From 61ae05c00378d355ac69c2ae95c3d5d3a3a547a9 Mon Sep 17 00:00:00 2001
From: themancalledjakob <jakob@jrkb.land>
Date: Mon, 3 Apr 2023 16:07:18 +0200
Subject: [PATCH] the power of two

---
 example/src/gpufont/font.hpp | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/example/src/gpufont/font.hpp b/example/src/gpufont/font.hpp
index 0e6673c..9a1df70 100644
--- a/example/src/gpufont/font.hpp
+++ b/example/src/gpufont/font.hpp
@@ -17,6 +17,22 @@
 #define F16DOT16_TO_DOUBLE(x) (1 / 65536. * double(x))
 #define DOUBLE_TO_F16DOT16(x) FT_Fixed(65536. * x)
 
+inline int32_t calculateUpperPowerOfTwo(int32_t v){
+    v--;
+    v |= v >> 1;
+    v |= v >> 2;
+    v |= v >> 4;
+    v |= v >> 8;
+    v |= v >> 16;
+    v++;
+    return v;
+}
+
+inline bool isPowerOfTwo(int i){
+    return (i & (i - 1)) == 0;
+}
+
+
 class Font {
     struct Glyph {
         FT_UInt index;
@@ -369,10 +385,15 @@ class Font {
                                 GL_NEAREST);
                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
                                 GL_NEAREST);
+
+                int bufferGlyphsSize = bufferGlyphs.size();
+                if(!isPowerOfTwo(bufferGlyphsSize)){
+                    bufferGlyphsSize = calculateUpperPowerOfTwo(bufferGlyphsSize);
+                }
                 glTexImage2D(GL_TEXTURE_2D,
                              0,
                              GL_RG32I,
-                             bufferGlyphs.size(),
+                             bufferGlyphsSize,
                              1,
                              0,
                              GL_RG_INTEGER,
@@ -412,6 +433,10 @@ class Font {
                 //GL_INT,
                 //data);
 
+                int bufferCurvesSize = bufferCurves.size();
+                if(!isPowerOfTwo(bufferCurvesSize)){
+                    bufferCurvesSize = calculateUpperPowerOfTwo(bufferCurvesSize);
+                }
                 glActiveTexture(GL_TEXTURE1);
                 glBindTexture(GL_TEXTURE_2D, curveBuffer);
                 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
@@ -423,7 +448,7 @@ class Font {
                 glTexImage2D(GL_TEXTURE_2D,
                              0,
                              GL_RG32F,
-                             bufferCurves.size(),
+                             bufferCurvesSize,
                              1,
                              0,
                              GL_RG,