Method ConsolidateFreeAreas

trinity/Tr2TextureAtlas.cpp:223–442

Consolidates free areas, attempting to improve the 'squareness' of the free regions of the atlas to improve further usage.

//Consolidates free areas, attempting to improve the 'squareness' of the free regions of the atlas
//to improve further usage.
void Tr2TextureAtlas::ConsolidateFreeAreas()
{
	CCP_STATS_ZONE( __FUNCTION__ );

	ReleasePendingFreeAreas();

	if( m_freeAreas.size() < 2 )
	{
		return;
	}

	struct Squareness
	{
		static float Metric( const Tr2Rect& a )
		{
			const int w = a.right - a.left;
			const int h = a.bottom - a.top;
			if( w == 0 || h == 0 )
				return 0.f;
			const float d = float( w - h );
			return d * d / float( w * h );
		}
	};

	bool restartLoop = true;

	while( restartLoop )
	{
		restartLoop = false;
		for( AreaList_t::iterator i = m_freeAreas.begin(); i != m_freeAreas.end(); ++i )
		{
			const auto& rect_i = ( *i )->rect;
			const float square_i = Squareness::Metric( rect_i );
			AreaList_t::iterator j = i;
			for( ++j; j != m_freeAreas.end(); ++j )
			{
				const auto& rect_j = ( *j )->rect;
				const float square_j = Squareness::Metric( rect_j );
				const float squareStart = square_i + square_j;


				if( rect_i.bottom == rect_i.top ||
					rect_i.top == rect_j.bottom )
				{
					//areas are vertically adjacent
					if( rect_i.right == rect_j.right &&
						rect_i.left == rect_j.left )
					{
						//have an exact match, can just merge these two areas
						Tr2Rect sum;
						sum.left = rect_i.left;
						sum.right = rect_i.right;
						sum.top = std::min( rect_i.top, rect_j.top );
						sum.bottom = std::max( rect_i.bottom, rect_j.bottom );

						CCP_DELETE( *j );
						j = m_freeAreas.erase( j );
						( *i )->rect = sum;