/*
MIT License

Copyright (c) 2018-2019 Jonathan Young

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
/*
thekla_atlas
MIT License
https://github.com/Thekla/thekla_atlas
Copyright (c) 2013 Thekla, Inc
Copyright NVIDIA Corporation 2006 -- Ignacio Castano <icastano@nvidia.com>
*/
#pragma once
#ifndef XATLAS_H
#define XATLAS_H
#include <stdint.h>

namespace xatlas {

// A group of connected faces, belonging to a single atlas.
struct Chart
{
	uint32_t atlasIndex; // Sub-atlas index.
	uint32_t *indexArray;
	uint32_t indexCount;
};

// Output vertex.
struct Vertex
{
	int32_t atlasIndex; // Sub-atlas index. -1 if the vertex doesn't exist in any atlas.
	float uv[2]; // Not normalized - values are in Atlas width and height range.
	uint32_t xref; // Index of input vertex from which this output vertex originated.
};

// Output mesh.
struct Mesh
{
	Chart *chartArray;
	uint32_t chartCount;
	uint32_t *indexArray;
	uint32_t indexCount;
	Vertex *vertexArray;
	uint32_t vertexCount;
};

// Empty on creation. Populated after charts are packed.
struct Atlas
{
	uint32_t width; // Atlas width in texels.
	uint32_t height; // Atlas height in texels.
	uint32_t atlasCount; // Number of sub-atlases. Equal to 0 unless PackOptions resolution is changed from default (0).
	uint32_t chartCount; // Total number of charts in all meshes.
	uint32_t meshCount; // Number of output meshes. Equal to the number of times AddMesh was called.
	Mesh *meshes; // The output meshes, corresponding to each AddMesh call.
	float *utilization; // Normalized atlas texel utilization array. E.g. a value of 0.8 means 20% empty space. atlasCount in length.
	float texelsPerUnit; // Equal to PackOptions texelsPerUnit if texelsPerUnit > 0, otherwise an estimated value to match PackOptions resolution.
};

// Create an empty atlas.
Atlas *Create();

void Destroy(Atlas *atlas);

struct IndexFormat
{
	enum Enum
	{
		UInt16,
		UInt32
	};
};

// Input mesh declaration.
struct MeshDecl
{
	uint32_t vertexCount = 0;
	const void *vertexPositionData = nullptr;
	uint32_t vertexPositionStride = 0;
	const void *vertexNormalData = nullptr; // optional
	uint32_t vertexNormalStride = 0; // optional
	const void *vertexUvData = nullptr; // optional. The input UVs are provided as a hint to the chart generator.
	uint32_t vertexUvStride = 0; // optional
	uint32_t indexCount = 0;
	const void *indexData = nullptr; // optional
	int32_t indexOffset = 0; // optional. Add this offset to all indices.
	IndexFormat::Enum indexFormat = IndexFormat::UInt16;
	
	// Optional. indexCount / 3 (triangle count) in length.
	// Don't atlas faces set to true. Ignored faces still exist in the output meshes, Vertex uv is set to (0, 0) and Vertex atlasIndex to -1.
	const bool *faceIgnoreData = nullptr;
};

struct AddMeshError
{
	enum Enum
	{
		Success, // No error.
		IndexOutOfRange, // An index is >= MeshDecl vertexCount.
		InvalidIndexCount // Not evenly divisible by 3 - expecting triangles.
	};
};

// Add a mesh to the atlas. MeshDecl data is copied, so it can be freed after AddMesh returns.
AddMeshError::Enum AddMesh(Atlas *atlas, const MeshDecl &meshDecl);

// Progress tracking.
struct ProgressCategory
{
	enum Enum
	{
		ComputeCharts,
		ParameterizeCharts,
		PackCharts,
		BuildOutputMeshes
	};
};

typedef void (*ProgressFunc)(ProgressCategory::Enum category, int progress, void *userData);

struct ChartOptions
{
	float maxChartArea = 0.0f; // Don't grow charts to be larger than this. 0 means no limit.
	float maxBoundaryLength = 0.0f; // Don't grow charts to have a longer boundary than this. 0 means no limit.

	// Weights determine chart growth. Higher weights mean higher cost for that metric.
	float proxyFitMetricWeight = 2.0f; // Angle between face and average chart normal.
	float roundnessMetricWeight = 0.01f;
	float straightnessMetricWeight = 6.0f;
	float normalSeamMetricWeight = 4.0f; // If > 1000, normal seams are fully respected.
	float textureSeamMetricWeight = 0.5f;

	float maxThreshold = 2.0f; // If total of all metrics * weights > maxThreshold, don't grow chart. Lower values result in more charts.
	uint32_t growFaceCount = 32; // Grow this many faces at a time.
	uint32_t maxIterations = 1; // Number of iterations of the chart growing and seeding phases. Higher values result in better charts.
};

// Call after all AddMesh calls. Can be called multiple times to recompute charts with different options.
void ComputeCharts(Atlas *atlas, ChartOptions chartOptions = ChartOptions(), ProgressFunc progressFunc = nullptr, void *progressUserData = nullptr);

// Custom parameterization function. texcoords initial values are an orthogonal parameterization.
typedef void (*ParameterizeFunc)(const float *positions, float *texcoords, uint32_t vertexCount, const uint32_t *indices, uint32_t indexCount, bool isPlanar);

// Call after ComputeCharts. Can be called multiple times to re-parameterize charts with a different ParameterizeFunc.
void ParameterizeCharts(Atlas *atlas, ParameterizeFunc func = nullptr, ProgressFunc progressFunc = nullptr, void *progressUserData = nullptr);

struct PackOptions
{
	// The number of attempts to find a suitable random chart location.
	// 0 is brute force - very slow, but best results. Faster if blockAlign is true;
	int attempts = 4096;

	// Unit to texel scale. e.g. a 1x1 quad with texelsPerUnit of 32 will take up approximately 32x32 texels in the atlas.
	// If 0, an estimated value will be calculated to approximately match the given resolution.
	// If resolution is also 0, the estimated value will approximately match a 1024x1024 atlas.
	float texelsPerUnit = 0.0f;

	// If 0, generate a single atlas with texelsPerUnit determining the final resolution.
	// If not 0, generate 1 or more atlases with that exact resolution.
	uint32_t resolution = 0;

	// Charts larger than this will be scaled down.
	uint32_t maxChartSize = 1024;

	// Align charts to 4x4 blocks. 
	bool blockAlign = false;

	// Pack charts with extra padding.
	bool conservative = false;

	// Number of pixels to pad. conservative must be true.
	uint32_t padding = 0;
};

// Call after ParameterizeCharts. Can be called multiple times to re-pack charts with different options.
void PackCharts(Atlas *atlas, PackOptions packOptions = PackOptions(), ProgressFunc progressFunc = nullptr, void *progressUserData = nullptr);

// Equivalent to calling ComputeCharts, ParameterizeCharts and PackCharts in sequence. Can be called multiple times to regenerate with different options.
void Generate(Atlas *atlas, ChartOptions chartOptions = ChartOptions(), ParameterizeFunc paramFunc = nullptr, PackOptions packOptions = PackOptions(), ProgressFunc progressFunc = nullptr, void *progressUserData = nullptr);

// Custom memory allocation.
typedef void *(*ReallocFunc)(void *, size_t);
void SetRealloc(ReallocFunc reallocFunc);

// Custom print function.
typedef int (*PrintFunc)(const char *, ...);
void SetPrint(PrintFunc print, bool verbose);

// Helper functions for error messages.
const char *StringForEnum(AddMeshError::Enum error);
const char *StringForEnum(ProgressCategory::Enum category);

} // namespace xatlas

#endif // XATLAS_H