diff --git a/src/LayerComposition.cpp b/src/LayerComposition.cpp
index 9e19007..349934b 100644
--- a/src/LayerComposition.cpp
+++ b/src/LayerComposition.cpp
@@ -241,5 +241,18 @@ void LayerComposition::setVFlip(bool vFlip){
 void LayerComposition::setLayerOrder(const vector <LayerID> & layerOrder){
     this->layerOrder = layerOrder;
 }
+void LayerComposition::setMsdfUniform1fv(const vector <string> & names,
+                                         const vector <float> & values){
+    for(const auto & [identifier, layerCombo] : atlasLayerCombos){
+        if(identifier.type == LayerType::MSDFGEN){
+            auto combo = static_pointer_cast <MsdfAtlasLayerCombo>(layerCombo);
+            combo->getShader()->begin();
+            for(int i = 0; i < names.size(); i++){
+                combo->getShader()->setUniform1f(names[i], values[i]);
+            }
+            combo->getShader()->end();
+        }
+    }
+}
 
 }
diff --git a/src/LayerComposition.h b/src/LayerComposition.h
index 117b154..ac76ec9 100644
--- a/src/LayerComposition.h
+++ b/src/LayerComposition.h
@@ -35,8 +35,9 @@ class LayerComposition {
         shared_ptr <Layer> getLayer(const LayerID & layerID);
         const unordered_map <ComboIdentifier, shared_ptr <AtlasLayerCombo> > & getAtlasLayerCombos() const;
         void setVFlip(bool vFlip);
-
         void setLayerOrder(const vector <LayerID> & layerOrder);
+        void setMsdfUniform1fv(const vector <string> & names,
+                               const vector <float> & values);
     private:
         VFlipState vFlipState = V_FLIP_UNKNOWN;
         unordered_map <LayerID, shared_ptr <Layer> > layers;
diff --git a/src/MsdfAtlasLayerCombo.cpp b/src/MsdfAtlasLayerCombo.cpp
index f8d29e4..faffae0 100644
--- a/src/MsdfAtlasLayerCombo.cpp
+++ b/src/MsdfAtlasLayerCombo.cpp
@@ -6,9 +6,12 @@
 #include "of3dGraphics.h"
 #include "ofFileUtils.h"
 #include "ofGraphics.h"
+#include "ofUtils.h"
 #include "ofxProfiler.h"
-#include <GL/glext.h>
-#include <GLES3/gl3.h>
+#ifdef TARGET_EMSCRIPTEN
+ #include <GL/glext.h>
+ #include <GLES3/gl3.h>
+#endif
 
 namespace ofxVariableLab {
 
@@ -154,8 +157,8 @@ void MsdfAtlasLayerCombo::draw(bool fade){
     for(const auto & layer : layers){
         elements += layer->nElements;
     }
-    //vertices.resize(elements * 4);
-    //indices.resize(elements * 6);
+    vertices.reserve(elements * 4);
+    indices.reserve(elements * 6);
     vertices.clear();
     indices.clear();
     int offset = 0;
@@ -230,4 +233,7 @@ const ofImage & MsdfAtlasLayerCombo::getAtlasImage(){
 string MsdfAtlasLayerCombo::getAtlasImagePath(){
     return atlas->getAtlasPath();
 }
+shared_ptr <ofShader> MsdfAtlasLayerCombo::getShader(){
+    return msdfShader;
+}
 }
diff --git a/src/MsdfAtlasLayerCombo.h b/src/MsdfAtlasLayerCombo.h
index 288e0dd..5145f30 100644
--- a/src/MsdfAtlasLayerCombo.h
+++ b/src/MsdfAtlasLayerCombo.h
@@ -3,6 +3,7 @@
 #include "AtlasLayerCombo.h"
 #include "MsdfLayer.h"
 #include "Utils.h"
+#include <memory>
 
 namespace ofxVariableLab {
 using BufferVertex = MsdfLayer::BufferVertex;
@@ -25,8 +26,8 @@ class MsdfAtlasLayerCombo : public AtlasLayerCombo {
         void exit();
         const ofImage & getAtlasImage();
         string getAtlasImagePath();
-        shared_ptr <Layer> getLayer(); // TODO: is this used
         shared_ptr <ofxMsdfgen::Atlas> atlas;
+        shared_ptr <ofShader> getShader();
 
     private:
         MsdfAtlasLayerComboSettings settings;
diff --git a/src/MsdfLayer.cpp b/src/MsdfLayer.cpp
index 6b7bd40..d78e5f2 100644
--- a/src/MsdfLayer.cpp
+++ b/src/MsdfLayer.cpp
@@ -376,8 +376,8 @@ bool MsdfLayer::collectCharacter(const char character,
     glm::vec4 p2 = glm::vec4(w, h, 0, 1);
     glm::vec4 p3 = glm::vec4(w, 0, 0, 1);
 
-    vertices.reserve(nodes.size() * 4);
-    indices.reserve(nodes.size() * 6);
+    //vertices.reserve(nodes.size() * 4);
+    //indices.reserve(nodes.size() * 6);
     for(int i = 0; i < nodes.size(); i++){
         const glm::vec4 & color = colors[i];
         ofNode & node = nodes[i];
@@ -387,37 +387,42 @@ bool MsdfLayer::collectCharacter(const char character,
         //glm::vec4 p3 = node.getGlobalTransformMatrix() * glm::vec4(w, 0, 0, 1);
         glm::mat4 globalTransform = node.getGlobalTransformMatrix();
 
+        //std::lock_guard <std::mutex> vm(vertices_mutex);
+        vertices_mutex.lock();
         int32_t base = static_cast <int32_t>(vertices.size());
-        vertices.push_back(BufferVertex{
-                {p0.x, p0.y, p0.z, p0.w},
-                {uv0_a.x, uv0_a.y},
-                {uv0_b.x, uv0_b.y},
-                {color.r, color.g, color.b, color.a},
-                mix, globalTransform
-            });
-        vertices.push_back(BufferVertex{
-                {p1.x, p1.y, p1.z, p1.w},
-                {uv1_a.x, uv1_a.y},
-                {uv1_b.x, uv1_b.y},
-                {color.r, color.g, color.b, color.a},
-                mix, globalTransform
-            });
-        vertices.push_back(BufferVertex{
-                {p2.x, p2.y, p2.z, p2.w},
-                {uv2_a.x, uv2_a.y},
-                {uv2_b.x, uv2_b.y},
-                {color.r, color.g, color.b, color.a},
-                mix, globalTransform
-            });
-        vertices.push_back(BufferVertex{
-                {p3.x, p3.y, p3.z, p3.w},
-                {uv3_a.x, uv3_a.y},
-                {uv3_b.x, uv3_b.y},
-                {color.r, color.g, color.b, color.a},
-                mix, globalTransform
+        vertices.insert(vertices.end(), {
+                BufferVertex{
+                    {p0.x, p0.y, p0.z, p0.w},
+                    {uv0_a.x, uv0_a.y},
+                    {uv0_b.x, uv0_b.y},
+                    {color.r, color.g, color.b, color.a},
+                    mix, globalTransform
+                },
+                BufferVertex{
+                    {p1.x, p1.y, p1.z, p1.w},
+                    {uv1_a.x, uv1_a.y},
+                    {uv1_b.x, uv1_b.y},
+                    {color.r, color.g, color.b, color.a},
+                    mix, globalTransform
+                },
+                BufferVertex{
+                    {p2.x, p2.y, p2.z, p2.w},
+                    {uv2_a.x, uv2_a.y},
+                    {uv2_b.x, uv2_b.y},
+                    {color.r, color.g, color.b, color.a},
+                    mix, globalTransform
+                },
+                BufferVertex{
+                    {p3.x, p3.y, p3.z, p3.w},
+                    {uv3_a.x, uv3_a.y},
+                    {uv3_b.x, uv3_b.y},
+                    {color.r, color.g, color.b, color.a},
+                    mix, globalTransform
+                }
             });
         indices.insert(indices.end(), {base, base + 1, base + 2, base + 2, base + 3, base});
         nElements++;
+        vertices_mutex.unlock();
     }
     return true;
 }
diff --git a/src/MsdfLayer.h b/src/MsdfLayer.h
index 5bae77c..366abad 100644
--- a/src/MsdfLayer.h
+++ b/src/MsdfLayer.h
@@ -101,5 +101,7 @@ class MsdfLayer : public Layer {
         ofNode outerNode;
         ofNode innerNode;
         Layer::BoundingBox boundingBox;
+        std::mutex vertices_mutex;
+        std::mutex indices_mutex;
 };
 }