diff --git a/src/coders/BasicParser.hpp b/src/coders/BasicParser.hpp
index ba1cf5a8..e0a4445a 100644
--- a/src/coders/BasicParser.hpp
+++ b/src/coders/BasicParser.hpp
@@ -8,7 +8,9 @@ class BasicParser {
     using StringT = std::basic_string<CharT>;
     using StringViewT = std::basic_string_view<CharT>;
 
+    void skipWhitespaceBasic(bool newline = true);
     void skipWhitespaceHashComment(bool newline = true);
+    void skipWhitespaceCLikeComment(bool newline = true);
 protected:
     std::string_view filename;
     StringViewT source;
@@ -16,6 +18,7 @@ protected:
     uint line = 1;
     uint linestart = 0;
     bool hashComment = false;
+    bool clikeComment = false;
 
     void skipWhitespace(bool newline = true);
     void skip(size_t n);
@@ -35,7 +38,7 @@ protected:
     StringT parseString(CharT chr, bool closeRequired = true);
 
     parsing_error error(const std::string& message);
-public:
+
     StringViewT readUntil(CharT c);
     StringViewT readUntil(StringViewT s, bool nothrow);
     StringViewT readUntilWhitespace();
diff --git a/src/coders/BasicParser.inl b/src/coders/BasicParser.inl
index 3616b4a1..7ed9c10d 100644
--- a/src/coders/BasicParser.inl
+++ b/src/coders/BasicParser.inl
@@ -31,13 +31,9 @@ namespace {
 }
 
 template<typename CharT>
-void BasicParser<CharT>::skipWhitespace(bool newline) {
-    if (hashComment) {
-        skipWhitespaceHashComment(newline);
-        return;
-    }
+void BasicParser<CharT>::skipWhitespaceBasic(bool newline) {
     while (hasNext()) {
-        char next = source[pos];
+        CharT next = source[pos];
         if (next == '\n') {
             if (!newline) {
                 break;
@@ -55,23 +51,20 @@ void BasicParser<CharT>::skipWhitespace(bool newline) {
 }
 
 template<typename CharT>
-void BasicParser<CharT>::skipWhitespaceHashComment(bool newline) {
-    while (hasNext()) {
-        char next = source[pos];
-        if (next == '\n') {
-            if (!newline) {
-                break;
-            }
-            line++;
-            linestart = ++pos;
-            continue;
-        }
-        if (is_whitespace(next)) {
-            pos++;
-        } else {
-            break;
-        }
+void BasicParser<CharT>::skipWhitespace(bool newline) {
+    if (hashComment) {
+        skipWhitespaceHashComment(newline);
+        return;
+    } else if (clikeComment) {
+        skipWhitespaceCLikeComment(newline);
+        return;
     }
+    skipWhitespaceBasic(newline);
+}
+
+template<typename CharT>
+void BasicParser<CharT>::skipWhitespaceHashComment(bool newline) {
+    skipWhitespaceBasic(newline);
     if (hasNext() && source[pos] == '#') {
         if (!newline) {
             readUntilEOL();
@@ -84,6 +77,39 @@ void BasicParser<CharT>::skipWhitespaceHashComment(bool newline) {
     }
 }
 
+template<typename CharT>
+void BasicParser<CharT>::skipWhitespaceCLikeComment(bool newline) {
+    skipWhitespaceBasic(newline);
+    if (hasNext() && source[pos] == '/' && pos + 1 < source.length()) {
+        pos++;
+        switch (source[pos]) {
+            case '*':
+                pos++;
+                while (hasNext()) {
+                    if (source[pos] == '/' && source[pos-1] == '*') {
+                        pos++;
+                        skipWhitespace();
+                        return;
+                    }
+                    pos++;
+                }
+                break;
+            case '/':
+                if (!newline) {
+                    readUntilEOL();
+                    return;
+                }
+                skipLine();
+                if (hasNext() && (is_whitespace(source[pos]) || source[pos] == '/')) {
+                    skipWhitespaceCLikeComment(newline);
+                }
+            default:
+                pos--;
+                break;
+        }
+    }
+}
+
 template<typename CharT>
 void BasicParser<CharT>::skip(size_t n) {
     n = std::min(n, source.length() - pos);
diff --git a/src/coders/GLSLExtension.cpp b/src/coders/GLSLExtension.cpp
index b36e7a07..fcacc372 100644
--- a/src/coders/GLSLExtension.cpp
+++ b/src/coders/GLSLExtension.cpp
@@ -1,23 +1,28 @@
 #include "GLSLExtension.hpp"
 
-#include <iostream>
 #include <sstream>
 #include <stdexcept>
 #include <utility>
 
+#include "debug/Logger.hpp"
 #include "io/engine_paths.hpp"
 #include "typedefs.hpp"
 #include "util/stringutil.hpp"
+#include "coders/BasicParser.hpp"
+#include "graphics/core/PostEffect.hpp"
 
-void GLSLExtension::setVersion(std::string version) {
-    this->version = std::move(version);
-}
+static debug::Logger logger("glsl-extension");
+
+using Type = PostEffect::Param::Type;
 
 void GLSLExtension::setPaths(const ResPaths* paths) {
     this->paths = paths;
 }
 
 void GLSLExtension::loadHeader(const std::string& name) {
+    if (paths == nullptr) {
+        return;
+    }
     io::path file = paths->find("shaders/lib/" + name + ".glsl");
     std::string source = io::read_string(file);
     addHeader(name, "");
@@ -48,6 +53,10 @@ const std::string& GLSLExtension::getDefine(const std::string& name) const {
     return found->second;
 }
 
+const std::unordered_map<std::string, std::string>& GLSLExtension::getDefines() const {
+    return defines;
+}
+
 bool GLSLExtension::hasDefine(const std::string& name) const {
     return defines.find(name) != defines.end();
 }
@@ -72,76 +81,125 @@ inline std::runtime_error parsing_error(
 }
 
 inline void parsing_warning(
-    const io::path& file, uint linenum, const std::string& message
+    std::string_view file, uint linenum, const std::string& message
 ) {
-    std::cerr << "file " + file.string() + ": warning: " + message +
-                     " at line " + std::to_string(linenum)
-              << std::endl;
+    logger.warning() << "file " + std::string(file) + ": warning: " + message +
+                     " at line " + std::to_string(linenum);
 }
 
 inline void source_line(std::stringstream& ss, uint linenum) {
     ss << "#line " << linenum << "\n";
 }
 
+static std::optional<PostEffect::Param::Type> param_type_from(
+    const std::string& name
+) {
+    static const std::unordered_map<std::string, PostEffect::Param::Type> typeNames {
+        {"float", Type::FLOAT},
+        {"vec2", Type::VEC2},
+        {"vec3", Type::VEC3},
+        {"vec4", Type::VEC4},
+    };
+    const auto& found = typeNames.find(name);
+    if (found == typeNames.end()) {
+        return std::nullopt;
+    }
+    return found->second;
+}
+
+class GLSLParser : public BasicParser<char> {
+public:
+    GLSLParser(GLSLExtension& glsl, std::string_view file, std::string_view source, bool header)
+        : BasicParser(file, source), glsl(glsl) {
+        if (!header) {
+            ss << "#version " << GLSLExtension::VERSION << '\n';
+        }
+        for (auto& entry : glsl.getDefines()) {
+            ss << "#define " << entry.first << " " << entry.second << '\n';
+        }
+        uint linenum = 1;
+        source_line(ss, linenum);
+
+        clikeComment = true;
+    }
+
+    bool processPreprocessorDirective() {
+        skip(1);
+
+        auto name = parseName();
+
+        if (name == "version") {
+            parsing_warning(filename, line, "removed #version directive");
+            source_line(ss, line);
+            skipLine();
+            return false;
+        } else if (name == "include") {
+            skipWhitespace(false);
+            if (peekNoJump() != '<') {
+                throw error("'<' expected");
+            }
+            skip(1);
+            skipWhitespace(false);
+            auto headerName = parseName();
+            skipWhitespace(false);
+            if (peekNoJump() != '>') {
+                throw error("'>' expected");
+            }
+            skip(1);
+            skipWhitespace(false);
+            skipLine();
+
+            if (!glsl.hasHeader(headerName)) {
+                glsl.loadHeader(headerName);
+            }
+            ss << glsl.getHeader(headerName) << '\n';
+            source_line(ss, line);
+            return false;
+        } else if (name == "param") {
+            skipWhitespace(false);
+            auto typeName = parseName();
+            auto type = param_type_from(typeName);
+            if (!type.has_value()) {
+                throw error("unsupported param type " + util::quote(typeName));
+            }
+            skipWhitespace(false);
+            auto paramName = parseName();
+            if (params.find(paramName) != params.end()) {
+                throw error("duplicating param " + util::quote(paramName));
+            }
+            skipLine();
+
+            ss << "uniform " << typeName << " " << paramName << ";\n";
+            params[paramName] = PostEffect::Param(type.value());
+            return false;
+        }
+        return true;
+    }
+
+    std::string process() {
+        while (hasNext()) {
+            skipWhitespace(false);
+            if (!hasNext()) {
+                break;
+            }
+            if (source[pos] != '#' || processPreprocessorDirective()) {
+                pos = linestart;
+                ss << readUntilEOL() << '\n';
+                skip(1);
+            }
+        }
+        return ss.str();
+    }
+private:
+    GLSLExtension& glsl;
+    std::unordered_map<std::string, PostEffect::Param> params;
+    std::stringstream ss;
+};
+
 std::string GLSLExtension::process(
     const io::path& file, const std::string& source, bool header
 ) {
-    std::stringstream ss;
-    size_t pos = 0;
-    uint linenum = 1;
-    if (!header) {
-        ss << "#version " << version << '\n';
-    }
-    for (auto& entry : defines) {
-        ss << "#define " << entry.first << " " << entry.second << '\n';
-    }
-    source_line(ss, linenum);
-    while (pos < source.length()) {
-        size_t endline = source.find('\n', pos);
-        if (endline == std::string::npos) {
-            endline = source.length();
-        }
-        // parsing preprocessor directives
-        if (source[pos] == '#') {
-            std::string line = source.substr(pos + 1, endline - pos);
-            util::trim(line);
-            // parsing 'include' directive
-            if (line.find("include") != std::string::npos) {
-                line = line.substr(7);
-                util::trim(line);
-                if (line.length() < 3) {
-                    throw parsing_error(
-                        file, linenum, "invalid 'include' syntax"
-                    );
-                }
-                if (line[0] != '<' || line[line.length() - 1] != '>') {
-                    throw parsing_error(
-                        file, linenum, "expected '#include <filename>' syntax"
-                    );
-                }
-                std::string name = line.substr(1, line.length() - 2);
-                if (!hasHeader(name)) {
-                    loadHeader(name);
-                }
-                source_line(ss, 1);
-                ss << getHeader(name) << '\n';
-                pos = endline + 1;
-                linenum++;
-                source_line(ss, linenum);
-                continue;
-            }
-            // removing extra 'include' directives
-            else if (line.find("version") != std::string::npos) {
-                parsing_warning(file, linenum, "removed #version directive");
-                pos = endline + 1;
-                linenum++;
-                source_line(ss, linenum);
-                continue;
-            }
-        }
-        linenum++;
-        ss << source.substr(pos, endline + 1 - pos);
-        pos = endline + 1;
-    }
-    return ss.str();
+    std::string filename = file.string();
+    GLSLParser parser(*this, filename, source, header);
+    return parser.process();
 }
diff --git a/src/coders/GLSLExtension.hpp b/src/coders/GLSLExtension.hpp
index c619c9d0..63e15303 100644
--- a/src/coders/GLSLExtension.hpp
+++ b/src/coders/GLSLExtension.hpp
@@ -9,15 +9,8 @@
 class ResPaths;
 
 class GLSLExtension {
-    std::unordered_map<std::string, std::string> headers;
-    std::unordered_map<std::string, std::string> defines;
-    std::string version = "330 core";
-
-    const ResPaths* paths = nullptr;
-    void loadHeader(const std::string& name);
 public:
     void setPaths(const ResPaths* paths);
-    void setVersion(std::string version);
 
     void define(const std::string& name, std::string value);
     void undefine(const std::string& name);
@@ -26,12 +19,22 @@ public:
     const std::string& getHeader(const std::string& name) const;
     const std::string& getDefine(const std::string& name) const;
 
+    const std::unordered_map<std::string, std::string>& getDefines() const;
+
     bool hasHeader(const std::string& name) const;
     bool hasDefine(const std::string& name) const;
+    void loadHeader(const std::string& name);
 
     std::string process(
         const io::path& file,
         const std::string& source,
         bool header = false
     );
+
+    static inline std::string VERSION = "330 core";
+private:
+    std::unordered_map<std::string, std::string> headers;
+    std::unordered_map<std::string, std::string> defines;
+
+    const ResPaths* paths = nullptr;
 };
diff --git a/src/coders/toml.cpp b/src/coders/toml.cpp
index 1652745a..1a249435 100644
--- a/src/coders/toml.cpp
+++ b/src/coders/toml.cpp
@@ -16,7 +16,7 @@ using namespace toml;
 class TomlReader : BasicParser<char> {
     dv::value root;
 
-    // modified version of BaseParser.parseString
+    // modified version of BasicParser.parseString
     // todo: extract common part
     std::string parseMultilineString() {
         pos += 2;
diff --git a/src/graphics/core/PostEffect.cpp b/src/graphics/core/PostEffect.cpp
new file mode 100644
index 00000000..5f8b41fc
--- /dev/null
+++ b/src/graphics/core/PostEffect.cpp
@@ -0,0 +1,15 @@
+#include "PostEffect.hpp"
+
+#include "Shader.hpp"
+
+PostEffect::Param::Param() : type(Type::FLOAT) {}
+
+PostEffect::Param::Param(Type type) : type(type) {}
+
+PostEffect::PostEffect(std::unique_ptr<Shader> shader)
+    : shader(std::move(shader)) {
+}
+
+void PostEffect::use() {
+    shader->use();
+}
diff --git a/src/graphics/core/PostEffect.hpp b/src/graphics/core/PostEffect.hpp
new file mode 100644
index 00000000..78afda26
--- /dev/null
+++ b/src/graphics/core/PostEffect.hpp
@@ -0,0 +1,29 @@
+#pragma once
+
+#include <memory>
+#include <string>
+#include <variant>
+#include <unordered_map>
+#include <glm/glm.hpp>
+
+class Shader;
+
+class PostEffect {
+public:
+    struct Param {
+        enum class Type { FLOAT, VEC2, VEC3, VEC4 };
+        using Value = std::variant<float, glm::vec2, glm::vec3, glm::vec4>;
+
+        Type type;
+
+        Param();
+        Param(Type type);
+    };
+
+    PostEffect(std::unique_ptr<Shader> shader);
+
+    void use();
+private:
+    std::unique_ptr<Shader> shader;
+    std::unordered_map<std::string, Param> params;
+};
diff --git a/test/coders/GLSLExtension.cpp b/test/coders/GLSLExtension.cpp
new file mode 100644
index 00000000..ff26ebdf
--- /dev/null
+++ b/test/coders/GLSLExtension.cpp
@@ -0,0 +1,32 @@
+#include <gtest/gtest.h>
+
+#include "coders/commons.hpp"
+#include "coders/GLSLExtension.hpp"
+
+TEST(GLSLExtension, processing) {
+    GLSLExtension glsl;
+    glsl.addHeader("sum", 
+        "// sum function for glsl\n"
+        "float sum(float a, float b) {\n"
+        "    return a + b;\n"
+        "}\n"
+    );
+    try {
+        auto processed = glsl.process("test.glsl",
+            "in vec2 v_uv;\n"
+            "uniform sampler2D u_screen;\n"
+            "\n"
+            "#include /* hell\no */  <   sum     >\n"
+            "#param float p_intensity\n"
+            "\n"
+            "vec4 effect() {\n"
+            "    vec4 color = texture(u_screen, v_uv);\n"
+            "    return mix(color, 1.0 - color, p_intensity);\n"
+            "}\n",
+        false);
+        std::cout << processed << std::endl;
+    } catch (const parsing_error& err) {
+        std::cerr << err.errorLog() << std::endl;
+        throw;
+    }
+}