From d164943ee230b7cc036695eceb4cf376947c6e77 Mon Sep 17 00:00:00 2001
From: Frank Galligan <fgalligan@google.com>
Date: Sat, 7 Oct 2017 11:54:34 -0700
Subject: [PATCH] spec: Add connectivity_method == 0 to Sequential decoder

This addresses a comment in KhronosGroup/glTF#1114
---
 docs/spec/sequential.decoder.md | 42 ++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/docs/spec/sequential.decoder.md b/docs/spec/sequential.decoder.md
index 2209387..5ba0677 100644
--- a/docs/spec/sequential.decoder.md
+++ b/docs/spec/sequential.decoder.md
@@ -55,11 +55,10 @@ void ParseSequentialIndicesUI32() {
 {:.draco-syntax }
 
 
-### DecodeSequentialConnectivityData()
+### DecodeSequentialIndices()
 
 ~~~~~
-void DecodeSequentialConnectivityData() {
-  ParseSequentialConnectivityData();
+void DecodeSequentialIndices() {
   if (num_points < 256) {
     ParseSequentialIndicesUI8();
   } else if (num_points < (1 << 16)) {
@@ -70,3 +69,40 @@ void DecodeSequentialConnectivityData() {
 }
 ~~~~~
 {:.draco-syntax }
+
+
+### DecodeSequentialCompressedIndices()
+
+~~~~~
+void DecodeSequentialCompressedIndices() {
+  DecodeSymbols(num_faces * 3, 1, &decoded_symbols);
+  last_index_value = 0;
+  for (i = 0; i < num_faces; ++i) {
+    for (j = 0; j < 3; ++j) {
+      encoded_val = decoded_symbols[i * 3 + j];
+      index_diff = (encoded_val >> 1);
+      if (encoded_val & 1)
+        index_diff = -index_diff;
+      val = index_diff + last_index_value;
+      face_to_vertex[j][i] = val;
+      last_index_value = val;
+    }
+  }
+}
+~~~~~
+{:.draco-syntax }
+
+
+### DecodeSequentialConnectivityData()
+
+~~~~~
+void DecodeSequentialConnectivityData() {
+  ParseSequentialConnectivityData();
+  if (connectivity_method == 0) {
+    DecodeSequentialCompressedIndices();
+  } else if (connectivity_method == 1) {
+    DecodeSequentialIndices();
+  }
+}
+~~~~~
+{:.draco-syntax }