
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It is EXTREMELY important to note that once a tileset has been packed improperly and stray colors have bled into your overlay tiles, the damage has already been done.  You can’t simply rearrange them after the fact and expect the graphical artifacts to go away!!!

The color bleeding effect of DXT encoding is actually less of a problem than the way how the EE engine assembles the tiles to generate the map background in the game. Moreover, the bleeding effect occurs only if adjacent pixels lie inside a single DXT-encoded block of 4x4 pixels.

Reconverting a "problematic" tileset with NI can fix these issues in most cases. (There will still be edge cases where the lossy nature of DXT compression can produce visible artifacts, but they are rare.)

Example conversion of the High Hedge interior crystal animation with the very noticeable horizontal line:

Spoiler

 

Edited April 23 by argent77