Function ConstructSections

source/core/rendering/hw_sections.cpp:560–665

//==========================================================================

static void ConstructSections(TArray<sectionbuildsector>& builders)
{
	// count all sections and allocate the global buffers.
	TArray<int> splitwalls;

	// Allocate all Section walls.
	sectionLines.Resize(wall.Size() + splits.Size() * 2 / 3);

	for (unsigned i = 0; i < splits.Size(); i++)
	{
		if (i % 3) splitwalls.Push(splits[i]);
	}

	unsigned nextwall = wall.Size();
	for (unsigned i = 0; i < wall.Size(); i++)
	{
		sectionLines[i].startpoint = i;
		sectionLines[i].endpoint = wall[i].point2;
		sectionLines[i].wall = i;
		sectionLines[i].partner = wall[i].nextwall;
	}
	for (unsigned i = wall.Size(); i < sectionLines.Size(); i++)
	{
		unsigned pair = (i - wall.Size());
		sectionLines[i].startpoint = splitwalls[pair];
		sectionLines[i].endpoint = splitwalls[pair ^ 1];
		sectionLines[i].wall = -1;
		sectionLines[i].partner = wall.Size() + (pair ^ 1);
	}

	unsigned count = 0;
	// allocate as much as possible from the arena here.
	size_t size = sizeof(*sectionsPerSector.Data()) * sector.Size();
	auto data = sectionArena.Calloc(size);
	sectionsPerSector.Set(static_cast<decltype(sectionsPerSector.Data())>(data), sector.Size());

	for (unsigned i = 0; i < sector.Size(); i++)
	{
		auto& builder = builders[i];
		count += builder.sections.Size();

		size = sizeof(int) * builder.sections.Size();
		data = sectionArena.Calloc(size);
		sectionsPerSector[i].Set(static_cast<int* >(data), builder.sections.Size()); // although this may need reallocation, it is too small to warrant single allocations for each sector.
	}
	sections.Resize(count); // this we cannot put into the arena because its size may change.
	memset(sections.Data(), 0, count * sizeof(*sections.Data()));

	// now fill in the data

	int cursection = 0;
	for (unsigned i = 0; i < sector.Size(); i++)
	{
		auto& builder = builders[i];
		for (unsigned j = 0; j < builder.sections.Size(); j++)
		{
			auto section = &sections[cursection];
			auto& srcsect = builder.sections[j];