#include "stdafx.h"
#include "TerrainGenerator.h"

#include "Utility/stb_image.h"

using namespace wi::ecs;
using namespace wi::scene;

enum PRESET
{
	PRESET_HILLS,
	PRESET_ISLANDS,
	PRESET_MOUNTAINS,
	PRESET_ARCTIC,
};

void TerrainGenerator::init()
{
	terrainEntity = CreateEntity();

	indices.clear();
	lods.clear();
	lods.resize(max_lod);
	for (int lod = 0; lod < max_lod; ++lod)
	{
		lods[lod].indexOffset = (uint32_t)indices.size();

		if (lod == 0)
		{
			for (int x = 0; x < width - 1; x++)
			{
				for (int z = 0; z < width - 1; z++)
				{
					int lowerLeft = x + z * width;
					int lowerRight = (x + 1) + z * width;
					int topLeft = x + (z + 1) * width;
					int topRight = (x + 1) + (z + 1) * width;

					indices.push_back(topLeft);
					indices.push_back(lowerLeft);
					indices.push_back(lowerRight);

					indices.push_back(topLeft);
					indices.push_back(lowerRight);
					indices.push_back(topRight);
				}
			}
		}
		else
		{
			const int step = 1 << lod;
			// inner grid:
			for (int x = 1; x < width - 2; x += step)
			{
				for (int z = 1; z < width - 2; z += step)
				{
					int lowerLeft = x + z * width;
					int lowerRight = (x + step) + z * width;
					int topLeft = x + (z + step) * width;
					int topRight = (x + step) + (z + step) * width;

					indices.push_back(topLeft);
					indices.push_back(lowerLeft);
					indices.push_back(lowerRight);

					indices.push_back(topLeft);
					indices.push_back(lowerRight);
					indices.push_back(topRight);
				}
			}
			// bottom border:
			for (int x = 0; x < width - 1; ++x)
			{
				const int z = 0;
				int current = x + z * width;
				int neighbor = x + 1 + z * width;
				int connection = 1 + ((x + (step + 1) / 2 - 1) / step) * step + (z + 1) * width;

				indices.push_back(current);
				indices.push_back(neighbor);
				indices.push_back(connection);

				if (((x - 1) % (step)) == step / 2) // halfway fill triangle
				{
					int connection1 = 1 + (((x - 1) + (step + 1) / 2 - 1) / step) * step + (z + 1) * width;

					indices.push_back(current);
					indices.push_back(connection);
					indices.push_back(connection1);
				}
			}
			// top border:
			for (int x = 0; x < width - 1; ++x)
			{
				const int z = width - 1;
				int current = x + z * width;
				int neighbor = x + 1 + z * width;
				int connection = 1 + ((x + (step + 1) / 2 - 1) / step) * step + (z - 1) * width;

				indices.push_back(current);
				indices.push_back(connection);
				indices.push_back(neighbor);

				if (((x - 1) % (step)) == step / 2) // halfway fill triangle
				{
					int connection1 = 1 + (((x - 1) + (step + 1) / 2 - 1) / step) * step + (z - 1) * width;

					indices.push_back(current);
					indices.push_back(connection1);
					indices.push_back(connection);
				}
			}
			// left border:
			for (int z = 0; z < width - 1; ++z)
			{
				const int x = 0;
				int current = x + z * width;
				int neighbor = x + (z + 1) * width;
				int connection = x + 1 + (((z + (step + 1) / 2 - 1) / step) * step + 1) * width;

				indices.push_back(current);
				indices.push_back(connection);
				indices.push_back(neighbor);

				if (((z - 1) % (step)) == step / 2) // halfway fill triangle
				{
					int connection1 = x + 1 + ((((z - 1) + (step + 1) / 2 - 1) / step) * step + 1) * width;

					indices.push_back(current);
					indices.push_back(connection1);
					indices.push_back(connection);
				}
			}
			// right border:
			for (int z = 0; z < width - 1; ++z)
			{
				const int x = width - 1;
				int current = x + z * width;
				int neighbor = x + (z + 1) * width;
				int connection = x - 1 + (((z + (step + 1) / 2 - 1) / step) * step + 1) * width;

				indices.push_back(current);
				indices.push_back(neighbor);
				indices.push_back(connection);

				if (((z - 1) % (step)) == step / 2) // halfway fill triangle
				{
					int connection1 = x - 1 + ((((z - 1) + (step + 1) / 2 - 1) / step) * step + 1) * width;

					indices.push_back(current);
					indices.push_back(connection);
					indices.push_back(connection1);
				}
			}
		}

		lods[lod].indexCount = (uint32_t)indices.size() - lods[lod].indexOffset;
	}

	RemoveWidgets();
	ClearTransform();

	wi::gui::Window::Create("TerraGen (Preview version)");
	SetSize(XMFLOAT2(410, 560));

	float xx = 150;
	float yy = 0;
	float stepstep = 25;
	float heihei = 20;

	centerToCamCheckBox.Create("Center to Cam: ");
	centerToCamCheckBox.SetTooltip("Automatically generate chunks around camera. This sets the center chunk to camera position.");
	centerToCamCheckBox.SetSize(XMFLOAT2(heihei, heihei));
	centerToCamCheckBox.SetPos(XMFLOAT2(xx, yy += stepstep));
	centerToCamCheckBox.SetCheck(true);
	AddWidget(&centerToCamCheckBox);

	removalCheckBox.Create("Removal: ");
	removalCheckBox.SetTooltip("Automatically remove chunks that are farther than generation distance around center chunk.");
	removalCheckBox.SetSize(XMFLOAT2(heihei, heihei));
	removalCheckBox.SetPos(XMFLOAT2(xx + 100, yy));
	removalCheckBox.SetCheck(true);
	AddWidget(&removalCheckBox);

	lodSlider.Create(0.0001f, 0.01f, 0.005f, 10000, "LOD Distance: ");
	lodSlider.SetTooltip("Set the LOD (Level Of Detail) distance multiplier.\nLow values increase LOD detail in distance");
	lodSlider.SetSize(XMFLOAT2(200, heihei));
	lodSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	lodSlider.OnSlide([this](wi::gui::EventArgs args) {
		for (auto& it : chunks)
		{
			const ChunkData& chunk_data = it.second;
			if (chunk_data.entity != INVALID_ENTITY)
			{
				ObjectComponent* object = scene->objects.GetComponent(chunk_data.entity);
				if (object != nullptr)
				{
					object->lod_distance_multiplier = args.fValue;
				}
			}
		}
		});
	AddWidget(&lodSlider);

	generationSlider.Create(0, 16, 12, 16, "Generation Distance: ");
	generationSlider.SetTooltip("How far out chunks will be generated (value is in number of chunks)");
	generationSlider.SetSize(XMFLOAT2(200, heihei));
	generationSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&generationSlider);

	presetCombo.Create("Preset: ");
	presetCombo.SetTooltip("Select a terrain preset");
	presetCombo.SetSize(XMFLOAT2(200, heihei));
	presetCombo.SetPos(XMFLOAT2(xx, yy += stepstep));
	presetCombo.AddItem("Hills", PRESET_HILLS);
	presetCombo.AddItem("Islands", PRESET_ISLANDS);
	presetCombo.AddItem("Mountains", PRESET_MOUNTAINS);
	presetCombo.AddItem("Arctic", PRESET_ARCTIC);
	presetCombo.OnSelect([=](wi::gui::EventArgs args) {
		switch (args.userdata)
		{
		default:
		case PRESET_HILLS:
			seedSlider.SetValue(5333);
			bottomLevelSlider.SetValue(-60);
			topLevelSlider.SetValue(380);
			perlinBlendSlider.SetValue(0.5f);
			perlinFrequencySlider.SetValue(0.0008f);
			perlinOctavesSlider.SetValue(6);
			voronoiBlendSlider.SetValue(0.5f);
			voronoiFrequencySlider.SetValue(0.001f);
			voronoiFadeSlider.SetValue(2.59f);
			voronoiShapeSlider.SetValue(0.7f);
			voronoiFalloffSlider.SetValue(6);
			voronoiPerturbationSlider.SetValue(0.1f);
			region1Slider.SetValue(1);
			region2Slider.SetValue(2);
			region3Slider.SetValue(8);
			break;
		case PRESET_ISLANDS:
			seedSlider.SetValue(4691);
			bottomLevelSlider.SetValue(-79);
			topLevelSlider.SetValue(520);
			perlinBlendSlider.SetValue(0.5f);
			perlinFrequencySlider.SetValue(0.000991f);
			perlinOctavesSlider.SetValue(6);
			voronoiBlendSlider.SetValue(0.5f);
			voronoiFrequencySlider.SetValue(0.000317f);
			voronoiFadeSlider.SetValue(8.2f);
			voronoiShapeSlider.SetValue(0.126f);
			voronoiFalloffSlider.SetValue(1.392f);
			voronoiPerturbationSlider.SetValue(0.126f);
			region1Slider.SetValue(8);
			region2Slider.SetValue(0.7f);
			region3Slider.SetValue(8);
			break;
		case PRESET_MOUNTAINS:
			seedSlider.SetValue(8863);
			bottomLevelSlider.SetValue(0);
			topLevelSlider.SetValue(2960);
			perlinBlendSlider.SetValue(0.5f);
			perlinFrequencySlider.SetValue(0.00279f);
			perlinOctavesSlider.SetValue(8);
			voronoiBlendSlider.SetValue(0.5f);
			voronoiFrequencySlider.SetValue(0.000496f);
			voronoiFadeSlider.SetValue(5.2f);
			voronoiShapeSlider.SetValue(0.412f);
			voronoiFalloffSlider.SetValue(1.456f);
			voronoiPerturbationSlider.SetValue(0.092f);
			region1Slider.SetValue(1);
			region2Slider.SetValue(1);
			region3Slider.SetValue(0.8f);
			break;
		case PRESET_ARCTIC:
			seedSlider.SetValue(2124);
			bottomLevelSlider.SetValue(-50);
			topLevelSlider.SetValue(40);
			perlinBlendSlider.SetValue(1);
			perlinFrequencySlider.SetValue(0.002f);
			perlinOctavesSlider.SetValue(4);
			voronoiBlendSlider.SetValue(1);
			voronoiFrequencySlider.SetValue(0.004f);
			voronoiFadeSlider.SetValue(1.8f);
			voronoiShapeSlider.SetValue(0.518f);
			voronoiFalloffSlider.SetValue(0.2f);
			voronoiPerturbationSlider.SetValue(0.298f);
			region1Slider.SetValue(8);
			region2Slider.SetValue(8);
			region3Slider.SetValue(0);
			break;
		}
		Generation_Restart();
		});
	AddWidget(&presetCombo);

	seedSlider.Create(1, 12345, 3926, 12344, "Seed: ");
	seedSlider.SetTooltip("Seed for terrain randomness");
	seedSlider.SetSize(XMFLOAT2(200, heihei));
	seedSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&seedSlider);

	bottomLevelSlider.Create(-100, 0, -60, 10000, "Bottom Level: ");
	bottomLevelSlider.SetTooltip("Terrain mesh grid lowest level");
	bottomLevelSlider.SetSize(XMFLOAT2(200, heihei));
	bottomLevelSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&bottomLevelSlider);

	topLevelSlider.Create(0, 5000, 380, 10000, "Top Level: ");
	topLevelSlider.SetTooltip("Terrain mesh grid topmost level");
	topLevelSlider.SetSize(XMFLOAT2(200, heihei));
	topLevelSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&topLevelSlider);

	perlinBlendSlider.Create(0, 1, 0.5f, 10000, "Perlin Blend: ");
	perlinBlendSlider.SetTooltip("Amount of perlin noise to use");
	perlinBlendSlider.SetSize(XMFLOAT2(200, heihei));
	perlinBlendSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&perlinBlendSlider);

	perlinFrequencySlider.Create(0.0001f, 0.01f, 0.0008f, 10000, "Perlin Frequency: ");
	perlinFrequencySlider.SetTooltip("Frequency for the perlin noise");
	perlinFrequencySlider.SetSize(XMFLOAT2(200, heihei));
	perlinFrequencySlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&perlinFrequencySlider);

	perlinOctavesSlider.Create(1, 8, 6, 7, "Perlin Octaves: ");
	perlinOctavesSlider.SetTooltip("Octave count for the perlin noise");
	perlinOctavesSlider.SetSize(XMFLOAT2(200, heihei));
	perlinOctavesSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&perlinOctavesSlider);

	voronoiBlendSlider.Create(0, 1, 0.5f, 10000, "Voronoi Blend: ");
	voronoiBlendSlider.SetTooltip("Amount of voronoi to use for elevation");
	voronoiBlendSlider.SetSize(XMFLOAT2(200, heihei));
	voronoiBlendSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&voronoiBlendSlider);

	voronoiFrequencySlider.Create(0.0001f, 0.01f, 0.001f, 10000, "Voronoi Frequency: ");
	voronoiFrequencySlider.SetTooltip("Voronoi can create distinctly elevated areas, the more cells there are, smaller the consecutive areas");
	voronoiFrequencySlider.SetSize(XMFLOAT2(200, heihei));
	voronoiFrequencySlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&voronoiFrequencySlider);

	voronoiFadeSlider.Create(0, 100, 2.59f, 10000, "Voronoi Fade: ");
	voronoiFadeSlider.SetTooltip("Fade out voronoi regions by distance from cell's center");
	voronoiFadeSlider.SetSize(XMFLOAT2(200, heihei));
	voronoiFadeSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&voronoiFadeSlider);

	voronoiShapeSlider.Create(0, 1, 0.7f, 10000, "Voronoi Shape: ");
	voronoiShapeSlider.SetTooltip("How much the voronoi shape will be kept");
	voronoiShapeSlider.SetSize(XMFLOAT2(200, heihei));
	voronoiShapeSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&voronoiShapeSlider);

	voronoiFalloffSlider.Create(0, 8, 6, 10000, "Voronoi Falloff: ");
	voronoiFalloffSlider.SetTooltip("Controls the falloff of the voronoi distance fade effect");
	voronoiFalloffSlider.SetSize(XMFLOAT2(200, heihei));
	voronoiFalloffSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&voronoiFalloffSlider);

	voronoiPerturbationSlider.Create(0, 1, 0.1f, 10000, "Voronoi Perturbation: ");
	voronoiPerturbationSlider.SetTooltip("Controls the random look of voronoi region edges");
	voronoiPerturbationSlider.SetSize(XMFLOAT2(200, heihei));
	voronoiPerturbationSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&voronoiPerturbationSlider);


	heightmapButton.Create("Load Heightmap...");
	heightmapButton.SetTooltip("Load a heightmap texture, where the red channel corresponds to terrain height and the resolution to dimensions.\nThe heightmap will be placed in the world center.");
	heightmapButton.SetSize(XMFLOAT2(200, heihei));
	heightmapButton.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&heightmapButton);

	heightmapBlendSlider.Create(0, 1, 1, 10000, "Heightmap Blend: ");
	heightmapBlendSlider.SetTooltip("Amount of displacement coming from the heightmap texture");
	heightmapBlendSlider.SetSize(XMFLOAT2(200, heihei));
	heightmapBlendSlider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&heightmapBlendSlider);

	region1Slider.Create(0, 8, 1, 10000, "Slope Region: ");
	region1Slider.SetTooltip("The region's falloff power");
	region1Slider.SetSize(XMFLOAT2(200, heihei));
	region1Slider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&region1Slider);

	region2Slider.Create(0, 8, 2, 10000, "Low Altitude Region: ");
	region2Slider.SetTooltip("The region's falloff power");
	region2Slider.SetSize(XMFLOAT2(200, heihei));
	region2Slider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&region2Slider);

	region3Slider.Create(0, 8, 8, 10000, "High Altitude Region: ");
	region3Slider.SetTooltip("The region's falloff power");
	region3Slider.SetSize(XMFLOAT2(200, heihei));
	region3Slider.SetPos(XMFLOAT2(xx, yy += stepstep));
	AddWidget(&region3Slider);


	auto generate_callback = [=](wi::gui::EventArgs args) {
		Generation_Restart();
	};
	seedSlider.OnSlide(generate_callback);
	bottomLevelSlider.OnSlide(generate_callback);
	topLevelSlider.OnSlide(generate_callback);
	perlinFrequencySlider.OnSlide(generate_callback);
	perlinBlendSlider.OnSlide(generate_callback);
	perlinOctavesSlider.OnSlide(generate_callback);
	voronoiBlendSlider.OnSlide(generate_callback);
	voronoiFrequencySlider.OnSlide(generate_callback);
	voronoiFadeSlider.OnSlide(generate_callback);
	voronoiShapeSlider.OnSlide(generate_callback);
	voronoiFalloffSlider.OnSlide(generate_callback);
	voronoiPerturbationSlider.OnSlide(generate_callback);
	heightmapBlendSlider.OnSlide(generate_callback);
	region1Slider.OnSlide(generate_callback);
	region2Slider.OnSlide(generate_callback);
	region3Slider.OnSlide(generate_callback);

	heightmapButton.OnClick([=](wi::gui::EventArgs args) {

		wi::helper::FileDialogParams params;
		params.type = wi::helper::FileDialogParams::OPEN;
		params.description = "Texture";
		params.extensions = wi::resourcemanager::GetSupportedImageExtensions();
		wi::helper::FileDialog(params, [=](std::string fileName) {
			wi::eventhandler::Subscribe_Once(wi::eventhandler::EVENT_THREAD_SAFE_POINT, [=](uint64_t userdata) {

				heightmap = {};
				int bpp = 0;
				stbi_uc* rgba = stbi_load(fileName.c_str(), &heightmap.width, &heightmap.height, &bpp, 1);
				if (rgba != nullptr)
				{
					heightmap.data.resize(heightmap.width * heightmap.height);
					for (int i = 0; i < heightmap.width * heightmap.height; ++i)
					{
						heightmap.data[i] = rgba[i];
					}
					stbi_image_free(rgba);
					Generation_Restart();
				}
				});
			});
		});

	heightmap = {};

	SetPos(XMFLOAT2(50, 110));
	SetVisible(false);
	SetEnabled(true);

	presetCombo.SetSelectedByUserdata(PRESET_HILLS);
}

void TerrainGenerator::Generation_Restart()
{
	Generation_Cancel();
	generation_scene.Clear();
	generation_entities.clear();

	// If these already exist, save them before recreating:
	//	(This is helpful if eg: someone edits them in the editor and then regenerates the terrain)
	if (materialEntity_Base != INVALID_ENTITY)
	{
		MaterialComponent* material = scene->materials.GetComponent(materialEntity_Base);
		if (material != nullptr)
		{
			material_Base = *material;
		}
	}
	if (materialEntity_Slope != INVALID_ENTITY)
	{
		MaterialComponent* material = scene->materials.GetComponent(materialEntity_Slope);
		if (material != nullptr)
		{
			material_Slope = *material;
		}
	}
	if (materialEntity_LowAltitude != INVALID_ENTITY)
	{
		MaterialComponent* material = scene->materials.GetComponent(materialEntity_LowAltitude);
		if (material != nullptr)
		{
			material_LowAltitude = *material;
		}
	}
	if (materialEntity_HighAltitude != INVALID_ENTITY)
	{
		MaterialComponent* material = scene->materials.GetComponent(materialEntity_HighAltitude);
		if (material != nullptr)
		{
			material_HighAltitude = *material;
		}
	}

	chunks.clear();

	scene->Entity_Remove(terrainEntity);
	scene->transforms.Create(terrainEntity);
	scene->names.Create(terrainEntity) = "terrain";

	materialEntity_Base = scene->Entity_CreateMaterial("terrainMaterial_Base");
	materialEntity_Slope = scene->Entity_CreateMaterial("terrainMaterial_Slope");
	materialEntity_LowAltitude = scene->Entity_CreateMaterial("terrainMaterial_LowAltitude");
	materialEntity_HighAltitude = scene->Entity_CreateMaterial("terrainMaterial_HighAltitude");
	scene->Component_Attach(materialEntity_Base, terrainEntity);
	scene->Component_Attach(materialEntity_Slope, terrainEntity);
	scene->Component_Attach(materialEntity_LowAltitude, terrainEntity);
	scene->Component_Attach(materialEntity_HighAltitude, terrainEntity);
	// init/restore materials:
	*scene->materials.GetComponent(materialEntity_Base) = material_Base;
	*scene->materials.GetComponent(materialEntity_Slope) = material_Slope;
	*scene->materials.GetComponent(materialEntity_LowAltitude) = material_LowAltitude;
	*scene->materials.GetComponent(materialEntity_HighAltitude) = material_HighAltitude;

	const uint32_t seed = (uint32_t)seedSlider.GetValue();
	perlin.init(seed);

	// Add some nice weather and lighting if there is none yet:
	if (scene->weathers.GetCount() == 0)
	{
		Entity weatherEntity = CreateEntity();
		WeatherComponent& weather = scene->weathers.Create(weatherEntity);
		scene->names.Create(weatherEntity) = "terrainWeather";
		scene->Component_Attach(weatherEntity, terrainEntity);
		weather.ambient = XMFLOAT3(0.2f, 0.2f, 0.2f);
		weather.SetRealisticSky(true);
		weather.SetVolumetricClouds(true);
		weather.volumetricCloudParameters.CoverageAmount = 0.4f;
		weather.volumetricCloudParameters.CoverageMinimum = 1.35f;
		if (presetCombo.GetItemUserData(presetCombo.GetSelected()) == PRESET_ISLANDS)
		{
			weather.SetOceanEnabled(true);
		}
		else
		{
			scene->ocean = {};
		}
		weather.oceanParameters.waterHeight = -40;
		weather.oceanParameters.wave_amplitude = 120;
		weather.fogStart = 10;
		weather.fogEnd = 100000;
		weather.SetHeightFog(true);
		weather.fogHeightStart = 0;
		weather.fogHeightEnd = 100;
		weather.windDirection = XMFLOAT3(0.05f, 0.05f, 0.05f);
		weather.windSpeed = 4;
	}
	if (scene->lights.GetCount() == 0)
	{
		Entity sunEntity = scene->Entity_CreateLight("terrainSun");
		scene->Component_Attach(sunEntity, terrainEntity);
		LightComponent& light = *scene->lights.GetComponent(sunEntity);
		light.SetType(LightComponent::LightType::DIRECTIONAL);
		light.energy = 6;
		light.SetCastShadow(true);
		//light.SetVolumetricsEnabled(true);
		TransformComponent& transform = *scene->transforms.GetComponent(sunEntity);
		transform.RotateRollPitchYaw(XMFLOAT3(XM_PIDIV4, 0, XM_PIDIV4));
	}
}

void TerrainGenerator::Generation_Update()
{
	// The generation task is always cancelled every frame so we are sure that generation is not running at this point
	Generation_Cancel();

	if (terrainEntity == INVALID_ENTITY || !scene->transforms.Contains(terrainEntity))
	{
		chunks.clear();
		return;
	}

	// What was generated, will be merged in to the main scene and parented to the terrain entity
	scene->Merge(generation_scene);
	for (Entity entity : generation_entities)
	{
		scene->Component_Attach(entity, terrainEntity);
	}
	generation_entities.clear();

	if (centerToCamCheckBox.GetCheck())
	{
		const CameraComponent& camera = GetCamera();
		center_chunk.x = (int)std::floor((camera.Eye.x + half_width) * width_rcp);
		center_chunk.z = (int)std::floor((camera.Eye.z + half_width) * width_rcp);
	}

	// Chunk removal checks:
	if (removalCheckBox.GetCheck())
	{
		const int removal_threshold = (int)generationSlider.GetValue() + 2;
		for (auto it = chunks.begin(); it != chunks.end();)
		{
			const Chunk& chunk = it->first;
			ChunkData& chunk_data = it->second;
			const int dist = std::max(std::abs(center_chunk.x - chunk.x), std::abs(center_chunk.z - chunk.z));
			if (dist > removal_threshold)
			{
				scene->Entity_Remove(it->second.entity);
				it = chunks.erase(it);
				continue; // don't increment iterator
			}
			else
			{
				// Grass patch removal:
				if (chunk_data.grass.meshID != INVALID_ENTITY)
				{
					if (dist > 1)
					{
						wi::HairParticleSystem* grass = scene->hairs.GetComponent(chunk_data.entity);
						if (grass != nullptr)
						{
							// remove this chunk's grass patch from the scene
							scene->hairs.Remove(chunk_data.entity);
							chunk_data.grass_exists = false; // grass can be generated here by generation thread...
						}
					}
				}
			}
			it++;
		}
	}

	// Start the generation on a background thread and keep it running until the next frame
	wi::jobsystem::Execute(generation_workload, [=](wi::jobsystem::JobArgs args) {

		const float lodMultiplier = lodSlider.GetValue();
		const int generation = (int)generationSlider.GetValue();
		const float bottomLevel = bottomLevelSlider.GetValue();
		const float topLevel = topLevelSlider.GetValue();
		const float heightmapBlend = heightmapBlendSlider.GetValue();
		const float perlinBlend = perlinBlendSlider.GetValue();
		const uint32_t seed = (uint32_t)seedSlider.GetValue();
		const int perlinOctaves = (int)perlinOctavesSlider.GetValue();
		const float perlinFrequency = perlinFrequencySlider.GetValue();
		const float voronoiBlend = voronoiBlendSlider.GetValue();
		const float voronoiFrequency = voronoiFrequencySlider.GetValue();
		const float voronoiFade = voronoiFadeSlider.GetValue();
		const float voronoiShape = voronoiShapeSlider.GetValue();
		const float voronoiFalloff = voronoiFalloffSlider.GetValue();
		const float voronoiPerturbation = voronoiPerturbationSlider.GetValue();
		const float region1 = region1Slider.GetValue();
		const float region2 = region2Slider.GetValue();
		const float region3 = region3Slider.GetValue();

		auto request_chunk = [&](int offset_x, int offset_z)
		{
			Chunk chunk = center_chunk;
			chunk.x += offset_x;
			chunk.z += offset_z;
			auto it = chunks.find(chunk);
			if (it == chunks.end() || it->second.entity == INVALID_ENTITY)
			{
				// Generate a new chunk:
				ChunkData& chunk_data = chunks[chunk];

				chunk_data.entity = generation_scene.Entity_CreateObject("chunk_" + std::to_string(chunk.x) + "_" + std::to_string(chunk.z));
				ObjectComponent& object = *generation_scene.objects.GetComponent(chunk_data.entity);
				object.lod_distance_multiplier = lodMultiplier;
				generation_entities.push_back(chunk_data.entity);

				TransformComponent& transform = *generation_scene.transforms.GetComponent(chunk_data.entity);
				transform.ClearTransform();
				const XMFLOAT3 chunk_pos = XMFLOAT3(float(chunk.x * (width - 1)), 0, float(chunk.z * (width - 1)));
				transform.Translate(chunk_pos);
				transform.UpdateTransform();

				MeshComponent& mesh = generation_scene.meshes.Create(chunk_data.entity);
				object.meshID = chunk_data.entity;
				mesh.indices = indices;
				mesh.SetTerrain(true);
				mesh.terrain_material1 = materialEntity_Slope;
				mesh.terrain_material2 = materialEntity_LowAltitude;
				mesh.terrain_material3 = materialEntity_HighAltitude;
				for (auto& lod : lods)
				{
					mesh.subsets.emplace_back();
					mesh.subsets.back().materialID = materialEntity_Base;
					mesh.subsets.back().indexCount = lod.indexCount;
					mesh.subsets.back().indexOffset = lod.indexOffset;
				}
				mesh.subsets_per_lod = 1;
				mesh.vertex_positions.resize(vertexCount);
				mesh.vertex_normals.resize(vertexCount);
				mesh.vertex_colors.resize(vertexCount);
				mesh.vertex_uvset_0.resize(vertexCount);
				mesh.vertex_uvset_1.resize(vertexCount);
				mesh.vertex_atlas.resize(vertexCount);

				wi::HairParticleSystem grass;
				grass.vertex_lengths.resize(vertexCount);
				std::atomic<uint32_t> grass_valid_vertex_count{ 0 };

				// Do a parallel for loop over all the chunk's vertices and compute their properties:
				wi::jobsystem::context ctx;
				wi::jobsystem::Dispatch(ctx, vertexCount, width, [&](wi::jobsystem::JobArgs args) {
					uint32_t index = args.jobIndex;
					const float x = float(index % width) - half_width;
					const float z = float(index / width) - half_width;
					XMVECTOR corners[3];
					XMFLOAT2 corner_offsets[3] = {
						XMFLOAT2(0, 0),
						XMFLOAT2(1, 0),
						XMFLOAT2(0, 1),
					};
					for (int i = 0; i < arraysize(corners); ++i)
					{
						float height = 0;
						const XMFLOAT2 world_pos = XMFLOAT2(chunk_pos.x + x + corner_offsets[i].x, chunk_pos.z + z + corner_offsets[i].y);
						if (perlinBlend > 0)
						{
							XMFLOAT2 p = world_pos;
							p.x *= perlinFrequency;
							p.y *= perlinFrequency;
							height += (perlin.compute(p.x, p.y, 0, perlinOctaves) * 0.5f + 0.5f) * perlinBlend;
						}
						if (voronoiBlend > 0)
						{
							XMFLOAT2 p = world_pos;
							p.x *= voronoiFrequency;
							p.y *= voronoiFrequency;
							if (voronoiPerturbation > 0)
							{
								const float angle = perlin.compute(p.x, p.y, 0, 6) * XM_2PI;
								p.x += std::sin(angle) * voronoiPerturbation;
								p.y += std::cos(angle) * voronoiPerturbation;
							}
							wi::noise::voronoi::Result res = wi::noise::voronoi::compute(p.x, p.y, (float)seed);
							float weight = std::pow(1 - wi::math::saturate((res.distance - voronoiShape) * voronoiFade), std::max(0.0001f, voronoiFalloff));
							height *= weight * voronoiBlend;
						}
						if (!heightmap.data.empty())
						{
							XMFLOAT2 pixel = XMFLOAT2(world_pos.x + heightmap.width * 0.5f, world_pos.y + heightmap.height * 0.5f);
							if (pixel.x >= 0 && pixel.x < heightmap.width && pixel.y >= 0 && pixel.y < heightmap.height)
							{
								const int idx = int(pixel.x) + int(pixel.y) * heightmap.width;
								height = ((float)heightmap.data[idx] / 255.0f) * heightmapBlend;
							}
						}
						height = wi::math::Lerp(bottomLevel, topLevel, height);
						corners[i] = XMVectorSet(world_pos.x, height, world_pos.y, 0);
					}
					const float height = XMVectorGetY(corners[0]);
					const XMVECTOR T = XMVectorSubtract(corners[2], corners[1]);
					const XMVECTOR B = XMVectorSubtract(corners[1], corners[0]);
					const XMVECTOR N = XMVector3Normalize(XMVector3Cross(T, B));
					XMFLOAT3 normal;
					XMStoreFloat3(&normal, N);

					const float region_base = 1;
					const float region_slope = std::pow(1.0f - wi::math::saturate(normal.y), region1);
					const float region_low_altitude = bottomLevel == 0 ? 0 : std::pow(wi::math::saturate(wi::math::InverseLerp(0, bottomLevel, height)), region2);
					const float region_high_altitude = topLevel == 0 ? 0 : std::pow(wi::math::saturate(wi::math::InverseLerp(0, topLevel, height)), region3);

					XMFLOAT4 materialBlendWeights(region_base, 0, 0, 0);
					materialBlendWeights = wi::math::Lerp(materialBlendWeights, XMFLOAT4(0, 1, 0, 0), region_slope);
					materialBlendWeights = wi::math::Lerp(materialBlendWeights, XMFLOAT4(0, 0, 1, 0), region_low_altitude);
					materialBlendWeights = wi::math::Lerp(materialBlendWeights, XMFLOAT4(0, 0, 0, 1), region_high_altitude);
					const float weight_norm = 1.0f / (materialBlendWeights.x + materialBlendWeights.y + materialBlendWeights.z + materialBlendWeights.w);
					materialBlendWeights.x *= weight_norm;
					materialBlendWeights.y *= weight_norm;
					materialBlendWeights.z *= weight_norm;
					materialBlendWeights.w *= weight_norm;

					mesh.vertex_positions[index] = XMFLOAT3(x, height, z);
					mesh.vertex_normals[index] = normal;
					mesh.vertex_colors[index] = wi::Color::fromFloat4(materialBlendWeights);
					const XMFLOAT2 uv = XMFLOAT2(x * width_rcp, z * width_rcp);
					mesh.vertex_uvset_0[index] = uv;
					mesh.vertex_uvset_1[index] = uv;
					mesh.vertex_atlas[index] = uv;

					XMFLOAT3 vertex_pos(chunk_pos.x + x, height, chunk_pos.z + z);

					const float grass_noise_frequency = 0.1f;
					const float grass_noise = perlin.compute(vertex_pos.x * grass_noise_frequency, vertex_pos.y * grass_noise_frequency, vertex_pos.z * grass_noise_frequency) * 0.5f + 0.5f;
					const float region_grass = std::pow(materialBlendWeights.x * (1 - materialBlendWeights.w), 4.0f) * grass_noise;
					if (region_grass > 0.1f)
					{
						grass_valid_vertex_count.fetch_add(1);
						grass.vertex_lengths[index] = region_grass;
					}
					else
					{
						grass.vertex_lengths[index] = 0;
					}
					});
				wi::jobsystem::Wait(ctx); // wait until chunk's vertex buffer is fully generated

				mesh.CreateRenderData();

				// If there were any vertices in this chunk that could be valid for grass, store the grass particle system:
				if (grass_valid_vertex_count.load() > 0)
				{
					grass.meshID = chunk_data.entity;
					grass.length = 5;
					grass.strandCount = grass_valid_vertex_count.load() * 3;
					grass.viewDistance = 80;
					grass.frameCount = 2;
					grass.framesX = 1;
					grass.framesY = 2;
					grass.frameStart = 0;
					generation_scene.materials.Create(chunk_data.entity) = material_GrassParticle;
					chunk_data.grass = std::move(grass); // the grass will be added to the scene later, only when the chunk is close to the camera (center chunk's neighbors)
				}

				// Prop placement:
				chunk_data.prop_rand.seed((uint32_t)chunk.compute_hash() ^ seed);
				for (auto& prop : props)
				{
					std::uniform_int_distribution<uint32_t> gen_distr(prop.min_count_per_chunk, prop.max_count_per_chunk);
					int gen_count = gen_distr(chunk_data.prop_rand);
					for (int i = 0; i < gen_count; ++i)
					{
						std::uniform_real_distribution<float> float_distr(0.0f, 1.0f);
						std::uniform_int_distribution<uint32_t> ind_distr(0, lods[0].indexCount / 3 - 1);
						uint32_t tri = ind_distr(chunk_data.prop_rand); // random triangle on the chunk mesh
						uint32_t ind0 = mesh.indices[tri * 3 + 0];
						uint32_t ind1 = mesh.indices[tri * 3 + 1];
						uint32_t ind2 = mesh.indices[tri * 3 + 2];
						const XMFLOAT3& pos0 = mesh.vertex_positions[ind0];
						const XMFLOAT3& pos1 = mesh.vertex_positions[ind1];
						const XMFLOAT3& pos2 = mesh.vertex_positions[ind2];
						const uint32_t& col0 = mesh.vertex_colors[ind0];
						const uint32_t& col1 = mesh.vertex_colors[ind1];
						const uint32_t& col2 = mesh.vertex_colors[ind2];
						const XMFLOAT4 region0 = wi::Color(col0).toFloat4();
						const XMFLOAT4 region1 = wi::Color(col1).toFloat4();
						const XMFLOAT4 region2 = wi::Color(col2).toFloat4();
						// random barycentric coords on the triangle:
						float f = float_distr(chunk_data.prop_rand);
						float g = float_distr(chunk_data.prop_rand);
						if (f + g > 1)
						{
							f = 1 - f;
							g = 1 - g;
						}
						XMFLOAT3 vertex_pos;
						vertex_pos.x = pos0.x + f * (pos1.x - pos0.x) + g * (pos2.x - pos0.x);
						vertex_pos.y = pos0.y + f * (pos1.y - pos0.y) + g * (pos2.y - pos0.y);
						vertex_pos.z = pos0.z + f * (pos1.z - pos0.z) + g * (pos2.z - pos0.z);
						vertex_pos.x += chunk_pos.x;
						vertex_pos.z += chunk_pos.z;
						XMFLOAT4 region;
						region.x = region0.x + f * (region1.x - region0.x) + g * (region2.x - region0.x);
						region.y = region0.y + f * (region1.y - region0.y) + g * (region2.y - region0.y);
						region.z = region0.z + f * (region1.z - region0.z) + g * (region2.z - region0.z);
						region.w = region0.w + f * (region1.w - region0.w) + g * (region2.w - region0.w);

						const float noise = std::pow(perlin.compute(vertex_pos.x * prop.noise_frequency, vertex_pos.y * prop.noise_frequency, vertex_pos.z * prop.noise_frequency) * 0.5f + 0.5f, prop.noise_power);
						const float chance = std::pow(((float*)&region)[prop.region], prop.region_power) * noise;
						if (chance > prop.threshold)
						{
							Entity entity = generation_scene.Entity_CreateObject(prop.name + std::to_string(i));
							ObjectComponent* object = generation_scene.objects.GetComponent(entity);
							*object = prop.object;
							TransformComponent* transform = generation_scene.transforms.GetComponent(entity);
							XMFLOAT3 offset = vertex_pos;
							offset.y += wi::math::Lerp(prop.min_y_offset, prop.max_y_offset, float_distr(chunk_data.prop_rand));
							transform->Translate(offset);
							const float scaling = wi::math::Lerp(prop.min_size, prop.max_size, float_distr(chunk_data.prop_rand));
							transform->Scale(XMFLOAT3(scaling, scaling, scaling));
							transform->RotateRollPitchYaw(XMFLOAT3(0, XM_2PI * float_distr(chunk_data.prop_rand), 0));
							transform->UpdateTransform();
							generation_scene.Component_Attach(entity, chunk_data.entity);
						}
					}
				}

			}

			// Grass patch placement:
			it = chunks.find(chunk);
			if (it != chunks.end() && it->second.entity != INVALID_ENTITY)
			{
				ChunkData& chunk_data = it->second;
				if (chunk_data.grass.meshID != INVALID_ENTITY)
				{
					const int dist = std::max(std::abs(center_chunk.x - chunk.x), std::abs(center_chunk.z - chunk.z));
					if (dist <= 1)
					{
						if (!chunk_data.grass_exists)
						{
							// add patch for this chunk
							wi::HairParticleSystem& grass = generation_scene.hairs.Create(chunk_data.entity);
							grass = chunk_data.grass;
							const MeshComponent* mesh = generation_scene.meshes.GetComponent(chunk_data.entity);
							if (mesh != nullptr)
							{
								grass.CreateRenderData(*mesh);
							}
							chunk_data.grass_exists = true; // don't generate more grass here
						}
					}
				}
			}

		};

		// generate center chunk first:
		request_chunk(0, 0);
		if (generation_cancelled.load()) return;

		// then generate neighbor chunks in outward spiral:
		for (int growth = 0; growth < generation; ++growth)
		{
			const int side = 2 * (growth + 1);
			int x = -growth - 1;
			int z = -growth - 1;
			for (int i = 0; i < side; ++i)
			{
				request_chunk(x, z);
				if (generation_cancelled.load()) return;
				x++;
			}
			for (int i = 0; i < side; ++i)
			{
				request_chunk(x, z);
				if (generation_cancelled.load()) return;
				z++;
			}
			for (int i = 0; i < side; ++i)
			{
				request_chunk(x, z);
				if (generation_cancelled.load()) return;
				x--;
			}
			for (int i = 0; i < side; ++i)
			{
				request_chunk(x, z);
				if (generation_cancelled.load()) return;
				z--;
			}
		}

		});

}

void TerrainGenerator::Generation_Cancel()
{
	generation_cancelled.store(true); // tell the generation thread that work must be stopped
	wi::jobsystem::Wait(generation_workload); // waits until generation thread exits
	generation_cancelled.store(false); // the next generation can run
}