Rename crt → osc throughout

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-04-05 13:43:15 +10:00
parent 7ceac6c91f
commit 94d5b2cf63
9 changed files with 31 additions and 10 deletions
--- a/src/osc/phosphor.nim
+++ b/src/osc/phosphor.nim
@@ -0,0 +1,100 @@
+## Phosphor buffer with CRT physics: persistence decay, beam bloom,
+## and half-block rendering with intensity-based shading.
+
+import illwill, math
+
+const
+  PhosphorDecay*  = 0.60   # per-frame persistence (P31 green phosphor)
+  BeamIntensity*  = 0.9    # brightness at beam impact
+  BloomInner*     = 0.25   # glow spread to adjacent pixels
+  BloomOuter*     = 0.08   # faint halo from electron scatter
+  MinBright*      = 0.02   # below this, phosphor is considered off
+
+type
+  Intensity* = enum
+    iHot     ## beam core — white-hot
+    iBright  ## fluoro green phosphor
+    iMedium  ## green glow
+    iDim     ## faint persistence trail
+
+  PhosphorBuffer* = object
+    w*, h*: int          # terminal columns/rows
+    pixH*: int           # pixel height (2× rows via half-blocks)
+    data*: seq[float]    # brightness per pixel [w × pixH]
+
+proc initPhosphor*(w, h: int): PhosphorBuffer =
+  let pixH = h * 2
+  PhosphorBuffer(w: w, h: h, pixH: pixH, data: newSeq[float](w * pixH))
+
+proc idx(pb: PhosphorBuffer, x, y: int): int {.inline.} =
+  y * pb.w + x
+
+proc add(pb: var PhosphorBuffer, x, y: int, intensity: float) {.inline.} =
+  if x >= 0 and x < pb.w and y >= 0 and y < pb.pixH:
+    pb.data[pb.idx(x, y)] = min(pb.data[pb.idx(x, y)] + intensity, 1.0)
+
+proc decay*(pb: var PhosphorBuffer) =
+  for i in 0..<pb.data.len:
+    pb.data[i] *= PhosphorDecay
+    if pb.data[i] < MinBright:
+      pb.data[i] = 0.0
+
+proc plotDot*(pb: var PhosphorBuffer, fx, fy: float) =
+  ## Deposit a phosphor dot with physics-based bloom.
+  let x = int(fx)
+  let y = int(fy)
+  if x < 0 or x >= pb.w or y < 0 or y >= pb.pixH: return
+
+  # Beam impact
+  pb.add(x, y, BeamIntensity)
+  # Inner bloom — phosphor scatter
+  pb.add(x, y - 1, BloomInner)
+  pb.add(x, y + 1, BloomInner)
+  pb.add(x - 1, y, BloomInner * 0.5)
+  pb.add(x + 1, y, BloomInner * 0.5)
+  # Outer bloom — electron scatter
+  pb.add(x, y - 2, BloomOuter)
+  pb.add(x, y + 2, BloomOuter)
+  pb.add(x - 1, y - 1, BloomOuter)
+  pb.add(x + 1, y - 1, BloomOuter)
+  pb.add(x - 1, y + 1, BloomOuter)
+  pb.add(x + 1, y + 1, BloomOuter)
+
+proc plotLine*(pb: var PhosphorBuffer, x0, y0, x1, y1: float) =
+  ## Interpolated line of phosphor dots between two points.
+  let steps = max(int(max(abs(x1 - x0), abs(y1 - y0))), 1)
+  for i in 0..steps:
+    let t = i.float / steps.float
+    pb.plotDot(x0 + (x1 - x0) * t, y0 + (y1 - y0) * t)
+
+# ── Half-block rendering ────────────────────────────────────────────
+
+proc toIntensity*(b: float): Intensity =
+  if b > 0.7: iHot elif b > 0.4: iBright elif b > 0.15: iMedium else: iDim
+
+proc writePhosphor*(tb: var TerminalBuffer, x, y: int, ch: string,
+                    intensity: Intensity) =
+  case intensity
+  of iHot:    tb.write(x, y, fgWhite, styleBright, ch)
+  of iBright: tb.write(x, y, fgGreen, styleBright, ch)
+  of iMedium: tb.write(x, y, fgGreen, ch)
+  of iDim:    tb.write(x, y, fgGreen, styleDim, ch)
+
+proc render*(pb: PhosphorBuffer, tb: var TerminalBuffer) =
+  ## Blit the phosphor buffer to the terminal using half-block characters.
+  for ty in 0..<pb.h:
+    let topRow = ty * 2
+    let botRow = ty * 2 + 1
+    for x in 0..<pb.w:
+      let topB = if topRow < pb.pixH: pb.data[pb.idx(x, topRow)] else: 0.0
+      let botB = if botRow < pb.pixH: pb.data[pb.idx(x, botRow)] else: 0.0
+
+      if topB > MinBright or botB > MinBright:
+        let tOn = topB > MinBright
+        let bOn = botB > MinBright
+        if tOn and bOn:
+          tb.writePhosphor(x, ty, "█", toIntensity(max(topB, botB)))
+        elif tOn:
+          tb.writePhosphor(x, ty, "▀", toIntensity(topB))
+        else:
+          tb.writePhosphor(x, ty, "▄", toIntensity(botB))