AdventuresInLestoria/Crawler/olcUTIL_Animate2D.h

/*
OneLoneCoder - Animate2D v1.00
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Handles animated Sprites efficiently


License (OLC-3)
~~~~~~~~~~~~~~~

Copyright 2018 - 2022 OneLoneCoder.com

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contributors may be used to endorse or promote products derived
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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Links
~~~~~
YouTube:	https://www.youtube.com/javidx9
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Author
~~~~~~
David Barr, aka javidx9, <20>OneLoneCoder 2019, 2020, 2021, 2022

*/

#pragma once

#include "olcPixelGameEngine.h"
#include "olcUTIL_Geometry2D.h"

namespace olc::utils::Animate2D
{
	// This class rerpresents a valid "frame" of an animation. It could be from any image source, and
	// any location withing that image source. Once it's constructed, it's advised not to change it, as
	// this likely indicates a usage bug.
	//
	// "Sourceless" frames are valid too - this is useful if you have a particular animation set, but 
	// want to apply it to a variety of sources, for example sprite maps with common layouts.
	class Frame
	{
	public:
		inline Frame(const olc::Renderable* gfxSource, const geom2d::rect<int32_t>& rectSource = { {0,0},{0,0} })
			: gfxImageSource(gfxSource), rectFrameSource(rectSource)
		{
			// If no source rectangle specified then use whole image source. Ignore in the event 
			// that a frame is set up as source-less
			if(gfxSource && rectFrameSource.size.x == 0)
				rectFrameSource.size = gfxSource->Sprite()->Size();
		}

		inline const olc::Renderable* GetSourceImage() const
		{
			return gfxImageSource;
		}

		inline const geom2d::rect<int32_t>& GetSourceRect() const
		{
			return rectFrameSource;
		}

	private:
		const olc::Renderable* gfxImageSource;
		geom2d::rect<int32_t> rectFrameSource;
	};

	// Animation styles decide how the frames should be traversed in time
	enum class Style : uint8_t
	{
		Repeat,		// Cycle through, go back to beginning
		OneShot,	// Play once and suspend on final frame
		PingPong,   // Traverse through forwards, then backwards
		Reverse,    // Cycle through sequence backwards
	};

	class FrameSequence
	{
	public:
		// Constructs a sequence of frames with a duration and a traversal style
		inline FrameSequence(const float fFrameDuration = 0.1f, const Style nStyle = Style::Repeat)
		{
			m_fFrameDuration = fFrameDuration;
			m_fFrameRate = 1.0f / m_fFrameDuration;
			m_nStyle = nStyle;
		}

		// Adds a frame to this sequence
		inline void AddFrame(const Frame& frame)
		{
			m_vFrames.emplace_back(frame);
		}

		// Returns a Frame Object for a given time into an animation
		inline const Frame& GetFrame(const float fTime) const
		{
			return m_vFrames[ConvertTimeToFrame(fTime)];
		}

	private:
		Style m_nStyle;
		std::vector<Frame> m_vFrames;
		float m_fFrameDuration = 0.1f;
		float m_fFrameRate = 10.0f;

		inline const size_t ConvertTimeToFrame(const float fTime) const
		{
			switch (m_nStyle)
			{
			case Style::Repeat:
				return size_t(fTime * m_fFrameRate) % m_vFrames.size();
				break;
			case Style::OneShot:
				return std::clamp(size_t(fTime * m_fFrameRate), size_t(0), m_vFrames.size() - 1);
				break;
			case Style::PingPong:{
					size_t frame=size_t(m_fFrameRate*fTime) % (m_vFrames.size()*2-1);
					return frame>=m_vFrames.size()?m_vFrames.size()-frame%m_vFrames.size()-1:frame;
				}break;
			case Style::Reverse:
				return (m_vFrames.size() - 1) - (size_t(fTime * m_fFrameRate) % m_vFrames.size());
				break;
			}

			return 0;
		}
	};

	// A Animate2D::State is a lightweight token that can be attached to things
	// that are animated. Under normal circumstances, it is never updated manually
	struct AnimationState
	{
	private:
		size_t nIndex = 0;
		float fTime = 0.0f;		
		template<typename StatesEnum>
		friend class Animation;
	};

	// Animation object holds a group of frame sequences and can mutate an AnimationState token
	template<typename StatesEnum>
	class Animation
	{
	public:
		Animation() = default;

		// Change an animation state token to a new state
		inline bool ChangeState(AnimationState& state, const StatesEnum& sStateName) const
		{
			size_t idx = m_mapStateIndices.at(sStateName);
			if (state.nIndex != idx)
			{
				state.fTime = 0.0f;
				state.nIndex = idx;
				return true;
			}

			return false;
		}

		// Update an animation state token
		inline void UpdateState(AnimationState& state, const float fElapsedTime) const
		{
			state.fTime += fElapsedTime;
		}

	public:
		// Retrieve the frame information for a given animation state
		inline const Frame& GetFrame(const AnimationState& state) const
		{
			return m_vSequences[state.nIndex].GetFrame(state.fTime);
		}

	public:
		// Add a named Frame sequence as a state
		inline void AddState(const StatesEnum& sStateName, const FrameSequence& sequence)
		{
			m_vSequences.emplace_back(sequence);
			m_mapStateIndices[sStateName] = m_vSequences.size() - 1;
		}

	private:
		std::vector<FrameSequence> m_vSequences;
		std::unordered_map<StatesEnum, size_t> m_mapStateIndices;
	};
}

using namespace olc::utils;