GUI: Box drawing

assets/shaders/gui_text.frag

@@ -0,0 +1,15 @@
+#version 460
+#extension GL_EXT_nonuniform_qualifier : require
+#extension GL_EXT_scalar_block_layout : require
+#extension GL_EXT_shader_16bit_storage : require
+
+uint calcRootCode(float y1, float y2, float y3) {
+    uint i1 = floatBitsToUint(y1) >> 31U;
+    uint i2 = floatBitsToUint(y2) >> 30U;
+    uint i3 = floatBitsToUint(y3) >> 29U;
+
+    uint shift = (i2 & 2U) | (i1 & ~2U);
+    shift = (i3 & 4U) | (shift & ~4U);
+
+    return ((0x2E74U >> shift) & 0x0101U);
+}