refactoring loading shaders

src/OGL.cpp

@@ -1,5 +1,6 @@
 #include "OGL.h"
 #include "Camera.h"
+#include "utils.h"
 
 #include <iostream>
 #include <stdexcept>
@@ -122,6 +123,11 @@ void OGL::init() {
 		throw new std::runtime_error(errMsg);
 	}
 
+	// even successful call to glewInit() may cause setting global error GL_INVALID_ENUM,
+	// so we need clear it in order to use glGetError() later
+	// https://www.opengl.org/wiki/OpenGL_Loading_Library#GLEW_.28OpenGL_Extension_Wrangler.29
+	utils::clearGLError();
+
 	glEnable(GL_DEPTH_TEST);
 	glClearDepth(1.0);
 	glDepthFunc(GL_LEQUAL);

src/Shaders/Shader.cpp

@@ -0,0 +1,61 @@
+#include "Shader.h"
+#include "../utils.h"
+#include <iostream>
+#include <fstream>
+#include <sstream>
+#include <cstring>
+#include <memory>
+
+Shader::Shader(GLenum type, const std::string& path): _path(path), _type(type), _shader(0) {
+}
+
+void Shader::compile() {
+	std::ifstream is(_path, std::ios::binary);
+	if(is) {
+		std::ostringstream ss;
+		ss << is.rdbuf();
+		std::string text = ss.str();
+
+		_shader = glCreateShader(_type);
+		utils::throwIfGLError("error creating shader");
+
+		const GLchar* textBuffer = text.c_str();
+		glShaderSource(_shader, 1, &textBuffer, nullptr);
+		utils::throwIfGLError("error setting shader source");
+
+		glCompileShader(_shader);
+		utils::throwIfGLError("error compiling shader");
+
+		GLint success = GL_TRUE;
+		glGetShaderiv(_shader, GL_COMPILE_STATUS, &success);
+		if(success == GL_FALSE) {
+			logCompileError();
+			throw std::runtime_error("error compiling shader: " + _path);
+		}
+	} else {
+		throw std::runtime_error("error opening file: " + _path);
+	}
+}
+
+Shader::operator GLuint() const {
+	return _shader;
+}
+
+Shader::~Shader() {
+	glDeleteShader(_shader);
+}
+
+void Shader::logCompileError() {
+	std::cout << "shader: " << _shader << std::endl;
+	GLint logSize = 0;
+	glGetShaderiv(_shader, GL_INFO_LOG_LENGTH, &logSize);
+	std::cout << "log length: " << logSize << std::endl;
+
+	auto log = std::make_unique<GLchar[]>(logSize);
+	memset(log.get(), 0, (size_t)logSize);
+
+	glGetShaderInfoLog(_shader, logSize, &logSize, log.get());
+	std::cout << "log: " << log.get() << std::endl;
+}
+
+

src/Shaders/Shader.h

@@ -0,0 +1,23 @@
+#ifndef GLTEST_SHADER_H
+#define GLTEST_SHADER_H
+
+#include <string>
+#include <GL/glew.h>
+
+class Shader {
+private:
+	std::string _path;
+	GLenum _type;
+	GLuint _shader;
+
+public:
+	Shader(GLenum type, const std::string& path);
+	void compile();
+	operator GLuint() const;
+	~Shader();
+
+private:
+	void logCompileError();
+};
+
+#endif //GLTEST_SHADER_H

src/Shaders/ShaderProgram.cpp

@@ -1,52 +1,27 @@
 #include <iostream>
 #include <cstring>
 #include "ShaderProgram.h"
+#include "Shader.h"
+#include "../utils.h"
 
-ShaderProgram::ShaderProgram(const char* vertexShaderPath, const char* fragmentShaderPath) {
-	FILE* f = fopen(vertexShaderPath, "rb");
-	fseek(f, 0, SEEK_END);
-	long fsize = ftell(f);
-	fseek(f, 0, SEEK_SET);
-	_vertexShaderText = new char[fsize + 1];
-	fread(_vertexShaderText, fsize, 1, f);
-	fclose(f);
-	_vertexShaderText[fsize] = 0;
-
-	_vertexShader = glCreateShader(GL_VERTEX_SHADER);
-	glShaderSource(_vertexShader, 1, (const GLchar**)&_vertexShaderText, nullptr);
-	glCompileShader(_vertexShader);
-
-	GLint success = GL_TRUE;
-	glGetShaderiv(_vertexShader, GL_COMPILE_STATUS, &success);
-	if(success == GL_FALSE) {
-		std::cout << "error compilling vertex shader" << std::endl;
-		logCompileError(_vertexShader);
-	}
-
-	f = fopen(fragmentShaderPath, "rb");
-	fseek(f, 0, SEEK_END);
-	fsize = ftell(f);
-	fseek(f, 0, SEEK_SET);
-	_fragmentShaderText = new char[fsize + 1];
-	fread(_fragmentShaderText, fsize, 1, f);
-	fclose(f);
-	_fragmentShaderText[fsize] = 0;
-
-	_fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
-	glShaderSource(_fragmentShader, 1,(const GLchar**)&_fragmentShaderText, nullptr);
-	glCompileShader(_fragmentShader);
-
-	glGetShaderiv(_fragmentShader, GL_COMPILE_STATUS, &success);
-	if(success == GL_FALSE) {
-		std::cout << "error compilling fragment shader" << std::endl;
-		logCompileError(_fragmentShader);
-	}
+ShaderProgram::ShaderProgram(const std::string& vertexShaderPath, const std::string& fragmentShaderPath) {
+	Shader vShader(GL_VERTEX_SHADER, vertexShaderPath);
+	Shader fShader(GL_FRAGMENT_SHADER, fragmentShaderPath);
 
+	vShader.compile();
+	fShader.compile();
 
 	_program = glCreateProgram();
-	glAttachShader(_program, _vertexShader);
-	glAttachShader(_program, _fragmentShader);
+	if(_program == 0) {
+		throw std::runtime_error("error creating shader program");
+	}
+
+	glAttachShader(_program, vShader);
+	utils::throwIfGLError("error attaching vertex shader to program");
+	glAttachShader(_program, fShader);
+	utils::throwIfGLError("error attaching fragment shader to program");
 	glLinkProgram(_program);
+	utils::throwIfGLError("error linking program");
 }
 
 void ShaderProgram::use() const {
@@ -54,26 +29,8 @@ void ShaderProgram::use() const {
 }
 
 ShaderProgram::~ShaderProgram() {
-	delete[] _vertexShaderText;
-	delete[] _fragmentShaderText;
-
-	glDeleteShader(_vertexShader);
-	glDeleteShader(_fragmentShader);
 }
 
 ShaderProgram::operator GLuint() const {
 	return _program;
 }
-
-void ShaderProgram::logCompileError(GLuint shader) {
-	std::cout << "shader: " << shader << std::endl;
-	GLint logSize = 0;
-	glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &logSize);
-	std::cout << "log length: " << logSize << std::endl;
-
-	GLchar* log = new GLchar[logSize];
-	memset(log, 0, (size_t)logSize);
-
-	glGetShaderInfoLog(shader, logSize, &logSize, log);
-	std::cout << "log: " << log << std::endl;
-}

src/Shaders/ShaderProgram.h

@@ -8,19 +8,12 @@
 class ShaderProgram {
 private:
 	GLuint _program;
-	GLuint  _vertexShader;
-	GLuint  _fragmentShader;
-	char* _vertexShaderText;
-	char* _fragmentShaderText;
 
 public:
-	ShaderProgram(const char* vertexShaderPath, const char* fragmentShaderPath);
+	ShaderProgram(const std::string& vertexShaderPath, const std::string& fragmentShaderPath);
 	void use() const;
 	operator GLuint() const;
 	~ShaderProgram();
-
-private:
-	void logCompileError(GLuint shader);
 };
 
 

src/utils.cpp

@@ -0,0 +1,28 @@
+#include "utils.h"
+#include <GL/glew.h>
+#include <stdexcept>
+
+namespace utils {
+	void throwIfGLError(const std::string& msg) {
+		std::string err;
+		while(true) {
+			GLenum error = glGetError();
+			if(error != GL_NO_ERROR) {
+				const char* errorStr = (const char*)gluErrorString(error);
+				if(errorStr) {
+					err += std::string(errorStr) + "\n";
+				}
+			} else {
+				break;
+			}
+		}
+
+		if(!err.empty()) {
+			throw std::runtime_error(msg + ": " + err);
+		}
+	}
+
+	void clearGLError() {
+		while(glGetError() != GL_NO_ERROR);
+	}
+}

src/utils.h

@@ -0,0 +1,11 @@
+#ifndef GLTEST_UTILS_H
+#define GLTEST_UTILS_H
+
+#include <string>
+
+namespace utils {
+	void throwIfGLError(const std::string& msg);
+	void clearGLError();
+}
+
+#endif //GLTEST_UTILS_H