Nebula Terminal 0.2.1

tools/gen_fetch_art.py

@@ -0,0 +1,169 @@
+#!/usr/bin/env python3
+"""Procedurally bake the Nebula welcome art into nebula_fetch_art.rs.
+
+v3: SATURN, per the user's reference image (2026-07-04):
+- planet ball in three latitude bands: `o/0` indigo top, `*` cyan belt,
+  `~` magenta south — dense fill, hard round silhouette
+- a golden `=` ring tilted across the ball: the front arc passes IN FRONT
+  of the planet (overwrites it), the back arc hides behind the ball and
+  only shows outside the silhouette
+- sparse starfield around it: `+` `.` in white / gold / violet
+- 62 cols wide (welcome.rs info_col = 65 depends on this), 19 rows,
+  cell aspect ~2.6:1 corrected via ASPECT
+
+Regenerate: `python tools/gen_fetch_art.py` (stdout shows a true-color
+ANSI preview; D:\\SHARE\\nebula_fetch_preview.html the same in a browser).
+"""
+
+import math
+
+OUT_RS = r"D:\temp_build\nebula\nebula_app\src\window_context\nebula_fetch_art.rs"
+OUT_HTML = r"D:\SHARE\nebula_fetch_preview.html"
+
+W, H = 62, 19
+ASPECT = 2.6            # terminal cell height/width ratio
+
+# --- planet ---
+CX, CY = 27.0, 9.4      # ball center (cells); slightly left so the ring can sweep right
+R = 16.0                # ball radius in x-units
+BELT_TOP = -0.18        # latitude (normalized dy) where the cyan belt starts
+BELT_BOT = 0.30         # where the magenta south begins
+
+# --- ring ---
+TILT = math.radians(14.0)   # ring plane tilt: lower-left -> upper-right
+RING_A = 31.0           # ring ellipse semi-major (x-units)
+RING_B = 8.6            # semi-minor before aspect correction
+RING_HALF = 0.20        # band half-thickness in ellipse-e units (e in [1-h, 1+h])
+RING_EDGE = 0.12        # |e-1| beyond this renders `-` instead of `=`
+
+# --- starfield ---
+STAR_P = 0.022          # per-cell probability outside planet/ring
+
+# --- palette (sampled from the reference) ---
+TERMBG = (13, 15, 24)
+COL_TOP0 = (126, 138, 232)   # indigo `0/o` north, upper rows
+COL_TOP1 = (104, 116, 210)   # ... slightly darker toward the belt
+COL_BELT = (86, 202, 218)    # cyan `*` belt
+COL_SOUTH = (198, 112, 214)  # magenta `~` south
+COL_RING = (214, 170, 78)    # golden `=`
+STAR_COLS = [(212, 216, 230), (214, 170, 78), (150, 128, 224)]
+STAR_CHARS = ["+", ".", "."]
+
+
+def hash01(*args):
+    """Deterministic per-cell noise in [0,1) — bake must be reproducible."""
+    h = 2166136261
+    for a in args:
+        h ^= int(a) & 0xFFFFFFFF
+        h = (h * 16777619) & 0xFFFFFFFF
+    return ((h >> 8) & 0xFFFF) / 65536.0
+
+
+def planet_at(x, y):
+    """Inside the ball? -> (char, color) by latitude band."""
+    dx = x - CX
+    dy = (y - CY) * ASPECT
+    if dx * dx + dy * dy > R * R:
+        return None
+    lat = dy / R  # -1 (north pole) .. 1 (south pole)
+    if lat < BELT_TOP:
+        # North: mixed o/0 rows, indigo, slightly darker toward the belt.
+        t = (lat + 1.0) / max(1e-6, BELT_TOP + 1.0)  # 0 at pole -> 1 at belt
+        col = tuple(round(COL_TOP0[i] + (COL_TOP1[i] - COL_TOP0[i]) * t) for i in range(3))
+        ch = "0" if hash01(x * 31, y * 57) < 0.55 else "o"
+        return ch, col
+    if lat < BELT_BOT:
+        return "*", COL_BELT
+    return "~", COL_SOUTH
+
+
+def ring_at(x, y):
+    """On the ring band? -> (in_front, char, color). Ellipse in tilted plane."""
+    dx = x - CX
+    dy = (y - CY) * ASPECT
+    # Rotate into the ring plane (screen y points down, tilt is CCW).
+    u = dx * math.cos(TILT) - dy * math.sin(TILT)
+    v = dx * math.sin(TILT) + dy * math.cos(TILT)
+    e = math.hypot(u / RING_A, v / RING_B)
+    if abs(e - 1.0) > RING_HALF:
+        return None
+    # Band core reads `=`, the thin inner/outer fringes read `-`.
+    ch = "=" if abs(e - 1.0) <= RING_EDGE else "-"
+    # v > 0 = the arc dipping below the ring plane on screen -> in front.
+    return v > 0.0, ch, COL_RING
+
+
+grid = [[None] * W for _ in range(H)]  # (char, (r,g,b)) or None
+for y in range(H):
+    for x in range(W):
+        planet = planet_at(x, y)
+        ring = ring_at(x, y)
+
+        if ring is not None:
+            in_front, ring_ch, ring_col = ring
+            if in_front or planet is None:
+                # Front arc always wins; back arc only outside the ball.
+                grid[y][x] = (ring_ch, ring_col)
+                continue
+        if planet is not None:
+            grid[y][x] = planet
+            continue
+        # Starfield. Spatial-hash mix of both coords per word, otherwise
+        # nearby rows correlate and stars line up in fake columns.
+        rnd = hash01(x * 73856093 ^ y * 19349663, y * 83492791 ^ x * 2971215073)
+        if rnd < STAR_P:
+            pick = int(hash01(x * 419 + y, y * 631 + x) * len(STAR_COLS)) % len(STAR_COLS)
+            grid[y][x] = (STAR_CHARS[pick], STAR_COLS[pick])
+
+# --- emit ---
+rs_lines, html_lines, filled = [], [], 0
+for y in range(H):
+    row_rs, row_html = [], []
+    for x in range(W):
+        cell = grid[y][x]
+        if cell is None:
+            row_rs.append(" ")
+            row_html.append(" ")
+        else:
+            filled += 1
+            ch, (r, g, b) = cell
+            row_rs.append(f"\\x1b[38;2;{r};{g};{b}m{ch}")
+            row_html.append(f'<span style="color:rgb({r},{g},{b})">{ch}</span>')
+    line = "".join(row_rs).rstrip()
+    if line:
+        line += "\\x1b[0m"
+    rs_lines.append(line)
+    html_lines.append("".join(row_html).rstrip())
+
+header = (
+    "//! Nebula welcome-screen fetch art: Saturn (user reference 2026-07-04).\n"
+    "//! Latitude-banded ball (o/0 indigo, * cyan, ~ magenta), golden tilted\n"
+    "//! `=` ring with front/back occlusion, sparse starfield.\n"
+    "//! Regenerate with `python tools/gen_fetch_art.py`.\n\n"
+    "#[cfg(windows)]\n"
+    "pub const NEBULA_STAR_ART: &[&str] = &[\n"
+)
+body = "".join(f'    "{l}",\n' for l in rs_lines)
+with open(OUT_RS, "w", encoding="utf-8") as f:
+    f.write(header + body + "];\n")
+
+with open(OUT_HTML, "w", encoding="utf-8") as f:
+    f.write(
+        "<html><body style='background:#0d0f18'>"
+        "<pre style='font:14px/0.9 Consolas,monospace'>"
+        + "\n".join(html_lines)
+        + "</pre></body></html>"
+    )
+
+print(f"baked {W}x{H}, filled {filled} ({filled * 100 // (W * H)}%)")
+# True-color ANSI preview straight to the terminal.
+for y in range(H):
+    out = []
+    for x in range(W):
+        cell = grid[y][x]
+        if cell is None:
+            out.append(" ")
+        else:
+            ch, (r, g, b) = cell
+            out.append(f"\x1b[38;2;{r};{g};{b}m{ch}")
+    print("".join(out).rstrip() + "\x1b[0m")