#include <glad/glad.h>
#include <glfw3.h>
#include <iostream>
const unsigned int SCR_WIDTH = 800;
const unsigned int SCR_HEIGHT = 600;
const char* vertexShaderSource =
"#version 450 core\n"
"layout (location = 0) in vec3 aPos;\n"
"void main()\n"
"{\n"
" gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
"}\n\0";
const char* fragmentShaderBlueSource =
"#version 450 core\n"
"out vec4 FragmentColor;\n"
"void main()\n"
"{\n"
" FragmentColor = vec4(0.0f, 0.0f, 1.0f, 1.0f);\n"
"}\n\0";
const char* fragmentShaderYellowSource =
"#version 450 core\n"
"out vec4 FragmentColor;\n"
"void main()\n"
"{\n"
" FragmentColor = vec4(1.0f, 1.0f, 0.0f, 0.0f);\n"
"}\n\0";
// glfw: when window size changed this callback function executes // glfwSetFramebufferSizeCallback
void framebuffer_size_callback(GLFWwindow* window, int width, int height) {
// glfw: the viewport matches the new window dimensions
glViewport(0, 0, width, height);
}
// glfw: process keys
void processInput(GLFWwindow* window) {
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, true);
}
int main()
{
// glfw: initialize
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 5);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
// glfw: create window
GLFWwindow* window = glfwCreateWindow(SCR_WIDTH, SCR_HEIGHT, "Window Title", NULL, NULL);
if (window == NULL) {
std::cout << "Failed to create GLFW window" << "\n";
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
// glad: load all OpenGL function pointers
if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress)) {
std::cout << "Failed to initialize GLAD" << "\n";
return -1;
}
// build and compile shader program
int success;
char errorInfo[512] = "";
// vertex shader
unsigned int vertexShader = glCreateShader(GL_VERTEX_SHADER);
unsigned int fragmentShaderBlue = glCreateShader(GL_FRAGMENT_SHADER);
unsigned int fragmentShaderYellow = glCreateShader(GL_FRAGMENT_SHADER);
unsigned int shaderProgramBlue = glCreateProgram();
unsigned int shaderProgramYellow = glCreateProgram();
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, &success);
if (!success) {
glGetShaderInfoLog(vertexShader, 512, NULL, errorInfo);
std::cout << "glCompileShader(vertexShader); FAILED\n" << errorInfo << "\n";
}
glShaderSource(fragmentShaderBlue, 1, &fragmentShaderBlueSource, NULL);
glCompileShader(fragmentShaderBlue);
glGetShaderiv(fragmentShaderBlue, GL_COMPILE_STATUS, &success);
if (!success) {
glGetShaderInfoLog(fragmentShaderBlue, 512, NULL, errorInfo);
std::cout << "glCompileShader(fragmentShaderBlue); FAILED\n" << errorInfo << "\n";
}
glShaderSource(fragmentShaderYellow, 1, &fragmentShaderYellowSource, NULL);
glCompileShader(fragmentShaderYellow);
glGetShaderiv(fragmentShaderYellow, GL_COMPILE_STATUS, &success);
if (!success) {
glGetShaderInfoLog(fragmentShaderYellow, 512, NULL, errorInfo);
std::cout << "glCompileShader(fragmentShaderYellow); FAILED\n" << errorInfo << "\n";
}
glAttachShader(shaderProgramBlue, vertexShader);
glAttachShader(shaderProgramBlue, fragmentShaderBlue);
glLinkProgram(shaderProgramBlue);
glAttachShader(shaderProgramYellow, vertexShader);
glAttachShader(shaderProgramYellow, fragmentShaderYellow);
glLinkProgram(shaderProgramYellow);
// delete shaders after linking
glDeleteShader(vertexShader);
glDeleteShader(shaderProgramBlue);
glDeleteShader(shaderProgramYellow);
// set vertex data
float firstTriangleVertices[] = {
-0.9f, -0.6f, 0.0f, // left (x=-1,y=0 : x=0,y=-1)
-0.0f, -0.6f, 0.0f, // right (x=0,y=-1 : x=1,y=0)
-0.45f, 0.6f, 0.0f // top (x=0,y=1)
};
float secondTriangleVertices[] = {
0.0f, -0.6f, 0.0f, // left
0.9f, -0.6f, 0.0f, // right
0.45f, 0.6f, 0.0f // top
};
// set buffers vertex buffer object anb vertex array object
unsigned int VBO[2], VAO[2];
glGenVertexArrays(2, VAO);
glGenBuffers(2, VBO);
// first triangle
glBindVertexArray(VAO[0]);
glBindBuffer(GL_ARRAY_BUFFER, VBO[0]);
glBufferData(GL_ARRAY_BUFFER, sizeof(firstTriangleVertices), firstTriangleVertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
glEnableVertexAttribArray(0);
// second triangle setup
glBindVertexArray(VAO[1]);
glBindBuffer(GL_ARRAY_BUFFER, VBO[1]);
glBufferData(GL_ARRAY_BUFFER, sizeof(secondTriangleVertices), secondTriangleVertices, GL_STATIC_DRAW);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glEnableVertexAttribArray(0);
// render loop
while (!glfwWindowShouldClose(window)) {
processInput(window);
// render
glClearColor(0.2f, 0.3f, 0.4f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glUseProgram(shaderProgramBlue);
// draw first triangle
glBindVertexArray(VAO[0]);
glDrawArrays(GL_TRIANGLES, 0, 3);
glUseProgram(shaderProgramYellow);
// draw the second triangle
glBindVertexArray(VAO[1]);
glDrawArrays(GL_TRIANGLES, 0, 3);
// glfw: swap buffers
glfwSwapBuffers(window);
// glfw: poll IO events (keys & mouse)
glfwPollEvents();
}
// de-allocate all resources
glDeleteVertexArrays(2, VAO);
glDeleteBuffers(2, VBO);
glDeleteProgram(shaderProgramBlue);
glDeleteProgram(shaderProgramYellow);
// glfw: terminate and clear all previously GLFW allocated resources
glfwTerminate();
return 0;
}