bgfx/examples/common/cube_atlas.cpp

/* Copyright 2013 Jeremie Roy. All rights reserved.
 * License: http://www.opensource.org/licenses/BSD-2-Clause
*/
#include "cube_atlas.h"
#include <bx/bx.h>
#include <bgfx.h> 
#include <vector>


//********** Rectangle packer implementation ************
class RectanglePacker
{ 
public:
	RectanglePacker();
	RectanglePacker(uint32_t _width, uint32_t _height);
	
	/// non constructor initialization
	void init(uint32_t _width, uint32_t _height);
	/// find a suitable position for the given rectangle 
	/// @return true if the rectangle can be added, false otherwise	
	bool addRectangle(uint16_t _width, uint16_t _height, uint16_t& _outX, uint16_t& _outY );
	/// return the used surface in squared unit
	uint32_t getUsedSurface() { return m_usedSpace; }
	/// return the total available surface in squared unit
	uint32_t getTotalSurface() { return m_width*m_height; }
	/// return the usage ratio of the available surface [0:1]
	float getUsageRatio();
	/// reset to initial state
    void clear();

private:
	int32_t fit(uint32_t _skylineNodeIndex, uint16_t _width, uint16_t _height);
	/// Merges all skyline nodes that are at the same level.
	void merge();

	struct Node
	{
		Node(int16_t _x, int16_t _y, int16_t _width):m_x(_x), m_y(_y), m_width(_width) {} 
    
		/// The starting x-coordinate (leftmost).
		int16_t m_x;
		/// The y-coordinate of the skyline level line.
		int16_t m_y;
		/// The line _width. The ending coordinate (inclusive) will be x+width-1.
		int32_t m_width; //32bit to avoid padding
	};

	 /// width (in pixels) of the underlying texture
    uint32_t m_width;
    /// height (in pixels) of the underlying texture
    uint32_t m_height;
    /// Surface used in squared pixel
    uint32_t m_usedSpace;
	/// node of the skyline algorithm
    std::vector<Node> m_skyline;
};

RectanglePacker::RectanglePacker(): m_width(0), m_height(0), m_usedSpace(0)
{	
}

RectanglePacker::RectanglePacker(uint32_t _width, uint32_t _height):m_width(_width), m_height(_height), m_usedSpace(0)
{   
    // We want a one pixel border around the whole atlas to avoid any artefact when
    // sampling texture    
    m_skyline.push_back(Node(1,1, _width-2));
}

void RectanglePacker::init(uint32_t _width, uint32_t _height)
{
	BX_CHECK(_width > 2, "_width must be > 2");
	BX_CHECK(_height > 2, "_height must be > 2");
	m_width = _width;
	m_height = _height;
	m_usedSpace = 0;

	m_skyline.clear();
	// We want a one pixel border around the whole atlas to avoid any artifact when
    // sampling texture    
    m_skyline.push_back(Node(1,1, _width-2));
}

bool RectanglePacker::addRectangle(uint16_t _width, uint16_t _height, uint16_t& _outX, uint16_t& _outY)
{
	int y, best_height, best_index;
    int32_t best_width;
    Node* node;
    Node* prev;
    _outX = 0;
	_outY = 0;
	
	uint32_t ii;

    best_height = INT_MAX;
    best_index  = -1;
    best_width = INT_MAX;
	for( ii = 0; ii < m_skyline.size(); ++ii )
	{
        y = fit( ii, _width, _height );
		if( y >= 0 )
		{
            node = &m_skyline[ii];
			if( ( (y + _height) < best_height ) ||
                ( ((y + _height) == best_height) && (node->m_width < best_width)) )
			{
				best_height = y + _height;
				best_index = ii;
				best_width = node->m_width;
				_outX = node->m_x;
				_outY = y;
			}
        }
    }

    if( best_index == -1 )
    {
		return false;
    }
    
    Node newNode(_outX, _outY + _height, _width);
    m_skyline.insert(m_skyline.begin() + best_index, newNode);

    for(ii = best_index+1; ii < m_skyline.size(); ++ii)
    {
        node = &m_skyline[ii];
        prev = &m_skyline[ii-1];
        if (node->m_x < (prev->m_x + prev->m_width) )
        {
            int shrink = prev->m_x + prev->m_width - node->m_x;
            node->m_x += shrink;
            node->m_width -= shrink;
            if (node->m_width <= 0)
            {
                 m_skyline.erase(m_skyline.begin() + ii);
                --ii;
            }
            else
            {
                break;
            }
        }
        else
        {
            break;
        }
    }

    merge();
    m_usedSpace += _width * _height;
    return true;
}
		
float RectanglePacker::getUsageRatio()
{ 
	uint32_t total = m_width*m_height;
	if(total > 0) 
		return (float) m_usedSpace / (float) total;
	else
		return 0.0f;
}

void RectanglePacker::clear()
{
	m_skyline.clear();
    m_usedSpace = 0;
    
    // We want a one pixel border around the whole atlas to avoid any artefact when
    // sampling texture
    m_skyline.push_back(Node(1,1, m_width-2));
}

int32_t RectanglePacker::fit(uint32_t _skylineNodeIndex, uint16_t _width, uint16_t _height)
{
	int32_t width = _width;
    int32_t height = _height;
    
    const Node& baseNode = m_skyline[_skylineNodeIndex];
    
    int32_t x = baseNode.m_x, y;
	int32_t _width_left = width;
	int32_t i = _skylineNodeIndex;

    if ( (x + width) > (int32_t)(m_width-1) )
    {
		return -1;
    }
    y = baseNode.m_y;
	while( _width_left > 0 )
	{
        const Node& node = m_skyline[i];
        if( node.m_y > y )
        {
            y = node.m_y;
        }
		if( (y + height) > (int32_t)(m_height-1) )
        {
			return -1;
        }
        _width_left -= node.m_width;
		++i;
	}
	return y;
}
	
void RectanglePacker::merge()
{
	Node* node;
    Node* next;
    uint32_t ii;

	for( ii=0; ii < m_skyline.size()-1; ++ii )
    {
        node = (Node *) &m_skyline[ii];
        next = (Node *) &m_skyline[ii+1];
		if( node->m_y == next->m_y )
		{
			node->m_width += next->m_width;
            m_skyline.erase(m_skyline.begin() + ii + 1);
			--ii;
		}
    }
}

//********** Cube Atlas implementation ************

struct Atlas::PackedLayer
{
	RectanglePacker packer;
	AtlasRegion faceRegion;
};

Atlas::Atlas(uint16_t _textureSize, uint16_t _maxRegionsCount )
{
	BX_CHECK(_textureSize >= 64 && _textureSize <= 4096, "suspicious texture size" );
	BX_CHECK(_maxRegionsCount >= 64 && _maxRegionsCount <= 32000, "suspicious _regions count" );
	m_layers = new PackedLayer[24];
	for(int ii=0; ii<24;++ii)
	{
		m_layers[ii].packer.init(_textureSize, _textureSize);		
	}
	m_usedLayers = 0;
	m_usedFaces = 0;

	m_textureSize = _textureSize;
	m_regionCount = 0;
	m_maxRegionCount = _maxRegionsCount;
	m_regions = new AtlasRegion[_maxRegionsCount];
	m_textureBuffer = new uint8_t[ _textureSize * _textureSize * 6 * 4 ];
	memset(m_textureBuffer, 0,  _textureSize * _textureSize * 6 * 4);
	//BGFX_TEXTURE_MIN_POINT|BGFX_TEXTURE_MAG_POINT|BGFX_TEXTURE_MIP_POINT;
	//BGFX_TEXTURE_MIN_ANISOTROPIC|BGFX_TEXTURE_MAG_ANISOTROPIC|BGFX_TEXTURE_MIP_POINT
	//BGFX_TEXTURE_U_CLAMP|BGFX_TEXTURE_V_CLAMP
	uint32_t flags = 0;// BGFX_TEXTURE_MIN_ANISOTROPIC|BGFX_TEXTURE_MAG_ANISOTROPIC|BGFX_TEXTURE_MIP_POINT;

	//Uncomment this to debug atlas
	//const bgfx::Memory* mem = bgfx::alloc(textureSize*textureSize * 6 * 4);
	//memset(mem->data, 255, mem->size);	
	const bgfx::Memory* mem = NULL;	
	m_textureHandle = bgfx::createTextureCube(6
			, _textureSize
			, 1
			, bgfx::TextureFormat::BGRA8
			, flags
			,mem
			);
}

Atlas::Atlas(uint16_t _textureSize, const uint8_t* _textureBuffer , uint16_t _regionCount, const uint8_t* _regionBuffer, uint16_t _maxRegionsCount)
{
	BX_CHECK(_regionCount <= 64 && _maxRegionsCount <= 4096, "suspicious initialization");
	//layers are frozen
	m_usedLayers = 24;
	m_usedFaces = 6;

	m_textureSize = _textureSize;
	m_regionCount = _regionCount;
	//regions are frozen
	if(_regionCount < _maxRegionsCount)
		m_maxRegionCount = _regionCount;
	else
		m_maxRegionCount = _maxRegionsCount;
	m_regions = new AtlasRegion[_regionCount];
	m_textureBuffer = new uint8_t[getTextureBufferSize()];
	
	//BGFX_TEXTURE_MIN_POINT|BGFX_TEXTURE_MAG_POINT|BGFX_TEXTURE_MIP_POINT;
	//BGFX_TEXTURE_MIN_ANISOTROPIC|BGFX_TEXTURE_MAG_ANISOTROPIC|BGFX_TEXTURE_MIP_POINT
	//BGFX_TEXTURE_U_CLAMP|BGFX_TEXTURE_V_CLAMP
	uint32_t flags = 0;//BGFX_TEXTURE_MIN_ANISOTROPIC|BGFX_TEXTURE_MAG_ANISOTROPIC|BGFX_TEXTURE_MIP_POINT;
	memcpy(m_regions, _regionBuffer, _regionCount * sizeof(AtlasRegion));	
	memcpy(m_textureBuffer, _textureBuffer, getTextureBufferSize());

	m_textureHandle = bgfx::createTextureCube(6
			, _textureSize
			, 1
			, bgfx::TextureFormat::BGRA8
			, flags
			, bgfx::makeRef(m_textureBuffer, getTextureBufferSize())
			);
}

Atlas::~Atlas()
{
	delete[] m_layers;
	delete[] m_regions;
	delete[] m_textureBuffer;
}

uint16_t Atlas::addRegion(uint16_t _width, uint16_t _height, const uint8_t* _bitmapBuffer,  AtlasRegion::Type _type, uint16_t outline)
{
	if (m_regionCount >= m_maxRegionCount)
	{
		return UINT16_MAX;
	}
	
	uint16_t x=0,y=0;
	// We want each bitmap to be separated by at least one black pixel
	// TODO manage mipmaps
	uint32_t idx = 0;
	while(idx<m_usedLayers)
	{
		if(m_layers[idx].faceRegion.getType() == _type)
		{
			if(m_layers[idx].packer.addRectangle(_width+1,_height+1,x,y)) break;			
		}
		idx++;
	}

	if(idx >= m_usedLayers)
	{
		//do we have still room to add layers ?
		if( (idx + _type) > 24 || m_usedFaces>=6)
		{
				return UINT16_MAX;
		}		
		//create new layers
		for(int ii=0; ii < _type; ++ii)
		{
			m_layers[idx+ii].faceRegion.setMask(_type, m_usedFaces, ii);			
		}
		m_usedLayers += _type;
		m_usedFaces++;


		//add it to the created layer
		if(!m_layers[idx].packer.addRectangle(_width+1, _height+1, x, y))
		{
			return UINT16_MAX;
		}
	}
	
	AtlasRegion& region = m_regions[m_regionCount];
	region.m_x = x ;
	region.m_y = y ;
	region.m_width = _width;
	region.m_height = _height;
	region.m_mask = m_layers[idx].faceRegion.m_mask;

	updateRegion(region, _bitmapBuffer);
	
	region.m_x += outline;
	region.m_y += outline;
	region.m_width -= (outline*2);
	region.m_height -= (outline*2);	

	return m_regionCount++;
}

void Atlas::updateRegion(const AtlasRegion& _region, const uint8_t* _bitmapBuffer)
{	
	const bgfx::Memory* mem = bgfx::alloc(_region.m_width * _region.m_height * 4);
	//BAD!
	memset(mem->data,0, mem->size);
	if(_region.getType() == AtlasRegion::TYPE_BGRA8)
	{	
		const uint8_t* inLineBuffer = _bitmapBuffer;
		uint8_t* outLineBuffer = m_textureBuffer + _region.getFaceIndex() * (m_textureSize*m_textureSize*4) + (((_region.m_y *m_textureSize)+_region.m_x)*4);

		//update the cpu buffer
		for(int yy = 0; yy < _region.m_height; ++yy)
		{
			memcpy(outLineBuffer, inLineBuffer, _region.m_width * 4);
			inLineBuffer += _region.m_width*4;
			outLineBuffer += m_textureSize*4;
		}
		//update the GPU buffer
		memcpy(mem->data, _bitmapBuffer, mem->size);
	}else
	{
		uint32_t layer = _region.getComponentIndex();
		//uint32_t face = _region.getFaceIndex();
		const uint8_t* inLineBuffer = _bitmapBuffer;
		uint8_t* outLineBuffer = (m_textureBuffer + _region.getFaceIndex() * (m_textureSize*m_textureSize*4) + (((_region.m_y *m_textureSize)+_region.m_x)*4));
		
		//update the cpu buffer
		for(int yy = 0; yy<_region.m_height; ++yy)
		{
			for(int xx = 0; xx<_region.m_width; ++xx)
			{
				outLineBuffer[(xx*4) + layer] = inLineBuffer[xx];
			}
			//update the GPU buffer
			memcpy(mem->data + yy*_region.m_width*4, outLineBuffer, _region.m_width*4);
			inLineBuffer += _region.m_width;
			outLineBuffer +=  m_textureSize*4;
		}
	}
	bgfx::updateTextureCube(m_textureHandle, (uint8_t)_region.getFaceIndex(), 0, _region.m_x, _region.m_y, _region.m_width, _region.m_height, mem);		
}

void Atlas::packFaceLayerUV(uint32_t _idx, uint8_t* _vertexBuffer, uint32_t _offset, uint32_t _stride )
{
	packUV(m_layers[_idx].faceRegion, _vertexBuffer, _offset, _stride);
}

void Atlas::packUV( uint16_t handle, uint8_t* _vertexBuffer, uint32_t _offset, uint32_t _stride )
{
	const AtlasRegion& region = m_regions[handle];
	packUV(region, _vertexBuffer, _offset, _stride);
}

void Atlas::packUV( const AtlasRegion& _region, uint8_t* _vertexBuffer, uint32_t _offset, uint32_t _stride )
{
	float texMult = 65535.0f / ((float)(m_textureSize));
	static const int16_t minVal = -32768;
	static const int16_t maxVal = 32767;
	
	int16_t x0 = (int16_t)(_region.m_x * texMult)-32768;
	int16_t y0 = (int16_t)(_region.m_y * texMult)-32768;
	int16_t x1 = (int16_t)((_region.m_x + _region.m_width)* texMult)-32768;
	int16_t y1 = (int16_t)((_region.m_y + _region.m_height)* texMult)-32768;
	int16_t w =  (int16_t) ((32767.0f/4.0f) * _region.getComponentIndex());

	_vertexBuffer+=_offset;
	switch(_region.getFaceIndex())
	{
	case 0: // +X
		x0= -x0; 
		x1= -x1;
		y0= -y0; 
		y1= -y1;
		writeUV(_vertexBuffer, maxVal, y0, x0, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, maxVal, y1, x0, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, maxVal, y1, x1, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, maxVal, y0, x1, w); _vertexBuffer+=_stride;
		break;
	case 1: // -X		
		y0= -y0; 
		y1= -y1;
		writeUV(_vertexBuffer, minVal, y0, x0, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, minVal, y1, x0, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, minVal, y1, x1, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, minVal, y0, x1, w); _vertexBuffer+=_stride;	
		break;
	case 2: // +Y		
		writeUV(_vertexBuffer, x0, maxVal, y0, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x0, maxVal, y1, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x1, maxVal, y1, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x1, maxVal, y0, w); _vertexBuffer+=_stride;
		break;
	case 3: // -Y
		y0= -y0; 
		y1= -y1;
		writeUV(_vertexBuffer, x0, minVal, y0, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x0, minVal, y1, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x1, minVal, y1, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x1, minVal, y0, w); _vertexBuffer+=_stride;
		break;
	case 4: // +Z
		y0= -y0; 
		y1= -y1;
		writeUV(_vertexBuffer, x0, y0, maxVal, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x0, y1, maxVal, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x1, y1, maxVal, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x1, y0, maxVal, w); _vertexBuffer+=_stride;
		break;
	case 5: // -Z
		x0= -x0; 
		x1= -x1;
		y0= -y0; 
		y1= -y1;
		writeUV(_vertexBuffer, x0, y0, minVal, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x0, y1, minVal, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x1, y1, minVal, w); _vertexBuffer+=_stride;
		writeUV(_vertexBuffer, x1, y0, minVal, w); _vertexBuffer+=_stride;
		break;
	}
}