@@ -18,10 +18,17 @@ Overview of usage:

 #include <glshader.hpp>

+// Global data.

+constexpr auto light_count_max = 32;

+

+

 int main()

 {

     // Global settings.

     Shader::root("assets/shaders");

+    Shader::defines({

+        {"light_count_max", std::to_string(light_count_max)},

+    });

     // Create.

     auto player = Shader({

@@ -154,6 +161,14 @@ is to use `#version 110` if none is provided.)

 [`#version`]: https://www.khronos.org/opengl/wiki/Core_Language_(GLSL)#Version

+#### `#define`s

+

+[`#define`][]s specified with `Shader::defines(Shader::Defines const &

+defines)` are injected after the `#version`. `Shader::Defines` is an alias for

+`std::map<std::string, std::string>`.

+

+[`#define`]: https://www.khronos.org/opengl/wiki/Core_Language_(GLSL)#Preprocessor_directives

+

 ## Dependencies

 Public (interface):

@@ -3,5 +3,5 @@

 void main()

 {

-    gl_FragColor = vec4(1.0, 0.5, 0.25, 1.0);

+    gl_FragColor = vec4(red, 0.5, 0.25, 1.0);

 }

@@ -2,6 +2,7 @@

 #define GLSHADER_SHADER_HPP_

+#include <map>

 #include <set>

 #include <string>

@@ -21,7 +22,10 @@ public:

     Shader & operator=(Shader &&) = delete;

     Shader & operator=(Shader const &) = delete;

+    using Defines = std::map<std::string, std::string>;

+

     static void root(std::string const & root);

+    static void defines(Defines const & defines);

     GLuint program() const;

@@ -38,6 +42,7 @@ protected:

     GLuint             program_;

     std::string        program_name_;

     std::string static root_;

+    Defines     static defines_;

 };

@@ -58,6 +63,7 @@ protected:

         NAME##_ = NAME; \

     }

 GLSHADER_SET_(std::string, root)

+GLSHADER_SET_(Defines, defines)

 inline GLuint Shader::program() const

 {

@@ -25,6 +25,7 @@ using Here = std::tuple<std::string, int, std::string>;

 // NOLINTNEXTLINE

 #define GLSHADER_INIT_(NAME, INIT) decltype(NAME) NAME INIT;

 GLSHADER_INIT_(Shader::root_, {})

+GLSHADER_INIT_(Shader::defines_, {})

 template<typename Type>

@@ -79,7 +80,8 @@ static void info_log_action_(

 static std::string source_(

     std::string const & error,

     std::string const & path,

-    std::string const & root

+    std::string const & root,

+    Shader::Defines const & defines

 )

 {

     // Set here error.

@@ -154,6 +156,11 @@ static std::string source_(

             // Output.

             ostream << line << "\n";

+            for (auto const & define : defines)

+                ostream

+                    << "#define "

+                    << define.first << " "

+                    << define.second << "\n";

         }

         // Non-processed line.

@@ -263,7 +270,7 @@ Shader::Shader(Paths const & paths)

             // Set shader source.

             auto const source_error = STR("Failed to source " << shader_name);

-            auto const source = source_(source_error, path, root_);

+            auto const source = source_(source_error, path, root_, defines_);

             auto const sources = std::array<char const *, 1>{{

                 source.c_str()

             }};

@@ -72,6 +72,12 @@ GLTEST(2, 0, 640, 480, glshader)

         "assets/shaders/tests/version_repeated.vert:2: #version 110"

     )

+    // Defines.

+    constexpr auto red = 1.0F;

+    Shader::defines({

+        {"red", std::to_string(red)},

+    });

+

     auto all = Shader({

         "tests/all.vert",

         "tests/all.frag",