diff --git a/orx-fx/src/shaders/glsl/blur/box-blur.frag b/orx-fx/src/shaders/glsl/blur/box-blur.frag
index a84c6d6e..a47eca7e 100644
--- a/orx-fx/src/shaders/glsl/blur/box-blur.frag
+++ b/orx-fx/src/shaders/glsl/blur/box-blur.frag
@@ -1,5 +1,11 @@
+#ifdef OR_IN_OUT
 in vec2 v_texCoord0;
+#else
+varying vec2 v_texCoord0;
+#endif
+
 uniform sampler2D tex0;
+uniform vec2 textureSize0;
 uniform vec2 blurDirection;
 
 uniform int window;
@@ -7,21 +13,42 @@ uniform float sigma;
 uniform float gain;
 uniform vec4 subtract;
 uniform float spread;
+
+#ifndef OR_GL_FRAGCOLOR
 out vec4 o_color;
+#endif
+
 void main() {
-    vec2 s = textureSize(tex0, 0).xy;
-    s = vec2(1.0/s.x, 1.0/s.y);
+    vec2 s = textureSize0;
+    s = vec2(1.0 / s.x, 1.0 / s.y);
 
+    #ifndef OR_WEBGL1
     int w = window;
+    int WS = -window;
+    int WE = window;
+    #else
+    int w = 3;
+    #define WS -3
+    #define WE 3
+    #endif
 
-    vec4 sum = vec4(0, 0, 0, 0);
-    float weight = 0;
-    for (int x = -w; x<= w; ++x) {
+    vec4 sum = vec4(0.0, 0.0, 0.0, 0.0);
+    float weight = 0.0;
+    for (int x = WS; x<= WE; ++x) {
         float lw = 1.0;
-        sum += texture(tex0, v_texCoord0 + x * blurDirection * s * spread);
+        #ifndef OR_GL_TEXTURE2D
+        sum += texture(tex0, v_texCoord0 + float(x) * blurDirection * s * spread);
+        #else
+        sum += texture2D(tex0, v_texCoord0 + float(x) * blurDirection * s * spread);
+        #endif
+
         weight += lw;
     }
 
-    o_color = (sum / weight) * gain;
-//    o_color.a = 1.0;
+    vec4 result = (sum / weight) * gain;
+    #ifdef OR_GL_FRAGCOLOR
+    gl_FragColor = result;
+    #else
+    o_color = result;
+    #endif
 }
\ No newline at end of file