src/animation/state_machine_instance.cpp

#include "rive/animation/state_machine_instance.hpp"
#include "rive/animation/state_machine_input.hpp"
#include "rive/animation/state_machine_bool.hpp"
#include "rive/animation/state_machine_number.hpp"
#include "rive/animation/state_machine_trigger.hpp"
#include "rive/animation/state_machine_input_instance.hpp"
#include "rive/animation/state_machine.hpp"
#include "rive/animation/state_machine_layer.hpp"
#include "rive/animation/any_state.hpp"
#include "rive/animation/entry_state.hpp"
#include "rive/animation/state_transition.hpp"
#include "rive/animation/transition_condition.hpp"
#include "rive/animation/animation_state.hpp"
#include "rive/animation/state_instance.hpp"
#include "rive/animation/animation_state_instance.hpp"

using namespace rive;
namespace rive {
    class StateMachineLayerInstance {
    private:
        static const int maxIterations = 100;
        const StateMachineLayer* m_Layer = nullptr;

        StateInstance* m_AnyStateInstance = nullptr;
        StateInstance* m_CurrentState = nullptr;
        StateInstance* m_StateFrom = nullptr;

        // const LayerState* m_CurrentState = nullptr;
        // const LayerState* m_StateFrom = nullptr;
        const StateTransition* m_Transition = nullptr;

        bool m_HoldAnimationFrom = false;
        // LinearAnimationInstance* m_AnimationInstance = nullptr;
        // LinearAnimationInstance* m_AnimationInstanceFrom = nullptr;
        float m_Mix = 1.0f;
        float m_MixFrom = 1.0f;
        bool m_StateChangedOnAdvance = false;

        bool m_WaitingForExit = false;
        /// Used to ensure a specific animation is applied on the next apply.
        const LinearAnimation* m_HoldAnimation = nullptr;
        float m_HoldTime = 0.0f;

    public:
        ~StateMachineLayerInstance() {
            delete m_AnyStateInstance;
            delete m_CurrentState;
            delete m_StateFrom;
        }

        void init(const StateMachineLayer* layer) {
            assert(m_Layer == nullptr);
            m_AnyStateInstance = layer->anyState()->makeInstance();
            m_Layer = layer;
            changeState(m_Layer->entryState());
        }

        void updateMix(float seconds) {
            if (m_Transition != nullptr && m_StateFrom != nullptr &&
                m_Transition->duration() != 0)
            {
                m_Mix = std::min(
                    1.0f,
                    std::max(0.0f,
                             (m_Mix + seconds / m_Transition->mixTime(
                                                    m_StateFrom->state()))));
            } else {
                m_Mix = 1.0f;
            }
        }

        bool advance(Artboard* artboard,
                     float seconds,
                     SMIInput** inputs,
                     size_t inputCount) {
            m_StateChangedOnAdvance = false;

            if (m_CurrentState != nullptr) {
                m_CurrentState->advance(seconds, inputs);
            }

            updateMix(seconds);

            if (m_StateFrom != nullptr && m_Mix < 1.0f && !m_HoldAnimationFrom)
            {
                // This didn't advance during our updateState, but it should now
                // that we realize we need to mix it in.
                m_StateFrom->advance(seconds, inputs);
            }

            for (int i = 0; updateState(inputs, i != 0); i++) {
                apply(artboard);

                if (i == maxIterations) {
                    fprintf(stderr, "StateMachine exceeded max iterations.\n");
                    return false;
                }
            }

            apply(artboard);

            return m_Mix != 1.0f || m_WaitingForExit ||
                   (m_CurrentState != nullptr && m_CurrentState->keepGoing());
        }

        bool isTransitioning() {
            return m_Transition != nullptr && m_StateFrom != nullptr &&
                   m_Transition->duration() != 0 && m_Mix < 1.0f;
        }

        bool updateState(SMIInput** inputs, bool ignoreTriggers) {
            // Don't allow changing state while a transition is taking place
            // (we're mixing one state onto another).
            if (isTransitioning()) {
                return false;
            }

            m_WaitingForExit = false;

            if (tryChangeState(m_AnyStateInstance, inputs, ignoreTriggers)) {
                return true;
            }

            return tryChangeState(m_CurrentState, inputs, ignoreTriggers);
        }

        bool changeState(const LayerState* stateTo) {
            if ((m_CurrentState == nullptr
                     ? nullptr
                     : m_CurrentState->state()) == stateTo) {
                return false;
            }
            m_CurrentState =
                stateTo == nullptr ? nullptr : stateTo->makeInstance();
            return true;
        }

        bool tryChangeState(StateInstance* stateFromInstance,
                            SMIInput** inputs,
                            bool ignoreTriggers) {
            if (stateFromInstance == nullptr) {
                return false;
            }
            auto stateFrom = stateFromInstance->state();
            auto outState = m_CurrentState;
            for (size_t i = 0, length = stateFrom->transitionCount();
                 i < length;
                 i++) {
                auto transition = stateFrom->transition(i);
                auto allowed = transition->allowed(
                    stateFromInstance, inputs, ignoreTriggers);
                if (allowed == AllowTransition::yes &&
                    changeState(transition->stateTo())) {
                    m_StateChangedOnAdvance = true;
                    // state actually has changed
                    m_Transition = transition;
                    if (m_StateFrom != m_AnyStateInstance) {
                        // Old state from is done.
                        delete m_StateFrom;
                    }
                    m_StateFrom = outState;

                    // If we had an exit time and wanted to pause on exit, make
                    // sure to hold the exit time. Delegate this to the
                    // transition by telling it that it was completed.
                    if (outState != nullptr &&
                        transition->applyExitCondition(outState)) {
                        // Make sure we apply this state. This only returns true
                        // when it's an animation state instance.
                        auto instance =
                            static_cast<AnimationStateInstance*>(m_StateFrom)
                                ->animationInstance();

                        m_HoldAnimation = instance->animation();
                        m_HoldTime = instance->time();
                    }
                    m_MixFrom = m_Mix;

                    // Keep mixing last animation that was mixed in.
                    if (m_Mix != 0.0f) {
                        m_HoldAnimationFrom = transition->pauseOnExit();
                    }
                    if (m_StateFrom != nullptr &&
                        m_StateFrom->state()->is<AnimationState>() &&
                        m_CurrentState != nullptr)
                    {
                        auto instance =
                            static_cast<AnimationStateInstance*>(m_StateFrom)
                                ->animationInstance();

                        auto spilledTime = instance->spilledTime();
                        m_CurrentState->advance(spilledTime, inputs);
                    }
                    m_Mix = 0.0f;
                    updateMix(0.0f);
                    m_WaitingForExit = false;
                    return true;
                } else if (allowed == AllowTransition::waitingForExit) {
                    m_WaitingForExit = true;
                }
            }
            return false;
        }

        void apply(Artboard* artboard) {
            if (m_HoldAnimation != nullptr) {
                m_HoldAnimation->apply(artboard, m_HoldTime, m_MixFrom);
                m_HoldAnimation = nullptr;
            }

            if (m_StateFrom != nullptr && m_Mix < 1.0f) {
                m_StateFrom->apply(artboard, m_MixFrom);
            }
            if (m_CurrentState != nullptr) {
                m_CurrentState->apply(artboard, m_Mix);
            }
        }

        bool stateChangedOnAdvance() const { return m_StateChangedOnAdvance; }

        const LayerState* currentState() {
            return m_CurrentState == nullptr ? nullptr
                                             : m_CurrentState->state();
        }

        const LinearAnimationInstance* currentAnimation() const {
            if (m_CurrentState == nullptr ||
                !m_CurrentState->state()->is<AnimationState>()) {
                return nullptr;
            }
            return static_cast<AnimationStateInstance*>(m_CurrentState)
                ->animationInstance();
        }
    };
} // namespace rive

StateMachineInstance::StateMachineInstance(const StateMachine* machine) :
    m_Machine(machine) {
    m_InputCount = machine->inputCount();
    m_InputInstances = new SMIInput*[m_InputCount];
    for (size_t i = 0; i < m_InputCount; i++) {
        auto input = machine->input(i);
        if (input == nullptr) {
            m_InputInstances[i] = nullptr;
            continue;
        }
        switch (input->coreType()) {
            case StateMachineBool::typeKey:
                m_InputInstances[i] =
                    new SMIBool(input->as<StateMachineBool>(), this);
                break;
            case StateMachineNumber::typeKey:
                m_InputInstances[i] =
                    new SMINumber(input->as<StateMachineNumber>(), this);
                break;
            case StateMachineTrigger::typeKey:
                m_InputInstances[i] =
                    new SMITrigger(input->as<StateMachineTrigger>(), this);
                break;
            default:
                // Sanity check.
                m_InputInstances[i] = nullptr;
                break;
        }
    }

    m_LayerCount = machine->layerCount();
    m_Layers = new StateMachineLayerInstance[m_LayerCount];
    for (size_t i = 0; i < m_LayerCount; i++) {
        m_Layers[i].init(machine->layer(i));
    }
}

StateMachineInstance::~StateMachineInstance() {
    // TODO: can this and others be rewritten as for (auto inst : m_InputInstances) ?
    for (size_t i = 0; i < m_InputCount; i++) {
        delete m_InputInstances[i];
    }
    delete[] m_InputInstances;
    delete[] m_Layers;
}

bool StateMachineInstance::advance(Artboard* artboard, float seconds) {
    m_NeedsAdvance = false;
    for (size_t i = 0; i < m_LayerCount; i++) {
        if (m_Layers[i].advance(
                artboard, seconds, m_InputInstances, m_InputCount)) {
            m_NeedsAdvance = true;
        }
    }

    for (size_t i = 0; i < m_InputCount; i++) {
        m_InputInstances[i]->advanced();
    }

    return m_NeedsAdvance;
}

void StateMachineInstance::markNeedsAdvance() { m_NeedsAdvance = true; }
bool StateMachineInstance::needsAdvance() const { return m_NeedsAdvance; }

SMIInput* StateMachineInstance::input(size_t index) const {
    if (index < m_InputCount) {
        return m_InputInstances[index];
    }
    return nullptr;
}

SMIBool* StateMachineInstance::getBool(std::string name) const {
    for (size_t i = 0; i < m_InputCount; i++) {
        auto input = m_InputInstances[i]->input();
        if (input->is<StateMachineBool>() && input->name() == name) {
            return static_cast<SMIBool*>(m_InputInstances[i]);
        }
    }
    return nullptr;
}

SMINumber* StateMachineInstance::getNumber(std::string name) const {
    for (size_t i = 0; i < m_InputCount; i++) {
        auto input = m_InputInstances[i]->input();
        if (input->is<StateMachineNumber>() && input->name() == name) {
            return static_cast<SMINumber*>(m_InputInstances[i]);
        }
    }
    return nullptr;
}
SMITrigger* StateMachineInstance::getTrigger(std::string name) const {
    for (size_t i = 0; i < m_InputCount; i++) {
        auto input = m_InputInstances[i]->input();
        if (input->is<StateMachineTrigger>() && input->name() == name) {
            return static_cast<SMITrigger*>(m_InputInstances[i]);
        }
    }
    return nullptr;
}

size_t StateMachineInstance::stateChangedCount() const {
    size_t count = 0;
    for (size_t i = 0; i < m_LayerCount; i++) {
        if (m_Layers[i].stateChangedOnAdvance()) {
            count++;
        }
    }
    return count;
}

const LayerState*
StateMachineInstance::stateChangedByIndex(size_t index) const {
    size_t count = 0;
    for (size_t i = 0; i < m_LayerCount; i++) {
        if (m_Layers[i].stateChangedOnAdvance()) {
            if (count == index) {
                return m_Layers[i].currentState();
            }
            count++;
        }
    }
    return nullptr;
}

const size_t StateMachineInstance::currentAnimationCount() const {
    size_t count = 0;
    for (size_t i = 0; i < m_LayerCount; i++) {
        if (m_Layers[i].currentAnimation() != nullptr) {
            count++;
        }
    }
    return count;
}

const LinearAnimationInstance*
StateMachineInstance::currentAnimationByIndex(size_t index) const {
    size_t count = 0;
    for (size_t i = 0; i < m_LayerCount; i++) {
        if (m_Layers[i].currentAnimation() != nullptr) {
            if (count == index) {
                return m_Layers[i].currentAnimation();
            }
            count++;
        }
    }
    return nullptr;
}