contextual visarga

OTFbuild/font_builder.py

@@ -371,6 +371,9 @@ def build_font(assets_dir, output_path, no_bitmap=False, no_features=False):
             try:
                 fea_stream = io.StringIO(fea_code)
                 addOpenTypeFeatures(font, fea_stream)
+                # Obtain raw .fea text for debugging
+                # with open("debugout_features.fea", "w") as text_file:
+                    # text_file.write(fea_code)
                 print("  Features compiled successfully")
             except Exception as e:
                 print(f"  [WARNING] Feature compilation failed: {e}")

OTFbuild/opentype_features.py

@@ -856,6 +856,38 @@ def _generate_devanagari(glyphs, has, replacewith_subs=None):
         feat.append("} psts;")
         features.append('\n'.join(all_lookups + [''] + feat))
 
+    # --- calt: contextual Visarga ---
+    # When Visarga (U+0903) is followed by a Devanagari character (mid-word),
+    # substitute with interword variant (uF010A).  calt is applied globally
+    # across syllable boundaries, unlike psts which is per-syllable.
+    INTERWORD_VISARGA = 0xF010A
+    visarga = 0x0903
+    if has(visarga) and has(INTERWORD_VISARGA):
+        # Build class of Devanagari characters that can follow Visarga mid-word:
+        # PUA consonants (full, half, RA-appended, RA-appended half) + independent vowels
+        deva_following_cps = (
+            list(SC.DEVANAGARI_PRESENTATION_CONSONANTS) +
+            list(range(0xF0230, 0xF0320)) +   # half forms
+            list(SC.DEVANAGARI_PRESENTATION_CONSONANTS_WITH_RA) +
+            list(range(0xF0410, 0xF0500)) +   # RA-appended half forms
+            list(range(0x0904, 0x0915)) +      # independent vowels
+            list(range(0x0915, 0x093A)) +      # Unicode consonants (before ccmp)
+            list(range(0x0958, 0x0962))         # nukta consonants
+        )
+        deva_following = [glyph_name(cp) for cp in sorted(set(deva_following_cps)) if has(cp)]
+        if deva_following:
+            calt_lines = []
+            calt_lines.append(f"lookup InterwordVisarga {{")
+            calt_lines.append(f"    sub {glyph_name(visarga)} by {glyph_name(INTERWORD_VISARGA)};")
+            calt_lines.append(f"}} InterwordVisarga;")
+            calt_lines.append("")
+            calt_lines.append("feature calt {")
+            calt_lines.append("    script dev2;")
+            calt_lines.append(f"    @devaFollowing = [{' '.join(deva_following)}];")
+            calt_lines.append(f"    sub {glyph_name(visarga)}' lookup InterwordVisarga @devaFollowing;")
+            calt_lines.append("} calt;")
+            features.append('\n'.join(calt_lines))
+
     if not features:
         return ""
     return '\n\n'.join(features)

src/net/torvald/terrarumsansbitmap/gdx/TerrarumSansBitmap.kt

@@ -1401,6 +1401,10 @@ class TerrarumSansBitmap(
                 else {
                     seq0.add(c.toDevaInternal())
                 }
+            // Contextual Visarga: use interword variant when followed by a Devanagari character
+            else if (c == 0x0903 && (cNext in 0x0904..0x0939 || cNext in 0x0958..0x097F)) {
+                seq0.add(DEVANAGARI_INTERWORD_VISARGA)
+            }
             // re-order Sundanese diacritics
             else if ((c == 0x1BA1 || c == 0x1BA2) && cNext == 0x1BA5) {
                 seq0.add(cNext); seq0.add(c); i += 1
@@ -2744,6 +2748,8 @@ class TerrarumSansBitmap(
         private const val DEVANAGARI_EYELASH_RA = 0xF010B
         private const val DEVANAGARI_RA_SUPER = 0xF010C
         private const val DEVANAGARI_RA_SUPER_COMPLEX = 0xF010D
+        private const val DEVANAGARI_INTERWORD_VISARGA = 0xF010A
+
 
         private const val MARWARI_DD = 0x978