OpenSpace/modules/base/translation/luatranslation.cpp

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2019                                                               *
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#include <modules/base/translation/luatranslation.h>

#include <openspace/documentation/documentation.h>
#include <openspace/documentation/verifier.h>
#include <openspace/util/updatestructures.h>
#include <ghoul/fmt.h>
#include <ghoul/filesystem/file.h>
#include <ghoul/filesystem/filesystem.h>
#include <ghoul/logging/logmanager.h>
#include <ghoul/lua/ghoul_lua.h>
#include <ghoul/lua/lua_helper.h>

#include <chrono>

namespace {
    constexpr openspace::properties::Property::PropertyInfo ScriptInfo = {
        "Script",
        "Script",
        "This value is the path to the Lua script that will be executed to compute the "
        "translation for this transformation. The script needs to define a function "
        "'translate' that takes the current simulation time in seconds past the J2000 "
        "epoch as the first argument, the current wall time as milliseconds past the "
        "J2000 epoch as the second argument and computes the translation."
    };
} // namespace

namespace openspace {

documentation::Documentation LuaTranslation::Documentation() {
    using namespace documentation;
    return {
        "Lua Translation",
        "base_transform_translation_lua",
        {
            {
                "Type",
                new StringEqualVerifier("LuaTranslation"),
                Optional::No
            },
            {
                ScriptInfo.identifier,
                new StringVerifier,
                Optional::No,
                ScriptInfo.description
            }
        }
    };
}


LuaTranslation::LuaTranslation()
    : _luaScriptFile(ScriptInfo)
    , _state(ghoul::lua::LuaState::IncludeStandardLibrary::No)
{
    addProperty(_luaScriptFile);

    _luaScriptFile.onChange([&]() {
        requireUpdate();
        _fileHandle = std::make_unique<ghoul::filesystem::File>(_luaScriptFile);
        _fileHandle->setCallback([&](const ghoul::filesystem::File&) {
             requireUpdate();
             notifyObservers();
         });
    });
}

LuaTranslation::LuaTranslation(const ghoul::Dictionary& dictionary) : LuaTranslation() {
    documentation::testSpecificationAndThrow(
        Documentation(),
        dictionary,
        "StaticTranslation"
    );

    _luaScriptFile = absPath(dictionary.value<std::string>(ScriptInfo.identifier));
}

glm::dvec3 LuaTranslation::position(const UpdateData& data) const {
    ghoul::lua::runScriptFile(_state, _luaScriptFile);

    // Get the scaling function
    lua_getglobal(_state, "translation");
    const bool isFunction = lua_isfunction(_state, -1);
    if (!isFunction) {
        LERRORC(
            "LuaScale",
            fmt::format(
                "Script '{}' does not have a function 'translation'",
                _luaScriptFile
            )
        );
        return glm::dvec3(0.0);
    }

    // First argument is the number of seconds past the J2000 epoch in ingame time
    ghoul::lua::push(_state, data.time.j2000Seconds());

    // Second argument is the number of seconds past the J2000 epoch of the last frame
    ghoul::lua::push(_state, data.previousFrameTime.j2000Seconds());

    // Third argument is the number of milliseconds past the J2000 epoch in wallclock
    using namespace std::chrono;
    const auto now = high_resolution_clock::now();
    ghoul::lua::push(_state, duration_cast<milliseconds>(now.time_since_epoch()).count());

    // Execute the scaling function
    const int success = lua_pcall(_state, 2, 3, 0);
    if (success != 0) {
        LERRORC(
            "LuaScale",
            fmt::format("Error executing 'translation': {}", lua_tostring(_state, -1))
        );
    }

    double values[3];
    for (int i = 1; i <= 3; ++i) {
        values[i] = ghoul::lua::value<double>(_state, i);
    }

    return glm::make_vec3(values);
}

} // namespace openspace