#pragma once

#include "CoreMinimal.h"

/** Constants of the terrain: chunks, meshing, streaming budgets, carving (World/Descent*Terrain*, DESIGN_UE.md sections 2.3 - 2.6). */
namespace Descent::Tune::Terrain
{
	// ---- chunk geometry (section 2.3, v2) ------------------------------------------------------------------------
	constexpr double VoxelM = 1.25;                       // VS
	constexpr int32 CoreN = 16;                           // CN: core samples per axis
	constexpr double ChunkM = VoxelM * CoreN;             // CS = 20 m
	constexpr int32 Pad = 2;                              // samples of padding each side
	constexpr int32 P = CoreN + 2 * Pad;                  // 20
	constexpr int32 P2 = P * P;
	constexpr int32 P3 = P * P * P;                       // 8,000
	/** Cells the mesher visits per axis (CN + 1) and the vertex slots that gives. */
	constexpr int32 SC = CoreN + 1;
	constexpr int32 SC3 = SC * SC * SC;

	// ---- classification (section 2.3) ----------------------------------------------------------------------------
	/** |GenRaw(centre)| beyond ChunkM * ClassifyFactor + ClassifyBias is a uniform chunk. */
	constexpr double ClassifyFactor = 0.87;
	constexpr double ClassifyBias = 10.0;
	/** Radius around the chunk centre the fill job gathers primitives for. */
	constexpr double GatherRadiusFactor = 0.9;
	constexpr double GatherRadiusBias = 3.0;
	/** A chunk that touches a sponge box grown by this is always a candidate (the sponge is not a distance field). */
	constexpr double SpongeCandidateGrow = 12.0;

	// ---- streaming (section 2.6) ---------------------------------------------------------------------------------
	constexpr double LoadRadiusM = 160.0;                 // cvar descent.Terrain.StreamRadius
	constexpr double UnloadExtraM = 40.0;                 // RU = R + 40
	constexpr double LowLoadRadiusM = 120.0;
	constexpr double LowUnloadExtraM = 30.0;
	constexpr double PlanIntervalSec = 0.5;
	constexpr double PlanMoveM = 10.0;
	constexpr double UnloadIntervalSec = 0.33;
	constexpr int32 MaxJobsInFlight = 12;
	constexpr double ApplyBudgetMs = 1.5;                 // game-thread time per frame for finished jobs
	constexpr double RemeshBudgetMs = 2.5;                // synchronous remesh of carved chunks per frame
	constexpr int32 RemeshMinFrames = 3;                  // a chunk is remeshed at most once per this many frames
	constexpr int32 FilledChunkCap = 4000;                // memory cap: 160 MB
	/** The blocking initial stream at boot (section 1.5 step 4). */
	constexpr double InitialRadiusM = 120.0;

	// ---- carving (section 2.5) ------------------------------------------------------------------------------------
	constexpr double CarveBlendK = 1.6;
	constexpr double CarveCutRadiusExtra = 0.6;           // Cut = 200 where dist < Radius + this
	constexpr uint8 CutValue = 200;
	constexpr double CarveReachExtra = 2.0;               // samples within Radius + this are visited
	constexpr double CleanupFreedValue = -0.8;
	constexpr double CleanupMargin = 4.0;                 // region half-size = ceil((Radius + this) / VS) samples
	constexpr double RaycastStepFactor = 0.85;
	constexpr double RaycastMinStep = 0.3;
	constexpr int32 RaycastBisections = 7;
	constexpr double GradientH = 0.6;

	/** Mesher winding: the v2 index order is right-handed; set true if the first screenshot shows rock lit from inside. */
	constexpr bool FlipWinding = true;
}