math: begin rewrite of mach.math

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

src/math/quat.zig

@@ -0,0 +1,34 @@
+const std = @import("std");
+
+const mach = @import("../main.zig");
+const testing = mach.testing;
+const math = mach.math;
+const vec = @import("vec.zig");
+
+pub fn Quat(comptime Scalar: type) type {
+    return struct {
+        v: vec.Vec(4, Scalar),
+
+        /// The scalar type of this matrix, e.g. Mat3x3.T == f32
+        pub const T = Vec.T;
+
+        /// The underlying Vec type, e.g. math.Vec4, math.Vec4h, math.Vec4d
+        pub const Vec = vec.Vec(4, Scalar);
+
+        pub inline fn init(x: T, y: T, z: T, w: T) Quat(Scalar) {
+            return .{ .v = math.vec4(x, y, z, w) };
+        }
+    };
+}
+
+test "zero_struct_overhead" {
+    // Proof that using Quat is equal to @Vector(4, f32)
+    try testing.expect(usize, @alignOf(@Vector(4, f32))).eql(@alignOf(math.Quat));
+    try testing.expect(usize, @sizeOf(@Vector(4, f32))).eql(@sizeOf(math.Quat));
+}
+
+test "init" {
+    try testing.expect(math.Quat, math.quat(1, 2, 3, 4)).eql(math.Quat{
+        .v = math.vec4(1, 2, 3, 4),
+    });
+}