dave: auto-reply, initial avatar anim

Signed-off-by: William Casarin <jb55@jb55.com>

crates/notedeck_dave/src/vec3.rs

@@ -0,0 +1,38 @@
+#[derive(Debug, Clone, Copy)]
+pub struct Vec3 {
+    pub x: f32,
+    pub y: f32,
+    pub z: f32,
+}
+
+impl Vec3 {
+    pub fn new(x: f32, y: f32, z: f32) -> Self {
+        Vec3 { x, y, z }
+    }
+
+    pub fn squared_length(&self) -> f32 {
+        self.x * self.x + self.y * self.y + self.z * self.z
+    }
+
+    pub fn length(&self) -> f32 {
+        self.squared_length().sqrt()
+    }
+
+    pub fn normalize(&self) -> Vec3 {
+        let len = self.length();
+        if len != 0.0 {
+            Vec3 {
+                x: self.x / len,
+                y: self.y / len,
+                z: self.z / len,
+            }
+        } else {
+            // Return zero vector if length is zero to avoid NaNs
+            Vec3 {
+                x: 0.0,
+                y: 0.0,
+                z: 0.0,
+            }
+        }
+    }
+}