#include <GLFW/glfw3.h>
#include <iostream>
#include <cmath>

double a[] = {0., 0., 0.},
        b[] = {.5, 0, 0.},
        c[] = {.5, .5, 0.},
        d[] = {0, .7, 0};

static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GLFW_TRUE);
    if (key == GLFW_KEY_LEFT )
        glRotatef(5, 0, 1, 0);
    if (key == GLFW_KEY_RIGHT)
        glRotatef(-5, 0, 1, 0);
    if (key == GLFW_KEY_UP && action == GLFW_PRESS)
        a[1] += .1;
    if (key == GLFW_KEY_DOWN && action == GLFW_PRESS)
        a[1] -= .1;

}

void render(GLFWwindow *window) {
    int width, height;
    glfwGetFramebufferSize(window, &width, &height);
    glViewport(0, 0, width, height);

    glClear(GL_COLOR_BUFFER_BIT);

    glBegin(GL_POINTS);
    glPointSize(3);
    glColor3b(255, 0, 0);
    glVertex3d(-1, 0, 0);
    glVertex3d(1, 0, 0);
//    glVertex3d(0, -10, 0);
//    glVertex3d(0, 10, 0);
//    glVertex3d(0, 0, -10);
//    glVertex3d(0, 0, 10);
    glEnd();

    glBegin(GL_TRIANGLES);
    int dots = 100;
    double pi = 3.141591;
    double r = 0.5;
    double x_pr = 0, y_pr = 0;
    int col = 1;
    for (double alph = 2 * pi / dots; alph < 2 * pi; alph += 2 * pi / dots) {
        double x = r * cos(alph);
        double y = r * sin(alph);
        glColor3b(col, 100, 0);
        col = (col + 1) % 255;
        glVertex3d(x, y, 10);
        glVertex3d(x_pr, y_pr, 1);
        glVertex3dv(a);
        x_pr = x;
        y_pr = y;
    }
    glEnd();
}

int main()
{
    glfwInit();
    auto *window = glfwCreateWindow(500, 500, "hui",  NULL, NULL);
    glfwMakeContextCurrent(window);
    glfwSetKeyCallback(window, key_callback);
    // glfwSwapInterval(5);
    while (!glfwWindowShouldClose(window))
    {
        render(window);

        glfwSwapBuffers(window);
//        glfwPollEvents();
        glfwWaitEvents();
    }
    glfwTerminate();
    return 0;
}