atlas building

from sprite.cpp

/*

    Copyright (c) 2020 Daniel Valcour

    Permission is hereby granted, free of charge, to any person obtaining a copy of
    this software and associated documentation files (the "Software"), to deal in
    the Software without restriction, including without limitation the rights to
    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
    the Software, and to permit persons to whom the Software is furnished to do so,
    subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
    FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
    COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
    IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/

void jtk::SpriteAtlas::Build(jtk::TextureLibrary* library, const std::vector<std::string>& identifiers, size_t atlas_size)
{
	if (identifiers.size() == 0)
	{
		return;
	}
	auto rects = std::vector<AtlasRect>();
	auto page_dimensions = jtk::ivec2(0, 0);
	size_t page_index = 0;
	for (size_t i = 0; i < identifiers.size(); i++)
	{
		std::optional<jtk::tex_sptr_t> t = library->GetTexture(identifiers[i]);
		if (t.has_value())
		{
			rects.push_back(AtlasRect(identifiers[i], t.value()));
		}
		//todo else log error expected sprite texture not found
	}
	std::sort(rects.begin(), rects.end());
	auto& last_rect = rects[rects.size() - 1];
	if (last_rect.w > atlas_size || last_rect.h > atlas_size)
	{
		std::string message = "Texture of name \"";
		message += last_rect.identifier;
		message += "\" cannot be added to sprite atlas because it has one or more dimensions that are larger than the page size.";
		throw jtk::Exception("SPRITE ATLAS BUILD FAILURE", message.c_str());
	}
	{
		size_t rect_index = rects.size() - 1;
		auto nodes = std::vector<AtlasRect>();
		auto current_rect = &rects[rect_index--];
		page_dimensions = jtk::ivec2(current_rect->w, current_rect->h);
		
		current_rect->x = 0;
		current_rect->y = 0;
		current_rect->p = page_index;
		while (rect_index != -1)
		{
			current_rect = &rects[rect_index--];
			bool placed = false;
			size_t n = 0;
			while (!placed && n < nodes.size())
			{

				AtlasRect current_node = nodes[n];
				if (current_rect->w <= current_node.w && current_rect->h <= current_node.h)
				{
					current_rect->x = current_node.x;
					current_rect->y = current_node.y;
					current_rect->p = current_node.p;


					if (current_node.w - current_rect->w > current_node.h - current_rect->h)
					{
						if (current_rect->w < current_node.w)
						{
							nodes.push_back(AtlasRect(current_rect->x + current_rect->w, current_rect->y, current_node.w - current_rect->w, current_node.h, current_node.p));
						}
						if (current_rect->h < current_node.h)
						{
							nodes.push_back(AtlasRect(current_rect->x, current_rect->y + current_rect->h, current_rect->w, current_node.h - current_rect->h, current_node.p));
						}
					}
					else
					{
						if (current_rect->w < current_node.w)
						{
							nodes.push_back(AtlasRect(current_rect->x + current_rect->w, current_rect->y, current_node.w - current_rect->w, current_rect->h, current_node.p));
						}
						if (current_rect->h < current_node.h)
						{
							nodes.push_back(AtlasRect(current_rect->x, current_rect->y + current_rect->h, current_node.w, current_node.h - current_rect->h, current_node.p));
						}
					}
					nodes[n] = nodes[nodes.size() - 1];
					nodes.pop_back();
					std::sort(nodes.begin(), nodes.end());
					placed = true;
				}
				n++;
			}
			if (!placed)
			{
				if (current_rect->h <= page_dimensions.y && page_dimensions.y >= page_dimensions.x && page_dimensions.x + current_rect->w < atlas_size)
				{
					current_rect->x = page_dimensions.x;
					current_rect->y = 0;
					current_rect->p = page_index;
					page_dimensions.x += static_cast<jtk::int_t>(current_rect->w);
					nodes.push_back(AtlasRect(current_rect->x, current_rect->h, current_rect->w, page_dimensions.y - current_rect->h, page_index));
				}
				else if (current_rect->w <= page_dimensions.x && page_dimensions.x >= page_dimensions.y && page_dimensions.y + current_rect->h < atlas_size)
				{
					current_rect->x = 0;
					current_rect->y = page_dimensions.y;
					current_rect->p = page_index;
					page_dimensions.y += static_cast<jtk::int_t>(current_rect->h);
					nodes.push_back(AtlasRect(current_rect->w, current_rect->y, page_dimensions.x - current_rect->w, current_rect->h, page_index));
				}
				else if (current_rect->h <= page_dimensions.y && page_dimensions.x + current_rect->w < atlas_size)
				{
					current_rect->x = page_dimensions.x;
					current_rect->y = 0;
					current_rect->p = page_index;
					page_dimensions.x += static_cast<jtk::int_t>(current_rect->w);
					nodes.push_back(AtlasRect(current_rect->x, current_rect->h, current_rect->w, page_dimensions.y - current_rect->h, page_index));
				}
				else if (current_rect->w <= page_dimensions.x && page_dimensions.y + current_rect->h < atlas_size)
				{
					current_rect->x = 0;
					current_rect->y = page_dimensions.y;
					current_rect->p = page_index;
					page_dimensions.y += static_cast<jtk::int_t>(current_rect->h);
					nodes.push_back(AtlasRect(current_rect->w, current_rect->y, page_dimensions.x - current_rect->w, current_rect->h, page_index));
				}
				else
				{
					if (page_dimensions.x < atlas_size - 1) //create nodes for leftover space
					{
						nodes.push_back(AtlasRect(page_dimensions.x, 0, atlas_size - page_dimensions.x, atlas_size, page_index));
					}

					if (page_dimensions.y < atlas_size - 1)
					{
						nodes.push_back(AtlasRect(0, page_dimensions.y, page_dimensions.x, atlas_size - page_dimensions.y, page_index));
					}
					
					page_index++;
					page_dimensions = jtk::ivec2(current_rect->w, current_rect->h);
					current_rect->x = 0;
					current_rect->y = 0;
					current_rect->p = page_index;
				}
			}
		}
		{

			for (size_t page = 0; page <= page_index; page++)
			{
				pages.push_back(jtk::Texture::CreateShared(atlas_size, atlas_size, jtk::rgba8(0, 0, 0, 0)));
			}

			for (size_t rect_index = 0; rect_index < rects.size(); rect_index++)
			{
				auto& rect = rects[rect_index];
				auto& page = pages[rect.p];
				page->CopyTexture(rect.tex, rect.x, rect.y);
				fontmap.push_back(jtk::SpriteCoordinates(
					static_cast<jtk::int_t>(rect.p),
					(float)rect.x / (float)atlas_size,
					(float)rect.y / (float)atlas_size,
					(float)(rect.x + rect.w) / (float)atlas_size,
					(float(rect.y + rect.h)) / (float)atlas_size
				));
				sprite_map[rect.identifier] = jtk::Sprite(this, static_cast<jtk::uint_t>(rect_index));
			}
		}
	}
}