Optimize text rendering for long strings

shaders/text.frag

@@ -1,12 +1,18 @@
 #version 330 core
-in vec2 texuv;
+
 out vec4 color;
 
-uniform sampler2D text;
+in VS_OUT {
+    vec2 texuv;
+    flat int index;
+} fs_in;
+
+uniform sampler2DArray text;
+uniform int letter_map[400];
 uniform vec3 text_color;
 
 void main()
-{    
-    vec4 sampled = vec4(1.0, 1.0, 1.0, texture(text, texuv).r);
+{
+    vec4 sampled = vec4(1.0, 1.0, 1.0, texture(text, vec3(fs_in.texuv.xy, letter_map[fs_in.index])).r);
     color = vec4(text_color, 1.0) * sampled;
 }