OpenSpace/modules/base/scale/luascale.cpp

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 * OpenSpace                                                                             *
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#include <modules/base/scale/luascale.h>

#include <openspace/documentation/documentation.h>
#include <openspace/documentation/verifier.h>
#include <openspace/engine/globals.h>
#include <openspace/scripting/scriptengine.h>
#include <openspace/util/updatestructures.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 "
        "scaling factor for this transformation. The script needs to define a function "
        "'scale' that takes the current simulation time in seconds past the J2000 epoch "
        "as the first argument, the simulation time in seconds past the J2000 epoch of "
        "the last frame as the second argument, and the current wall time as "
        "milliseconds past the J2000 epoch the third argument and computes the three "
        "scaling factors returned as a table.",
        openspace::properties::Property::Visibility::AdvancedUser
    };

    // This `Scale` type generates the scale values for the attached scene graph node by
    // calling the provided Lua script. The script must return three scaling factors, one
    // for each principal axis. The script parameter describes in greater detail how the
    // Lua script file should be constructed.
    struct [[codegen::Dictionary(LuaScale)]] Parameters {
        // [[codegen::verbatim(ScriptInfo.description)]]
        std::filesystem::path script;
    };
#include "luascale_codegen.cpp"
} // namespace

namespace openspace {

documentation::Documentation LuaScale::Documentation() {
    return codegen::doc<Parameters>("base_transform_scale_lua");
}

LuaScale::LuaScale(const ghoul::Dictionary& dictionary)
    : Scale(dictionary)
    , _luaScriptFile(ScriptInfo)
{
    const Parameters p = codegen::bake<Parameters>(dictionary);

    _luaScriptFile.onChange([this]() {
        requireUpdate();
        _fileHandle = std::make_unique<ghoul::filesystem::File>(_luaScriptFile.value());
        _fileHandle->setCallback([this]() { requireUpdate(); });
    });
    addProperty(_luaScriptFile);
    global::scriptEngine->initializeLuaState(_state);

    _luaScriptFile = p.script.string();
}

glm::dvec3 LuaScale::scaleValue(const UpdateData& data) const {
    ghoul::lua::runScriptFile(_state, _luaScriptFile.value());

    // Get the scaling function
    lua_getglobal(_state, "scale");
    const bool isFunction = lua_isfunction(_state, -1);
    if (!isFunction) {
        LERRORC(
            "LuaScale",
            std::format(
                "Script '{}' does not have a function 'scale'", _luaScriptFile.value()
            )
        );
        return glm::dvec3(1.0);
    }

    // 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 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 = std::chrono::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, 3, 1, 0);
    if (success != 0) {
        LERRORC(
            "LuaScale",
            std::format("Error executing 'scale': {}", lua_tostring(_state, -1))
        );
    }

    const glm::dvec3 scale = ghoul::lua::value<glm::dvec3>(_state);
    return scale;
}

} // namespace openspace