Relates to MC-264576 and MC-269935.

The bug

If a mcmeta file is used to change the scaling behaviour used by the textures of progress bars such as the experience bar, horse/camel/etc. jump bar, boss bars, villager trading bars and so on, the bars will scale strangely and in unexpected ways.

How to reproduce

Three resource packs are attached to this ticket that retexture the jump bar used for horses and such. One sets it to use stretch scaling (default), one makes it use tile scaling, and the last one makes it use nine_slice scaling.

It is worth noting that the progress texture is 32x5, whereas the background is the default 182x5.

1. Download and apply each resource pack
2. Check how the jump bar looks as you jump

Expected results

The following image depicts expected results (left) versus actual results (right):

For stretch scaling, the jump bar's progress texture would stretch horizontally to fill the bar as you hold down longer.

For tile scaling, the progress texture would repeat itself from left to right to fill out the bar.

For nine_slice scaling, the progress would also repeat itself from left to right to fill out the bar, but the dark outer border would not show up until the bar is filled completely since the nine_slice scaling specifies that the outer area is special and should not reappear internally.

Actual results

For stretch scaling, a version of the progress texture which is stretched out to fit the background shape is shown, which is truncated to fit the current progress level.

For tile scaling and nine_slice scaling, the progress texture stretches horizontally to fill the bar. This is the behaviour that was expected for stretch scaling - see above section.

Further notes

If this issue is fixed, then bar textures should use the "tile" scaling method by default as to preserve how things currently look. Since the progress texture is always the same size as the background texture for the default resource pack, the progress will never repeat itself unless it somehow exceeds the dimensions of the background bar (which should never happen) and will be truncated accordingly just like it currently is.