glsl-basic/src/graphics.cpp

#include <boost/log/trivial.hpp>
#include <exception>
#include <glad/glad.c>
// glad must be loaded before GLFW
#include "graphics.hpp"
#include "main.hpp"

#include <iostream>

using namespace std;

/* class ShaderProgram Implementations */
string ShaderProgram::baseName() {
  /*
  BOOST_LOG_TRIVIAL(debug) << "this->base: " << this->base
                           << " Base::Empty: " << Base::Empty
                           << " Base::Triangle: " << Base::Triangle;
  */
  switch (this->base) {
  case ShaderProgram::Base::Empty:
    return "Empty";
  case ShaderProgram::Base::Triangle:
    return "Triangle";
  default:
    // this should never occur, as the switch case should cover all variants.
    throw std::runtime_error("Undefined base Program");
  }
}

ShaderProgram::ShaderProgram(Base base, char **vertexSource,
                             char **fragSource) {
  this->base = base;
  BOOST_LOG_TRIVIAL(info) << "With base program \"" << this->baseName() << "\"";
  // NOTE: char arrays and char pointers are not actually the same.
  // glShaderSource requires a char[] as it appears. We pass the
  // variable by reference to avoid duplication in memory.
  BOOST_LOG_TRIVIAL(trace) << "creating empty shaders";
  this->vertex = glCreateShader(GL_VERTEX_SHADER);
  this->frag = glCreateShader(GL_FRAGMENT_SHADER);
  BOOST_LOG_TRIVIAL(trace) << "loading vertex shader";
  glShaderSource(this->vertex, 1, vertexSource, NULL);
  BOOST_LOG_TRIVIAL(trace) << "compiling vertex shader";
  glCompileShader(this->vertex);
  BOOST_LOG_TRIVIAL(trace) << "loading fragments shader";
  glShaderSource(this->frag, 2, fragSource, NULL);
  BOOST_LOG_TRIVIAL(trace) << "compiling fragments shader";
  glCompileShader(this->frag);
}

/** runs for every frame
 *
 * will be called in `mainWindow`.
 *
 * FIXME: dont run the switch case every frame.
 */
int ShaderProgram::run() {
  switch (this->base) {
  case Empty: // same as default
  default:
    glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);
    break;
  }
  return 0;
}

void framebuffer_size_callback(GLFWwindow *window, int width, int height) {
  glViewport(0, 0, width, height);
}

GLFWwindow *initGl() {
  /* graphics stuff */
  glfwInit();
  glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
  glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
  glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
  // glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);

  GLFWwindow *window = glfwCreateWindow(800, 600, "Shader Loader", NULL, NULL);
  if (window == NULL) {
    printf("Failed to create GLFW window\n");
    glfwTerminate();
    exit(EXIT_GL);
  }
  glfwMakeContextCurrent(window);

  if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
    printf("Failed to initialize GLAD\n");
    exit(EXIT_GL);
  }

  glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
  return window;
}

int mainWindow(ShaderProgram *shaderProgram, GLFWwindow *window) {

  int result = 0;

  BOOST_LOG_TRIVIAL(trace) << "Entering window loop";
  while (!glfwWindowShouldClose(window)) {
    processInput(window);
    shaderProgram->run();
    glfwSwapBuffers(window);
    glfwPollEvents();
  }
  BOOST_LOG_TRIVIAL(trace) << "Left window loop";

  glfwTerminate();
  return result;
}

void processInput(GLFWwindow *window) {
  if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
    glfwSetWindowShouldClose(window, true);
}