8 files changed, 736 insertions, 0 deletions

diff --git a/src/libjin/graphics/shaders/built-in/je_default.shader.h b/src/libjin/graphics/shaders/built-in/je_default.shader.h
new file mode 100644
index 0000000..3f57c44
--- /dev/null
+++ b/src/libjin/graphics/shaders/built-in/je_default.shader.h
@@ -0,0 +1,21 @@
+// Ĭ��shader
+static const char* default_shader = R"(
+
+#VERTEX_SHADER
+
+Vertex vert(Vertex v)
+{
+    return v;
+}
+
+#END_VERTEX_SHADER
+
+#FRAGMENT_SHADER
+
+Color frag(Color col, Texture tex, Vertex v)
+{
+    return col * texel(tex, v.uv);
+}
+
+#END_FRAGMENT_SHADER
+)";
\ No newline at end of file
diff --git a/src/libjin/graphics/shaders/built-in/je_font.shader.h b/src/libjin/graphics/shaders/built-in/je_font.shader.h
new file mode 100644
index 0000000..e04c225
--- /dev/null
+++ b/src/libjin/graphics/shaders/built-in/je_font.shader.h
@@ -0,0 +1,21 @@
+// ����shader
+static const char* font_shader = R"(
+
+#VERTEX_SHADER
+
+Vertex vert(Vertex v)
+{
+    return v;
+}
+
+#END_VERTEX_SHADER
+
+#FRAGMENT_SHADER
+
+Color frag(Color col, Texture tex, Vertex v)
+{
+    return Color(col.rgb, texel(tex, v.uv).a);
+}
+
+#END_FRAGMENT_SHADER
+)";
\ No newline at end of file
diff --git a/src/libjin/graphics/shaders/built-in/je_texture.shader.h b/src/libjin/graphics/shaders/built-in/je_texture.shader.h
new file mode 100644
index 0000000..d1fc86f
--- /dev/null
+++ b/src/libjin/graphics/shaders/built-in/je_texture.shader.h
@@ -0,0 +1,21 @@
+// ��ͼshader
+static const char* texture_shader = R"(
+
+#VERTEX_SHADER
+
+Vertex vert(Vertex v)
+{
+    return v;
+}
+
+#END_VERTEX_SHADER
+
+#FRAGMENT_SHADER
+
+Color frag(Color col, Texture tex, Vertex v)
+{
+    return col * texel(tex, v.uv);
+}
+
+#END_FRAGMENT_SHADER
+)";
\ No newline at end of file
diff --git a/src/libjin/graphics/shaders/je_base.shader.h b/src/libjin/graphics/shaders/je_base.shader.h
new file mode 100644
index 0000000..34996bc
--- /dev/null
+++ b/src/libjin/graphics/shaders/je_base.shader.h
@@ -0,0 +1,89 @@
+#ifndef __JE_BASE_SHADER_H__
+#define __JE_BASE_SHADER_H__
+
+static const char* base_shared = R"(
+#define Number	float
+#define Texture sampler2D 
+#define Canvas  sampler2D 
+#define Color   vec4
+#define Vec2	vec2
+#define Vec3	vec3
+#define Vec4	vec4
+
+#define texel   texture2D
+
+struct Vertex
+{
+    vec2 xy; 
+    vec2 uv;
+};
+
+)";
+
+static const int BASE_SHARED_SIZE = strlen(base_shared);
+
+static const char* base_vertex = R"(
+#version 130 core
+
+%s
+// Projection matrix
+uniform mat4 jin_ProjectionMatrix;
+// Model view matrix
+uniform mat4 jin_ModelViewMatrix;
+
+in vec2 jin_VertexCoords;
+in vec2 jin_TextureCoords;
+
+out vec4 jin_Color;
+out vec2 jin_XY;
+out vec2 jin_UV;
+
+%s
+
+void main()
+{
+	vec4 v = jin_ModelViewMatrix * vec4(jin_VertexCoords, 0, 1.0);
+    Vertex _v = vert(Vertex(v.xy, jin_TextureCoords));
+	gl_Position = jin_ProjectionMatrix * vec4(_v.xy, 0, 1.0f);
+	jin_Color = gl_Color;
+    jin_XY = _v.xy;
+    jin_UV = _v.uv;
+}
+)";
+
+static const int BASE_VERTEX_SHADER_SIZE = strlen(base_vertex) + BASE_SHARED_SIZE;
+
+#define formatVertexShader(buf, program) sprintf(buf,base_vertex, base_shared, program)
+
+static const char* base_fragment = R"(
+#version 130 core
+
+%s
+
+uniform Texture jin_MainTexture;
+
+in vec4 jin_Color;
+in vec2 jin_XY; 
+in vec2 jin_UV;
+
+out vec4 jin_OutColor;
+
+%s
+
+void main()
+{
+    jin_OutColor = frag(jin_Color, jin_MainTexture, Vertex(jin_XY, jin_UV));
+}
+)";
+
+static const int BASE_FRAGMENT_SHADER_SIZE = strlen(base_fragment) + BASE_SHARED_SIZE;
+
+#define formatFragmentShader(buf, program) sprintf(buf, base_fragment, base_shared, program)
+
+static const char* SHADER_PROJECTION_MATRIX = "jin_ProjectionMatrix";
+static const char* SHADER_MODELVIEW_MATRIX = "jin_ModelViewMatrix";
+static const char* SHADER_MAIN_TEXTURE = "jin_MainTexture";
+static const char* SHADER_VERTEX_COORDS = "jin_VertexCoords";
+static const char* SHADER_TEXTURE_COORDS = "jin_TextureCoords";
+
+#endif // __JE_BASE_SHADER_H__
diff --git a/src/libjin/graphics/shaders/je_jsl_compiler.cpp b/src/libjin/graphics/shaders/je_jsl_compiler.cpp
new file mode 100644
index 0000000..feb88d4
--- /dev/null
+++ b/src/libjin/graphics/shaders/je_jsl_compiler.cpp
@@ -0,0 +1,57 @@
+#include "../../core/je_configuration.h"
+#if defined(jin_graphics) && (jin_graphics & jin_graphics_shader)
+
+#include "../../Filesystem/je_buffer.h"
+
+#include "je_jsl_compiler.h"
+
+using namespace std;
+using namespace JinEngine::Filesystem;
+
+namespace JinEngine
+{
+    namespace Graphics
+    {
+        namespace Shaders
+        {
+
+            #include "je_base.shader.h"
+
+            bool JSLCompiler::compile(const string& jsl, string* vertex_shader, string* fragment_shader)
+            {
+                // parse shader source, need some optimizations
+                int loc_VERTEX_SHADER = jsl.find("#VERTEX_SHADER");
+                int loc_END_VERTEX_SHADER = jsl.find("#END_VERTEX_SHADER");
+                int loc_FRAGMENT_SHADER = jsl.find("#FRAGMENT_SHADER");
+                int loc_END_FRAGMENT_SHADER = jsl.find("#END_FRAGMENT_SHADER");
+                if (loc_VERTEX_SHADER == string::npos
+                    || loc_END_VERTEX_SHADER == string::npos
+                    || loc_FRAGMENT_SHADER == string::npos
+                    || loc_END_FRAGMENT_SHADER == string::npos
+                    )
+                    return false;
+                // Load vertex and fragment shader source into buffers.
+                {
+                    // Compile JSL vertex program.
+                    int start = loc_VERTEX_SHADER + strlen("#VERTEX_SHADER");
+                    *vertex_shader = jsl.substr(start, loc_END_VERTEX_SHADER - start);
+                    Buffer vbuffer = Buffer(vertex_shader->length() + BASE_VERTEX_SHADER_SIZE);
+                    formatVertexShader((char*)&vbuffer, vertex_shader->c_str());
+                    vertex_shader->assign((char*)&vbuffer);
+                }
+                {
+                    // Compile JSL fragment program.
+                    int start = loc_FRAGMENT_SHADER + strlen("#FRAGMENT_SHADER");
+                    *fragment_shader = jsl.substr(start, loc_END_FRAGMENT_SHADER - start);
+                    Buffer fbuffer = Buffer(fragment_shader->length() + BASE_FRAGMENT_SHADER_SIZE);
+                    formatFragmentShader((char*)&fbuffer, fragment_shader->c_str());
+                    fragment_shader->assign((char*)&fbuffer);
+                }
+                return true;
+            }
+
+        } // namespace Shaders
+    } // namespace Graphics
+} // namespace JinEngine
+
+#endif // (jin_graphics) && (jin_graphics & jin_graphics_shader)
\ No newline at end of file
diff --git a/src/libjin/graphics/shaders/je_jsl_compiler.h b/src/libjin/graphics/shaders/je_jsl_compiler.h
new file mode 100644
index 0000000..df1e827
--- /dev/null
+++ b/src/libjin/graphics/shaders/je_jsl_compiler.h
@@ -0,0 +1,45 @@
+#ifndef __JE_JSL_COMPILER_H__
+#define __JE_JSL_COMPILER_H__
+
+#include "../../core/je_configuration.h"
+#if defined(jin_graphics) && (jin_graphics & jin_graphics_shader)
+
+#include <string>
+
+#include "../../common/je_singleton.hpp"
+
+namespace JinEngine
+{
+    namespace Graphics
+    {
+        namespace Shaders
+        {
+
+            ///
+            /// Compile JSL into GLSL.
+            ///
+            class JSLCompiler : public Singleton<JSLCompiler>
+            {
+            public:
+                ///
+                /// Compile JSL shader source into GLSL. 
+                /// 
+                /// @param jsl JSL shader source. 
+                /// @param glsl_vertex Output of vertex glsl shader source. 
+                /// @param glsl_fragment Output of fragment glsl shader source.
+                /// @return True if compile successful, otherwise return false.
+                ///
+                bool compile(const std::string& jsl, std::string* glsl_vertex, std::string* glsl_fragment);
+
+            private:
+                singleton(JSLCompiler);
+
+            };
+
+        } // namespace Shaders
+    } // namespace Graphics
+} // namespace JinEngine
+
+#endif // (jin_graphics) && (jin_graphics & jin_graphics_shader)
+
+#endif // __JE_JSL_COMPILER_H__
diff --git a/src/libjin/graphics/shaders/je_shader.cpp b/src/libjin/graphics/shaders/je_shader.cpp
new file mode 100644
index 0000000..c1abbf0
--- /dev/null
+++ b/src/libjin/graphics/shaders/je_shader.cpp
@@ -0,0 +1,281 @@
+#include "../../core/je_configuration.h"
+#if defined(jin_graphics) && (jin_graphics & jin_graphics_shader)
+
+#include <iostream>
+
+#include "../../filesystem/je_buffer.h"
+#include "../../utils/je_macros.h"
+
+#include "je_jsl_compiler.h"
+#include "je_shader.h"
+
+using namespace std;
+using namespace JinEngine::Filesystem;
+
+namespace JinEngine
+{
+	namespace Graphics
+	{
+        namespace Shaders
+        {
+
+            // 
+            // default_texture
+            // base_shader
+            // SHADER_FORMAT_SIZE
+            // formatShader
+            // 
+#include "built-in/je_default.shader.h"
+
+// 
+// https://stackoverflow.com/questions/27941496/use-sampler-without-passing-through-value
+// The default value of a sampler variable is 0. From the GLSL 3.30 spec,
+//     section "4.3.5 Uniforms":
+// 
+// The link time initial value is either the value of the variable's 
+// initializer, if present, or 0 if no initializer is present.Sampler
+// types cannot have initializers.
+// 
+// Since a value of 0 means that it's sampling from texture unit 0, it will 
+// work without ever setting the value as long as you bind your textures to
+// unit 0. This is well defined behavior.
+// 
+// Since texture unit 0 is also the default until you call glActiveTexture()
+// with a value other than GL_TEXTURE0, it's very common to always use unit 
+// 0 as long as shaders do not need more than one texture.Which means that
+// often times, setting the sampler uniforms is redundant for simple
+// applications.
+// 
+// I would still prefer to always set the values.If nothing else, it makes
+// it clear to anybody reading your code that you really mean to sample from
+// texture unit 0, and did not just forget to set the value.
+// 
+            const int DEFAULT_TEXTURE_UNIT = 0;
+
+            /*static*/ Shader* Shader::CurrentShader = nullptr;
+
+            Shader* Shader::createShader(const string& program)
+            {
+                Shader* shader = nullptr;
+                try
+                {
+                    shader = new Shader(program);
+                }
+                catch (...)
+                {
+                    return nullptr;
+                }
+                return shader;
+            }
+
+            Shader::Shader(const string& program)
+                : mCurrentTextureUnit(DEFAULT_TEXTURE_UNIT)
+            {
+                if (!compile(program))
+                    throw 0;
+            }
+
+            Shader::~Shader()
+            {
+                if (CurrentShader == this)
+                    unuse();
+                // delete shader program 
+                glDeleteShader(mPID);
+            }
+
+            bool Shader::compile(const string& program)
+            {
+                string vertex_shader, fragment_shader;
+                // Compile JSL shader source into GLSL shader source. 
+                JSLCompiler* compiler = JSLCompiler::get();
+                if (!compiler->compile(program, &vertex_shader, &fragment_shader))
+                {
+                    return false;
+                }
+#define glsl(SHADER_MODE, SHADER, SRC)              \
+do{                                                 \
+const GLchar* src = SRC.c_str();                    \
+glShaderSource(SHADER, 1, &src, NULL);              \
+glCompileShader(SHADER);                            \
+GLint success;                                      \
+glGetShaderiv(SHADER, GL_COMPILE_STATUS, &success); \
+if (success == GL_FALSE)                            \
+    return false;                                   \
+}while(0)
+                // Compile vertex shader.
+                GLuint vid = glCreateShader(GL_VERTEX_SHADER);
+                glsl(GL_VERTEX_SHADER, vid, vertex_shader);
+                // Compile fragment shader.
+                GLuint fid = glCreateShader(GL_FRAGMENT_SHADER);
+                glsl(GL_FRAGMENT_SHADER, fid, fragment_shader);
+#undef glsl
+                // Create OpenGL shader program.
+                mPID = glCreateProgram();
+                glAttachShader(mPID, vid);
+                glAttachShader(mPID, fid);
+                glLinkProgram(mPID);
+                GLint success;
+                glGetProgramiv(mPID, GL_LINK_STATUS, &success);
+                if (success == GL_FALSE)
+                    return false;
+            }
+
+            static inline GLint getMaxTextureUnits()
+            {
+                GLint maxTextureUnits = 0;
+                glGetIntegerv(GL_MAX_TEXTURE_IMAGE_UNITS, &maxTextureUnits);
+                return maxTextureUnits;
+            }
+
+            void Shader::use()
+            {
+                glUseProgram(mPID);
+                CurrentShader = this;
+                sendInt(SHADER_MAIN_TEXTURE, DEFAULT_TEXTURE_UNIT);
+            }
+
+            /*static*/ void Shader::unuse()
+            {
+                glUseProgram(0);
+                CurrentShader = nullptr;
+            }
+
+            GLint Shader::claimTextureUnit(const std::string& name)
+            {
+                std::map<std::string, GLint>::iterator unit = mTextureUnits.find(name);
+                if (unit != mTextureUnits.end())
+                    return unit->second;
+                static GLint MAX_TEXTURE_UNITS = getMaxTextureUnits();
+                if (++mCurrentTextureUnit >= MAX_TEXTURE_UNITS)
+                    return 0;
+                mTextureUnits[name] = mCurrentTextureUnit;
+                return mCurrentTextureUnit;
+            }
+
+#define checkJSL() \
+		if (CurrentShader != this) \
+			 return
+
+            void Shader::sendInt(const char* name, int value)
+            {
+                checkJSL();
+                int loc = glGetUniformLocation(mPID, name);
+                glUniform1i(loc, value);
+            }
+
+            void Shader::sendFloat(const char* variable, float number)
+            {
+                checkJSL();
+                int loc = glGetUniformLocation(mPID, variable);
+                glUniform1f(loc, number);
+            }
+
+            // 
+            // https://www.douban.com/note/627332677/
+            // struct TextureUnit
+            // {
+            //     GLuint targetTexture1D;
+            //     GLuint targetTexture2D;
+            //     GLuint targetTexture3D;
+            //     GLuint targetTextureCube;
+            //     ...
+            // };
+            // 
+            // TextureUnit mTextureUnits[GL_MAX_TEXTURE_IMAGE_UNITS]
+            // GLuint mCurrentTextureUnit = 0;
+            // 
+            void Shader::sendTexture(const char* variable, const Texture* tex)
+            {
+                checkJSL();
+                GLint location = glGetUniformLocation(mPID, variable);
+                if (location == -1)
+                    return;
+                GLint unit = claimTextureUnit(variable);
+                if (unit == 0)
+                {
+                    // TODO: �쳣�������󶨵����������������
+                    return;
+                }
+                gl.activeTexUnit(unit);
+                glUniform1i(location, unit);
+                gl.bindTexture(tex->getGLTexture());
+                gl.activeTexUnit(0);
+            }
+
+            void Shader::sendCanvas(const char* variable, const Canvas* canvas)
+            {
+                checkJSL();
+                GLint location = glGetUniformLocation(mPID, variable);
+                if (location == -1)
+                    return;
+                GLint unit = claimTextureUnit(variable);
+                if (unit == 0)
+                {
+                    // TODO: �쳣�������󶨵����������������
+                    return;
+                }
+                glUniform1i(location, unit);
+                glActiveTexture(GL_TEXTURE0 + unit);
+                gl.bindTexture(canvas->getGLTexture());
+
+                glActiveTexture(GL_TEXTURE0);
+            }
+
+            void Shader::sendVec2(const char* name, float x, float y)
+            {
+                checkJSL();
+                int loc = glGetUniformLocation(mPID, name);
+                glUniform2f(loc, x, y);
+            }
+
+            void Shader::sendVec3(const char* name, float x, float y, float z)
+            {
+                checkJSL();
+                int loc = glGetUniformLocation(mPID, name);
+                glUniform3f(loc, x, y, z);
+            }
+
+            void Shader::sendVec4(const char* name, float x, float y, float z, float w)
+            {
+                checkJSL();
+                int loc = glGetUniformLocation(mPID, name);
+                glUniform4f(loc, x, y, z, w);
+            }
+
+            void Shader::sendColor(const char* name, const Color* col)
+            {
+                checkJSL();
+                int loc = glGetUniformLocation(mPID, name);
+                glUniform4f(loc,
+                    col->r / 255.f,
+                    col->g / 255.f,
+                    col->b / 255.f,
+                    col->a / 255.f
+                );
+            }
+
+            void Shader::sendMatrix4(const char* name, const Math::Matrix* mat4)
+            {
+                int loc = glGetUniformLocation(mPID, name);
+                glUniformMatrix4fv(loc, 1, GL_FALSE, mat4->getElements());
+            }
+
+            void Shader::setVertexPointer(int n, GLenum type, GLsizei stride, const GLvoid * pointers)
+            {
+                GLint loc = glGetAttribLocation(mPID, SHADER_VERTEX_COORDS);
+                glEnableVertexAttribArray(0);
+                glVertexAttribPointer(loc, n, type, GL_FALSE, stride, pointers);
+            }
+
+            void Shader::setUVPointer(int n, GLenum type, GLsizei stride, const GLvoid * pointers)
+            {
+                GLint loc = glGetAttribLocation(mPID, SHADER_TEXTURE_COORDS);
+                glEnableVertexAttribArray(1);
+                glVertexAttribPointer(loc, n, type, GL_FALSE, stride, pointers);
+            }
+
+        } // namespace Shaders
+	} // namespace Graphics
+} // namespace JinEngine
+
+#endif // (jin_graphics) && (jin_graphics & jin_graphics_shader)
\ No newline at end of file
diff --git a/src/libjin/graphics/shaders/je_shader.h b/src/libjin/graphics/shaders/je_shader.h
new file mode 100644
index 0000000..2009e79
--- /dev/null
+++ b/src/libjin/graphics/shaders/je_shader.h
@@ -0,0 +1,201 @@
+#ifndef __JE_SHADER_H__
+#define __JE_SHADER_H__
+
+#include "../../core/je_configuration.h"
+#if defined(jin_graphics) && (jin_graphics & jin_graphics_shader)
+
+#include <string>
+#include <map>
+
+#include "GLee/GLee.h"
+
+#include "../je_color.h"
+#include "../je_texture.h"
+#include "../je_canvas.h"
+
+#include "je_base.shader.h"
+
+namespace JinEngine
+{
+	namespace Graphics
+	{
+        namespace Shaders
+        {
+
+            /// 
+            /// Built in shader program.
+            /// 
+            /// Built in shader program written with custom shading language called JSL (jin shading language). A 
+            /// JSL program is compiled into glsl, so most glsl built in functions and structs are available in 
+            /// JSL.
+            /// 
+            class Shader
+            {
+            public:
+                /// 
+                /// Create shader program from source code.
+                /// 
+                /// @param source The shader source code.
+                /// 
+                static Shader* createShader(const std::string& source);
+
+                /// 
+                /// Get current shader.
+                /// 
+                /// @return Current used shader program.
+                ///
+                static inline Shader* getCurrentShader() { return CurrentShader; }
+
+                /// 
+                /// Unuse current shader.
+                ///
+                static void unuse();
+
+                /// 
+                /// Destructor of shader.
+                /// 
+                virtual ~Shader();
+
+                /// 
+                /// Use specific shader.
+                /// 
+                void use();
+
+                /// 
+                /// Send float value to shader.
+                /// 
+                /// @param name Name of the uniform variable to be assigned. 
+                /// @param number Value of uniform variable to be sent.
+                /// 
+                void sendFloat(const char* name, float number);
+
+                /// 
+                /// Send texture to shader.
+                ///
+                /// @param name Name of the uniform variable to be assigned.
+                /// @param texture Texture to be sent.
+                /// 
+                void sendTexture(const char*  name, const Texture* texture);
+
+                /// 
+                /// Send integer value to shader 
+                /// 
+                /// @param name Name of the uniform variable to be assigned. 
+                /// @param value Value to be sent.
+                ///
+                void sendInt(const char* name, int value);
+
+                /// 
+                /// Send 2D vector to shader.
+                /// 
+                /// @param name Name of the uniform variable to be assigned.
+                /// @param x X value of the vector to be sent.
+                /// @param y Y value of the vector to be sent.
+                ///
+                void sendVec2(const char* name, float x, float y);
+
+                /// 
+                /// Send 3D vector to shader.
+                /// 
+                /// @param name Name of the uniform variable to be assigned.
+                /// @param x X value of the vector to be sent.
+                /// @param y Y value of the vector to be sent.
+                /// @param z Z value of the vector to be sent.
+                ///
+                void sendVec3(const char* name, float x, float y, float z);
+
+                /// 
+                /// Send 4D vector to shader.
+                /// 
+                /// @param name Name of the uniform variable to be assigned.
+                /// @param x X value of the vector to be sent.
+                /// @param y Y value of the vector to be sent.
+                /// @param z Z value of the vector to be sent.
+                /// @param w W value of the vector to be sent.
+                ///
+                void sendVec4(const char* name, float x, float y, float z, float w);
+
+                ///
+                /// Send canvas to shader. 
+                /// 
+                /// @param name Name of the uniform variable to be assigned. 
+                /// @param canvas Canvas to be sent.
+                ///
+                void sendCanvas(const char* name, const Canvas* canvas);
+
+                ///
+                /// Send color to shader.
+                /// 
+                /// @param name Name of the uniform variable to be assigned.
+                /// @param color Color to be sent.
+                ///
+                void sendColor(const char* name, const Color* color);
+
+                ///
+                /// Send 4 by 4 matrix to shader.
+                /// 
+                /// @param name Name of the uniform variable to be assigned.
+                /// @param mat4 Matrix to be sent.
+                ///
+                void sendMatrix4(const char* name, const Math::Matrix* mat4);
+
+                ///
+                /// Set vertices value.
+                /// 
+                /// @param n Number of vertices. 
+                /// @param type Data type of each component in the array.
+                /// @param stride Byte offset between consecutive generic vertex attributes.
+                /// @param pointers Pointer to the first component of the first generic vertex attribute in the array. 
+                ///
+                void setVertexPointer(int n, GLenum type, GLsizei stride, const GLvoid * pointers);
+
+                ///
+                /// Set texture UV coordinates.
+                /// 
+                /// @param n Number of vertices. 
+                /// @param type Data type of each component in the array.
+                /// @param stride Byte offset between consecutive generic vertex attributes.
+                /// @param pointers Pointer to the first component of the first generic vertex attribute in the array. 
+                ///
+                void setUVPointer(int n, GLenum type, GLsizei stride, const GLvoid * pointers);
+
+            protected:
+                /// 
+                /// Reference of current used shader.
+                /// 
+                static Shader* CurrentShader;
+
+                /// 
+                /// Get texture unit of the uniform texture. If not, assign one.
+                /// 
+                /// @param name Name of the texture uniform variable.
+                /// @return Texture unit which texture variable be assigned.
+                /// 
+                GLint claimTextureUnit(const std::string& name);
+
+                /// 
+                /// Shader constructor.
+                /// 
+                Shader(const std::string& program);
+
+                /// 
+                /// Compile JSL program into GLSL source. 
+                /// 
+                /// @param program JSL source code. 
+                /// @return Return true if compile successed, otherwise return false.
+                /// 
+                bool compile(const std::string& program);
+
+                GLuint mPID;
+                GLint mCurrentTextureUnit;
+                std::map<std::string, GLint> mTextureUnits;
+
+            };
+
+        } // namespace Shaders
+	} // namespace Graphics
+} // namespace JinEngine
+
+#endif // (jin_graphics) && (jin_graphics & jin_graphics_shader)
+
+#endif // __JE_SHADER_H__
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