fix for https://github.com/godotengine/godot/issues/3226

drivers/gles2/shader_compiler_gles2.cpp

@@ -818,7 +818,8 @@ ShaderCompilerGLES2::ShaderCompilerGLES2() {
 	//mode_replace_table[ShaderLanguage::SHADER_MATERIAL_FRAGMENT]["POSITION"]="IN_POSITION";
 	mode_replace_table[ShaderLanguage::SHADER_MATERIAL_FRAGMENT]["NORMAL"]="normal";
 	mode_replace_table[ShaderLanguage::SHADER_MATERIAL_FRAGMENT]["TANGENT"]="tangent";
-	mode_replace_table[ShaderLanguage::SHADER_MATERIAL_FRAGMENT]["POSITION"]="gl_Position";
+	//mode_replace_table[ShaderLanguage::SHADER_MATERIAL_FRAGMENT]["POSITION"]="gl_Position";
+	mode_replace_table[ShaderLanguage::SHADER_MATERIAL_FRAGMENT]["POSITION"]="gl_FragCoord";
 	mode_replace_table[ShaderLanguage::SHADER_MATERIAL_FRAGMENT]["BINORMAL"]="binormal";
 	mode_replace_table[ShaderLanguage::SHADER_MATERIAL_FRAGMENT]["NORMALMAP"]="normalmap";
 	mode_replace_table[ShaderLanguage::SHADER_MATERIAL_FRAGMENT]["NORMALMAP_DEPTH"]="normaldepth";
@@ -875,7 +876,8 @@ ShaderCompilerGLES2::ShaderCompilerGLES2() {
 	mode_replace_table[ShaderLanguage::SHADER_CANVAS_ITEM_VERTEX]["EXTRA_MATRIX"]="extra_matrix";
 	mode_replace_table[ShaderLanguage::SHADER_CANVAS_ITEM_VERTEX]["TIME"]="time";
 
-	mode_replace_table[ShaderLanguage::SHADER_CANVAS_ITEM_FRAGMENT]["POSITION"]="gl_Position";
+	//mode_replace_table[ShaderLanguage::SHADER_CANVAS_ITEM_FRAGMENT]["POSITION"]="gl_Position";
+	mode_replace_table[ShaderLanguage::SHADER_CANVAS_ITEM_FRAGMENT]["POSITION"]="gl_FragCoord";
 	mode_replace_table[ShaderLanguage::SHADER_CANVAS_ITEM_FRAGMENT]["NORMAL"]="normal";
 	mode_replace_table[ShaderLanguage::SHADER_CANVAS_ITEM_FRAGMENT]["NORMALMAP"]="normal_map";
 	mode_replace_table[ShaderLanguage::SHADER_CANVAS_ITEM_FRAGMENT]["NORMALMAP_DEPTH"]="normal_depth";