more geometry stuff, shapes

Cargo.lock

@@ -20,6 +20,18 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "enum_dispatch"
+version = "0.3.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aa18ce2bc66555b3218614519ac839ddb759a7d6720732f979ef8d13be147ecd"
+dependencies = [
+ "once_cell",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "glam"
 version = "0.30.2"
@@ -52,6 +64,7 @@ name = "mechthild_core"
 version = "0.1.0"
 dependencies = [
  "bytemuck",
+ "enum_dispatch",
  "glam",
 ]
 

core/Cargo.toml

@@ -8,6 +8,7 @@ repository.workspace = true
 
 [dependencies]
 bytemuck = { version = "1.22.0", optional = true }
+enum_dispatch = "0.3.13"
 glam = "0.30.2"
 
 [features]

core/src/geometry.rs

@@ -1,9 +1,24 @@
-use std::ops::{Add, Div, Mul, Sub};
+use std::{
+    fmt,
+    ops::{Add, Div, Mul, Sub},
+};
+
+pub mod shapes;
 
 #[repr(transparent)]
-#[derive(Debug, Clone, Copy)]
+#[derive(Clone, Copy)]
 pub struct Vector(glam::Vec3A);
 
+impl fmt::Debug for Vector {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple(stringify!(Vector))
+            .field(&self.0.x)
+            .field(&self.0.y)
+            .field(&self.0.z)
+            .finish()
+    }
+}
+
 impl From<Vector> for glam::Vec3 {
     fn from(value: Vector) -> Self {
         value.0.into()
@@ -30,6 +45,10 @@ impl Vector {
         self.0.length()
     }
 
+    pub fn length_squared(self) -> f32 {
+        self.0.length_squared()
+    }
+
     pub fn dot(self, other: Vector) -> f32 {
         self.0.dot(other.0)
     }
@@ -72,9 +91,19 @@ impl Add for Vector {
 }
 
 #[repr(transparent)]
-#[derive(Debug, Clone, Copy)]
+#[derive(Clone, Copy)]
 pub struct Point(glam::Vec3A);
 
+impl fmt::Debug for Point {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple(stringify!(Point))
+            .field(&self.0.x)
+            .field(&self.0.y)
+            .field(&self.0.z)
+            .finish()
+    }
+}
+
 impl From<Point> for glam::Vec3 {
     fn from(value: Point) -> Self {
         value.0.into()
@@ -93,6 +122,10 @@ impl Point {
     pub fn new(x: f32, y: f32, z: f32) -> Self {
         Self(glam::vec3a(x, y, z))
     }
+
+    pub fn to_vector(self) -> Vector {
+        Vector(self.0)
+    }
 }
 
 impl Add<Vector> for Point {
@@ -111,10 +144,19 @@ impl Sub for Point {
     }
 }
 
-#[derive(Debug, Copy, Clone)]
+#[derive(Copy, Clone)]
 #[repr(transparent)]
 pub struct Transform(glam::Affine3A);
 
+impl fmt::Debug for Transform {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct(stringify!(Transform))
+            .field(stringify!(matrix3), &self.0.matrix3)
+            .field(stringify!(translation), &self.0.translation)
+            .finish()
+    }
+}
+
 impl Transform {
     pub fn scale(x: f32, y: f32, z: f32) -> Self {
         Self(glam::Affine3A::from_scale(glam::vec3(x, y, z)))
@@ -149,6 +191,14 @@ impl Mul<Vector> for Transform {
     }
 }
 
+impl Mul<Point> for Transform {
+    type Output = Point;
+
+    fn mul(self, rhs: Point) -> Self::Output {
+        Point(self.0.transform_point3a(rhs.0))
+    }
+}
+
 pub struct Ray {
     origin: Point,
     direction: Vector,

core/src/geometry/shapes.rs

@@ -0,0 +1,90 @@
+use std::fmt;
+
+use enum_dispatch::enum_dispatch;
+
+use super::{Point, Ray, Vector};
+
+#[derive(Debug)]
+pub(crate) struct Hit {
+    point: Point,
+    normal: Vector,
+    t: f32,
+}
+
+#[enum_dispatch]
+pub(crate) trait Hittable {
+    fn intersect(&self, ray: Ray, t_max: f32) -> Option<Hit>;
+}
+
+#[derive(Debug)]
+pub struct Sphere {
+    center: Point,
+    radius: f32,
+}
+
+impl Hittable for Sphere {
+    fn intersect(&self, ray: Ray, t_max: f32) -> Option<Hit> {
+        let oc = self.center - ray.origin;
+        let a = ray.direction.length_squared();
+        let h = ray.direction.dot(oc);
+        let c = oc.length_squared() - self.radius * self.radius;
+        let d = h * h - a * c;
+
+        (d > 0.0)
+            .then(|| (h - d.sqrt()) / a)
+            .filter(|t| *t < t_max && *t > 0.0)
+            .map(|t| {
+                let point = ray.at(t);
+                let normal = point - self.center;
+                Hit { point, normal, t }
+            })
+    }
+}
+
+#[derive(Debug)]
+pub struct Plane {
+    normal: Vector,
+    d: f32,
+}
+
+impl Hittable for Plane {
+    fn intersect(&self, ray: Ray, t_max: f32) -> Option<Hit> {
+        let n_dot_r = self.normal.dot(ray.direction);
+        (n_dot_r.abs() > f32::EPSILON)
+            .then(|| {
+                let n_dot_o = self.normal.dot(ray.origin.to_vector());
+                -(n_dot_o + self.d) / n_dot_r
+            })
+            .filter(|t| *t < t_max && *t > 0.0)
+            .map(|t| Hit {
+                point: ray.at(t),
+                normal: self.normal,
+                t,
+            })
+    }
+}
+
+#[enum_dispatch(Hittable)]
+pub enum Shape {
+    Sphere,
+    Plane,
+}
+
+impl fmt::Debug for Shape {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Sphere(s) => s.fmt(f),
+            Self::Plane(p) => p.fmt(f),
+        }
+    }
+}
+
+impl Shape {
+    pub fn sphere(center: Point, radius: f32) -> Shape {
+        Shape::from(Sphere { center, radius })
+    }
+
+    pub fn plane(normal: Vector, d: f32) -> Shape {
+        Shape::from(Plane { normal, d })
+    }
+}

core/src/lib.rs

@@ -2,8 +2,11 @@
 pub mod impl_bytemuck;
 
 pub mod color;
+
 mod geometry;
 
+pub use geometry::{Point, Transform, Vector, shapes::Shape};
+
 use color::Rgba;
 
 pub struct Scene;

examples/basic.py

@@ -1,11 +1,10 @@
-from PIL import Image
-from mechthild import Scene
+#!python
 
-WIDTH = 800
-HEIGHT = 600
+from mechthild import Shape
 
-render_result = Scene().render(WIDTH, HEIGHT)
-rgba = bytes([int(v * 255) for v in render_result])
+s1 = Shape.sphere((0.0, 0.5, 0.0), 0.5)
+s2 = Shape.sphere((1.5, 2.0, -1.0), 2.0)
 
-img = Image.frombuffer('RGBA', (WIDTH, HEIGHT), rgba)
-img.save("test.png")
+ground = Shape.plane((0.0, 1.0, 0.0), 0.0)
+
+print(f"{s1}\n{s2}\n{ground}")

py/src/lib.rs

@@ -1,7 +1,27 @@
 use bytemuck::allocation::cast_slice_box;
-use mechthild_core::{Scene, color::Rgba};
+use mechthild_core::{Scene, Shape, color::Rgba};
 use pyo3::prelude::*;
 
+#[pyclass(name = "Shape")]
+struct PyShape(Shape);
+
+#[pymethods]
+impl PyShape {
+    #[staticmethod]
+    pub fn sphere(center: (f32, f32, f32), radius: f32) -> Self {
+        Self(Shape::sphere(center.into(), radius))
+    }
+
+    #[staticmethod]
+    pub fn plane(normal: (f32, f32, f32), d: f32) -> Self {
+        Self(Shape::plane(normal.into(), d))
+    }
+
+    pub fn __str__(&self) -> PyResult<String> {
+        Ok(format!("{:?}", self.0))
+    }
+}
+
 #[pyclass(name = "Scene")]
 struct PyScene(Scene);
 
@@ -22,6 +42,7 @@ impl PyScene {
 /// A Python module implemented in Rust.
 #[pymodule]
 fn mechthild(m: &Bound<'_, PyModule>) -> PyResult<()> {
+    m.add_class::<PyShape>()?;
     m.add_class::<PyScene>()?;
     Ok(())
 }