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diff --git a/projects/learning-rust/1.html b/projects/learning-rust/1.html new file mode 100644 index 0000000..840a968 --- /dev/null +++ b/projects/learning-rust/1.html @@ -0,0 +1,69 @@ +<!DOCTYPE html> +<html> +<head> + <title>1: Solar Systems</title> + + <link rel="stylesheet" href="/style.css"/> + <link rel="stylesheet" href="/prism/prism.css"/> + <script src="/prism/prism.js"></script> +</head> +<body> + <div class="window"> + <div class="window-title"><h2 style="padding: 0px; margin: 0px;">Learning Rust : Solar Systems</h2></div> + <i>How do I store non-owning references to collection members?</i> + <div class="window-content"> + <a class="link-button" href="/projects/learning-rust"><</a> + <p>I want to make a data-driven viewer for the solar system, as part of a game inspired by <a href="https://www.aurora2.pentarch.org/">Aurora 4x</a> but Rust is an entirely different beast from C.</p> + <p>I have prior experience writing systems like this, so I figured it would be as easy as:</p> + <pre><code class="language-rust"> +pub struct Orbital { + //Some optional non-owning reference to the parent orbital + mass : f64, + semi_major_axis : f64, + eccentricity : f64, + inclination : f64, + long_asc_node : f64, + argument_periapsis : f64, + mean_anomaly_epoch : f64 +} + </code></pre> + <p>The question then is: How do we store the reference to the parent orbital?</p> + <p>note: by parent orbital, I mean the orbital body that the given orbital body orbits.</p> + <p>In C, we would just store a pointer into the data of the owning container (i.e. a dynamic array).</p> + <p>I understand that the method above could cause problems with object lifetimes and dead references, but in this case we are assuming a static lifetime with a fixed-width container.</p> + <p>So my first instinct is to look in the Rust docs for a non-owning reference type.</p> + <p>I wasted about a day researching Rc's and RefCell's when I had a revelation; what I wanted was over-engineered. Instead of storing a reference to the parent orbital, I could just store an index into the system's orbital container. All I need to do to make this work is pass a borrowed ref to the system object to the orbital's update function.</p> + <p>But not every part of the update function needs the parent orbital's position, so I can split the update into two parts:</p> + <p>1: Update the orbital elements relative to the parent object</p> + <p>2: Use the parent orbital's position to transform the relative coordinates into absolute coordinates</p> + <p>So here's what I came up with.</p> + <pre><code class="language-rust"> +pub struct Orbital { + parent_index : usize, + //Temporary state variables for later update. + rel_pos : (f64, f64, f64) + //Orbital parameters + mass : f64, + semi_major_axis : f64, + eccentricity : f64, + inclination : f64, + long_asc_node : f64, + argument_periapsis : f64, + mean_anomaly_epoch : f64 +} +//... +impl Orbital { +//... + pub fn update_rel(&mut self) -> Orbital { + //... + } + + pub fn update(&self, &system : System) -> (f64, f64, f64) { + //... + } +} + </code></pre> + </div> + </div> +</body> +</html> diff --git a/projects/learning-rust/index.html b/projects/learning-rust/index.html new file mode 100644 index 0000000..5e0e9ba --- /dev/null +++ b/projects/learning-rust/index.html @@ -0,0 +1,27 @@ +<!DOCTYPE html> +<html> +<head> + <title>Learning Rust</title> + + <link rel="stylesheet" href="/style.css"> +</head> +<body> + <div class="window"> + <div class="window-title"><h2 style="padding: 0px; margin: 0px;">Learning Rust</h2></div> + <div class="window-content"> + <p>I am a long-time proponent of C. I have been using it for most of my life, and change is scary.</p> + <p>However, I also believe in broadening my skillset and learning new things.</p> + <p>This defines my dilemma. I want to learn something new, but I want to keep using C.</p> + <p>And then the US government decree'd that us C plebs should move on to rust</p> + <p>So without further adieu, as my first foray into "blogging", welcome to my attempt to document my journey into the Rust ecosystem</p> + </div> + </div> + <div class="window"> + <div class="window-title"></div> + <div class="window-content"> + <a class="link-button" href="1.html">1: Solar Systems</a> + <p style="display: inline-block"> : How do I store non-owning references to other objects?</p> + </div> + </div> +</body> +</html> |