Y offset for 4x zoom sprites does not precisely match specification.

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
55/100
Issue type
Bug
Clarity
Mostly clear
Activity status
Quiet
Domain
computer-graphics

Research direction

Read the linked RealSprites zoom-level specification, then locate the 4x zoom sprite Y-offset scaling described in the issue. Verify the adjustment against ground tiles and half-tile foundation sprites; it is done when the vertical offset follows the specification and the affected tiles align precisely.

Written by the indexing model from the issue text.

Description

The 4x extra zoom sprites do not follow the specified offset requirements: Scaling of Y offset is currently simply zoom*yrel, wheras the specifications indicate it should have an additional ceil(zoom*-1/2).

This is needed for ground tiles to have perfect alignment with the half tile foundation sprite. Currently, the vertical offset is off by 2. By extension, all ground tiles for buildings etc. need the same offset adjustment, and so all buildings on them do too.

Image The effect is subtle, perhaps most visible for snowy rail half tiles against the normal arctic terrain background. The half tile rail sprite is not cut at precisely the widest part of the tile, and the half tile foundation does not tesselate in (the 2px wide rear wall is not visible).
Dominant language
Python
Stars
94
Forks
16
Avg merge
7d 4h
Merged PRs (30d)
3

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