From f3269a49c474ffe4d382c3d60826ad1cfbb7cdc4 Mon Sep 17 00:00:00 2001
From: rtk0c <mail.tianyig@gmail.com>
Date: Fri, 25 Nov 2022 17:28:07 -0800
Subject: Changeset: 93 Branch comment: [] Port font and UTF-8 string utilities
 from p6503

---
 source/30-game/Font.hpp | 131 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 source/30-game/Font.hpp

(limited to 'source/30-game/Font.hpp')

diff --git a/source/30-game/Font.hpp b/source/30-game/Font.hpp
new file mode 100644
index 0000000..cc64c0c
--- /dev/null
+++ b/source/30-game/Font.hpp
@@ -0,0 +1,131 @@
+#pragma once
+
+#include "Color.hpp"
+#include "CommonVertexIndex.hpp"
+#include "RcPtr.hpp"
+
+#include <glad/glad.h>
+#include <cstddef>
+#include <cstdint>
+#include <glm/glm.hpp>
+#include <memory>
+#include <span>
+#include <string_view>
+#include <vector>
+
+enum class FontType {
+	Regular,
+	Italic,
+	Bold,
+	BoldItalic,
+};
+
+struct GlyphVariant {
+	int horizontalAdvance;
+	float x0, y0;
+	float x1, y1;
+	float u0, v0;
+	float u1, v1;
+};
+
+// TODO optimize for memory when most glyphs don't have a non-regular variant
+// such as CJK characters rarely use bold or italics
+struct GlyphInfo {
+	char32_t codepoint;
+	GlyphVariant regular;
+	GlyphVariant italic;
+	GlyphVariant bold;
+	GlyphVariant boldItalic;
+};
+
+class Font : public RefCounted {
+public:
+	static const char32_t* GetGlyphRangesDefault();
+	static const char32_t* GetGlyphRangesKorean();
+	static const char32_t* GetGlyphRangesJapanese();
+	static const char32_t* GetGlyphRangesChineseFull();
+	static const char32_t* GetGlyphRangesChineseSimplifiedCommon();
+	static const char32_t* GetGlyphRangesCyrillic();
+	static const char32_t* GetGlyphRangesThai();
+	static const char32_t* GetGlyphRangesVietnamese();
+
+private:
+	std::vector<GlyphInfo> mGlyphs;
+	std::vector<int> mGlyphLookup;
+	RcPtr<Texture> mAtlas;
+	float mFontHeight;
+	int mFallbackGlyphIdx;
+
+public:
+	struct LoadingCandidate {
+		// No std::string_view here because iostreams only support null termianted string
+		const char* ttfPath;
+		const char32_t* glyphRange;
+		FontType type = FontType::Regular;
+	};
+
+	Font() = default;
+	Font(const Font&) = delete;
+	Font& operator=(const Font&) = delete;
+	Font(Font&&) = default;
+	Font& operator=(Font&&) = default;
+
+	enum ErrorCode {
+		EC_Success,
+		EC_FileIOFailed,
+		EC_FontLoadingFailed,
+	};
+	struct InitResult {
+		ErrorCode errorCode;
+		int failedItemIdx;
+	};
+
+	/// Initialize this font object from a list of ttf files. Each ttf covers a range of unicode characters,
+	/// and a specific font type, which are combined together into an atlas texture.
+	///
+	/// \see FontType
+	/// \see Font::LoadingCandidate
+	InitResult Init(std::span<LoadingCandidate> candidates, float fontHeight, char32_t fallbackCodepoint = '?', int oversampleH = 1, int oversampleV = 1);
+
+	float GetFontHeight() const;
+	int HorizontalAdvance(char32_t c, FontType type = FontType::Regular) const;
+	int HorizontalAdvance(std::string_view str, FontType type = FontType::Regular) const;
+
+	int GetGlyphCount() const;
+	const GlyphInfo& GetFallbackGlyph() const;
+
+	/// Find the glyph corresponding to the given codepoint. If none is present, return the fallback glyph
+	/// specified in Init().
+	const GlyphInfo& FindGlyphFallback(char32_t codepoint) const;
+	/// Find the glyph corresponding to the given codepoint. If none is present, `nullptr` is returned.
+	const GlyphInfo* FindGlyph(char32_t codepoint) const;
+
+	struct DrawTargetPointer {
+		// Draw target info
+		Vertex_PTC* vertices;
+		uint32_t* indices;
+		uint32_t initialVertexIdx;
+
+		// Text info
+		glm::vec3 pos;
+		FontType type = FontType::Regular;
+		RgbaColor color = RgbaColor{};
+
+		// Output info, written to by DrawTo()
+		int glyphsRendered;
+		float horizontalAdvance;
+	};
+
+	/// Populate the target with quads, with first character's origin at `pos` and every vertex colored `color`.
+	/// User must allocate enough space for all characers beforehand (one way is to reserve the # of bytes).
+	/// Suitable for raw array allocations or something like PodVector<T> that doesn't do zero-initialization on
+	/// resize.
+	///
+	/// \see Font::DrawTargetPointer
+	void DrawTo(std::string_view text, DrawTargetPointer& t) const;
+	void DrawTo(std::u32string_view text, DrawTargetPointer& t) const;
+
+	/// OpenGL texture containing the font atlas. Format is in GL_RED because we don't need the other channels, due to the
+	/// font atlas being black and white (in other words, opacity only).
+	const Texture& GetGlyphAtlas() const;
+};
-- 
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