/*************************************************************************/
/*  register_types.cpp                                                   */
/*************************************************************************/
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#include "register_types.h"

#include "core/error_macros.h"

#include "thirdparty/xatlas/xatlas.h"

#include <stdio.h>
#include <stdlib.h>

extern bool (*array_mesh_lightmap_unwrap_callback)(float p_texel_size, const float *p_vertices, const float *p_normals, int p_vertex_count, const int *p_indices, const int *p_face_materials, int p_index_count, float **r_uv, int **r_vertex, int *r_vertex_count, int **r_index, int *r_index_count, int *r_size_hint_x, int *r_size_hint_y);

bool xatlas_mesh_lightmap_unwrap_callback(float p_texel_size, const float *p_vertices, const float *p_normals, int p_vertex_count, const int *p_indices, const int *p_face_materials, int p_index_count, float **r_uv, int **r_vertex, int *r_vertex_count, int **r_index, int *r_index_count, int *r_size_hint_x, int *r_size_hint_y) {
	// set up input mesh
	xatlas::MeshDecl input_mesh;
	input_mesh.indexData = p_indices;
	input_mesh.indexCount = p_index_count;
	input_mesh.indexFormat = xatlas::IndexFormat::UInt32;

	input_mesh.vertexCount = p_vertex_count;
	input_mesh.vertexPositionData = p_vertices;
	input_mesh.vertexPositionStride = sizeof(float) * 3;
	input_mesh.vertexNormalData = p_normals;
	input_mesh.vertexNormalStride = sizeof(uint32_t) * 3;
	input_mesh.vertexUvData = nullptr;
	input_mesh.vertexUvStride = 0;

	xatlas::ChartOptions chart_options;
	chart_options.fixWinding = true;

	ERR_FAIL_COND_V_MSG(p_texel_size <= 0.0f, false, "Texel size must be greater than 0.");

	xatlas::PackOptions pack_options;
	pack_options.padding = 1;
	pack_options.maxChartSize = 4094; // Lightmap atlassing needs 2 for padding between meshes, so 4096-2
	pack_options.blockAlign = true;
	pack_options.texelsPerUnit = 1.0 / p_texel_size;

	xatlas::Atlas *atlas = xatlas::Create();

	xatlas::AddMeshError err = xatlas::AddMesh(atlas, input_mesh, 1);
	ERR_FAIL_COND_V_MSG(err != xatlas::AddMeshError::Success, false, xatlas::StringForEnum(err));

	xatlas::Generate(atlas, chart_options, pack_options);

	*r_size_hint_x = atlas->width;
	*r_size_hint_y = atlas->height;

	float w = *r_size_hint_x;
	float h = *r_size_hint_y;

	if (w == 0 || h == 0) {
		xatlas::Destroy(atlas);
		return false; //could not bake because there is no area
	}

	const xatlas::Mesh &output = atlas->meshes[0];

	*r_vertex = (int *)malloc(sizeof(int) * output.vertexCount);
	ERR_FAIL_NULL_V_MSG(*r_vertex, false, "Out of memory.");
	*r_uv = (float *)malloc(sizeof(float) * output.vertexCount * 2);
	ERR_FAIL_NULL_V_MSG(*r_uv, false, "Out of memory.");
	*r_index = (int *)malloc(sizeof(int) * output.indexCount);
	ERR_FAIL_NULL_V_MSG(*r_index, false, "Out of memory.");

	float max_x = 0;
	float max_y = 0;
	for (uint32_t i = 0; i < output.vertexCount; i++) {
		(*r_vertex)[i] = output.vertexArray[i].xref;
		(*r_uv)[i * 2 + 0] = output.vertexArray[i].uv[0] / w;
		(*r_uv)[i * 2 + 1] = output.vertexArray[i].uv[1] / h;
		max_x = MAX(max_x, output.vertexArray[i].uv[0]);
		max_y = MAX(max_y, output.vertexArray[i].uv[1]);
	}

	*r_vertex_count = output.vertexCount;

	for (uint32_t i = 0; i < output.indexCount; i++) {
		(*r_index)[i] = output.indexArray[i];
	}

	*r_index_count = output.indexCount;

	xatlas::Destroy(atlas);

	return true;
}

void register_xatlas_unwrap_types() {
	array_mesh_lightmap_unwrap_callback = xatlas_mesh_lightmap_unwrap_callback;
}

void unregister_xatlas_unwrap_types() {
}
