Merge pull request 'Tight atlas packing' (#183) from misc into master

Reviewed-on: https://git.madvoxel.net/OpenVulkano/OpenVulkano/pulls/183
Reviewed-by: Georg Hagen <georg.hagen@madvoxel.com>

openVulkanoCpp/Scene/BitmapFontAtlasGenerator.cpp

@@ -33,28 +33,14 @@ namespace OpenVulkano::Scene
 
 		m_atlasData = std::make_shared<AtlasData>();
 		const auto& [lib, face] = FontAtlasGeneratorBase::InitFreetype(source);
+		FT_Set_Pixel_Sizes(face.get(), 0, m_pixelSizeConfig.CalculatePixelSize());
 
-		Math::Vector2ui cellSize; 
-		if (m_pixelSizeConfig.isPixelSize)
-		{
-			cellSize = { m_pixelSizeConfig.size, m_pixelSizeConfig.size };
-			// set pixel width/height lower than glyph size above, otherwise some glyphs will be cropped or some overlapping will be present
-			FT_Set_Pixel_Sizes(face.get(), 0, cellSize.y - cellSize.y / 3);
-		}
-		else
-		{
-			const float pixelSize = (m_pixelSizeConfig.size * m_pixelSizeConfig.dpi) / 72.0f;
-			//int fontHeight = round((face->bbox.yMax - face->bbox.yMin) * pixelSize / face->units_per_EM);
-			//int fontWidth = round((face->bbox.xMax - face->bbox.xMin) * pixelSize / face->units_per_EM);
-			cellSize = { pixelSize, pixelSize };
-			FT_Set_Char_Size(face.get(), 0, static_cast<FT_F26Dot6>(m_pixelSizeConfig.size) * 64,
-			                 static_cast<FT_UInt>(m_pixelSizeConfig.dpi), static_cast<FT_UInt>(m_pixelSizeConfig.dpi));
-		}
-		
-		const double sq = std::sqrt(chset.size());
-		const size_t glyphsPerRow = (static_cast<size_t>(sq)) + (sq - static_cast<size_t>(sq) != 0);
-		const size_t rows = (chset.size() / glyphsPerRow) + (chset.size() % glyphsPerRow != 0);
-		const Math::Vector2ui atlasResolution = { glyphsPerRow * cellSize.x, rows * cellSize.y };
+		auto [allGlyphs, area] = InitGlyphsForPacking(chset, face);
+		const double atlasWidth = ceil(sqrt(area));
+		std::vector<Shelf> shelves = Shelf::CreateShelves(atlasWidth, allGlyphs, face);
+		uint32_t atlasHeight = 0;
+		std::for_each(shelves.begin(), shelves.end(), [&](const Shelf& shelf) { atlasHeight += shelf.GetHeight(); });
+		const Math::Vector2ui atlasResolution = { atlasWidth, atlasHeight };
 
 		// same as in msdfgen lib by default. see import-font.h for reference
 		// TODO: probably also support keeping coordinates as the integer values native to the font file
@@ -62,69 +48,68 @@ namespace OpenVulkano::Scene
 		// The coordinates will be normalized to the em size, i.e. 1 = 1 em
 		const double scaleFactor = (1. / face->units_per_EM);
 		SetupAtlasData(atlasResolution, face->height * scaleFactor, FontAtlasType::BITMAP);
+		FillGlyphsInfo(allGlyphs, face, scaleFactor);
+		if (pngOutput)
+		{
+			SavePng(*pngOutput);
+		}
+	}
 
-		size_t loadedGlyphs = 0;
+	std::pair<std::vector<GlyphForPacking>, double> 
+		BitmapFontAtlasGenerator::InitGlyphsForPacking(const std::set<uint32_t>& chset, const FtFaceRecPtr& face)
+	{
 		FT_Error error = 0;
-		int currentPosX = 0;
-		int currentPosY = 0;
-		Math::Vector2ui gridPos = { 0, 0 };
+		double area = 0;
+		std::vector<GlyphForPacking> allGlyphs;
+		allGlyphs.reserve(chset.size());
 		for (uint32_t codepoint : chset)
 		{
 			error = FT_Load_Char(face.get(), codepoint, FT_LOAD_RENDER);
 			if (error)
 			{
-				Logger::APP->error("FT_Load_Char for codepoint {} has failed. {}", codepoint, GetFreetypeErrorDescription(error));
+				Logger::SCENE->error("FT_Load_Char for codepoint {} has failed. {}", codepoint,
+				                     GetFreetypeErrorDescription(error));
+				continue;
+			}
+			FT_GlyphSlot slot = face->glyph;
+			GlyphForPacking& glyph = allGlyphs.emplace_back(codepoint, Math::Vector2ui(slot->bitmap.width, slot->bitmap.rows));
+			area += slot->bitmap.rows * slot->bitmap.width;
+		}
+		std::sort(allGlyphs.begin(), allGlyphs.end(),
+		          [](const GlyphForPacking& a, const GlyphForPacking& b) { return a.size.y > b.size.y; });
+		return { allGlyphs, area };
+	}
+
+	void BitmapFontAtlasGenerator::FillGlyphsInfo(const std::vector<GlyphForPacking>& allGlyphs, const FtFaceRecPtr& face, double scaleFactor)
+	{
+		size_t loadedGlyphs = 0;
+		for (const GlyphForPacking& glyph : allGlyphs)
+		{
+			FT_Error error = FT_Load_Char(face.get(), glyph.code, FT_LOAD_RENDER);
+			if (error)
+			{
+				Logger::SCENE->error("FT_Load_Char for codepoint {} has failed. {}", glyph.code,
+				                     GetFreetypeErrorDescription(error));
 				continue;
 			}
 
 			FT_GlyphSlot slot = face->glyph;
-			if (slot->bitmap.width > cellSize.x || slot->bitmap.rows > cellSize.y)
-			{
-				Logger::APP->warn("Glyph size exceeds grid cell size: {}x{} exceeds {}x{}", slot->bitmap.width, slot->bitmap.rows, cellSize.x, cellSize.y);
-				// skip such glyph for now to avoid crash
-				continue;
-			}
-
-			const size_t firstGlyphByte = (gridPos.y * cellSize.x + gridPos.x * atlasResolution.x * cellSize.y);
 			for (int row = 0; row < slot->bitmap.rows; row++)
 			{
-				for (int col = 0; col < slot->bitmap.width; col++)
-				{
-					m_atlasData->img->data[firstGlyphByte + row * atlasResolution.x + col] = slot->bitmap.buffer[(slot->bitmap.rows - 1 - row) * slot->bitmap.pitch + col];
-				}
+				std::memcpy(&m_atlasData->img->data[glyph.firstGlyphByteInAtlas + row * m_atlasData->img->resolution.x],
+				            &slot->bitmap.buffer[(slot->bitmap.rows - 1 - row) * slot->bitmap.pitch],
+				            slot->bitmap.width);
 			}
 
-			GlyphInfo& glyphInfo = m_atlasData->glyphs[codepoint];
-			const Math::Vector2d glyphMetrics = { slot->metrics.width * scaleFactor, slot->metrics.height * scaleFactor };
-			const Math::Vector2d glyphBearing = { slot->metrics.horiBearingX * scaleFactor, slot->metrics.horiBearingY * scaleFactor };
-			// metrics are 1/64 of a pixel
-			constexpr double toPixelScaler = 1. / 64;
-			const Math::Vector2d whPixel = { static_cast<double>(slot->metrics.width * toPixelScaler),
-				                             static_cast<double>(slot->metrics.height * toPixelScaler) };
-			Math::AABB glyphAtlasAABB(Math::Vector3f(currentPosX, currentPosY, 0), Math::Vector3f(currentPosX + whPixel.x, currentPosY + whPixel.y, 0));
+			GlyphInfo& glyphInfo = m_atlasData->glyphs[glyph.code];
+			const Math::Vector2d glyphMetrics = { slot->metrics.width * scaleFactor,
+				                                  slot->metrics.height * scaleFactor };
+			const Math::Vector2d glyphBearing = { slot->metrics.horiBearingX * scaleFactor,
+				                                  slot->metrics.horiBearingY * scaleFactor };
+			Math::AABB glyphAtlasAABB(Math::Vector3f(glyph.atlasPos.x, glyph.atlasPos.y, 0), Math::Vector3f(glyph.atlasPos.x + slot->bitmap.width, glyph.atlasPos.y + slot->bitmap.rows, 0));
 			SetGlyphData(glyphInfo, glyphBearing, glyphMetrics, glyphAtlasAABB, slot->advance.x * scaleFactor);
-			
-			currentPosX += cellSize.x;
 			loadedGlyphs++;
-
-			if (currentPosX + cellSize.x > atlasResolution.x)
-			{
-				currentPosX = 0;
-				currentPosY += cellSize.y;
-				gridPos.y = 0;
-				gridPos.x++;
-			}
-			else
-			{
-				gridPos.y++;
-			}
 		}
-
-		if (pngOutput)
-		{
-			SavePng(*pngOutput);
-		}
-		Logger::APP->debug("Created atlas with {} glyphs, {} glyphs could not be loaded", loadedGlyphs, chset.size() - loadedGlyphs);
-
+		Logger::SCENE->debug("Created atlas with {} glyphs, {} glyphs could not be loaded", loadedGlyphs, allGlyphs.size() - loadedGlyphs);
 	}
 }

openVulkanoCpp/Scene/BitmapFontAtlasGenerator.hpp

@@ -7,14 +7,28 @@
 #pragma once
 
 #include "FontAtlasGeneratorBase.hpp"
+#include "Shelf.hpp"
 
 namespace OpenVulkano::Scene
 {
-	struct FontPixelSizeConfig
+	class FontPixelSizeConfig
 	{
-		float size = 16.f;
-		float dpi = 72.f;
-		bool isPixelSize = true;
+	public:
+		FontPixelSizeConfig(float size = 24.f, float dpi = 72.f, bool isPixelSize = true)
+		    : m_size(size), m_dpi(dpi), m_isPixelSize(isPixelSize)
+		{
+		}
+		void SetSize(float size) { m_size = size; }
+		void SetDpi(float dpi) { m_dpi = dpi; }
+		void SetIsPixelSize(bool isPixelSize) { m_isPixelSize = isPixelSize; }
+		[[nodiscard]] float GetSize() const { return m_size; }
+		[[nodiscard]] float GetDpi() const { return m_dpi; }
+		[[nodiscard]] bool GetIsPixelSize() const { return m_isPixelSize; }
+		[[nodiscard]] unsigned CalculatePixelSize() const { return m_isPixelSize ? m_size : (m_size * m_dpi) / 72.0f; }
+	private:
+		float m_size;
+		float m_dpi;
+		bool m_isPixelSize;
 	};
 
 	class BitmapFontAtlasGenerator : public FontAtlasGeneratorBase
@@ -27,6 +41,8 @@ namespace OpenVulkano::Scene
 		                   const std::optional<std::string>& pngOutput = std::nullopt) override;
 	private:
 		void Generate(const std::variant<std::string, Array<char>>& source, const std::set<uint32_t>& chset, const std::optional<std::string>& pngOutput);
+		void FillGlyphsInfo(const std::vector<GlyphForPacking>& allGlyphs, const FtFaceRecPtr& face, double scaleFactor);
+		std::pair<std::vector<GlyphForPacking>, double> InitGlyphsForPacking(const std::set<uint32_t>& chset, const FtFaceRecPtr& face);
 	private:
 		FontPixelSizeConfig m_pixelSizeConfig;
 	};

openVulkanoCpp/Scene/Shelf.hpp

@@ -0,0 +1,96 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#pragma once
+
+#include "Math/Math.hpp"
+#include "Scene/FreetypeHelper.hpp"
+#include <vector>
+#include <optional>
+
+namespace OpenVulkano::Scene
+{
+	struct GlyphForPacking
+	{
+		uint32_t code;
+		Math::Vector2i size;
+		Math::Vector2d atlasPos;
+		size_t firstGlyphByteInAtlas;
+	};
+
+	struct Shelf
+	{
+		inline static std::vector<Shelf> CreateShelves(uint32_t atlasWidth, std::vector<GlyphForPacking>& glyphs,
+		                                        const FtFaceRecPtr& face);
+
+		Shelf(uint32_t width, uint32_t height) : m_width(width), m_height(height), m_remainingWidth(width) {}
+		bool HasSpaceForGlyph(uint32_t glyphWidth, uint32_t glyphHeight) const
+		{
+			return m_remainingWidth >= glyphWidth && m_height >= glyphHeight;
+		}
+		uint32_t GetWidth() const { return m_width; }
+		uint32_t GetHeight() const { return m_height; }
+		uint32_t GetNextGlyphPos() const { return m_nextGlyphPos; };
+		uint32_t GetOccupiedSize() const { return ((m_width - m_remainingWidth) * m_height); }
+		std::optional<uint32_t> AddGlyph(uint32_t glyphWidth, uint32_t glyphHeight)
+		{
+			if (!HasSpaceForGlyph(glyphWidth, glyphHeight))
+			{
+				return {};
+			}
+			uint32_t insertionPos = m_nextGlyphPos;
+			m_nextGlyphPos += glyphWidth;
+			m_remainingWidth -= glyphWidth;
+			return insertionPos;
+		}
+
+	private:
+		uint32_t m_width;
+		uint32_t m_height;
+		uint32_t m_remainingWidth;
+		uint32_t m_nextGlyphPos = 0;
+	};
+
+	std::vector<Shelf> Shelf::CreateShelves(uint32_t atlasWidth, std::vector<GlyphForPacking>& glyphs,
+																					const FtFaceRecPtr& face)
+	{
+		std::vector<Shelf> shelves;
+		for (GlyphForPacking& glyph : glyphs)
+		{
+			FT_Error error = FT_Load_Char(face.get(), glyph.code, FT_LOAD_RENDER);
+			if (error)
+			{
+				continue;
+			}
+
+			FT_GlyphSlot slot = face->glyph;
+			bool needNewShelf = true;
+			uint32_t totalPrevShelvesHeight = 0;
+			for (Shelf& shelf : shelves)
+			{
+				if (std::optional<uint32_t> insertionPosX = shelf.AddGlyph(glyph.size.x, glyph.size.y))
+				{
+					glyph.firstGlyphByteInAtlas = *insertionPosX + (totalPrevShelvesHeight * atlasWidth);
+					glyph.atlasPos.x = *insertionPosX;
+					glyph.atlasPos.y = totalPrevShelvesHeight;
+					needNewShelf = false;
+					break;
+				}
+				totalPrevShelvesHeight += shelf.GetHeight();
+			}
+
+			if (needNewShelf)
+			{
+				shelves.emplace_back(atlasWidth, glyph.size.y);
+				shelves.back().AddGlyph(glyph.size.x, glyph.size.y);
+				glyph.firstGlyphByteInAtlas = totalPrevShelvesHeight * atlasWidth;
+				glyph.atlasPos.x = 0;
+				glyph.atlasPos.y = totalPrevShelvesHeight;
+			}
+		}
+		return shelves;
+	}
+}