tiny.linear.Affine

1pub const Affine = extern struct {2    linear: Mat3 = .{},3    translation: Vec3 = .{},45    pub const identity: Affine = .{};67    pub fn fromTranslation(translation: Vec3) Affine {8        return .{ .translation = translation };9    }1011    /// Scale, then rotate by the unit quaternion `rotation`, then translate.12    pub fn fromScaleRotationTranslation(s: Vec3, rotation: Quat, translation: Vec3) Affine {13        return .{14            .linear = Mat3.fromQuat(rotation).mul(Mat3.fromScale(s)),15            .translation = translation,16        };17    }1819    /// `a b`: applying `b`, then `a`.20    pub fn mul(a: Affine, b: Affine) Affine {21        return .{22            .linear = a.linear.mul(b.linear),23            .translation = a.transformPoint(b.translation),24        };25    }2627    pub fn transformPoint(a: Affine, p: Vec3) Vec3 {28        return a.linear.mulVec(p).add(a.translation);29    }3031    pub fn transformVector(a: Affine, v: Vec3) Vec3 {32        return a.linear.mulVec(v);33    }3435    /// The matrix that carries surface normals through `a`, or null when the36    /// linear part is singular. Transformed normals keep their direction but37    /// not their length.38    pub fn normalMatrix(a: Affine) ?Mat3 {39        return a.linear.inverseTranspose();40    }4142    /// The inverse transform, or null when the linear part is singular.43    pub fn inverse(a: Affine) ?Affine {44        const linear = a.linear.inverse() orelse return null;45        return .{46            .linear = linear,47            .translation = linear.mulVec(a.translation).negate(),48        };49    }5051    pub fn toMat4(a: Affine) Mat4 {52        return Mat4.fromLinearTranslation(a.linear, a.translation);53    }54};

1pub const Affine = affine.Affine;