Implemented FontRenderer

2026-09-05 13:01:52 +00:00 · 2021-06-23 19:17:17 +02:00
parent 8c957f9d9f
commit 7f8379ea6c
8 changed files with 533 additions and 6 deletions
@@ -0,0 +1,124 @@
+using System;
+using FreeType;
+using System.Diagnostics;
+using GlitchyEngine.Math;
+using System.Collections;
+
+using internal GlitchyEngine.Renderer.Text;
+
+namespace GlitchyEngine.Renderer.Text
+{
+	public class FontRenderer
+	{
+		internal static FT_Library Library ~ FreeType.Done_FreeType(_);
+
+		internal static void InitLibrary()
+		{
+			if(Library == null)
+			{
+				var res = FreeType.Init_FreeType(&Library);
+				Log.EngineLogger.Assert(res.Success, scope $"Init_FreeType failed({(int)res}): {res}");
+			}
+		}
+
+		private GraphicsContext _context ~ _.ReleaseRef();
+
+		public this(GraphicsContext context)
+		{
+			FontRenderer.InitLibrary();
+			
+			_context = context..AddRef();
+		}
+
+		public void DrawText(Renderer2D renderer, Font font, String text, float x, float y, Color fontColor = .White, Color bitmapColor = .White)
+		{
+			if(text.IsWhiteSpace)
+				return;
+
+			// Todo:
+			float scale = 1.0f;
+
+			// Space between two baselines
+			float linespace = ((font._face.size.metrics.ascender - font._face.size.metrics.descender) >> 6);// + lineGap;
+			
+			// The line we are writing on
+			float baseline = y + linespace;
+            // Where we are writing the next glyph on the line
+			float penPosition = x;
+
+			int32 lastLine = 0;
+			int32 line = 0;
+
+			List<Texture2D> atlasses = scope .();
+
+			//GlyphDescriptor missingGlyph = font.CharMap.GetValue('\0');
+			String.UTF8Enumerator textEnumerator = String.UTF8Enumerator(text, 0, text.Length);
+			for(char32 char in textEnumerator)
+			{
+				if(char == '\n')
+				{
+					line++;
+					continue;
+				}
+
+				// number of lines that the cursor moved up or down
+				int32 lineDiff = line - lastLine;
+				if(lineDiff != 0)
+				{
+                	baseline += linespace * lineDiff;
+
+					// TODO: make carriage return optional?
+                	penPosition = x;
+
+					lastLine = line;
+				}
+
+				// Get glyph from Font
+				var glyphDesc = font.GetGlyph(char);
+
+				// This never happens
+				if(glyphDesc == null)
+				{
+					Debug.Break();
+					continue;
+				}
+
+				// Rectangle on the screen
+				Vector4 viewportRect = .(penPosition + (glyphDesc.Metrics.horiBearingX / 64) * scale, baseline - (glyphDesc.Metrics.horiBearingY / 64) * scale, glyphDesc.SizeX * scale, glyphDesc.SizeY * scale);
+				// Rectangle on the font atlas
+				Vector4 texRect = .(glyphDesc.MapCoord.X, glyphDesc.MapCoord.Y, glyphDesc.SizeX, glyphDesc.SizeY);
+
+				Color glyphColor = glyphDesc.IsBitmap ? bitmapColor : fontColor;
+
+				/*
+				if(QueueQuad!(viewportRect, texRect, glyphDesc.MapZ, glyphColor))
+				{
+					DrawQueue(context);
+				}
+				*/
+
+				Texture2D atlas = glyphDesc.Font.[Friend]_atlas;
+
+				if(!atlasses.Contains(atlas))
+				{
+					atlasses.Add(atlas..AddRef());
+				}
+
+				Vector2 atlasSize = .(atlas.Width, atlas.Height);
+
+				texRect /= Vector4(atlasSize, atlasSize);
+
+				renderer.Draw(atlas, viewportRect.X, viewportRect.Y, viewportRect.Z, viewportRect.W, glyphColor, 0.0f, texRect);
+
+				penPosition += (glyphDesc.Metrics.horiAdvance / 64) * scale;
+			}
+
+			renderer.End();
+
+			for(int i < atlasses.Count)
+			{
+				atlasses[i].ReleaseRef();
+			}
+		}
+	}
+}