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glfwImgui.cpp
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glfwImgui.cpp
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#include <cstdlib>
#include <iostream>
#include <string>
#include <sstream>
#include <vector>
// Dear imgui related headers
#include "imgui/imgui.h"
#include "imgui/imgui_impl_glfw.h"
#include "imgui/imgui_impl_opengl3.h"
#include <GL/glew.h>
#include <GLFW/glfw3.h>
#define GLM_FORCE_PURE
#define GLM_FORCE_RADIANS
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
// Define helpful macros for handling offsets into buffer objects
#define BUFFER_OFFSET( offset ) ((GLvoid*) (offset))
#define OFFSET_OF(type, member) ((GLvoid*)(offsetof(type, member)))
// GLFW related callbacks
void glfw_error_callback(int error, const char* description);
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods);
void resize_callback(GLFWwindow* window, int new_window_width, int new_window_height);
void mouse_button_callback(GLFWwindow* window, int button, int action, int mods);
void cursor_position_callback(GLFWwindow* window, double xpos, double ypos);
// OpenGL's debug logger callback (needs context 4.3 or above)
void APIENTRY opengl_error_callback(GLenum source, GLenum type, GLuint id, GLenum severity,
GLsizei length, const GLchar *message, const void *userParam);
class OpenGLApplication {
public:
OpenGLApplication() {};
void run();
bool m_rotating = false;
float m_current_angle = 0.0f;
bool m_mouse_drag = false;
private:
// Window and context handle
GLFWwindow* m_window = nullptr;
// Location for shader variables
GLint m_u_PVM_location = -1;
GLint m_a_position_loc = -1;
GLint m_a_color_loc = -1;
// OpenGL program handlers
GLuint m_vertex_shader = 0;
GLuint m_fragment_shader = 0;
GLuint m_program = 0;
// Global variables for the program logic
int m_nTriangles = 0;
double m_last_time = 0.0;
std::string m_context_info;
// Manage the Vertex Buffer Objects using a Vertex Array Object
GLuint m_vao = 0;
// Function declarations
void init_glfw();
void load_OpenGL();
void init_program();
void create_primitives_and_send_to_gpu();
void setup_menu();
void create_menu();
void render();
void update();
void free_resources();
// GLFW related callbacks
void register_glfw_callbacks();
// Print shader compilation errors
void print_shader_log(GLint const shader);
// get info from the used libraries versions
std::string enviroment_info();
};
int main (int argc, char* argv[]) {
OpenGLApplication app;
try {
app.run();
} catch (const std::exception& e) {
std::cerr << e.what() << std::endl;
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
void OpenGLApplication::run() {
init_glfw();
load_OpenGL();
setup_menu();
init_program();
register_glfw_callbacks();
while (!glfwWindowShouldClose(m_window)) {
create_menu();
render();
update();
glfwSwapBuffers(m_window);
glfwPollEvents();
}
free_resources();
}
void OpenGLApplication::setup_menu() {
// Setup Dear ImGui context
IMGUI_CHECKVERSION();
ImGui::CreateContext();
ImGuiIO& io = ImGui::GetIO(); (void)io;
ImGui::StyleColorsDark();
ImGui_ImplGlfw_InitForOpenGL(m_window, true);
const char* glsl_version{"#version 130"};
ImGui_ImplOpenGL3_Init(glsl_version);
}
void OpenGLApplication::create_menu() {
// Start the Dear ImGui frame
ImGui_ImplOpenGL3_NewFrame();
ImGui_ImplGlfw_NewFrame();
ImGui::NewFrame();
// Draw the menu
ImGui::Begin("Triangle's basic menu");
ImGui::Text("Options");
if (ImGui::Checkbox("Rotate", &m_rotating)) { //Imgui's controls return true on interaction
m_current_angle = 0.0f;
}
if (ImGui::CollapsingHeader("Enviroment info:")) {
ImGui::Text("%s", m_context_info.c_str());
}
if (ImGui::CollapsingHeader("Application stats")) {
ImGui::Text("Average frame: %.3f ms", 1000.0f / ImGui::GetIO().Framerate);
ImGui::Text("FPS: %.1f", ImGui::GetIO().Framerate);
}
ImGui::End();
}
void OpenGLApplication::init_glfw() {
using std::cerr;
using std::endl;
// Set error log for GLFW
glfwSetErrorCallback(glfw_error_callback);
// Try to init libary
if (!glfwInit()) {
// Initialization failed
throw std::runtime_error("GLFW initialization failed!");
}
// Library was initializated, now try window and context
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 6);
glfwWindowHint(GLFW_SAMPLES, 4);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, GL_TRUE);
m_window = glfwCreateWindow(900, 600, "OpenGL Menu sample - glfw", nullptr, nullptr);
if (!m_window) {
// Window or context creation failed
glfwTerminate();
throw std::runtime_error("OpenGL context not available");
}
// Context setting to happen before OpenGL's extension loader
glfwMakeContextCurrent(m_window);
glfwSwapInterval(1);
}
void OpenGLApplication::load_OpenGL() {
using std::cout;
using std::cerr;
using std::endl;
/************************************************************************/
/* Init OpenGL context */
/************************************************************************/
GLenum err = glewInit();
if (GLEW_OK != err) {
std::stringstream ss;
ss << "Glew initialization failed: " << glewGetErrorString(err);
throw std::runtime_error(ss.str());
}
m_context_info = enviroment_info();
/************************************************************************/
/* OpenGL Debug context */
/************************************************************************/
GLint flags;
glGetIntegerv(GL_CONTEXT_FLAGS, &flags);
if (flags & GL_CONTEXT_FLAG_DEBUG_BIT) {
glEnable(GL_DEBUG_OUTPUT);
glEnable(GL_DEBUG_OUTPUT_SYNCHRONOUS);
glDebugMessageCallback(opengl_error_callback, nullptr);
glDebugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DONT_CARE, 0, nullptr, GL_TRUE);
cout << "OpenGL's debug logger active" << endl;
} else {
cout << "OpenGL's debug disabled" << endl;
}
}
void OpenGLApplication::init_program() {
/************************************************************************/
/* OpenGL program (pipeline) creation */
/************************************************************************/
using std::string;
using std::cerr;
using std::endl;
/* In a normal program the shader should be in separate text files
I put them here to avoid another layer of complexity */
const string vertex_shader_src = R"GLSL(
#version 130
in vec3 Position;
in vec3 Color;
uniform mat4 PVM;
out vec4 vColor;
void main(void) {
gl_Position = PVM * vec4(Position, 1.0f);
vColor = vec4(Color, 1.0);
}
)GLSL";
const string fragment_shader_src = R"GLSL(
#version 130
in vec4 vColor;
out vec4 fragcolor;
void main(void) {
fragcolor = vColor;
}
)GLSL";
m_vertex_shader = glCreateShader(GL_VERTEX_SHADER);
const char* start = &vertex_shader_src[0];
glShaderSource(m_vertex_shader, 1, &start, nullptr);
m_fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
start = &fragment_shader_src[0];
glShaderSource(m_fragment_shader, 1, &start, nullptr);
int status{0};
glCompileShader(m_vertex_shader);
glGetShaderiv(m_vertex_shader, GL_COMPILE_STATUS, &status);
if (status == GL_FALSE) {
cerr << "Vertex shader was not compiled!!" << endl;
print_shader_log(m_vertex_shader);
}
glCompileShader(m_fragment_shader);
glGetShaderiv(m_fragment_shader, GL_COMPILE_STATUS, &status);
if (status == GL_FALSE) {
cerr << "Fragment shader was not compiled!!" << endl;
print_shader_log(m_fragment_shader);
}
m_program = glCreateProgram();
glAttachShader(m_program, m_vertex_shader);
glAttachShader(m_program, m_fragment_shader);
//glBindFragDataLocation(program, 0, "fragcolor");
glLinkProgram(m_program);
glGetProgramiv(m_program, GL_LINK_STATUS, &status);
if (status == GL_FALSE) {
cerr << "OpenGL program was not linked!!" << endl;
}
/* Now, that we have the program, query location of shader variables */
m_u_PVM_location = glGetUniformLocation(m_program, "PVM");
m_a_position_loc = glGetAttribLocation(m_program, "Position");
m_a_color_loc = glGetAttribLocation(m_program, "Color");
/* Then, create primitives and send data to GPU */
create_primitives_and_send_to_gpu();
//Initialize some basic rendering state
glEnable(GL_DEPTH_TEST);
//Dark gray background color
glClearColor(0.15f, 0.15f, 0.15f, 1.0f);
}
void OpenGLApplication::create_primitives_and_send_to_gpu() {
//Create primitives
struct Vertex {
glm::vec3 position;
glm::vec3 color;
};
std::vector<Vertex> vertices;
vertices.push_back({ { -1.0f, -1.0f, 0.0f }, { 0.0f, 1.0f, 0.0f } }); //0
vertices.push_back({ { 1.0f, -1.0f, 0.0f }, { 1.0f, 0.0f, 0.0f } }); //1
vertices.push_back({ { 0.0f, 1.0f, 0.0f }, { 0.0f, 0.0f, 1.0f } }); //2
std::vector<unsigned short> indices;
indices.push_back(0);
indices.push_back(1);
indices.push_back(2);
m_nTriangles = indices.size() / 3;
//Create the vertex buffer objects and VAO
GLuint vbo;
GLuint indexBuffer;
glGenVertexArrays(1, &m_vao);
glGenBuffers(1, &vbo);
glGenBuffers(1, &indexBuffer);
// Bind the vao this need to be done before anything
glBindVertexArray(m_vao);
//Send data to GPU: first send the vertices
glBindBuffer(GL_ARRAY_BUFFER, vbo);
glBufferData(GL_ARRAY_BUFFER, vertices.size() * sizeof(Vertex), vertices.data(), GL_STATIC_DRAW);
glEnableVertexAttribArray(m_a_position_loc);
glVertexAttribPointer(m_a_position_loc, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex),
OFFSET_OF(Vertex, position));
glEnableVertexAttribArray(m_a_color_loc);
glVertexAttribPointer(m_a_color_loc, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex),
OFFSET_OF(Vertex, color));
//Now, the indices
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, indexBuffer);
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.size() * sizeof(unsigned short),
indices.data(), GL_STATIC_DRAW);
// Unbind the vao we will use it for render
glBindVertexArray(0);
// Now that we have the data in the GPU and the reference in vao we do not need to keep it
glDeleteBuffers(1, &vbo);
glDeleteBuffers(1, &indexBuffer);
vertices.clear();
indices.clear();
}
void OpenGLApplication::render() {
ImGui::Render(); // Prepare to render our menu, before clearing buffers
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(m_program);
/************************************************************************/
/* Calculate Model View Projection Matrices */
/************************************************************************/
//Math constant equal two PI (Remember, we are in radians)
const float TAU = 6.28318f;
//Identity matrix
glm::mat4 I(1.0f);
//Model
glm::mat4 M = I;
if (m_rotating) {
M = glm::rotate(M, glm::radians(m_current_angle), glm::vec3(0.0f, 1.0f, 0.0f));
}
//View
glm::vec3 camera_up = glm::vec3(0.0f, 1.0f, 0.0f);
glm::vec3 camera_position = glm::vec3(0.0f, 0.0f, 3.5f);
glm::vec3 camera_eye = glm::vec3(0.0f, 0.0f, 0.0f);
glm::mat4 V = glm::lookAt(camera_position, camera_eye, camera_up);
//Projection
int width;
int height;
glfwGetWindowSize(m_window, &width, &height);
GLfloat aspect = float(width) / float(height);
GLfloat fovy = TAU / 8.0f;
GLfloat zNear = 1.0f;
GLfloat zFar = 5.0f;
glm::mat4 P = glm::perspective(fovy, aspect, zNear, zFar);
/************************************************************************/
/* Send uniform values to shader */
/************************************************************************/
if (m_u_PVM_location != -1) {
glUniformMatrix4fv(m_u_PVM_location, 1, GL_FALSE, glm::value_ptr(P * V * M));
}
/************************************************************************/
/* Bind buffer object and their corresponding attributes (use VAO) */
/************************************************************************/
glBindVertexArray(m_vao);
/* Draw */
const int start_index = 0; //In location corresponding the index array
glDrawElements(GL_TRIANGLES, 3 * m_nTriangles, GL_UNSIGNED_SHORT,
BUFFER_OFFSET(start_index * sizeof(unsigned short)));
//Unbind and clean
glBindVertexArray(0);
glUseProgram(0);
/* Render menu after the geometry of our actual app*/
ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
}
void OpenGLApplication::update() {
double time = glfwGetTime();
double elapsed = time - m_last_time;
m_last_time = time;
/*If rotating update angle*/
if (m_rotating) {
const float speed = 180.0f; //In degrees per second
m_current_angle += float(elapsed) * speed;
if (m_current_angle > 360.0f) {
int quotient = int(m_current_angle / 360.0f);
m_current_angle -= quotient * 360.0f;
}
}
}
void OpenGLApplication::register_glfw_callbacks() {
// Associate the class instance so, it can be acceses from
// inside the static callback functions
glfwSetWindowUserPointer(m_window, static_cast<void*>(this));
glfwSetWindowSizeCallback(m_window, resize_callback);
glfwSetKeyCallback(m_window, key_callback);
glfwSetMouseButtonCallback(m_window, mouse_button_callback);
glfwSetCursorPosCallback(m_window, cursor_position_callback);
//glfwSetMousePosCallback(mouse_motion_callback);
}
void key_callback(GLFWwindow* windowPtr, int key, int scancode, int action, int mods) {
ImGuiIO& io = ImGui::GetIO();
//Imgui wants this event, since it happen inside the GUI
if (io.WantCaptureKeyboard) {
return;
}
//The event happen outside the GUI, your application should try to handle it
//Get reference to the main class instance
auto* app = static_cast<OpenGLApplication*>(glfwGetWindowUserPointer(windowPtr));
if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS) {
glfwSetWindowShouldClose(windowPtr, GLFW_TRUE);
} else if (key == GLFW_KEY_R && action == GLFW_PRESS) {
app->m_rotating = !app->m_rotating;
app->m_current_angle = 0.0f;
}
}
void mouse_button_callback(GLFWwindow* window, int button, int action, int mods) {
ImGuiIO& io = ImGui::GetIO();
//Imgui wants this event, since it happen inside the GUI
if (io.WantCaptureMouse) {
return;
}
//The event happen outside the GUI, your application should try to handle it
//Get reference to the main class instance
auto* app = static_cast<OpenGLApplication*>(glfwGetWindowUserPointer(window));
if (button == GLFW_MOUSE_BUTTON_LEFT && action == GLFW_PRESS) {
//std::cout << "Click in!" << std::endl;
app->m_mouse_drag = true;
} else if (button == GLFW_MOUSE_BUTTON_LEFT && action == GLFW_RELEASE) {
//std::cout << "Click out" << std::endl;
app->m_mouse_drag = false;
}
}
void cursor_position_callback(GLFWwindow* window, double xpos, double ypos) {
ImGuiIO& io = ImGui::GetIO();
//Imgui wants this event, since it happen inside the GUI
if (io.WantCaptureMouse) {
return;
}
//The event happen outside the GUI, your application should try to handle it
//if (mouse_drag) {
// std::cout << "(" << xpos << ", " << ypos << ")" << std::endl;
//}
}
void resize_callback(GLFWwindow* windowPtr, int new_window_width, int new_window_height) {
glViewport(0, 0, new_window_width, new_window_height);
}
void glfw_error_callback(int error, const char* description) {
using std::cerr;
using std::endl;
cerr << "GLFW Error: " << description << endl;
}
void OpenGLApplication::free_resources() {
/* Release imgui resources */
ImGui_ImplOpenGL3_Shutdown();
ImGui_ImplGlfw_Shutdown();
ImGui::DestroyContext();
/* Delete OpenGL program */
glDetachShader(m_program, m_vertex_shader);
glDetachShader(m_program, m_fragment_shader);
glDeleteShader(m_vertex_shader);
glDeleteShader(m_fragment_shader);
glDeleteProgram(m_program);
//Window and context destruction
glfwDestroyWindow(m_window);
}
void APIENTRY opengl_error_callback(GLenum source,
GLenum type,
GLuint id,
GLenum severity,
GLsizei length,
const GLchar *message,
const void *userParam) {
using std::cout;
using std::endl;
using std::string;
using std::to_string;
// ignore non-significant error/warning codes
if(id == 131169 || id == 131185 || id == 131218 || id == 131204) {
return;
}
// Gather all the info in strings
string source_str;
switch (source) {
case GL_DEBUG_SOURCE_API: source_str = "API"; break;
case GL_DEBUG_SOURCE_WINDOW_SYSTEM: source_str = "Window System"; break;
case GL_DEBUG_SOURCE_SHADER_COMPILER: source_str = "Shader Compiler"; break;
case GL_DEBUG_SOURCE_THIRD_PARTY: source_str = "Third Party"; break;
case GL_DEBUG_SOURCE_APPLICATION: source_str = "Application"; break;
case GL_DEBUG_SOURCE_OTHER: source_str = "Other"; break;
}
string type_str;
switch (type) {
case GL_DEBUG_TYPE_ERROR: type_str = "Error"; break;
case GL_DEBUG_TYPE_DEPRECATED_BEHAVIOR: type_str = "Deprecated Behaviour"; break;
case GL_DEBUG_TYPE_UNDEFINED_BEHAVIOR: type_str = "Undefined Behaviour"; break;
case GL_DEBUG_TYPE_PORTABILITY: type_str = "Portability"; break;
case GL_DEBUG_TYPE_PERFORMANCE: type_str = "Performance"; break;
case GL_DEBUG_TYPE_MARKER: type_str = "Marker"; break;
case GL_DEBUG_TYPE_PUSH_GROUP: type_str = "Push Group"; break;
case GL_DEBUG_TYPE_POP_GROUP: type_str = "Pop Group"; break;
case GL_DEBUG_TYPE_OTHER: type_str = "Other"; break;
}
string severity_str;
switch (severity) {
case GL_DEBUG_SEVERITY_HIGH: severity_str = "high"; break;
case GL_DEBUG_SEVERITY_MEDIUM: severity_str = "medium"; break;
case GL_DEBUG_SEVERITY_LOW: severity_str = "low"; break;
case GL_DEBUG_SEVERITY_NOTIFICATION: severity_str = "notification"; break;
}
// format message
string msg = string("OpenGL error (") + to_string(id) + string("): ") + message + string("\n") +
string("Source: ") + source_str + string("\n") +
string("Type: ") + type_str + string("\n") +
string("Severity: ") + severity_str + string("\n");
// print error to console
cout << msg << endl;
}
void OpenGLApplication::print_shader_log(GLint const shader) {
using std::cerr;
using std::endl;
int log_length = 0;
int chars_written = 0;
glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &log_length);
if (log_length > 0) {
GLchar *log = new GLchar[log_length];
glGetShaderInfoLog(shader, log_length, &chars_written, log);
cerr << "Shader Info Log:" << endl;
cerr << log << endl;
delete [] log;
}
}
std::string OpenGLApplication::enviroment_info() {
using std::endl;
std::stringstream info;
info << "Hardware: " << endl;
info << "\tVendor: " << glGetString(GL_VENDOR) << endl;
info << "\tRenderer: " << glGetString(GL_RENDERER) << endl;
info << "Software: " << endl;
info << "\tDriver:" << endl;
info << "\t\tOpenGL version: " << glGetString(GL_VERSION) << endl;
info << "\t\tGLSL version: " << glGetString(GL_SHADING_LANGUAGE_VERSION) << endl;
info << "\tLibraries:" << endl;
info << "\t\tGLEW version: " << glewGetString(GLEW_VERSION) << endl;
info << "\t\tGLFW version: " << GLFW_VERSION_MAJOR << "." << GLFW_VERSION_MINOR
<< "." << GLFW_VERSION_REVISION << endl;
info << "\t\tGLM version: " << (GLM_VERSION / 1000) << "." << (GLM_VERSION / 100)
<< "." << (GLM_VERSION % 100 / 10) << "." << (GLM_VERSION % 10) << endl;
info << "\t\tDear Imgui version: " << ImGui::GetVersion();
return info.str();
}