diff --git a/data/layout.xml b/data/layout.xml
index caa4f70..dcbe2b9 100644
--- a/data/layout.xml
+++ b/data/layout.xml
@@ -159,7 +159,7 @@
           </node>
           <border dir="col" align="center" grow="1" width="1" flood-events="1">
             <node height="30" pad="1" width="100%" dir="row">
-              <combobox id="blend-mode" text="Normal" width="100%" height="30" combo-list="Normal,Multiply,Screen,Color Dodge" default="0"/>
+              <combobox id="blend-mode" text="Normal" width="100%" height="30" combo-list="Normal,Multiply,Screen,Color Dodge,Overlay" default="0"/>
             </node>
             <node height="20" pad="1" width="100%" dir="row">
               <slider-h id="tip-size"  width="1" grow="1" value=".25"/>
diff --git a/engine/app_shaders.cpp b/engine/app_shaders.cpp
index 8ea5459..615feb3 100644
--- a/engine/app_shaders.cpp
+++ b/engine/app_shaders.cpp
@@ -105,11 +105,13 @@ void App::initShaders()
         "vec3 blend_multiply(vec4 base, vec4 stroke, float alpha_tot) { return mix(stroke.rgb, mix(base.rgb, base.rgb*stroke.rgb, stroke.a/alpha_tot), base.a/alpha_tot); }\n"
         "vec3 blend_screen(vec4 base, vec4 stroke, float alpha_tot) { return mix(stroke.rgb, mix(base.rgb, 1.0-(1.0-base.rgb)*(1.0-stroke.rgb), stroke.a/alpha_tot), base.a/alpha_tot); }\n"
         "vec3 blend_colorDodge(vec4 base, vec4 stroke, float alpha_tot) { return mix(stroke.rgb, mix(base.rgb, base.rgb/(1.0-stroke.rgb), stroke.a/alpha_tot), base.a/alpha_tot); }\n"
+        "vec3 blend_overlay(vec4 base, vec4 stroke, float alpha_tot) { return mix(stroke.rgb, mix(base.rgb, mix(2.0*base.rgb*stroke.rgb, 1.0-2.0*(1.0-base.rgb)*(1.0-stroke.rgb), floor(base.rgb*2.0)), stroke.a/alpha_tot), base.a/alpha_tot); }\n"
         "vec3 blend(vec4 base, vec4 stroke, float alpha_tot, int mode) { switch(mode){\n"
         "   case 0: return blend_normal(base, stroke, alpha_tot);"
         "   case 1: return blend_multiply(base, stroke, alpha_tot);"
         "   case 2: return blend_screen(base, stroke, alpha_tot);"
         "   case 3: return blend_colorDodge(base, stroke, alpha_tot);"
+        "   case 4: return blend_overlay(base, stroke, alpha_tot);"
         "}}\n"
         "void main(){\n"
         "   mediump vec4 base = texture(tex, uv.xy);\n"