From 02a8a49961190cb2076955d0960695134ba83fe2 Mon Sep 17 00:00:00 2001
From: Hanaxar <87268284+hanaxar@users.noreply.github.com>
Date: Wed, 22 Mar 2023 12:59:28 +0300
Subject: [PATCH] Calculate exact image size in GenImageFontAtlas (#2963)

* Calculate exact image size in GenImageFontAtlas

Calculate exact image size with a method based on total glyph width and glyph row count
Current method seemed a little bit overkill with square root, log and power functions and only approximates image size which can be wonky with some weird fonts like cursive fonts.
Proposed method calculates image size directly with a simpler method and results exact image size needed.

* Update rtext.c

* Update rtext.c

Changed do-while to while loop, and also added an extra step to calculate maximum glyph width and excluding it from image width for extra safety.
---
 src/rtext.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/rtext.c b/src/rtext.c
index 9eec0059f..da93af7e3 100644
--- a/src/rtext.c
+++ b/src/rtext.c
@@ -694,14 +694,19 @@ Image GenImageFontAtlas(const GlyphInfo *chars, Rectangle **charRecs, int glyphC
     // NOTE: Rectangles memory is loaded here!
     Rectangle *recs = (Rectangle *)RL_MALLOC(glyphCount*sizeof(Rectangle));
 
-    // Calculate image size based on required pixel area
-    // NOTE 1: Image is forced to be squared and POT... very conservative!
-    // NOTE 2: SDF font characters already contain an internal padding,
-    // so image size would result bigger than default font type
-    float requiredArea = 0;
-    for (int i = 0; i < glyphCount; i++) requiredArea += ((chars[i].image.width + 2*padding)*(fontSize + 2*padding));
-    float guessSize = sqrtf(requiredArea)*1.4f;
-    int imageSize = (int)powf(2, ceilf(logf((float)guessSize)/logf(2)));    // Calculate next POT
+    // Calculate image size based on total glyph width and glyph row count
+    int totalWidth = 0, maxGlyphWidth = 0;
+    for (int i = 0; i < glyphCount; i++)
+    {
+        if (chars[i].image.width > maxGlyphWidth) maxGlyphWidth = chars[i].image.width;
+        totalWidth += chars[i].image.width + 2*padding;
+    }
+    int rowCount = 0, imageSize = 64;  // A minimum starting value to avoid unnecessary calculation steps for very small images
+    while (totalWidth > (imageSize - maxGlyphWidth)*rowCount) // maxGlyphWidth is maximum possible space left at the end of row
+    {
+        imageSize *= 2;                                 // Double the size of image (to keep POT)
+        rowCount = imageSize/(fontSize + 2*padding);    // Calculate new row count for the new image size
+    }
 
     atlas.width = imageSize;   // Atlas bitmap width
     atlas.height = imageSize;  // Atlas bitmap height