Vec3 sample implementation

src/main.zig

@@ -2,8 +2,14 @@
 //! you are building an executable. If you are making a library, the convention
 //! is to delete this file and start with root.zig instead.
 const std = @import("std");
+const Vec3 = @import("vector.zig").Vec3;
 
 pub fn main() !void {
+    const a = Vec3.new(1.0, 2.0, 3.0);
+    const b = Vec3.new(4.0, 5.0, 6.0);
+    const c = a.dot(b);
+    std.debug.print("a dot b = {d}\n", .{c});
+
     // Prints to stderr (it's a shortcut based on `std.io.getStdErr()`)
     std.debug.print("All your {s} are belong to us.\n", .{"codebase"});
 

src/vector.zig

@@ -0,0 +1,44 @@
+const expect = @import("std").testing.expect;
+
+/// A 3D vector.
+pub const Vec3 = struct {
+    x: f32,
+    y: f32,
+    z: f32,
+
+    /// Creates a new vector with the given components.
+    pub fn new(x: f32, y: f32, z: f32) Vec3 {
+        return Vec3{ .x = x, .y = y, .z = z };
+    }
+
+    /// Returns the dot product of this vector and another.
+    pub fn dot(self: Vec3, other: Vec3) f32 {
+        return self.x * other.x + self.y * other.y + self.z * other.z;
+    }
+
+    /// Returns the cross product of this vector and another.
+    pub fn cross(self: Vec3, other: Vec3) Vec3 {
+        return Vec3{
+            .x = self.y * other.z - self.z * other.y,
+            .y = self.z * other.x - self.x * other.z,
+            .z = self.x * other.y - self.y * other.x,
+        };
+    }
+
+    // Returns true if this vector is equal to another.
+    pub fn equals(self: *const Vec3, other: *const Vec3) bool {
+        return self.x == other.x and self.y == other.y and self.z == other.z;
+    }
+};
+
+test "Dot product" {
+    const a = Vec3{ .x = 1, .y = 2, .z = 3 };
+    const b = Vec3{ .x = 4, .y = 5, .z = 6 };
+    try expect(a.dot(b) == 32);
+}
+
+test "Cross product" {
+    const a = Vec3{ .x = 1, .y = 2, .z = 3 };
+    const b = Vec3{ .x = 4, .y = 5, .z = 6 };
+    try expect(a.cross(b).equals(&Vec3{ .x = -3, .y = 6, .z = -3 }));
+}