Copyright 2023 Travis J. West, https://traviswest.ca, Input Devices and Music Interaction Laboratory (IDMIL), Centre for Interdisciplinary Research in Music Media and Technology (CIRMMT), McGill University, Montréal, Canada, and Univ. Lille, Inria, CNRS, Centrale Lille, UMR 9189 CRIStAL, F-59000 Lille, France

SPDX-License-Identifier: MIT

This document describes the endpoint helpers intended to be used in the implementation of MIMU components. A MIMU is any component that has the following endpoints:

struct outputs_t {
    vec3_message<"accelerometer"> accl; /* or acceleration or accelerometer or accel or a */
    vec3_message<"gyroscope"> gyro;     /* or gyroscope or angular_rate or g */
    vec3_message<"magnetometer"> magn;  /* or magnetometer or magnetic_field or m */
} outputs;

vec3_message

MIMU sensors are generally measured synchronously, but it's not uncommon for the accelerometer, gyroscope, and magnetometer to have different sampling rates. For this reason, we employ the array_message endpoint helper so that updates to each sensor can be recognized by converting the endpoint to a boolean. We then augment this base endpoint with methods for vector-style access x(), y(), z(), and a unit of measurement metadata string.

// @+'vec3_message'
template< string_literal name
        , typename T = float
        , num_literal<T> min = -1.0f
        , num_literal<T> max = 1.0f
        , string_literal unit = "normalized"
        , string_literal desc = ""
        , typename ... Tags
        >
struct vec3_message
: array_message<name, 3, desc, T, min, max, T{}, Tags...>
, unit_<unit>
{
    using Parent = array_message<name, 3, desc, T, min, max, T{}, Tags...>;
    using Parent::operator=;
    constexpr auto& x() noexcept { return Parent::state[0]; }
    constexpr auto& y() noexcept { return Parent::state[1]; }
    constexpr auto& z() noexcept { return Parent::state[2]; }
    constexpr const auto& x() const noexcept { return Parent::state[0]; }
    constexpr const auto& y() const noexcept { return Parent::state[1]; }
    constexpr const auto& z() const noexcept { return Parent::state[2]; }
};
// @/

Note that, due to the semantics of array_message, only updates via the assignment operator will set the updated flag of the endpoint. Changes made via the array access and vector access methods must be followed with a manual call to set_updated().

// @+'tests'
TEST_CASE("sygaldry MIMU endpoint helpers")
{
    vec3_message<"testvec"> v{};
    CHECK(not v.updated);
    CHECK(v.x() == 0.0f);
    CHECK(v.y() == 0.0f);
    CHECK(v.z() == 0.0f);
    v.x() = 1.0f;
    CHECK(not v.updated); // update through accessor doesn't set updated flag
    v = {1.0f, 2.0f, 3.0f}; // update by operator= instead!
    CHECK(v.updated);
    CHECK(v.x() == 1.0f);
    CHECK(v.y() == 2.0f);
    CHECK(v.z() == 3.0f);
}
 
struct TestMimu
{
    struct outputs_t {
        vec3_message<"accl"> accl;
        vec3_message<"gyro"> gyro;
        vec3_message<"magn"> magn;
    } outputs;
};
static_assert(MimuComponent<TestMimu>);
 
// @/

Summary

// @#'sygah-mimu.hpp'
#pragma once
/*
Copyright 2023 Travis J. West, https://traviswest.ca, Input Devices and Music
Interaction Laboratory (IDMIL), Centre for Interdisciplinary Research in Music
Media and Technology (CIRMMT), McGill University, Montréal, Canada, and Univ.
Lille, Inria, CNRS, Centrale Lille, UMR 9189 CRIStAL, F-59000 Lille, France
 
SPDX-License-Identifier: MIT
*/
 
#include "sygah-metadata.hpp"
#include "sygah-endpoints.hpp"
 
namespace sygaldry {
 
@{vec3_message}
}
// @/
 
// @#'sygah-mimu.test.cpp'
/*
Copyright 2023 Travis J. West, https://traviswest.ca, Input Devices and Music
Interaction Laboratory (IDMIL), Centre for Interdisciplinary Research in Music
Media and Technology (CIRMMT), McGill University, Montréal, Canada, and Univ.
Lille, Inria, CNRS, Centrale Lille, UMR 9189 CRIStAL, F-59000 Lille, France
 
SPDX-License-Identifier: MIT
*/
 
#include <catch2/catch_test_macros.hpp>
#include "sygac-mimu.hpp"
#include "sygah-mimu.hpp"
 
using namespace sygaldry;
 
@{tests}
// @/

# @#'CMakeLists.txt'
set(lib sygah-mimu)
add_library(${lib} INTERFACE)
target_link_libraries(${lib} INTERFACE sygah-metadata)
target_link_libraries(${lib} INTERFACE sygah-endpoints)
target_include_directories(${lib} INTERFACE .)
 
if (SYGALDRY_BUILD_TESTS)
add_executable(${lib}-test ${lib}.test.cpp)
target_link_libraries(${lib}-test PRIVATE Catch2::Catch2WithMain
        PRIVATE sygah-mimu
        PRIVATE sygac-mimu
        )
catch_discover_tests(${lib}-test)
endif()
# @/

Table of Contents

vec3_message

Summary