add triangle vcm shape - 'tri'

src/coders/xml.cpp

@@ -105,6 +105,19 @@ glm::vec4 Attribute::asColor() const {
     }
 }
 
+int Attribute::asNumbers(float* dst, size_t dstSize) const {
+    size_t pos = 0;
+    size_t count = 0;
+    while (pos < text.length() && count < dstSize) {
+        size_t end = text.find(',', pos);
+        dst[count++] = util::parse_double(
+            text, pos, std::min<size_t>(end - pos, text.length() - pos)
+        );
+        pos = end + 1;
+    }
+    return count;
+}
+
 Node::Node(std::string tag) : tag(std::move(tag)) {
 }