refactor!: separate rendering functionality

1 files changed, 60 insertions, 0 deletions

diff --git a/src/sdf.rs b/src/sdf.rs
new file mode 100644
index 0000000..00a4a11
--- /dev/null
+++ b/src/sdf.rs
@@ -0,0 +1,60 @@
+use std::f32::consts::PI;
+use cgmath::Vector3;
+use cgmath::prelude::*;
+
+type Vector = Vector3<f32>;
+
+pub fn sd_sphere(point: Vector, center: Vector, radius: f32) -> f32 {
+    (point - center).magnitude() - radius
+}
+
+pub fn sd_box(point: Vector, center: Vector, size: Vector) -> f32 {
+    let diff = center - point;
+    let q = diff.map(|n| n.abs()) - size / 2.0;
+    return q.map(|n| n.max(0.0)).magnitude() + (q.y.max(q.z).max(q.x)).min(0.0)
+}
+
+pub fn sd_gear(point: Vector, time: f32, center: Vector, radius: f32, thickness: f32, turn_rate: f32) -> f32 {
+    let mut dist: f32;
+
+    let thickness_over_2 = thickness / 2.0;
+    let thickness_over_4 = thickness / 4.0;
+
+    // Ring
+    {
+        let cylinder_dist = (Vector::new(0.0, point.y, point.z) - center).magnitude() - (radius - thickness_over_4);
+        dist = cylinder_dist.abs() - thickness_over_2; // Make cylinder hollow
+    }
+    // Teeth
+    {
+        let sector_angle: f32 = 2.0 * PI / 12.0;
+
+        // Account for rotation with time
+        let angle = sector_angle * time / turn_rate;
+        let rotated_point = Vector::new(
+            point.x,
+            point.y * angle.cos() - point.z * angle.sin(),
+            point.y * angle.sin() + point.z * angle.cos()
+        );
+
+        // Map all space to the first sector
+        let point_angle = (rotated_point.z / rotated_point.y).atan();
+        let angle2 = -sector_angle * (point_angle / sector_angle).round();
+
+        let mapped_point = Vector::new(
+            rotated_point.x,
+            (rotated_point.y * angle2.cos() - rotated_point.z * angle2.sin()).abs(),
+            rotated_point.y * angle2.sin() + rotated_point.z * angle2.cos()
+        );
+
+        let center = Vector { x: 0.0, y: radius + thickness_over_2, z: 0.0 };
+        let size = Vector::new(thickness, thickness * 2.0, thickness);
+        // Make teeth smooth by subtracting some amount
+        dist = dist.min(sd_box(mapped_point, center, size) - thickness_over_4);
+    }
+
+    // Take a slice
+    dist = dist.max(point.x.abs() - thickness_over_2);
+
+    return dist;
+}