1 files changed, 138 insertions, 0 deletions
diff --git a/src/glsl_program.cpp b/src/glsl_program.cpp
new file mode 100644
index 00000000..6fe7cf07
--- /dev/null
+++ b/src/glsl_program.cpp
@@ -0,0 +1,138 @@
+#include "glsl_program.hpp"
+
+#include <fstream>
+#include <stdexcept>
+#include <vector>
+
+GlslProgram::GlslProgram()
+{}
+
+GlslProgram::~GlslProgram()
+{
+    // cleanup all the shaders and the program
+    if(fragment_shader_id_ != 0)
+	glDeleteShader(fragment_shader_id_);
+    
+    if(vertex_shader_id_ != 0)
+	glDeleteShader(vertex_shader_id_);
+    
+    if(program_id_ != 0)
+	glDeleteProgram(program_id_);
+}
+
+void GlslProgram::compileShader(const GLuint &shader, const std::string &file_path)
+{
+    // get a string with the input from the shader file
+    std::ifstream file(file_path);
+    if(!file.is_open())
+	throw std::runtime_error("Failed to open '"+file_path+"'");
+
+    std::string content = "";
+    std::string line;
+
+    while(std::getline(file, line))
+	content+=line+"\n";
+    file.close();
+
+    // cast source to a c string to get the address of it and input it for compilation
+    const GLchar *vertex_source = (const GLchar *)content.c_str();
+    glShaderSource(shader, 1, &vertex_source, nullptr);
+    glCompileShader(shader);
+
+    // check if compilation was successful
+    GLint is_compiled = 0;
+    glGetShaderiv(shader, GL_COMPILE_STATUS, (int *)&is_compiled);
+
+    // if it isn't compiled throw exception to clean up
+    if(is_compiled == GL_FALSE)
+    {
+	GLint max_length = 0;
+	glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &max_length);
+ 
+	std::vector<GLchar> error_log(max_length);
+	glGetShaderInfoLog(shader, max_length, &max_length, &error_log[0]);
+	std::string error_log_str((const char *)&error_log[0]);
+	
+	throw std::runtime_error("Couldn't compile "+file_path+" : "+error_log_str);
+    }
+}
+
+void GlslProgram::compileShaders(const std::string &vertex_shader_path, const std::string &fragment_shader_path)
+{
+    // create the program that will be run on GPU
+    program_id_ = glCreateProgram();
+
+    // create vertex shader
+    vertex_shader_id_ = glCreateShader(GL_VERTEX_SHADER);
+    if(vertex_shader_id_ == 0)
+	throw std::runtime_error("Vertex shader failed to be created");
+
+    // create fragment shader
+    fragment_shader_id_ = glCreateShader(GL_FRAGMENT_SHADER);
+    if(fragment_shader_id_ == 0)
+	throw std::runtime_error("Fragment shader failed to be created");
+
+    // compile the two shaders
+    compileShader(vertex_shader_id_, vertex_shader_path);
+    compileShader(fragment_shader_id_, fragment_shader_path);    
+}
+
+void GlslProgram::linkShaders()
+{
+    // attach the shaders that we want
+    glAttachShader(program_id_, vertex_shader_id_);
+    glAttachShader(program_id_, fragment_shader_id_);
+
+    // link our program
+    glLinkProgram(program_id_);
+
+    GLint is_linked = 0;
+    glGetProgramiv(program_id_, GL_LINK_STATUS, (int *)&is_linked);
+    if(is_linked == GL_FALSE)
+    {
+	GLint max_length = 0;
+	glGetProgramiv(program_id_, GL_INFO_LOG_LENGTH, &max_length);
+
+	std::vector<GLchar> error_log(max_length);
+	glGetProgramInfoLog(program_id_, max_length, &max_length, &error_log[0]);
+
+	std::string error_log_str((const char *)&error_log[0]);
+
+	throw std::runtime_error("Could not link program : "+error_log_str);
+    }
+
+    // detach shaders after successful link
+    glDetachShader(program_id_, fragment_shader_id_);
+    glDetachShader(program_id_, vertex_shader_id_);
+
+    // we can then delete the shaders once we have the program
+    glDeleteShader(fragment_shader_id_);
+    glDeleteShader(vertex_shader_id_);    
+}
+
+void GlslProgram::addAttribute(const std::string &attribute_name)
+{
+    glBindAttribLocation(program_id_, attribute_index_++, attribute_name.c_str());
+}
+
+GLint GlslProgram::getUniformLocation(const std::string &uniform_name)
+{
+    GLint location = glGetUniformLocation(program_id_, uniform_name.c_str());
+    if((GLuint)location == GL_INVALID_INDEX)
+	throw std::runtime_error("'"+uniform_name+"' not found");
+    return location;
+}
+
+void GlslProgram::use()
+{
+    glUseProgram(program_id_);
+    for(int i = 0; i < attribute_index_; ++i)
+	glEnableVertexAttribArray(i);
+}
+
+void GlslProgram::unuse()
+{
+    for(int i = 0; i < attribute_index_; ++i)
+	glDisableVertexAttribArray(i);
+    glUseProgram(0);
+}