particle_system.hpp

#pragma once

#include <Maths/vector2.hpp>

#include "Mountain/core.hpp"
#include "Mountain/rendering/gpu_buffer.hpp"
#include "Mountain/rendering/gpu_vertex_array.hpp"
#include "Mountain/rendering/particle_system_modules.hpp"
#include "Mountain/resource/compute_shader.hpp"
#include "Mountain/resource/shader.hpp"
#include "Mountain/utils/color.hpp"
#include "Mountain/utils/list.hpp"

// OpenGL type forward declaration
// ReSharper disable once CppInconsistentNaming
struct __GLsync;  // NOLINT(clang-diagnostic-reserved-identifier, bugprone-reserved-identifier)

namespace Mountain
{
    struct ParticleSystemBurst
    {
        float_t time = 0.f;
        uint32_t count = 30;
        uint32_t cycles = 1;
        float_t interval = 0.01f;
        float_t probability = 1.f;
    };

    class ParticleSystem
    {
    public:
        // Particle system settings

        Vector2 position;
        float_t rotation;
        float_t duration = 5.f;
        bool_t looping = true;
        float_t startDelay;
        bool_t useUnscaledDeltaTime = false;

        // Emission settings

        float_t emissionRateOverTime = 10.f;
        float_t emissionRateOverDistance = 0.f;
        List<ParticleSystemBurst> emissionBursts;

        // Particle settings

        float_t particleLifetime = 5.f;
        float_t particleSpeed = 5.f;
        Color particleStartColor = Color::White();

        // Modules

        List<std::shared_ptr<ParticleSystemModules::Base>> modules;
        ParticleSystemModules::Types enabledModules = ParticleSystemModules::Types::Default;

        MOUNTAIN_API ParticleSystem() = default;
        MOUNTAIN_API explicit ParticleSystem(uint32_t maxParticles);
        MOUNTAIN_API virtual ~ParticleSystem();

        DEFAULT_COPY_MOVE_OPERATIONS(ParticleSystem)

        MOUNTAIN_API void Update();
        MOUNTAIN_API void Render();
        MOUNTAIN_API void RenderImGui();
        MOUNTAIN_API void RenderDebug();

        MOUNTAIN_API void TogglePlay();
        MOUNTAIN_API void Restart();
        MOUNTAIN_API void Stop();

        [[nodiscard]]
        MOUNTAIN_API uint32_t GetCurrentParticles();

        [[nodiscard]]
        MOUNTAIN_API uint32_t GetMaxParticles() const;
        MOUNTAIN_API void SetMaxParticles(uint32_t newMaxParticles);

        [[nodiscard]]
        MOUNTAIN_API bool_t IsPlaying() const;

    private:
        uint32_t m_MaxParticles = 0;
        int32_t* m_LiveParticles = nullptr;
        __GLsync* m_SyncObject = nullptr;

        float_t m_PlaybackTime = 0.f; // System lifetime
        float_t m_LastPlaybackTime = 0.f;
        double_t m_SpawnTimer = 0.0;
        bool_t m_Playing = true;
        Vector2 m_LastPosition;

        Pointer<ComputeShader> m_UpdateComputeShader;

        Pointer<Shader> m_DrawShader;
        Graphics::GpuBuffer m_LiveSsbo, m_ParticleSsbo;
        Graphics::GpuVertexArray m_DrawVao;

        bool_t m_GuiParticleBurstTimeHeld = false;
        Vector2 m_RenderTargetSize;

        void SetComputeShaderUniforms(float_t deltaTime) const;
        void SpawnNewParticles();

        static void WaitBufferSync(__GLsync* syncObject);
        static void LockBuffer(__GLsync*& syncObject);
    };
}