From 5a8e7a9ccb232350d899ececf05963a8d81e8c34 Mon Sep 17 00:00:00 2001
From: Harrison <yunyangdeng@gmail.com>
Date: Sat, 4 Jul 2020 16:14:32 -0500
Subject: [PATCH] Added line breaks to bitmap font.

---
 .../Graphics/Text/BitmapFont.cs               | 20 +++++++++++++++----
 .../Utilities/Playground/MainState.cs         |  2 +-
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/SlatedGameToolkit.Framework/Graphics/Text/BitmapFont.cs b/src/SlatedGameToolkit.Framework/Graphics/Text/BitmapFont.cs
index ec63677..30e120d 100644
--- a/src/SlatedGameToolkit.Framework/Graphics/Text/BitmapFont.cs
+++ b/src/SlatedGameToolkit.Framework/Graphics/Text/BitmapFont.cs
@@ -37,6 +37,7 @@ namespace SlatedGameToolkit.Framework.Graphics.Text
         }
         private Dictionary<(char, float), int> glyphTexLocations = new Dictionary<(char, float), int>();
         private LRUCache<char, CharacterMetrics> metricsCache;
+        private int ascent, descent, lineGap;
         private int drawingTo;
         private bool disposed;
 
@@ -58,6 +59,11 @@ namespace SlatedGameToolkit.Framework.Graphics.Text
             int spaceAdvance, leftSideBearing;
             StbTrueType.stbtt_GetCodepointHMetrics(info, ' ', &spaceAdvance, &leftSideBearing);
             this.spaceAdvance = spaceAdvance;
+            int ascent, descent, lineGap;
+            StbTrueType.stbtt_GetFontVMetrics(info, &ascent, &descent, &lineGap);
+            this.ascent = ascent;
+            this.descent = descent;
+            this.lineGap = lineGap;
         }
 
         public BitmapFont(string path, GLContext glContext = null, int cacheSize = 1024, int textures = 2, uint textureSizes = 512) : this(File.ReadAllBytes(path), glContext, cacheSize, textures, textureSizes) {
@@ -89,12 +95,15 @@ namespace SlatedGameToolkit.Framework.Graphics.Text
                         if (textureChanges > textures.Length) throw new FrameworkUsageException(string.Format("Character group \"{0}\" takes up too much texture space! Consider increasing decreasing font size, or increasing texture lengths, or number of backing textures.", new string(characters)));
                     }
                     glyphTexLocations.Add((c, scale), drawingTo);
+                    int glyphIndex = glyphIndices.ComputeIfNonExistent(c, (p) => StbTrueType.stbtt_FindGlyphIndex(info, p));
+                    metricsCache.ComputeIfNonExistent(c, (p) => new CharacterMetrics(glyphIndex, info));
                 }
             }
         }
 
-        public unsafe void Draw(MeshBatch batch, float x, float baseLine, string text, Color color) {
+        public unsafe void WriteLine(MeshBatch batch, float x, float y, string text, Color color) {
             float currentPoint = x;
+            float baseLine = y;
             char[] chars = text.ToCharArray();
             for (int i = 0; i < chars.Length; i++) {
                 char c = chars[i];
@@ -103,7 +112,12 @@ namespace SlatedGameToolkit.Framework.Graphics.Text
                 int viewWidth, viewHeight, vX, vY;
                 context.GetViewport(out vX, out vY, out viewWidth, out viewHeight);
 
-                if (c != ' ') {
+                if (c == ' ') {
+                    currentPoint += (scale * spaceAdvance) / viewWidth;
+                } else if (c == '\n') {
+                    currentPoint = x;
+                    baseLine -= ((ascent - descent + lineGap) * scale) / viewHeight;
+                } else {
                     //Check if glyph is loaded, if not, throw exception.
                     if (!glyphTexLocations.ContainsKey((c, scale)) || !textures[glyphTexLocations[(c, scale)]].ContainsChar(c, scale)) {
                         throw new FrameworkUsageException(string.Format("Character \'{0}\' was not prepared and is missing!", c));
@@ -124,8 +138,6 @@ namespace SlatedGameToolkit.Framework.Graphics.Text
                         int nextGlyph = glyphIndices.ComputeIfNonExistent(chars[i + 1], (p) => StbTrueType.stbtt_FindGlyphIndex(info, p));
                         currentPoint += (StbTrueType.stbtt_GetGlyphKernAdvance(info, glyphIndex, nextGlyph) * scale) / viewWidth;
                     }
-                } else {
-                    currentPoint += (scale * spaceAdvance) / viewWidth;
                 }
             }
         }
diff --git a/src/SlatedGameToolkit.Tools/Utilities/Playground/MainState.cs b/src/SlatedGameToolkit.Tools/Utilities/Playground/MainState.cs
index 63c0c28..e864a5a 100644
--- a/src/SlatedGameToolkit.Tools/Utilities/Playground/MainState.cs
+++ b/src/SlatedGameToolkit.Tools/Utilities/Playground/MainState.cs
@@ -89,7 +89,7 @@ namespace SlatedGameToolkit.Tools.Utilities.Playground
             renderer.Draw(logo);
             renderer.Draw(textureTester);
             renderer.Draw(untextured);
-            font.Draw(renderer, 0.25f, -0.35f, "ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890", Color.White);
+            font.WriteLine(renderer, 0.25f, -0.35f, "ABCDEFGHIJKLMNOPQRSTUVWXYZ\n1234567890", Color.White);
             renderer.End();
         }