NouVeL/ADVect/Track.h

#pragma once
#include <Common.h>
#include <Environment.h>
#include "Graphics.h"

namespace ADVect {
	template <typename T>
	struct Varying {
		u64 begin = 0, duration = 0;
		std::function<T(f32)> interp;
		bool done = true;

		T get(u64 current_time) const {
			if (done)
				return interp(1.f);
			else
				return interp((current_time - begin) / static_cast<f32>(duration));
		}
		void kickoff(u64 current_time, u64 dur, const std::function<T(f32)>& f = [](f32 x) { return static_cast<T>(x); }) {
			begin = current_time;
			done = false;
			duration = dur;
			interp = f;
		}
		bool check(u64 current_time) {
			if (done) return true;
			else if (current_time >= begin + duration) {
				done = true;
				return true;
			}
			else return false;
		}
	};

	template <typename T, bool UsePointer, bool IsNamed, bool IsVisual, bool IsVisualFill, bool HasTransition>
	struct Track {
		std::conditional_t<UsePointer, T*, T> current{};
		[[no_unique_address]] std::conditional_t<IsNamed, std::string, std::monostate> name{};

		// Visual
		[[no_unique_address]] std::conditional_t<IsVisual, i32, std::monostate> pos_x{}, pos_y{};
		[[no_unique_address]] std::conditional_t<IsVisual, u32, std::monostate> w{}, h{};
		[[no_unique_address]] std::conditional_t<IsVisual, f32, std::monostate> opacity{};
		// TODO other transforms

		// Fill
		static_assert(IsVisual || !IsVisualFill, "Track cannot have fill unless visual");
		[[no_unique_address]] std::conditional_t<IsVisualFill, u32, std::monostate> fill{};

		// Transition, with assumption that we need to access the original when transition is underway
		[[no_unique_address]] std::conditional_t<HasTransition, std::conditional_t<UsePointer, T*, T>, std::monostate> next{};
		[[no_unique_address]] std::conditional_t<HasTransition, Varying<f32>, std::monostate> transition{};
		void check(u64 current_time) requires HasTransition {
			if constexpr (UsePointer) {
				if (next != nullptr && transition.check(current_time)) {
					current = next;
					next = nullptr;
				}
			}
			else {
				if (transition.check(current_time))
					current = next;
			}
		}
		void change(u64 current_time, const std::conditional_t<UsePointer, T*, T> n, u64 dur, const std::function<f32(f32)>& f = [](f32 x) { return x; }) requires HasTransition {
			if constexpr (UsePointer) {
				if (current == nullptr)
					current = n;
				else if (n == nullptr) current = n;
				else {
					next = n;
					transition.kickoff(current_time, dur, f);
				}
			}
			else {
				next = n;
				transition.kickoff(current_time, dur, f);
			}
		}
	};

	template<typename T, bool UsePointer>
	using VisualTrack = Track<T, UsePointer, false, true, false, false>;
	template<typename T, bool UsePointer>
	using VisualTransitionTrack = Track<T, UsePointer, false, true, false, true>;

	template<typename T, bool UsePointer>
	using FillVisualTrack = Track<T, UsePointer, false, true, true, false>;
	template<typename T, bool UsePointer>
	using FillVisualTransitionTrack = Track<T, UsePointer, false, true, true, true>;

	/* TODO impl
	struct AudioTrack {};
	*/

	using TextTrack = FillVisualTrack<NVL::String, false>;
	using MarkupTextTrack = FillVisualTrack<NVL::Environment::MarkupString, false>;
	using MarkupTextTransitionTrack = FillVisualTransitionTrack<NVL::Environment::MarkupString, false>;
	using ImageTrack = VisualTrack<ADVect::Graphics::ImageTexture, true>;
	using ImageTransitionTrack = VisualTransitionTrack<ADVect::Graphics::ImageTexture, true>;
	/* TODO VideoTrack */

	void draw_typewriter(u64 current_time, const MarkupTextTransitionTrack& t) {
		if (t.transition.done)
			ADVect::Graphics::RenderSubstringMarkupBox(t.current, t.pos_x, t.pos_y, t.w, t.fill);
		else
			ADVect::Graphics::RenderSubstringMarkupBox(t.next, t.pos_x, t.pos_y, t.w, t.fill, t.transition.get(current_time));
	}

	void draw_image_transition_fade(u64 current_time, const ImageTransitionTrack& t) {
		if (t.current != nullptr) {
			if (t.next != nullptr) {
				ADVect::Graphics::DrawTextureImage(*t.current, t.pos_x, t.pos_y);
				ADVect::Graphics::DrawTextureImageAlpha(*t.next, t.pos_x, t.pos_y, t.transition.get(current_time));
			}
			else {
				ADVect::Graphics::DrawTextureImage(*t.current, t.pos_x, t.pos_y);
			}
		}
	}
	void draw_image_transition_crossfade(u64 current_time, const ImageTransitionTrack& t) {
		if (t.current != nullptr) {
			if (t.next != nullptr) {
				ADVect::Graphics::DrawTextureImageAlpha(*t.current, t.pos_x, t.pos_y, 1.0f - t.transition.get(current_time));
				ADVect::Graphics::DrawTextureImageAlpha(*t.next, t.pos_x, t.pos_y, t.transition.get(current_time));
			}
			else {
				ADVect::Graphics::DrawTextureImage(*t.current, t.pos_x, t.pos_y);
			}
		}
	}
}