fix inconsistent spacing for multiline text and support special characters

openVulkanoCpp/Scene/TextDrawable.cpp

@@ -22,6 +22,33 @@ namespace OpenVulkano::Scene
 		Shader DEFAULT_SHADER_BITMAP_SUBPIXEL = TextDrawable::MakeDefaultShader(FontAtlasType::BITMAP_SUBPIXEL);
 		Shader DEFAULT_SHADER_SDF = TextDrawable::MakeDefaultShader(FontAtlasType::SDF);
 		Shader DEFAULT_SHADER_MSDF = TextDrawable::MakeDefaultShader(FontAtlasType::MSDF);
+
+		void HandleSpecialCharacter(const std::map<uint32_t, GlyphInfo>& symbols, uint32_t c, float heightBetweenLines,
+		                            float initialPosX, float& cursorX, float& cursorY, float& prevGlyphXBound)
+		{
+			if (c == '\n')
+			{
+				cursorY -= heightBetweenLines;
+				prevGlyphXBound = -INFINITY;
+				cursorX = initialPosX;
+			}
+			else if (c == '\t')
+			{
+				if (!symbols.contains(' '))
+				{
+					Logger::RENDER->warn("Tab special character can't be handled since no space glyph is available", c);
+					return;
+				}
+				const GlyphInfo& info = symbols.at(' ');
+				cursorX += info.advance * 4;
+				prevGlyphXBound = cursorX;
+			}
+			else if (c == '\v')
+			{
+				cursorY -= heightBetweenLines;
+			}
+
+		}
 	}
 
 	Shader TextDrawable::MakeDefaultShader(const FontAtlasType type)
@@ -79,11 +106,11 @@ namespace OpenVulkano::Scene
 		return m_atlasData->GetGlyphs().begin()->first;
 	}
 
-	std::vector<float> TextDrawable::GetHeightsBetweenLines(const std::string& text) const
+	float TextDrawable::GetHeightBetweenLines(const std::string& text) const
 	{
 		if (!m_cfg.minimalSpacingBetweenMultipleLines)
 		{
-			return {};
+			return m_atlasData->GetLineHeight();
 		}
 		const std::map<uint32_t, GlyphInfo>& symbols = m_atlasData->GetGlyphs();
 		const uint32_t fallbackGlyph = GetFallbackGlyph();
@@ -97,7 +124,7 @@ namespace OpenVulkano::Scene
 		for (auto begin = text.begin(), end = text.end(); begin != end;)
 		{
 			uint32_t c = utf8::next(begin, end);
-			if (c == '\n')
+			if (c == '\n' || c == '\v')
 			{
 				isMultiline = true;
 				if (prevLineHeightBelowBaseline != -INFINITY)
@@ -125,7 +152,19 @@ namespace OpenVulkano::Scene
 			heightBetweenLines.push_back(std::abs(prevLineHeightBelowBaseline)
 			                             + std::abs(currentLineHeightAboveBaseline) + extraOffset);
 		}
-		return heightBetweenLines;
+
+		if (heightBetweenLines.empty())
+		{
+			return 0;
+		}
+
+		float maxH = *std::max_element(heightBetweenLines.begin(), heightBetweenLines.end());
+		return std::min<float>(m_atlasData->GetLineHeight(), maxH);
+	}
+
+	bool TextDrawable::IsSpecialCharacter(uint32_t c) const
+	{
+		return c == '\t' || c == '\n' || c == '\v';
 	}
 
 	void TextDrawable::GenerateText(const std::string& text, const Math::Vector2f& pos)
@@ -141,33 +180,21 @@ namespace OpenVulkano::Scene
 		TextGlyphVertex* vertices = m_vertexBuffer.Init<TextGlyphVertex>(len);
 		const std::map<uint32_t, GlyphInfo>& symbols = m_atlasData->GetGlyphs();
 
-		double cursorX = pos.x;
-		double posY = pos.y;
+		float cursorX = pos.x;
+		float cursorY = pos.y;
 		Math::Vector2f bmin(pos), bmax(pos);
 		float prevGlyphXBound = -INFINITY;
-		int currentLine = 0;
-		const std::vector<float> heightsBetweenLines = GetHeightsBetweenLines(text);
+		const float heightBetweenLines = GetHeightBetweenLines(text);
 
 		for (auto begin = text.begin(), end = text.end(); begin != end;)
 		{
 			uint32_t c = utf8::next(begin, end);
-			if (c == '\n')
+			if (IsSpecialCharacter(c))
 			{
-				// use fixed line height
-				if (heightsBetweenLines.empty())
-				{
-					posY -= m_atlasData->GetLineHeight();
-				}
-				else
-				{
-					posY -= heightsBetweenLines[currentLine++];
-				}
-				prevGlyphXBound = -INFINITY;
-				cursorX = pos.x;
+				HandleSpecialCharacter(symbols, c, heightBetweenLines, pos.x, cursorX, cursorY, prevGlyphXBound);
 				continue;
 			}
-			// TODO handle special chars
-
+			
 			if (!symbols.contains(c))
 			{
 				Logger::RENDER->warn("Could not find glyph for character {}, using fallback", c);
@@ -190,15 +217,19 @@ namespace OpenVulkano::Scene
 				vertices->uv[i] = info.uv[i];
 				if (i < 2)
 				{
-					vertices->position[i].y = posY - info.pos[i].y;
+					vertices->position[i].y = cursorY - info.pos[i].y;
 				}
 				else
 				{
-					vertices->position[i].y = posY + info.pos[i].y;
+					vertices->position[i].y = cursorY + info.pos[i].y;
 				}
 				vertices->color = m_cfg.textColor;
 				vertices->background = m_cfg.backgroundColor;
 			}
+
+			// somehow it's possible that cursorX can be less than prevGlyphXBound for sdf atlases
+			// e.g. string `A, _` where space is not noticeable in the resulting output
+			cursorX = std::max(cursorX, prevGlyphXBound);
 			// slight offset for bitmap atlas since it's tightly packed without any extra padding, while sdf has additional padding
 			cursorX += info.advance + (isBitmap ? 0.05 : 0);
 			prevGlyphXBound = isZeroLenGlyph ? cursorX : vertices->position[2].x;

openVulkanoCpp/Scene/TextDrawable.hpp

@@ -42,7 +42,8 @@ namespace OpenVulkano::Scene
 		TextConfig m_cfg;
 
 		uint32_t GetFallbackGlyph() const;
-		std::vector<float> GetHeightsBetweenLines(const std::string& text) const;
+		float GetHeightBetweenLines(const std::string& text) const;
+		bool IsSpecialCharacter(uint32_t c) const;
 
 	public:
 		TextDrawable(const TextConfig& config = TextConfig());