much more elegant solution than stretching texture using batch

src/shaders/blendGlow.frag

@@ -11,9 +11,10 @@ uniform sampler2D u_texture; // world texture, has alpha value that is meaningfu
 uniform sampler2D tex1; // glow texture, SHOULD contain alpha of all 1.0
 out vec4 fragColor;
 
+vec2 boolean = vec2(0.0, 1.0);
+
 void main(void) {
     vec4 colorTex0 = texture(u_texture, v_texCoords); // lightmap (RGB) pre-mixed
     vec4 colorTex1 = texture(tex1, v_texCoords); // lightmap (A) pre-mixed
-
-    fragColor = vec4(max(colorTex0.rgb, colorTex1.rgb), colorTex0.a);
+    fragColor = (max(colorTex0, colorTex1) * boolean.yyyx) + (colorTex0 * boolean.xxxy);
 }

src/shaders/blendMax.frag

@@ -0,0 +1,22 @@
+#version 150
+#ifdef GL_ES
+    precision mediump float;
+#endif
+
+
+in vec4 v_color;
+in vec2 v_texCoord0;
+in vec2 v_texCoord1;
+uniform sampler2D u_texture; // world texture, has alpha value that is meaningful
+
+uniform sampler2D tex1; // glow texture, SHOULD contain alpha of all 1.0
+out vec4 fragColor;
+
+vec2 boolean = vec2(0.0, 1.0);
+
+void main(void) {
+    vec4 colorTex0 = texture(u_texture, v_texCoord0); // lightmap (RGB) pre-mixed
+    vec4 colorTex1 = texture(tex1, v_texCoord1); // lightmap (A) pre-mixed
+//    fragColor = (max(colorTex0, colorTex1) * boolean.yyyx) + boolean.xxxy;
+    fragColor = colorTex0;
+}

src/shaders/blendMax.vert

@@ -0,0 +1,19 @@
+#version 150
+
+in vec4 a_position;
+in vec4 a_color;
+in vec2 a_texCoord0;
+in vec2 a_texCoord1;
+
+uniform mat4 u_projTrans; // camera.combined
+
+out vec4 v_color;
+out vec2 v_texCoord0;
+out vec2 v_texCoord1;
+
+void main() {
+    v_color = a_color;
+    v_texCoord0 = a_texCoord0;
+    v_texCoord1 = a_texCoord1;
+    gl_Position = u_projTrans * a_position;
+}

src/shaders/passthrurgb.frag

@@ -1,16 +0,0 @@
-#version 150
-#ifdef GL_ES
-    precision mediump float;
-#endif
-
-
-in vec4 v_color;
-in vec2 v_texCoords;
-
-uniform sampler2D u_texture;
-
-out vec4 fragColor;
-
-void main(void) {
-    fragColor = vec4(texture(u_texture, v_texCoords).rgb, 1.0);
-}

src/shaders/rgbonly.frag

@@ -8,5 +8,5 @@ vec2 boolean = vec2(0.0, 1.0);
 out vec4 fragColor;
 
 void main(void) {
-    fragColor = texture(u_texture, v_texCoords).rgba * boolean.yyyx + boolean.xxxy;
+    fragColor = texture(u_texture, v_texCoords) * boolean.yyyx + boolean.xxxy;
 }