//PLEASE NOTE: The ParticleEmitter class functions have changed since this tutorial
//after I reorganized some things for the SIMD update loop. The final code for that
//is linked in the optimization section.

enum ParticleFacingType
{
	ParticleFacing_2D_Billboard,
	ParticleFacing_3D_Billboard
};

struct ParticleEmitterDepthSettings
{
	ParticleEmitterDepthSettings()
	{
		UsesDepthSoftening = false;
		DepthFadeDistance = 1.0f;
		DepthFadePower = 1.0f;
	}

	bool  UsesDepthSoftening;
	float DepthFadeDistance;
	float DepthFadePower;
};

struct ParticleEmitterTextureAnimation
{
	ParticleEmitterTextureAnimation()
	{
		IsAnimated = false;
		RandomizeInitialFrame = false;
		FrameCountX = 0;
		FrameCountY = 0;
		FramesPerSecond = 0;
		IsAnimatedForTextureIndex[0] = false;
		IsAnimatedForTextureIndex[1] = false;
		IsAnimatedForTextureIndex[2] = false;
		FrameTimeVariance = 0.0f;
	}

	bool   IsAnimated;
	bool   RandomizeInitialFrame;
	uint32 FrameCountX;
	uint32 FrameCountY;
	float  FramesPerSecond;
	float  FrameTimeVariance;
	bool   IsAnimatedForTextureIndex[3];
};

enum ParticleBlendMode
{
	ParticleBlendMode_AlphaBlend = 0,
	ParticleBlendMode_Additive,
	ParticleBlendMode_Multiply,
	ParticleBlendMode_Multiply2x,
	ParticleBlendMode_Subtract
};

struct ParticleEmitterWideUpdates
{
	float rotationalVelocity;
	Vector2 uvScrollDelta[3];

	Vector3 particleUp;
	Vector3 particleRight;
	Vector3 particleForward;
};

class ParticleEmitter
{
public:
	ParticleEmitter();
	~ParticleEmitter();

	void OnFree();
	void Initialize(uint32_t maxParticles, uint32 poolId);
	
	void Render(ID3D11DeviceContext *deviceContext, ParticleVertexBuffer *managedBuffer);
	void Update(ParticleVertexBuffer *managedBuffer, float deltaTime, const Vector3 &cameraDirection, const Vector3 &cameraPosition);
	void SetShaderParameters(ID3D11DeviceContext* deviceContext, ShaderParams &inputParams);

	void SetTexture(Texture *texture, uint32 index) { mTextures[index] = texture; }
	void SetMaterial(MaterialInstance *material) { mMaterial = material; }

	float GetDistanceFromCamera() { return mDistanceFromCamera; }

	bool IsInitialized() { return mInitialized; }
	bool IsComplete();
	void Start();
	void Stop();

	ParticleBlendMode GetBlendMode() { return mBlendMode; }

	void SetPosition(Vector3 position) { mPosition = position; }

private:
	void CleanUp();
	void UpdateParticle(Particle *particle, ParticleVertexBuffer *managedBuffer, float deltaTime, const ParticleEmitterWideUpdates &particleUpdates);
	void UpdateParticles(Particle *particle[4], ParticleVertexBuffer *managedBuffer, float deltaTime, const ParticleEmitterWideUpdates &particleUpdates);

	uint32 mPoolId;
	bool mInitialized;
	bool mShouldEmit;
	bool mLoop;

	Vector3 mPosition;
	Vector3 mRotation;
	float	mDistanceFromCamera;

	Vector3 mSpawnArea;
	AnimatedValue<Vector4> mColorMultiplier;
	Vector4				   mColorVariance;
	AnimatedValue<Vector3> mScale;
	float				   mScaleVariance;
	AnimatedValue<Vector3> mVelocity;
	AnimatedValue<Vector3> mVelocityOverLifetime;
	Vector3				   mVelocityVariance;
	Vector3				   mGravity;
	AnimatedValue<float>   mRotationalVelocity;
	float				   mRotationVariance;
	float				   mRotationRateVariance;
	AnimatedValue<float>   mMaterialIntensity;
	float				   mMaterialIntensityVariance;

	AnimatedValue<float> mEmissionPerSecond;
	float mEmitterLifeTime;
	float mEmitterCurrentLife;
	float mParticleLifeTime;
	float mParticleLifeTimeVariance;

	ParticleBlendMode mBlendMode;
	ParticleFacingType mFacingType;
	ParticleEmitterDepthSettings mDepthSettings;
	
	AnimatedValue<Vector2> mUVScroll[3];
	Vector2 mUVScrollOffsets[3];
	Vector2 mUVScrollVariance[3];
	Texture *mTextures[3];
	ParticleEmitterTextureAnimation mTextureAnimation;
	
	uint32_t mMaxParticles;
	uint32 mMinActiveParticles;
	float mPartialParticle;
	MaterialInstance *mMaterial;
	DynamicArray<Particle*> mParticles;
	uint32 mStartVert;
	uint32 mEndVert;
};