terminal delight
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Text crawl

Brief

Text crawl tips a pane back into the screen, the way a space film opens. Every row is centred and set in a bold condensed italic, the bottom rows are large, and the text shrinks and narrows as it goes up. Whatever the terminal is showing, it shows it like that.

crawl off centred rows crawl on 12°, depth 2.5×
Figure 1. The same centred rows, flat and under the crawl at its defaults. The top row ends up 73% as wide as the bottom one, and the lower half of the pane holds only the bottom 39% of the rows. Each bar is a row of text. Drawn by docsite/tools/crawl-figure.mjs from the crawl shader.

Turn it on in a pane's GAUGES tray (Ctrl+Shift+G) under TEXT CRAWL. Two knobs appear: angle, how sharply the sides lean in, and depth, how much bigger the bottom rows are than the top ones. It's a way of looking at a terminal rather than working in one: selecting text in a crawling pane is only approximate.

There's a version on the web: the crawl kiosk.

Technical has the ranges and the math.

Technical

Angle and depth

GaugeMCP fieldRangeDefault
crawl on / crawl offcrawlon or offoff
anglecrawl_angle2°–59°12°
depthcrawl_depth0.05–15×2.5×

Crawl is a gauge like warp, so it's set per pane, and a pane follows the window's unless you change it on the pane. Turning it on in GAUGES — OUTER crawls every pane that follows the window. reset turns it off. An agent can set it through the MCP server's set_pane_config, with the angle and depth as percentages of their ranges. There's no theme key for it.

The math#

The top edge's width, as a share of the bottom's, is a = 1 − 1.3 × sin(angle), kept between 0.2 and 1. Depth D is how many times taller the bottom row is than the top. For each point on the pane at height v from the bottom (0 to 1), the renderer shows the content row at (D^v − 1) / (D − 1), and each row's width runs from 1 at the bottom to a at the top. Anything outside that trapezoid is black, and still takes the glass's glare. It's one extra power per pixel in the same pass as the barrel warp, which it stacks with.

What changes and what doesn't#

  • The font becomes News Cycle, a free News Gothic lookalike under the SIL Open Font License, in italic. It ships with Terminal Delight.
  • Rows are centred for display only. The terminal underneath is unchanged.
  • Only the terminal face crawls; the workbench stays flat.
  • A crawling pane is never skipped by the renderer, even at warp 0.
  • The focus reader keeps the crawl's font and centring but reads flat.
  • Clicks are mapped through the barrel warp and not the crawl, which is why selection is approximate.

Sources

  1. The perspective: 0003-text-crawl.patch; the gauges and crawl_coeffs: theme.rs; the font and centring: pane.rs.