encode icon texture coordinate in buffer so we can render all pois with 1 draw call

src/geometry/icon_buffer.cpp

@@ -5,8 +5,14 @@
 
 using namespace llmr;
 
-void IconVertexBuffer::add(vertex_type x, vertex_type y) {
-    vertex_type *vertices = static_cast<vertex_type *>(addElement());
+void IconVertexBuffer::add(vertex_type x, vertex_type y, uint16_t tx, uint16_t ty) {
+    void *data = addElement();
+
+    vertex_type *vertices = static_cast<vertex_type *>(data);
     vertices[0] = x;
     vertices[1] = y;
+
+    uint16_t *texture = static_cast<uint16_t *>(data);
+    texture[2] = tx;
+    texture[3] = ty;
 }