161 lines
6.4 KiB
Markdown
161 lines
6.4 KiB
Markdown
# vectordesert
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An infinite wire-mesh vector desert flythrough, written in C with OpenGL
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(GLFW). A vast, mostly-flat wireframe plain rolls past, interrupted now and
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then by vector mountain ranges, with saguaro cacti scattered across both.
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The terrain is built from **square wire-mesh frames**; the saguaros are
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ribbed wire-mesh tubes shaped to resemble real cacti (tapered, dome-tipped
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trunks with arms that curve out and sweep upward).
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## Build
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Requires a C compiler, GLFW 3, and OpenGL.
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Debian/Ubuntu:
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```
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sudo apt install build-essential libglfw3-dev
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```
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Fedora:
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```
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sudo dnf install glfw-devel
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```
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macOS (Homebrew):
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```
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brew install glfw
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```
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Then:
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```
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make
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```
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## Run
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```
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./vectordesert # windowed
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./vectordesert --fullscreen # full screen
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```
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### Command-line settings
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```
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--terrain-hue=0..1 hue of the terrain mesh (default 0.075)
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--mountain-freq=0.2..4 how often the plain is interrupted by a range
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(low = rare; high = frequent) (default 1.0)
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--mountain-rough=0..1 flat-topped mesas .. jagged peaks (default 0.5)
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--mountain-min-height=0..80 height of a range's low parts (default 6)
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--mountain-max-height=0..80 height of the tallest peaks (default 26)
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--cactus-freq=0..1 chance of a cactus per cell (default 0.35)
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--cactus-size-var=0..0.95 random cactus size spread (default 0.55)
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--cactus-min-size=1..30 smallest cactus height (default 4)
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--cactus-max-size=1..30 largest cactus height (default 12)
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--cactus-hue=0..1 hue of the cacti (default 0.33)
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--max-arms=0..12 arms on the largest cacti (default 5)
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```
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Example:
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```
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./vectordesert --fullscreen --terrain-hue=0.55 --mountain-freq=1.8 \
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--cactus-hue=0.30 --cactus-freq=0.5 --max-arms=8
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```
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### Camera
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| keys | does |
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|------|------|
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| `W` / `S` | throttle: accelerate / decelerate forward speed (holds when released; `S` past zero goes into reverse) |
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| `X` | full stop (zero the camera's velocity) |
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| `A` / `D` | strafe left / right |
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| `Page Up` / `Page Down` | raise / lower camera altitude |
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| `←` / `→` | pan view left / right |
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| `↑` / `↓` | pan view up / down |
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| `[` / `]` | decrease / increase rendering distance |
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| `G` | toggle the floor-altitude indicator |
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| `Space` | drop a bomb |
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Velocity is held in world space, so panning the view with the arrow keys
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only changes where you look — it does not change the direction you are
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travelling. To steer, turn and then apply throttle.
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The terrain is generated around the camera and cached — rebuilt only as you
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travel out of the cached region — so the plain extends infinitely in every
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direction. Rendering distance (`[` / `]`) ranges from 40 up to 960 units.
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### Live setting controls
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| keys | adjusts |
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|------|---------|
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| `1` / `2` | terrain hue |
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| `3` / `4` | mountain range frequency |
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| `,` / `.` | mountain roughness (flat mesas ↔ jagged peaks) |
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| `T` / `Y` | minimum mountain range height |
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| `U` / `I` | maximum mountain range height |
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| `5` / `6` | cactus frequency |
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| `7` / `8` | cactus size variation |
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| `J` / `K` | minimum cactus size |
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| `N` / `M` | maximum cactus size |
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| `9` / `0` | cactus hue |
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| `-` / `=` | maximum cactus arms |
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| `F` | toggle fullscreen |
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| `ESC` | quit |
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Current settings are printed to the terminal as you change them, and an
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on-screen heads-up display (drawn in the same vector style) lists every
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setting next to the key(s) that change it. The HUD fades out after 10
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seconds with no keypresses and snaps back as soon as you press a key.
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All settings (and the rendering distance) are saved to `~/.vectordesert.cfg`
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on exit and reloaded at startup, so the program resumes with the values from
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your last session. Command-line options still override the saved values for
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that run.
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## Bombs
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Press `Space` to drop a bomb. It falls from the sky onto a random spot in
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your field of view, between half the rendering distance and the full
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rendering distance away. When it strikes the ground it detonates into an
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animated, all-vector mushroom cloud twenty times the height of the tallest
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mountains, in an extremely bright random hue (additively blended so it
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glows):
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- an initial blinding fireball,
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- a rising stem with climbing vortex rings,
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- a billowing cap that stays joined to the stem — a rolling vortex torus
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whose outer edge curls up and over — and keeps animating as the whole
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cloud fades away.
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The blast **obliterates every mountain and cactus within the cloud's total
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radius** and **gouges a deep crater** — a steep-walled bowl with a raised
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rim thrown up above the surrounding surface — at the impact point. Every
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bomb leaves its own permanent crater, and craters never erase one another:
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repeated blasts in the same place **accumulate**, deepening and reshaping
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the crater. Drop as many as you like; the clouds animate and dissipate
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independently.
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## Notes
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- **Arms scale with size:** the number of arms is derived from a cactus's
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normalized size, so the smallest cacti always have the fewest arms (down
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to a bare trunk) and the largest always reach `max-arms`.
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- The world is generated procedurally from a hash-based value-noise height
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field, so it is effectively infinite — the camera flies forever. As well
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as mountain ranges rising above the plain, the terrain carves valleys and
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basins below it (and bomb craters), so it has real depth, not just relief.
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- Distance fog fades distant geometry into the dusk sky for depth.
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## Performance
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The renderer is built for throughput at large draw distances:
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- All wireframe segments for a frame are collected into one vertex/colour
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array and drawn with a single `glDrawArrays(GL_LINES)` per mesh, instead
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of per-object immediate-mode `glBegin`/`glEnd`.
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- Terrain and cactus meshes are **cached** and only rebuilt when a relevant
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setting changes or the camera leaves the cached region; most frames do no
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geometry work at all.
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- Terrain uses a **cell budget** (level of detail): the grid spacing grows
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with the rendering distance, so the cell count stays bounded as the radius
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scales up.
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- Each terrain vertex's height is computed once and shared by its edges (no
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redundant noise evaluations).
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- Cacti render out to the full rendering distance (like the terrain), but
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drop ring facets and trunk segments with distance so far-off ones stay
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cheap. The distance fade is done by **hardware fog** rather than the CPU.
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