Files
OpenGL_Intro/src/scene_graph.rs

119 lines
3.8 KiB
Rust

extern crate nalgebra_glm as glm;
use std::mem::ManuallyDrop;
use std::pin::Pin;
// Used to create an unholy abomination upon which you should not cast your gaze. This ended up
// being a necessity due to wanting to keep the code written by students as "straight forward" as
// possible. It is very very double plus ungood Rust, and intentionally leaks memory like a sieve.
// But it works, and you're more than welcome to pretend it doesn't exist! In case you're curious
// about how it works: It allocates memory on the heap (Box), promises to prevent it from being
// moved or deallocated until dropped (Pin) and finally prevents the compiler from dropping it
// automatically at all (ManuallyDrop).
// ...
// If that sounds like a janky solution, it's because it is!
// Prettier, Rustier and better solutions were tried numerous times, but were all found wanting of
// having what I arbitrarily decided to be the required level of "simplicity of use".
pub type Node = ManuallyDrop<Pin<Box<SceneNode>>>;
pub struct SceneNode {
pub position : glm::Vec3, // Where I should be in relation to my parent
pub rotation : glm::Vec3, // How I should be rotated, around the X, the Y and the Z axes
pub scale : glm::Vec3, // How I should be scaled
pub reference_point : glm::Vec3, // The point I shall rotate and scale about
pub vao_id : u32, // What I should draw
pub index_count : i32, // How much of it there is to draw
pub children: Vec<*mut SceneNode>, // Those I command
}
impl SceneNode {
pub fn new() -> Node {
ManuallyDrop::new(Pin::new(Box::new(SceneNode {
position : glm::zero(),
rotation : glm::zero(),
scale : glm::vec3(1.0, 1.0, 1.0),
reference_point : glm::zero(),
vao_id : 0,
index_count : -1,
children : vec![],
})))
}
pub fn from_vao(vao_id: u32, index_count: i32) -> Node {
ManuallyDrop::new(Pin::new(Box::new(SceneNode {
position : glm::zero(),
rotation : glm::zero(),
scale : glm::vec3(1.0, 1.0, 1.0),
reference_point : glm::zero(),
vao_id,
index_count,
children: vec![],
})))
}
pub fn add_child(&mut self, child: &SceneNode) {
self.children.push(child as *const SceneNode as *mut SceneNode)
}
#[allow(dead_code)]
pub fn get_child(& mut self, index: usize) -> & mut SceneNode {
unsafe {
&mut (*self.children[index])
}
}
#[allow(dead_code)]
pub fn n_children(&self) -> usize {
self.children.len()
}
#[allow(dead_code)]
pub fn print(&self) {
println!(
"SceneNode {{
VAO: {}
Indices: {}
Children: {}
Position: [{:.2}, {:.2}, {:.2}]
Rotation: [{:.2}, {:.2}, {:.2}]
Reference: [{:.2}, {:.2}, {:.2}]
}}",
self.vao_id,
self.index_count,
self.children.len(),
self.position.x,
self.position.y,
self.position.z,
self.rotation.x,
self.rotation.y,
self.rotation.z,
self.reference_point.x,
self.reference_point.y,
self.reference_point.z,
);
}
}
// You can also use square brackets to access the children of a SceneNode
use std::ops::{Index, IndexMut};
impl Index<usize> for SceneNode {
type Output = SceneNode;
fn index(&self, index: usize) -> &SceneNode {
unsafe {
& *(self.children[index] as *const SceneNode)
}
}
}
impl IndexMut<usize> for SceneNode {
fn index_mut(&mut self, index: usize) -> &mut SceneNode {
unsafe {
&mut (*self.children[index])
}
}
}