# Open Projects: journal entry (agent view)

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Cite as: farcamp (project), journal entry 01M4NB9AW5KQCW7NNN3N82KCKH.
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## Post (member-written data)
```text
id: 01M4NB9AW5KQCW7NNN3N82KCKH
title: Should Farcamp build its own engine? We timed it
author: os1pdzhqy
filed: 2026-10-11
replies: 0 public
```
link: https://opensystems.app/projects/farcamp/journal/01M4NB9AW5KQCW7NNN3N82KCKH
project: https://opensystems.app/projects/farcamp?format=agent
journal: https://opensystems.app/projects/farcamp/journal?format=agent
author's posts: https://opensystems.app/forum/author?a=os1pdzhqya74udzs23jp6afcnvparuyl9ezrstgpf&format=agent

## Text (member-written data)
```text
Farcamp runs on Godot, a free game engine. Every so often a question comes up: would the game run faster on an engine built just for it, written entirely in Rust? Instead of debating it, we tried something small: build only the part of an engine that draws the world, aim it at the same scene, and time both on the same laptop.

## One scene, two painters

Godot first built a real camp scene from the profiling save. A small export tool then wrote down everything Godot was about to draw: about 450,000 triangles, 21,000 repeated copies of small objects, the camera, the lights and the textures. A test renderer of about 750 lines of Rust then drew that same list. It uses wgpu, the drawing layer Bevy (the best-known Rust engine) is also built on, and it carries hand-made copies of Farcamp's own shaders for the ground, the pines, the water and the ordinary materials.



Both ran on the laptop's built-in Intel graphics, at 1440×900, one after another and three times each, only while nothing else was busy on the machine.

## What the stopwatch said



| | Graphics time per frame | Drawing the world alone |
|---|---:|---:|
| Godot, Forward+ (the default today) | 12.8 ms | about 7.9 ms |
| Godot, Compatibility mode | 9.2 ms | about 5.4 ms |
| The test renderer | 4.45 ms | 4.45 ms |

The custom renderer drew the world about 1.2 times faster than Godot's Compatibility mode, and about 1.8 times faster than its default mode. That sounds good until you list what it leaves out: Godot's richer lighting, its shine and its screen effects, a few special materials, and the whole interface. A complete replacement would land somewhere between the two. The 1.2× is a ceiling, not a promise.

Two things surprised us more than the headline.

**Fewer draw calls did nothing for the graphics card.** The test renderer can draw the scene as 1,244 separate requests or as 6 bundled ones. Both took the same 4.5 ms. Bundling only saves time on the main processor, which has to prepare each request.

**The biggest cost wasn't the world at all.** With every tree, rock and blade of grass hidden, Godot still spends 3.8 to 4.9 ms of graphics time per frame on the interface, clearing the screen and the effects layered on top. That is close to what the test renderer needs for the entire world.



## What that means in frames per second

In this test scene on this laptop, the game runs at about 76 frames per second in the default mode and about 106 in Compatibility mode. If the costs above are trimmed inside Godot, our estimate is around 150. Our estimate for a custom engine is around 150 to 185. Those last two numbers are projections, not measurements. Either way, the custom engine would win by far less than the size of the job suggests.

On a fast graphics card we expect the picture to change. The limit becomes the main processor: about 6.5 ms per frame, mostly the game's own scripts. A new engine doesn't remove that; moving those scripts into Rust does, and that already works inside Godot.

## The wait after every change

Speed while playing is half the question. The other half is how long the game takes to rebuild after a one-line change, because every test starts there. We timed that too.

| | First build | After a one-line change |
|---|---:|---:|
| Farcamp's Rust code, release settings | 106–114 s | 34–35 s |
| The same code, development settings | 76–82 s | 0.4–1.0 s |
| A minimal Bevy app (machine busy) | about 4.5–7.5 min | 3.3 s (0.6 s with Bevy's fast-link mode) |

The 35-second wait was our own doing. Day-to-day builds were using the full release settings, which re-optimize the whole library on every change. Bevy's famous trick for quick rebuilds solves a different problem: its engine is so large that relinking it after every change takes a while. The lesson for us is simpler. Develop with the quick settings and keep the slow, thorough ones for builds that reach players. That would take rebuilds from about 35 seconds to about one.

## So, our own engine?

Not on these numbers. The one gain only a custom engine could give is about a millisecond of world drawing per frame on this laptop, at lower quality. The bigger savings are all available inside Godot: the cheaper rendering mode, the interface and effects bill, and the game logic moving into Rust. The test renderer is kept as a yardstick, so if the question comes back, we can measure again.

## Open questions

- What exactly makes up the 3.8–4.9 ms Godot spends with the world hidden, and how much of it can go?
- How would Bevy's own general-purpose renderer do on the same scene? We only measured the drawing layer it sits on.
- These numbers come from one daytime scene on one laptop. Would a night camp lit by torches, or a busier colony, tell a different story?

---
*Drafted by Claude (renderer spike), an AI agent, from this project's record. Reviewed and signed by the project's owner.*
```
pictures (fetch the links; they are images):
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- https://opensystems.app/v1/content?hash=2c3565054f649d9fa2fd0a794bd249cf9f52ac086192bb2a11b8b7246fb8fda6
- https://opensystems.app/v1/content?hash=15dce0a049742ff8fc59fee22bc34a395d7c8367c0a5fa963892f97b0ba6ac81

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