Working -- prior to mushroom cloud addition.

README.md

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+# vectordesert
+
+An infinite wire-mesh vector desert flythrough, written in C with OpenGL
+(GLFW). A vast, mostly-flat wireframe plain rolls past, interrupted now and
+then by vector mountain ranges, with saguaro cacti scattered across both.
+The terrain is built from **square wire-mesh frames**; the saguaros are
+ribbed wire-mesh tubes shaped to resemble real cacti (tapered, dome-tipped
+trunks with arms that curve out and sweep upward).
+
+## Build
+
+Requires a C compiler, GLFW 3, and OpenGL.
+
+Debian/Ubuntu:
+```
+sudo apt install build-essential libglfw3-dev
+```
+Fedora:
+```
+sudo dnf install glfw-devel
+```
+macOS (Homebrew):
+```
+brew install glfw
+```
+
+Then:
+```
+make
+```
+
+## Run
+
+```
+./vectordesert                 # windowed
+./vectordesert --fullscreen    # full screen
+```
+
+### Command-line settings
+```
+--terrain-hue=0..1        hue of the terrain mesh         (default 0.075)
+--mountain-freq=0.2..4    how often the plain is interrupted by a range
+                          (low = rare; high = frequent)   (default 1.0)
+--mountain-rough=0..1     flat-topped mesas .. jagged peaks    (default 0.5)
+--mountain-min-height=0..80 height of a range's low parts     (default 6)
+--mountain-max-height=0..80 height of the tallest peaks        (default 26)
+--cactus-freq=0..1        chance of a cactus per cell      (default 0.35)
+--cactus-size-var=0..0.95 random cactus size spread        (default 0.55)
+--cactus-min-size=1..30   smallest cactus height           (default 4)
+--cactus-max-size=1..30   largest cactus height            (default 12)
+--cactus-hue=0..1         hue of the cacti                 (default 0.33)
+--max-arms=0..12          arms on the largest cacti        (default 5)
+```
+Example:
+```
+./vectordesert --fullscreen --terrain-hue=0.55 --mountain-freq=1.8 \
+               --cactus-hue=0.30 --cactus-freq=0.5 --max-arms=8
+```
+
+### Camera
+| keys | does |
+|------|------|
+| `W` / `S` | throttle: accelerate / decelerate forward speed (holds when released; `S` past zero goes into reverse) |
+| `A` / `D` | strafe left / right |
+| `Page Up` / `Page Down` | raise / lower camera altitude |
+| `←` / `→` | pan view left / right |
+| `↑` / `↓` | pan view up / down |
+| `[` / `]` | decrease / increase rendering distance |
+
+Velocity is held in world space, so panning the view with the arrow keys
+only changes where you look — it does not change the direction you are
+travelling. To steer, turn and then apply throttle.
+
+The terrain is generated around the camera and cached — rebuilt only as you
+travel out of the cached region — so the plain extends infinitely in every
+direction. Rendering distance (`[` / `]`) ranges from 40 up to 960 units.
+
+### Live setting controls
+| keys | adjusts |
+|------|---------|
+| `1` / `2` | terrain hue |
+| `3` / `4` | mountain range frequency |
+| `,` / `.` | mountain roughness (flat mesas ↔ jagged peaks) |
+| `T` / `Y` | minimum mountain range height |
+| `U` / `I` | maximum mountain range height |
+| `5` / `6` | cactus frequency |
+| `7` / `8` | cactus size variation |
+| `J` / `K` | minimum cactus size |
+| `N` / `M` | maximum cactus size |
+| `9` / `0` | cactus hue |
+| `-` / `=` | maximum cactus arms |
+| `F` | toggle fullscreen |
+| `ESC` | quit |
+
+Current settings are printed to the terminal as you change them, and an
+on-screen heads-up display (drawn in the same vector style) lists every
+setting next to the key(s) that change it. The HUD fades out after 10
+seconds with no keypresses and snaps back as soon as you press a key.
+
+## Notes
+
+- **Arms scale with size:** the number of arms is derived from a cactus's
+  normalized size, so the smallest cacti always have the fewest arms (down
+  to a bare trunk) and the largest always reach `max-arms`.
+- The world is generated procedurally from a hash-based value-noise height
+  field, so it is effectively infinite — the camera flies forever.
+- Distance fog fades distant geometry into the dusk sky for depth.
+
+## Performance
+
+The renderer is built for throughput at large draw distances:
+
+- All wireframe segments for a frame are collected into one vertex/colour
+  array and drawn with a single `glDrawArrays(GL_LINES)` per mesh, instead
+  of per-object immediate-mode `glBegin`/`glEnd`.
+- Terrain and cactus meshes are **cached** and only rebuilt when a relevant
+  setting changes or the camera leaves the cached region; most frames do no
+  geometry work at all.
+- Terrain uses a **cell budget** (level of detail): the grid spacing grows
+  with the rendering distance, so the cell count stays bounded as the radius
+  scales up.
+- Each terrain vertex's height is computed once and shared by its edges (no
+  redundant noise evaluations).
+- Cacti render out to the full rendering distance (like the terrain), but
+  drop ring facets and trunk segments with distance so far-off ones stay
+  cheap. The distance fade is done by **hardware fog** rather than the CPU.