metaballs.cpp

/*
 * Copyright 2011-2024 Branimir Karadzic. All rights reserved.
 * License: https://github.com/bkaradzic/bgfx/blob/master/LICENSE
 */

#include "common.h"
#include "bgfx_utils.h"
#include "imgui/imgui.h"

#include <bgfx/embedded_shader.h>

// embedded shaders
#include "vs_metaballs.bin.h"
#include "fs_metaballs.bin.h"

namespace
{

static const bgfx::EmbeddedShader s_embeddedShaders[] =
{
	BGFX_EMBEDDED_SHADER(vs_metaballs),
	BGFX_EMBEDDED_SHADER(fs_metaballs),

	BGFX_EMBEDDED_SHADER_END()
};

struct PosNormalColorVertex
{
	float m_pos[3];
	float m_normal[3];
	uint32_t m_abgr;

	static void init()
	{
		ms_layout
			.begin()
			.add(bgfx::Attrib::Position, 3, bgfx::AttribType::Float)
			.add(bgfx::Attrib::Normal,   3, bgfx::AttribType::Float)
			.add(bgfx::Attrib::Color0,   4, bgfx::AttribType::Uint8, true)
			.end();
	};

	static bgfx::VertexLayout ms_layout;
};

bgfx::VertexLayout PosNormalColorVertex::ms_layout;

struct Grid
{
	Grid()
		: m_val(0.0f)
	{
		m_normal[0] = 0.0f;
		m_normal[1] = 0.0f;
		m_normal[2] = 0.0f;
	}

	float m_val;
	float m_normal[3];
};

// Reference(s):
// - Polygonising a scalar field
//   https://web.archive.org/web/20181127124338/http://paulbourke.net/geometry/polygonise/

static const uint16_t s_edges[256] =
{
	0x000, 0x109, 0x203, 0x30a, 0x406, 0x50f, 0x605, 0x70c,
	0x80c, 0x905, 0xa0f, 0xb06, 0xc0a, 0xd03, 0xe09, 0xf00,
	0x190, 0x099, 0x393, 0x29a, 0x596, 0x49f, 0x795, 0x69c,
	0x99c, 0x895, 0xb9f, 0xa96, 0xd9a, 0xc93, 0xf99, 0xe90,
	0x230, 0x339, 0x033, 0x13a, 0x636, 0x73f, 0x435, 0x53c,
	0xa3c, 0xb35, 0x83f, 0x936, 0xe3a, 0xf33, 0xc39, 0xd30,
	0x3a0, 0x2a9, 0x1a3, 0x0aa, 0x7a6, 0x6af, 0x5a5, 0x4ac,
	0xbac, 0xaa5, 0x9af, 0x8a6, 0xfaa, 0xea3, 0xda9, 0xca0,
	0x460, 0x569, 0x663, 0x76a, 0x66 , 0x16f, 0x265, 0x36c,
	0xc6c, 0xd65, 0xe6f, 0xf66, 0x86a, 0x963, 0xa69, 0xb60,
	0x5f0, 0x4f9, 0x7f3, 0x6fa, 0x1f6, 0x0ff, 0x3f5, 0x2fc,
	0xdfc, 0xcf5, 0xfff, 0xef6, 0x9fa, 0x8f3, 0xbf9, 0xaf0,
	0x650, 0x759, 0x453, 0x55a, 0x256, 0x35f, 0x055, 0x15c,
	0xe5c, 0xf55, 0xc5f, 0xd56, 0xa5a, 0xb53, 0x859, 0x950,
	0x7c0, 0x6c9, 0x5c3, 0x4ca, 0x3c6, 0x2cf, 0x1c5, 0x0cc,
	0xfcc, 0xec5, 0xdcf, 0xcc6, 0xbca, 0xac3, 0x9c9, 0x8c0,
	0x8c0, 0x9c9, 0xac3, 0xbca, 0xcc6, 0xdcf, 0xec5, 0xfcc,
	0x0cc, 0x1c5, 0x2cf, 0x3c6, 0x4ca, 0x5c3, 0x6c9, 0x7c0,
	0x950, 0x859, 0xb53, 0xa5a, 0xd56, 0xc5f, 0xf55, 0xe5c,
	0x15c, 0x55 , 0x35f, 0x256, 0x55a, 0x453, 0x759, 0x650,
	0xaf0, 0xbf9, 0x8f3, 0x9fa, 0xef6, 0xfff, 0xcf5, 0xdfc,
	0x2fc, 0x3f5, 0x0ff, 0x1f6, 0x6fa, 0x7f3, 0x4f9, 0x5f0,
	0xb60, 0xa69, 0x963, 0x86a, 0xf66, 0xe6f, 0xd65, 0xc6c,
	0x36c, 0x265, 0x16f, 0x066, 0x76a, 0x663, 0x569, 0x460,
	0xca0, 0xda9, 0xea3, 0xfaa, 0x8a6, 0x9af, 0xaa5, 0xbac,
	0x4ac, 0x5a5, 0x6af, 0x7a6, 0x0aa, 0x1a3, 0x2a9, 0x3a0,
	0xd30, 0xc39, 0xf33, 0xe3a, 0x936, 0x83f, 0xb35, 0xa3c,
	0x53c, 0x435, 0x73f, 0x636, 0x13a, 0x033, 0x339, 0x230,
	0xe90, 0xf99, 0xc93, 0xd9a, 0xa96, 0xb9f, 0x895, 0x99c,
	0x69c, 0x795, 0x49f, 0x596, 0x29a, 0x393, 0x099, 0x190,
	0xf00, 0xe09, 0xd03, 0xc0a, 0xb06, 0xa0f, 0x905, 0x80c,
	0x70c, 0x605, 0x50f, 0x406, 0x30a, 0x203, 0x109, 0x000,
};

static const int8_t s_indices[256][16] =
{
	{  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  8,  3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  1,  9, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  8,  3,  9,  8,  1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  2, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  8,  3,  1,  2, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  2, 10,  0,  2,  9, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   2,  8,  3,  2, 10,  8, 10,  9,  8, -1, -1, -1, -1, -1, -1, -1 },
	{   3, 11,  2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0, 11,  2,  8, 11,  0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  9,  0,  2,  3, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1, 11,  2,  1,  9, 11,  9,  8, 11, -1, -1, -1, -1, -1, -1, -1 },
	{   3, 10,  1, 11, 10,  3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0, 10,  1,  0,  8, 10,  8, 11, 10, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  9,  0,  3, 11,  9, 11, 10,  9, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  8, 10, 10,  8, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  7,  8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  3,  0,  7,  3,  4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  1,  9,  8,  4,  7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  1,  9,  4,  7,  1,  7,  3,  1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  2, 10,  8,  4,  7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  4,  7,  3,  0,  4,  1,  2, 10, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  2, 10,  9,  0,  2,  8,  4,  7, -1, -1, -1, -1, -1, -1, -1 },
	{   2, 10,  9,  2,  9,  7,  2,  7,  3,  7,  9,  4, -1, -1, -1, -1 },
	{   8,  4,  7,  3, 11,  2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{  11,  4,  7, 11,  2,  4,  2,  0,  4, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  0,  1,  8,  4,  7,  2,  3, 11, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  7, 11,  9,  4, 11,  9, 11,  2,  9,  2,  1, -1, -1, -1, -1 },
	{   3, 10,  1,  3, 11, 10,  7,  8,  4, -1, -1, -1, -1, -1, -1, -1 },
	{   1, 11, 10,  1,  4, 11,  1,  0,  4,  7, 11,  4, -1, -1, -1, -1 },
	{   4,  7,  8,  9,  0, 11,  9, 11, 10, 11,  0,  3, -1, -1, -1, -1 },
	{   4,  7, 11,  4, 11,  9,  9, 11, 10, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  5,  4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  5,  4,  0,  8,  3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  5,  4,  1,  5,  0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   8,  5,  4,  8,  3,  5,  3,  1,  5, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  2, 10,  9,  5,  4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  0,  8,  1,  2, 10,  4,  9,  5, -1, -1, -1, -1, -1, -1, -1 },
	{   5,  2, 10,  5,  4,  2,  4,  0,  2, -1, -1, -1, -1, -1, -1, -1 },
	{   2, 10,  5,  3,  2,  5,  3,  5,  4,  3,  4,  8, -1, -1, -1, -1 },
	{   9,  5,  4,  2,  3, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0, 11,  2,  0,  8, 11,  4,  9,  5, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  5,  4,  0,  1,  5,  2,  3, 11, -1, -1, -1, -1, -1, -1, -1 },
	{   2,  1,  5,  2,  5,  8,  2,  8, 11,  4,  8,  5, -1, -1, -1, -1 },
	{  10,  3, 11, 10,  1,  3,  9,  5,  4, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  9,  5,  0,  8,  1,  8, 10,  1,  8, 11, 10, -1, -1, -1, -1 },
	{   5,  4,  0,  5,  0, 11,  5, 11, 10, 11,  0,  3, -1, -1, -1, -1 },
	{   5,  4,  8,  5,  8, 10, 10,  8, 11, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  7,  8,  5,  7,  9, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  3,  0,  9,  5,  3,  5,  7,  3, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  7,  8,  0,  1,  7,  1,  5,  7, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  5,  3,  3,  5,  7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  7,  8,  9,  5,  7, 10,  1,  2, -1, -1, -1, -1, -1, -1, -1 },
	{  10,  1,  2,  9,  5,  0,  5,  3,  0,  5,  7,  3, -1, -1, -1, -1 },
	{   8,  0,  2,  8,  2,  5,  8,  5,  7, 10,  5,  2, -1, -1, -1, -1 },
	{   2, 10,  5,  2,  5,  3,  3,  5,  7, -1, -1, -1, -1, -1, -1, -1 },
	{   7,  9,  5,  7,  8,  9,  3, 11,  2, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  5,  7,  9,  7,  2,  9,  2,  0,  2,  7, 11, -1, -1, -1, -1 },
	{   2,  3, 11,  0,  1,  8,  1,  7,  8,  1,  5,  7, -1, -1, -1, -1 },
	{  11,  2,  1, 11,  1,  7,  7,  1,  5, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  5,  8,  8,  5,  7, 10,  1,  3, 10,  3, 11, -1, -1, -1, -1 },
	{   5,  7,  0,  5,  0,  9,  7, 11,  0,  1,  0, 10, 11, 10,  0, -1 },
	{  11, 10,  0, 11,  0,  3, 10,  5,  0,  8,  0,  7,  5,  7,  0, -1 },
	{  11, 10,  5,  7, 11,  5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{  10,  6,  5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  8,  3,  5, 10,  6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  0,  1,  5, 10,  6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  8,  3,  1,  9,  8,  5, 10,  6, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  6,  5,  2,  6,  1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  6,  5,  1,  2,  6,  3,  0,  8, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  6,  5,  9,  0,  6,  0,  2,  6, -1, -1, -1, -1, -1, -1, -1 },
	{   5,  9,  8,  5,  8,  2,  5,  2,  6,  3,  2,  8, -1, -1, -1, -1 },
	{   2,  3, 11, 10,  6,  5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{  11,  0,  8, 11,  2,  0, 10,  6,  5, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  1,  9,  2,  3, 11,  5, 10,  6, -1, -1, -1, -1, -1, -1, -1 },
	{   5, 10,  6,  1,  9,  2,  9, 11,  2,  9,  8, 11, -1, -1, -1, -1 },
	{   6,  3, 11,  6,  5,  3,  5,  1,  3, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  8, 11,  0, 11,  5,  0,  5,  1,  5, 11,  6, -1, -1, -1, -1 },
	{   3, 11,  6,  0,  3,  6,  0,  6,  5,  0,  5,  9, -1, -1, -1, -1 },
	{   6,  5,  9,  6,  9, 11, 11,  9,  8, -1, -1, -1, -1, -1, -1, -1 },
	{   5, 10,  6,  4,  7,  8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  3,  0,  4,  7,  3,  6,  5, 10, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  9,  0,  5, 10,  6,  8,  4,  7, -1, -1, -1, -1, -1, -1, -1 },
	{  10,  6,  5,  1,  9,  7,  1,  7,  3,  7,  9,  4, -1, -1, -1, -1 },
	{   6,  1,  2,  6,  5,  1,  4,  7,  8, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  2,  5,  5,  2,  6,  3,  0,  4,  3,  4,  7, -1, -1, -1, -1 },
	{   8,  4,  7,  9,  0,  5,  0,  6,  5,  0,  2,  6, -1, -1, -1, -1 },
	{   7,  3,  9,  7,  9,  4,  3,  2,  9,  5,  9,  6,  2,  6,  9, -1 },
	{   3, 11,  2,  7,  8,  4, 10,  6,  5, -1, -1, -1, -1, -1, -1, -1 },
	{   5, 10,  6,  4,  7,  2,  4,  2,  0,  2,  7, 11, -1, -1, -1, -1 },
	{   0,  1,  9,  4,  7,  8,  2,  3, 11,  5, 10,  6, -1, -1, -1, -1 },
	{   9,  2,  1,  9, 11,  2,  9,  4, 11,  7, 11,  4,  5, 10,  6, -1 },
	{   8,  4,  7,  3, 11,  5,  3,  5,  1,  5, 11,  6, -1, -1, -1, -1 },
	{   5,  1, 11,  5, 11,  6,  1,  0, 11,  7, 11,  4,  0,  4, 11, -1 },
	{   0,  5,  9,  0,  6,  5,  0,  3,  6, 11,  6,  3,  8,  4,  7, -1 },
	{   6,  5,  9,  6,  9, 11,  4,  7,  9,  7, 11,  9, -1, -1, -1, -1 },
	{  10,  4,  9,  6,  4, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   4, 10,  6,  4,  9, 10,  0,  8,  3, -1, -1, -1, -1, -1, -1, -1 },
	{  10,  0,  1, 10,  6,  0,  6,  4,  0, -1, -1, -1, -1, -1, -1, -1 },
	{   8,  3,  1,  8,  1,  6,  8,  6,  4,  6,  1, 10, -1, -1, -1, -1 },
	{   1,  4,  9,  1,  2,  4,  2,  6,  4, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  0,  8,  1,  2,  9,  2,  4,  9,  2,  6,  4, -1, -1, -1, -1 },
	{   0,  2,  4,  4,  2,  6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   8,  3,  2,  8,  2,  4,  4,  2,  6, -1, -1, -1, -1, -1, -1, -1 },
	{  10,  4,  9, 10,  6,  4, 11,  2,  3, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  8,  2,  2,  8, 11,  4,  9, 10,  4, 10,  6, -1, -1, -1, -1 },
	{   3, 11,  2,  0,  1,  6,  0,  6,  4,  6,  1, 10, -1, -1, -1, -1 },
	{   6,  4,  1,  6,  1, 10,  4,  8,  1,  2,  1, 11,  8, 11,  1, -1 },
	{   9,  6,  4,  9,  3,  6,  9,  1,  3, 11,  6,  3, -1, -1, -1, -1 },
	{   8, 11,  1,  8,  1,  0, 11,  6,  1,  9,  1,  4,  6,  4,  1, -1 },
	{   3, 11,  6,  3,  6,  0,  0,  6,  4, -1, -1, -1, -1, -1, -1, -1 },
	{   6,  4,  8, 11,  6,  8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   7, 10,  6,  7,  8, 10,  8,  9, 10, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  7,  3,  0, 10,  7,  0,  9, 10,  6,  7, 10, -1, -1, -1, -1 },
	{  10,  6,  7,  1, 10,  7,  1,  7,  8,  1,  8,  0, -1, -1, -1, -1 },
	{  10,  6,  7, 10,  7,  1,  1,  7,  3, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  2,  6,  1,  6,  8,  1,  8,  9,  8,  6,  7, -1, -1, -1, -1 },
	{   2,  6,  9,  2,  9,  1,  6,  7,  9,  0,  9,  3,  7,  3,  9, -1 },
	{   7,  8,  0,  7,  0,  6,  6,  0,  2, -1, -1, -1, -1, -1, -1, -1 },
	{   7,  3,  2,  6,  7,  2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   2,  3, 11, 10,  6,  8, 10,  8,  9,  8,  6,  7, -1, -1, -1, -1 },
	{   2,  0,  7,  2,  7, 11,  0,  9,  7,  6,  7, 10,  9, 10,  7, -1 },
	{   1,  8,  0,  1,  7,  8,  1, 10,  7,  6,  7, 10,  2,  3, 11, -1 },
	{  11,  2,  1, 11,  1,  7, 10,  6,  1,  6,  7,  1, -1, -1, -1, -1 },
	{   8,  9,  6,  8,  6,  7,  9,  1,  6, 11,  6,  3,  1,  3,  6, -1 },
	{   0,  9,  1, 11,  6,  7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   7,  8,  0,  7,  0,  6,  3, 11,  0, 11,  6,  0, -1, -1, -1, -1 },
	{   7, 11,  6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   7,  6, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  0,  8, 11,  7,  6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  1,  9, 11,  7,  6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   8,  1,  9,  8,  3,  1, 11,  7,  6, -1, -1, -1, -1, -1, -1, -1 },
	{  10,  1,  2,  6, 11,  7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  2, 10,  3,  0,  8,  6, 11,  7, -1, -1, -1, -1, -1, -1, -1 },
	{   2,  9,  0,  2, 10,  9,  6, 11,  7, -1, -1, -1, -1, -1, -1, -1 },
	{   6, 11,  7,  2, 10,  3, 10,  8,  3, 10,  9,  8, -1, -1, -1, -1 },
	{   7,  2,  3,  6,  2,  7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   7,  0,  8,  7,  6,  0,  6,  2,  0, -1, -1, -1, -1, -1, -1, -1 },
	{   2,  7,  6,  2,  3,  7,  0,  1,  9, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  6,  2,  1,  8,  6,  1,  9,  8,  8,  7,  6, -1, -1, -1, -1 },
	{  10,  7,  6, 10,  1,  7,  1,  3,  7, -1, -1, -1, -1, -1, -1, -1 },
	{  10,  7,  6,  1,  7, 10,  1,  8,  7,  1,  0,  8, -1, -1, -1, -1 },
	{   0,  3,  7,  0,  7, 10,  0, 10,  9,  6, 10,  7, -1, -1, -1, -1 },
	{   7,  6, 10,  7, 10,  8,  8, 10,  9, -1, -1, -1, -1, -1, -1, -1 },
	{   6,  8,  4, 11,  8,  6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  6, 11,  3,  0,  6,  0,  4,  6, -1, -1, -1, -1, -1, -1, -1 },
	{   8,  6, 11,  8,  4,  6,  9,  0,  1, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  4,  6,  9,  6,  3,  9,  3,  1, 11,  3,  6, -1, -1, -1, -1 },
	{   6,  8,  4,  6, 11,  8,  2, 10,  1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  2, 10,  3,  0, 11,  0,  6, 11,  0,  4,  6, -1, -1, -1, -1 },
	{   4, 11,  8,  4,  6, 11,  0,  2,  9,  2, 10,  9, -1, -1, -1, -1 },
	{  10,  9,  3, 10,  3,  2,  9,  4,  3, 11,  3,  6,  4,  6,  3, -1 },
	{   8,  2,  3,  8,  4,  2,  4,  6,  2, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  4,  2,  4,  6,  2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  9,  0,  2,  3,  4,  2,  4,  6,  4,  3,  8, -1, -1, -1, -1 },
	{   1,  9,  4,  1,  4,  2,  2,  4,  6, -1, -1, -1, -1, -1, -1, -1 },
	{   8,  1,  3,  8,  6,  1,  8,  4,  6,  6, 10,  1, -1, -1, -1, -1 },
	{  10,  1,  0, 10,  0,  6,  6,  0,  4, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  6,  3,  4,  3,  8,  6, 10,  3,  0,  3,  9, 10,  9,  3, -1 },
	{  10,  9,  4,  6, 10,  4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  9,  5,  7,  6, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  8,  3,  4,  9,  5, 11,  7,  6, -1, -1, -1, -1, -1, -1, -1 },
	{   5,  0,  1,  5,  4,  0,  7,  6, 11, -1, -1, -1, -1, -1, -1, -1 },
	{  11,  7,  6,  8,  3,  4,  3,  5,  4,  3,  1,  5, -1, -1, -1, -1 },
	{   9,  5,  4, 10,  1,  2,  7,  6, 11, -1, -1, -1, -1, -1, -1, -1 },
	{   6, 11,  7,  1,  2, 10,  0,  8,  3,  4,  9,  5, -1, -1, -1, -1 },
	{   7,  6, 11,  5,  4, 10,  4,  2, 10,  4,  0,  2, -1, -1, -1, -1 },
	{   3,  4,  8,  3,  5,  4,  3,  2,  5, 10,  5,  2, 11,  7,  6, -1 },
	{   7,  2,  3,  7,  6,  2,  5,  4,  9, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  5,  4,  0,  8,  6,  0,  6,  2,  6,  8,  7, -1, -1, -1, -1 },
	{   3,  6,  2,  3,  7,  6,  1,  5,  0,  5,  4,  0, -1, -1, -1, -1 },
	{   6,  2,  8,  6,  8,  7,  2,  1,  8,  4,  8,  5,  1,  5,  8, -1 },
	{   9,  5,  4, 10,  1,  6,  1,  7,  6,  1,  3,  7, -1, -1, -1, -1 },
	{   1,  6, 10,  1,  7,  6,  1,  0,  7,  8,  7,  0,  9,  5,  4, -1 },
	{   4,  0, 10,  4, 10,  5,  0,  3, 10,  6, 10,  7,  3,  7, 10, -1 },
	{   7,  6, 10,  7, 10,  8,  5,  4, 10,  4,  8, 10, -1, -1, -1, -1 },
	{   6,  9,  5,  6, 11,  9, 11,  8,  9, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  6, 11,  0,  6,  3,  0,  5,  6,  0,  9,  5, -1, -1, -1, -1 },
	{   0, 11,  8,  0,  5, 11,  0,  1,  5,  5,  6, 11, -1, -1, -1, -1 },
	{   6, 11,  3,  6,  3,  5,  5,  3,  1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  2, 10,  9,  5, 11,  9, 11,  8, 11,  5,  6, -1, -1, -1, -1 },
	{   0, 11,  3,  0,  6, 11,  0,  9,  6,  5,  6,  9,  1,  2, 10, -1 },
	{  11,  8,  5, 11,  5,  6,  8,  0,  5, 10,  5,  2,  0,  2,  5, -1 },
	{   6, 11,  3,  6,  3,  5,  2, 10,  3, 10,  5,  3, -1, -1, -1, -1 },
	{   5,  8,  9,  5,  2,  8,  5,  6,  2,  3,  8,  2, -1, -1, -1, -1 },
	{   9,  5,  6,  9,  6,  0,  0,  6,  2, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  5,  8,  1,  8,  0,  5,  6,  8,  3,  8,  2,  6,  2,  8, -1 },
	{   1,  5,  6,  2,  1,  6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  3,  6,  1,  6, 10,  3,  8,  6,  5,  6,  9,  8,  9,  6, -1 },
	{  10,  1,  0, 10,  0,  6,  9,  5,  0,  5,  6,  0, -1, -1, -1, -1 },
	{   0,  3,  8,  5,  6, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{  10,  5,  6, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{  11,  5, 10,  7,  5, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{  11,  5, 10, 11,  7,  5,  8,  3,  0, -1, -1, -1, -1, -1, -1, -1 },
	{   5, 11,  7,  5, 10, 11,  1,  9,  0, -1, -1, -1, -1, -1, -1, -1 },
	{  10,  7,  5, 10, 11,  7,  9,  8,  1,  8,  3,  1, -1, -1, -1, -1 },
	{  11,  1,  2, 11,  7,  1,  7,  5,  1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  8,  3,  1,  2,  7,  1,  7,  5,  7,  2, 11, -1, -1, -1, -1 },
	{   9,  7,  5,  9,  2,  7,  9,  0,  2,  2, 11,  7, -1, -1, -1, -1 },
	{   7,  5,  2,  7,  2, 11,  5,  9,  2,  3,  2,  8,  9,  8,  2, -1 },
	{   2,  5, 10,  2,  3,  5,  3,  7,  5, -1, -1, -1, -1, -1, -1, -1 },
	{   8,  2,  0,  8,  5,  2,  8,  7,  5, 10,  2,  5, -1, -1, -1, -1 },
	{   9,  0,  1,  5, 10,  3,  5,  3,  7,  3, 10,  2, -1, -1, -1, -1 },
	{   9,  8,  2,  9,  2,  1,  8,  7,  2, 10,  2,  5,  7,  5,  2, -1 },
	{   1,  3,  5,  3,  7,  5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  8,  7,  0,  7,  1,  1,  7,  5, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  0,  3,  9,  3,  5,  5,  3,  7, -1, -1, -1, -1, -1, -1, -1 },
	{   9,  8,  7,  5,  9,  7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   5,  8,  4,  5, 10,  8, 10, 11,  8, -1, -1, -1, -1, -1, -1, -1 },
	{   5,  0,  4,  5, 11,  0,  5, 10, 11, 11,  3,  0, -1, -1, -1, -1 },
	{   0,  1,  9,  8,  4, 10,  8, 10, 11, 10,  4,  5, -1, -1, -1, -1 },
	{  10, 11,  4, 10,  4,  5, 11,  3,  4,  9,  4,  1,  3,  1,  4, -1 },
	{   2,  5,  1,  2,  8,  5,  2, 11,  8,  4,  5,  8, -1, -1, -1, -1 },
	{   0,  4, 11,  0, 11,  3,  4,  5, 11,  2, 11,  1,  5,  1, 11, -1 },
	{   0,  2,  5,  0,  5,  9,  2, 11,  5,  4,  5,  8, 11,  8,  5, -1 },
	{   9,  4,  5,  2, 11,  3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   2,  5, 10,  3,  5,  2,  3,  4,  5,  3,  8,  4, -1, -1, -1, -1 },
	{   5, 10,  2,  5,  2,  4,  4,  2,  0, -1, -1, -1, -1, -1, -1, -1 },
	{   3, 10,  2,  3,  5, 10,  3,  8,  5,  4,  5,  8,  0,  1,  9, -1 },
	{   5, 10,  2,  5,  2,  4,  1,  9,  2,  9,  4,  2, -1, -1, -1, -1 },
	{   8,  4,  5,  8,  5,  3,  3,  5,  1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  4,  5,  1,  0,  5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   8,  4,  5,  8,  5,  3,  9,  0,  5,  0,  3,  5, -1, -1, -1, -1 },
	{   9,  4,  5, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   4, 11,  7,  4,  9, 11,  9, 10, 11, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  8,  3,  4,  9,  7,  9, 11,  7,  9, 10, 11, -1, -1, -1, -1 },
	{   1, 10, 11,  1, 11,  4,  1,  4,  0,  7,  4, 11, -1, -1, -1, -1 },
	{   3,  1,  4,  3,  4,  8,  1, 10,  4,  7,  4, 11, 10, 11,  4, -1 },
	{   4, 11,  7,  9, 11,  4,  9,  2, 11,  9,  1,  2, -1, -1, -1, -1 },
	{   9,  7,  4,  9, 11,  7,  9,  1, 11,  2, 11,  1,  0,  8,  3, -1 },
	{  11,  7,  4, 11,  4,  2,  2,  4,  0, -1, -1, -1, -1, -1, -1, -1 },
	{  11,  7,  4, 11,  4,  2,  8,  3,  4,  3,  2,  4, -1, -1, -1, -1 },
	{   2,  9, 10,  2,  7,  9,  2,  3,  7,  7,  4,  9, -1, -1, -1, -1 },
	{   9, 10,  7,  9,  7,  4, 10,  2,  7,  8,  7,  0,  2,  0,  7, -1 },
	{   3,  7, 10,  3, 10,  2,  7,  4, 10,  1, 10,  0,  4,  0, 10, -1 },
	{   1, 10,  2,  8,  7,  4, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  9,  1,  4,  1,  7,  7,  1,  3, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  9,  1,  4,  1,  7,  0,  8,  1,  8,  7,  1, -1, -1, -1, -1 },
	{   4,  0,  3,  7,  4,  3, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   4,  8,  7, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   9, 10,  8, 10, 11,  8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  0,  9,  3,  9, 11, 11,  9, 10, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  1, 10,  0, 10,  8,  8, 10, 11, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  1, 10, 11,  3, 10, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  2, 11,  1, 11,  9,  9, 11,  8, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  0,  9,  3,  9, 11,  1,  2,  9,  2, 11,  9, -1, -1, -1, -1 },
	{   0,  2, 11,  8,  0, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   3,  2, 11, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   2,  3,  8,  2,  8, 10, 10,  8,  9, -1, -1, -1, -1, -1, -1, -1 },
	{   9, 10,  2,  0,  9,  2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   2,  3,  8,  2,  8, 10,  0,  1,  8,  1, 10,  8, -1, -1, -1, -1 },
	{   1, 10,  2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   1,  3,  8,  9,  1,  8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  9,  1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{   0,  3,  8, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
	{  -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1 },
};

static const float s_cube[8][3] =
{
	{ 0.0f, 1.0f, 1.0f }, // 0
	{ 1.0f, 1.0f, 1.0f }, // 1
	{ 1.0f, 1.0f, 0.0f }, // 2
	{ 0.0f, 1.0f, 0.0f }, // 3
	{ 0.0f, 0.0f, 1.0f }, // 4
	{ 1.0f, 0.0f, 1.0f }, // 5
	{ 1.0f, 0.0f, 0.0f }, // 6
	{ 0.0f, 0.0f, 0.0f }, // 7
};

float vertLerp(float* _result, float _iso, uint32_t _idx0, float _v0, uint32_t _idx1, float _v1)
{
	const float* edge0 = s_cube[_idx0];
	const float* edge1 = s_cube[_idx1];

	if (bx::abs(_iso-_v1) < 0.00001f)
	{
		_result[0] = edge1[0];
		_result[1] = edge1[1];
		_result[2] = edge1[2];
		return 1.0f;
	}

	if (bx::abs(_iso-_v0) < 0.00001f
	||  bx::abs(_v0-_v1) < 0.00001f)
	{
		_result[0] = edge0[0];
		_result[1] = edge0[1];
		_result[2] = edge0[2];
		return 0.0f;
	}

	float lerp = (_iso - _v0) / (_v1 - _v0);
	_result[0] = edge0[0] + lerp * (edge1[0] - edge0[0]);
	_result[1] = edge0[1] + lerp * (edge1[1] - edge0[1]);
	_result[2] = edge0[2] + lerp * (edge1[2] - edge0[2]);

	return lerp;
}

uint32_t triangulate(
	  uint8_t* _result
	, uint32_t _stride
	, const float* _rgb
	, const float* _xyz
	, const Grid* _val[8]
	, float _iso
	, float _scale
	)
{
	uint8_t cubeindex = 0;
	cubeindex |= (_val[0]->m_val < _iso) ? 0x01 : 0;
	cubeindex |= (_val[1]->m_val < _iso) ? 0x02 : 0;
	cubeindex |= (_val[2]->m_val < _iso) ? 0x04 : 0;
	cubeindex |= (_val[3]->m_val < _iso) ? 0x08 : 0;
	cubeindex |= (_val[4]->m_val < _iso) ? 0x10 : 0;
	cubeindex |= (_val[5]->m_val < _iso) ? 0x20 : 0;
	cubeindex |= (_val[6]->m_val < _iso) ? 0x40 : 0;
	cubeindex |= (_val[7]->m_val < _iso) ? 0x80 : 0;

	if (0 == s_edges[cubeindex])
	{
		return 0;
	}

	float verts[12][6];
	uint16_t flags = s_edges[cubeindex];

	for (uint32_t ii = 0; ii < 12; ++ii)
	{
		if (flags & (1<<ii) )
		{
			uint32_t idx0 = ii&7;
			uint32_t idx1 = "\x1\x2\x3\x0\x5\x6\x7\x4\x4\x5\x6\x7"[ii];
			float* vertex = verts[ii];
			float lerp = vertLerp(vertex, _iso, idx0, _val[idx0]->m_val, idx1, _val[idx1]->m_val);

			const float* na = _val[idx0]->m_normal;
			const float* nb = _val[idx1]->m_normal;
			vertex[3] = na[0] + lerp * (nb[0] - na[0]);
			vertex[4] = na[1] + lerp * (nb[1] - na[1]);
			vertex[5] = na[2] + lerp * (nb[2] - na[2]);
		}
	}

	const float dr = _rgb[3] - _rgb[0];
	const float dg = _rgb[4] - _rgb[1];
	const float db = _rgb[5] - _rgb[2];

	uint32_t num = 0;
	const int8_t* indices = s_indices[cubeindex];
	for (uint32_t ii = 0; indices[ii] != -1; ++ii)
	{
		const float* vertex = verts[uint8_t(indices[ii])];

		float* xyz = (float*)_result;
		xyz[0] = _xyz[0] + vertex[0]*_scale;
		xyz[1] = _xyz[1] + vertex[1]*_scale;
		xyz[2] = _xyz[2] + vertex[2]*_scale;

		xyz[3] = vertex[3]*_scale;
		xyz[4] = vertex[4]*_scale;
		xyz[5] = vertex[5]*_scale;

		uint32_t rr = uint8_t( (_rgb[0] + vertex[0]*dr)*255.0f);
		uint32_t gg = uint8_t( (_rgb[1] + vertex[1]*dg)*255.0f);
		uint32_t bb = uint8_t( (_rgb[2] + vertex[2]*db)*255.0f);

		uint32_t* abgr = (uint32_t*)&_result[24];
		*abgr = 0xff000000
			  | (bb<<16)
			  | (gg<<8)
			  | rr
			  ;

		_result += _stride;
		++num;
	}

	return num;
}

constexpr uint32_t kMaxDims  = 32;
constexpr float    kMaxDimsF = float(kMaxDims);

class ExampleMetaballs : public entry::AppI
{
public:
	ExampleMetaballs(const char* _name, const char* _description, const char* _url)
		: entry::AppI(_name, _description, _url)
	{
	}

	void init(int32_t _argc, const char* const* _argv, uint32_t _width, uint32_t _height) override
	{
		Args args(_argc, _argv);

		m_width  = _width;
		m_height = _height;
		m_debug  = BGFX_DEBUG_NONE;
		m_reset  = BGFX_RESET_VSYNC;

		bgfx::Init init;
		init.type     = args.m_type;
		init.vendorId = args.m_pciId;
		init.platformData.nwh  = entry::getNativeWindowHandle(entry::kDefaultWindowHandle);
		init.platformData.ndt  = entry::getNativeDisplayHandle();
		init.platformData.type = entry::getNativeWindowHandleType();
		init.resolution.width  = m_width;
		init.resolution.height = m_height;
		init.resolution.reset  = m_reset;
		bgfx::init(init);

		// Enable debug text.
		bgfx::setDebug(m_debug);

		// Set view 0 clear state.
		bgfx::setViewClear(0
				, BGFX_CLEAR_COLOR|BGFX_CLEAR_DEPTH
				, 0x303030ff
				, 1.0f
				, 0
				);

		// Create vertex stream declaration.
		PosNormalColorVertex::init();

		bgfx::RendererType::Enum type = bgfx::getRendererType();

		bgfx::ShaderHandle vsh = bgfx::createEmbeddedShader(s_embeddedShaders, type, "vs_metaballs");
		bgfx::ShaderHandle fsh = bgfx::createEmbeddedShader(s_embeddedShaders, type, "fs_metaballs");

		// Create program from shaders.
		m_program = bgfx::createProgram(vsh, fsh, true /* destroy shaders when program is destroyed */);

		m_grid = new Grid[kMaxDims*kMaxDims*kMaxDims];
		m_timeOffset = bx::getHPCounter();

		imguiCreate();
	}

	int shutdown() override
	{
		imguiDestroy();

		delete [] m_grid;

		// Cleanup.
		bgfx::destroy(m_program);

		// Shutdown bgfx.
		bgfx::shutdown();

		return 0;
	}

	bool update() override
	{
		const uint32_t ypitch = kMaxDims;
		const uint32_t zpitch = kMaxDims*kMaxDims;

		if (!entry::processEvents(m_width, m_height, m_debug, m_reset, &m_mouseState) )
		{
			imguiBeginFrame(m_mouseState.m_mx
				,  m_mouseState.m_my
				, (m_mouseState.m_buttons[entry::MouseButton::Left  ] ? IMGUI_MBUT_LEFT   : 0)
				| (m_mouseState.m_buttons[entry::MouseButton::Right ] ? IMGUI_MBUT_RIGHT  : 0)
				| (m_mouseState.m_buttons[entry::MouseButton::Middle] ? IMGUI_MBUT_MIDDLE : 0)
				,  m_mouseState.m_mz
				, uint16_t(m_width)
				, uint16_t(m_height)
				);

			showExampleDialog(this);

			ImGui::SetNextWindowPos(
				  ImVec2(m_width - m_width / 5.0f - 10.0f, 10.0f)
				, ImGuiCond_FirstUseEver
				);
			ImGui::SetNextWindowSize(
				  ImVec2(m_width / 5.0f, m_height / 7.0f)
				, ImGuiCond_FirstUseEver
				);
			ImGui::Begin("Settings"
				, NULL
				, 0
				);
			static float iso = 0.75f;
			ImGui::SliderFloat("ISO", &iso, 0.1f, 4.0f);

			static uint32_t numDims = kMaxDims;
			ImGui::SliderInt("Size", (int*)&numDims, 8, kMaxDims);
			ImGui::End();

			const float numDimsF = float(numDims);
			const float scale    = kMaxDimsF/numDimsF;
			const float invDim   = 1.0f/(numDimsF-1.0f);

			// Set view 0 default viewport.
			bgfx::setViewRect(0, 0, 0, uint16_t(m_width), uint16_t(m_height) );

			// This dummy draw call is here to make sure that view 0 is cleared
			// if no other draw calls are submitted to view 0.
			bgfx::touch(0);

			int64_t now = bx::getHPCounter();
			static int64_t last = now;
			const int64_t frameTime = now - last;
			last = now;
			const double freq = double(bx::getHPFrequency() );
			const double toMs = 1000.0/freq;
			float time = (float)( (now - m_timeOffset)/double(bx::getHPFrequency() ) );

			const bx::Vec3 at  = { 0.0f, 0.0f,   0.0f };
			const bx::Vec3 eye = { 0.0f, 0.0f, -50.0f };

			// Set view and projection matrix for view 0.
			{
				float view[16];
				bx::mtxLookAt(view, eye, at);

				float proj[16];
				bx::mtxProj(proj, 60.0f, float(m_width)/float(m_height), 0.1f, 100.0f, bgfx::getCaps()->homogeneousDepth);
				bgfx::setViewTransform(0, view, proj);

				// Set view 0 default viewport.
				bgfx::setViewRect(0, 0, 0, uint16_t(m_width), uint16_t(m_height) );
			}

			// Stats.
			uint32_t numVertices = 0;
			int64_t profUpdate = 0;
			int64_t profNormal = 0;
			int64_t profTriangulate = 0;

			// Allocate 32K vertices in transient vertex buffer.
			uint32_t maxVertices = (32<<10);
			bgfx::TransientVertexBuffer tvb;
			bgfx::allocTransientVertexBuffer(&tvb, maxVertices, PosNormalColorVertex::ms_layout);

			const uint32_t numSpheres = 16;
			float sphere[numSpheres][4];
			for (uint32_t ii = 0; ii < numSpheres; ++ii)
			{
				sphere[ii][0] = bx::sin(time*(ii*0.21f)+ii*0.37f) * (kMaxDimsF * 0.5f - 8.0f);
				sphere[ii][1] = bx::sin(time*(ii*0.37f)+ii*0.67f) * (kMaxDimsF * 0.5f - 8.0f);
				sphere[ii][2] = bx::cos(time*(ii*0.11f)+ii*0.13f) * (kMaxDimsF * 0.5f - 8.0f);
				sphere[ii][3] = 1.0f/(3.0f + (bx::sin(time*(ii*0.13f) )*0.5f+0.5f)*0.9f );
			}

			profUpdate = bx::getHPCounter();

			for (uint32_t zz = 0; zz < numDims; ++zz)
			{
				for (uint32_t yy = 0; yy < numDims; ++yy)
				{
					uint32_t offset = (zz*kMaxDims+yy)*kMaxDims;

					for (uint32_t xx = 0; xx < numDims; ++xx)
					{
						uint32_t xoffset = offset + xx;

						float dist = 0.0f;
						float prod = 1.0f;
						for (uint32_t ii = 0; ii < numSpheres; ++ii)
						{
							const float* pos = sphere[ii];
							float dx   = pos[0] - (-kMaxDimsF*0.5f + float(xx)*scale);
							float dy   = pos[1] - (-kMaxDimsF*0.5f + float(yy)*scale);
							float dz   = pos[2] - (-kMaxDimsF*0.5f + float(zz)*scale);
							float invR = pos[3];
							float dot  = dx*dx + dy*dy + dz*dz;
							dot *= bx::square(invR);

							dist *= dot;
							dist += prod;
							prod *= dot;
						}

						m_grid[xoffset].m_val = dist / prod - 1.0f;
					}
				}
			}

			profUpdate = bx::getHPCounter() - profUpdate;

			profNormal = bx::getHPCounter();

			for (uint32_t zz = 1; zz < numDims-1; ++zz)
			{
				for (uint32_t yy = 1; yy < numDims-1; ++yy)
				{
					uint32_t offset = (zz*kMaxDims+yy)*kMaxDims;

					for (uint32_t xx = 1; xx < numDims-1; ++xx)
					{
						uint32_t xoffset = offset + xx;

						Grid* grid = m_grid;
						const bx::Vec3 normal =
						{
							grid[xoffset-1     ].m_val - grid[xoffset+1     ].m_val,
							grid[xoffset-ypitch].m_val - grid[xoffset+ypitch].m_val,
							grid[xoffset-zpitch].m_val - grid[xoffset+zpitch].m_val,
						};

						bx::store(grid[xoffset].m_normal, bx::normalize(normal) );
					}
				}
			}

			profNormal = bx::getHPCounter() - profNormal;

			profTriangulate = bx::getHPCounter();

			PosNormalColorVertex* vertex = (PosNormalColorVertex*)tvb.data;

			for (uint32_t zz = 0; zz < numDims-1 && numVertices+12 < maxVertices; ++zz)
			{
				float rgb[6];
				rgb[2] = zz*invDim;
				rgb[5] = (zz+1)*invDim;

				for (uint32_t yy = 0; yy < numDims-1 && numVertices+12 < maxVertices; ++yy)
				{
					uint32_t offset = (zz*kMaxDims+yy)*kMaxDims;

					rgb[1] = yy*invDim;
					rgb[4] = (yy+1)*invDim;

					for (uint32_t xx = 0; xx < numDims-1 && numVertices+12 < maxVertices; ++xx)
					{
						uint32_t xoffset = offset + xx;

						rgb[0] = xx*invDim;
						rgb[3] = (xx+1)*invDim;

						float pos[3] =
						{
							-kMaxDimsF*0.5f + float(xx)*scale,
							-kMaxDimsF*0.5f + float(yy)*scale,
							-kMaxDimsF*0.5f + float(zz)*scale,
						};

						const Grid* grid = m_grid;
						const Grid* val[8] = {
							&grid[xoffset+zpitch+ypitch  ],
							&grid[xoffset+zpitch+ypitch+1],
							&grid[xoffset+ypitch+1       ],
							&grid[xoffset+ypitch         ],
							&grid[xoffset+zpitch         ],
							&grid[xoffset+zpitch+1       ],
							&grid[xoffset+1              ],
							&grid[xoffset                ],
						};

						uint32_t num = triangulate(
							  (uint8_t*)vertex
							, PosNormalColorVertex::ms_layout.getStride()
							, rgb
							, pos
							, val
							, iso
							, scale
							);
						vertex += num;
						numVertices += num;
					}
				}
			}

			profTriangulate = bx::getHPCounter() - profTriangulate;

			float mtx[16];
			bx::mtxRotateXY(mtx, time*0.67f, time);

			// Set model matrix for rendering.
			bgfx::setTransform(mtx);

			// Set vertex and index buffer.
			bgfx::setVertexBuffer(0, &tvb, 0, numVertices);

			// Set render states.
			bgfx::setState(BGFX_STATE_DEFAULT);

			// Submit primitive for rendering to view 0.
			bgfx::submit(0, m_program);

			// Display stats.
			ImGui::SetNextWindowPos(
				  ImVec2(m_width - m_width / 5.0f - 10.0f, m_height / 7.0f + 30.0f)
				, ImGuiCond_FirstUseEver
				);
			ImGui::SetNextWindowSize(
				  ImVec2(m_width / 5.0f, m_height / 4.0f)
				, ImGuiCond_FirstUseEver
				);
			ImGui::Begin("Stats"
				, NULL
				, 0
				);

			ImGui::Text("Num vertices:"); ImGui::SameLine(100); ImGui::Text("%5d (%6.4f%%)", numVertices, float(numVertices)/maxVertices * 100);
			ImGui::Text("Update:");       ImGui::SameLine(100); ImGui::Text("% 7.3f[ms]", double(profUpdate)*toMs);
			ImGui::Text("Calc normals:"); ImGui::SameLine(100); ImGui::Text("% 7.3f[ms]", double(profNormal)*toMs);
			ImGui::Text("Triangulate:");  ImGui::SameLine(100); ImGui::Text("% 7.3f[ms]", double(profTriangulate)*toMs);
			ImGui::Text("Frame:");        ImGui::SameLine(100); ImGui::Text("% 7.3f[ms]", double(frameTime)*toMs);

			ImGui::End();

			imguiEndFrame();

			// Advance to next frame. Rendering thread will be kicked to
			// process submitted rendering primitives.
			bgfx::frame();

			return true;
		}

		return false;
	}

	entry::MouseState m_mouseState;

	uint32_t m_width;
	uint32_t m_height;
	uint32_t m_debug;
	uint32_t m_reset;
	bgfx::ProgramHandle m_program;

	Grid* m_grid;
	int64_t m_timeOffset;
};

} // namespace

ENTRY_IMPLEMENT_MAIN(
	  ExampleMetaballs
	, "02-metaball"
	, "Rendering with transient buffers and embedding shaders."
	, "https://bkaradzic.github.io/bgfx/examples.html#metaballs"
	);