diff --git a/Hohmann b/Hohmann
index 46d95cc..f2f99d1 100755
Binary files a/Hohmann and b/Hohmann differ
diff --git a/src/main.cpp b/src/main.cpp
index af8f9ee..98cd761 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,6 +1,72 @@
-#include <glad/glad.h> 
+#include <glad/glad.h>
 #include <GLFW/glfw3.h>
+#include <stdio.h>
+
+#define WINDOW_WIDTH 640
+#define WINDOW_HEIGHT 480
+
+float verts[] = {
+	-0.5f, -0.5f, 0.0f,
+	 0.5f, -0.5f, 0.0f,
+	 0.0f,  0.5f, 0.0f
+};  
+
+void framebuffer_size_callback(GLFWwindow* win, int w, int h) {
+	glViewport(0, 0, w, h);
+}
+
+void processInput(GLFWwindow *win) {
+	int action = glfwGetKey(win, GLFW_KEY_ESCAPE);
+	if (action == GLFW_PRESS) {
+		glfwSetWindowShouldClose(win, true);
+	}
+}
+
+void renderCallback(GLFWwindow *win) {
+	glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
+	glClear(GL_COLOR_BUFFER_BIT);
+
+	unsigned int VBO;
+	glGenBuffers(1, &VBO);
+
+	glBindBuffer(GL_ARRAY_BUFFER, VBO);
+}
 
 int main() {
+	glfwInit();
+	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
+	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
+	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+
+	GLFWwindow* win = glfwCreateWindow(WINDOW_WIDTH, WINDOW_HEIGHT, "Hohmann", NULL, NULL);
+	if (win == NULL) {
+		printf("Failed to create a window.");
+		glfwTerminate();
+		return 1;
+	}
+
+	glfwMakeContextCurrent(win);
+
+	if ( !gladLoadGLLoader((GLADloadproc)glfwGetProcAddress) ) {
+		printf("Failed to init GLAD.");
+		return 1;
+	}
+
+	glViewport(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
+	glfwSetFramebufferSizeCallback(win, framebuffer_size_callback);
+
+	while (!glfwWindowShouldClose(win)) {
+		// Handle input
+		processInput(win);
+
+		// rendering
+		renderCallback(win);
+
+		// glfw
+		glfwSwapBuffers(win);
+		glfwPollEvents();
+	}
+
+	glfwTerminate();
 	return 0;
 }