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math: Add vec3.mulQuat() (#1067)

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Co-authored-by: Stephen Gutekanst <stephen@hexops.com>
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Caleb Katzenstein 2023-12-16 12:28:47 -08:00 • committed by GitHub
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commit 11aed4d16f
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src/math/vec.zig
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@ -4,6 +4,7 @@ const mach = @import("../main.zig");
const testing = mach.testing;
const math = mach.math;
const mat = @import("mat.zig");
const quat = @import("quat.zig");
pub const VecComponent = enum { x, y, z, w };
@ -88,6 +89,29 @@ pub fn Vec(comptime n_value: usize, comptime Scalar: type) type {
}
return .{ .v = result };
}
/// Vector * Quat multiplication
/// https://github.com/greggman/wgpu-matrix/blob/main/src/vec3-impl.ts#L718
pub inline fn mulQuat(v: *const VecN, q: *const quat.Quat(Scalar)) VecN {
const qx = q.v.x();
const qy = q.v.y();
const qz = q.v.z();
const w2 = q.v.w() * 2;
const vx = v.x();
const vy = v.y();
const vz = v.z();
const uv_x = qy * vz - qz * vy;
const uv_y = qz * vx - qx * vz;
const uv_z = qx * vy - qy * vx;
return math.vec3(
vx + uv_x * w2 + (qy * uv_z - qz * uv_y) * 2,
vy + uv_y * w2 + (qz * uv_x - qx * uv_z) * 2,
vz + uv_z * w2 + (qz * uv_y - qy * uv_x) * 2,
);
}
},
inline 4 => struct {
pub inline fn init(xs: Scalar, ys: Scalar, zs: Scalar, ws: Scalar) VecN {
@ -913,6 +937,13 @@ test "Mat4x4_mulMat" {
try testing.expect(math.Vec4, expected).eql(m);
}
test "mulQuat" {
const up = math.vec3(0, 1, 0);
const id = math.Quat.identity();
const rot = math.Quat.rotateZ(&id, -std.math.pi / 2.0);
try testing.expect(math.Vec3, math.vec3(1, 0, 0)).eql(up.mulQuat(&rot));
}
test "Vec2_fromInt" {
const x: i8 = 0;
const y: i32 = 1;