Check out my first novel, midnight's simulacra!
Theory and Practice of Sprixels: Difference between revisions
From dankwiki
| Line 69: | Line 69: | ||
===Temporal vs Positional=== | ===Temporal vs Positional=== | ||
Sixel writes the provided glyph as a unit, starting at the current cursor position (assuming we've entered DECSDM aka "Sixel Display Mode", which we always do—otherwise all sixels are emitted at the upper left corner of the display). Bits not specified in the sixel are transparent (assuming the Device Control String has used the value 1 for parameter <tt>P2</tt>), and transparent pixels leave undisturbed whatever was already present at the time of emission. Writing an entirely transparent region is a no-op. Writing a new character (or new Sixel pixels) anywhere in the graphic's region will wipe out the entirety of that cell. The Sixel data thus annihilated | Sixel writes the provided glyph as a unit, starting at the current cursor position (assuming we've entered DECSDM aka "Sixel Display Mode", which we always do—otherwise all sixels are emitted at the upper left corner of the display). Bits not specified in the sixel are transparent (assuming the Device Control String has used the value 1 for parameter <tt>P2</tt>), and transparent pixels leave undisturbed whatever was already present at the time of emission. Writing an entirely transparent region is a no-op. Writing a new character (or new Sixel pixels) anywhere in the graphic's region will wipe out the entirety of that cell. The Sixel data thus annihilated are not recoverable. This means that updating the text underneath a Sixel will blow the obscuring graphics away, requiring that the affected Sixel pixels be rerendered. In the event of stacked sprixels, we would potentially need to rerender the entire stack. In a naive implementation, changing one text cell "underneath" the octopus could result in painting 781 cells (the text cell actually being changed, and the 780 cells of the octopus). This is plainly undesirable. | ||
With Kitty, a graphic is positional. All text is assumed to be at z=0. Graphics with non-negative coordinates obscure text. Graphics with negative coordinates sit underneath text. Note that this means we must choose whether a Kitty sprixel is going to have text above it, or under it, but no arbitrary single sprixel can do both. | With Kitty, a graphic is positional. All text is assumed to be at z=0. Graphics with non-negative coordinates obscure text. Graphics with negative coordinates sit underneath text. Note that this means we must choose whether a Kitty sprixel is going to have text above it, or under it, but no arbitrary single sprixel can do both. | ||
