https://github.com/64/cmake-raytracer
Ray tracer written in pure CMake
https://github.com/64/cmake-raytracer
cmake ray-tracer
Last synced: about 1 month ago
JSON representation
Ray tracer written in pure CMake
- Host: GitHub
- URL: https://github.com/64/cmake-raytracer
- Owner: 64
- License: mit
- Created: 2020-04-23T05:43:17.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2024-06-07T21:04:54.000Z (over 1 year ago)
- Last Synced: 2025-03-02T15:31:05.271Z (7 months ago)
- Topics: cmake, ray-tracer
- Language: CMake
- Homepage:
- Size: 280 KB
- Stars: 856
- Watchers: 9
- Forks: 14
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE.md
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- awesome-list - cmake-raytracer
README
# CMake Ray Tracer
A simple ray tracer written in pure CMake. Inspired by [raytracer.hpp](https://github.com/tcbrindle/raytracer.hpp). More information can be found at [my blog](https://64.github.io/cmake-raytracer).
## Usage
The ray tracer writes its output to `stderr`, so you can use it with:
```shell
cmake -Dimage_width=64 -Dimage_height=64 -Dnum_procs=4 -P CMakeLists.txt 2> image.ppm
```
Which renders using 4 CPU cores and writes the output to `image.ppm`. Then use an image viewer capable of opening PPM files (or [this](http://www.cs.rhodes.edu/welshc/COMP141_F16/ppmReader.html)) to view.
**Alternatively, the ray tracer can directly write PNG files** (thanks to @benmcmorran for contributing this). The PNG encoder is also implemented in pure CMake, but either PowerShell or Python is required with this method since CMake is unable to write binary files directly. Set the `use_png` variable to set the name of the PNG file (without the extension). The example below will write output to `render.png`:
```shell
cmake -Dimage_width=64 -Dimage_height=64 -Dnum_procs=4 -Duse_png=render -P CMakeLists.txt
```
`num_procs` controls the number of worker processes spawned. It is recommended to set this to a value no greater than the number of cores in your CPU, for maximum performance. If not provided, it will be automatically detected based on the number of available cores.
To keep the code simple, the `image_width`, `image_height` and `num_procs` must be powers of 2, otherwise the image will not be fully formed. If not specified, these arguments default to the values shown above.
## Performance
Using cmake 3.19.2 on Linux 5.4 on a i5-10210U (4 cores, 8 threads), running this command:
```shell
for X in 1 2 4 8 16 32 64 128 256 512 ; do echo SIZE $X ; time cmake -Dimage_width=$X -Dimage_height=$X -Dnum_procs=8 -P CMakeLists.txt 2> image_size_${X}.ppm ; done
```
PowerShell alternative:
```powershell
1, 2, 4, 8, 16, 32, 64, 128, 256, 512 | foreach {Write-Host $_; (Measure-Command { cmake "-Dimage_width=$_" "-Dimage_height=$_" "-Dnum_procs=$Env:NUMBER_OF_PROCESSORS" -P CMakeLists.txt 2> image_size_$_.ppm }).TotalSeconds}
```
Figures reported by `time` command below (reformatted). As usual, the "real" time is the wall clock time. The others are summed on all processors.
| size | real | user | sys |
| ---: | ---: | ---: | --: |
| 1 | 0,054s | 0,130s | 0,051s |
| 2 | 0,035s | 0,098s | 0,041s |
| 4 | 0,077s | 0,274s | 0,018s |
| 8 | 0,106s | 0,460s | 0,023s |
| 16 | 0,367s | 1,871s | 0,059s |
| 32 | 1,296s | 7,617s | 0,132s |
| 64 | 5,175s | 29,455s | 0,356s |
| 128 | 21,093s | 2m06,299s | 1,566s |
| 256 | 1m33,395s | 9m21,875s | 5,999s |
| 512 | 7m23,094s | 45m36,327s | 32,588s |
## Contributing
All contributions (issue, PRs) are welcome. This project is licensed under the MIT license.