emd's engine

#include <stdio.h>
#include <string.h>
#include <GLFW/glfw3.h>
#include <GL/gl.h>
#include <GL/glu.h>

typedef struct {
    float x, y, z;
    float yaw, pitch;
} camera_t;

camera_t camera;

camera_t camera_new(void) {
    camera_t camera;
    memset(&camera, 0, sizeof(camera_t));
    return camera;
}

void camera_update(camera_t *camera) {
    glTranslatef(-camera->x, -camera->y, -camera->z);
    glRotatef(-camera->pitch, 1, 0, 0);
    glRotatef(-camera->yaw,   0, 1, 0);
}

void init() {
    glClearColor(1, 0, 0, 1);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    const int eye_angle = 45;
    const float cam_len = 1.0f;
    const float dim_ratio = (float)640/(float)480;
    gluPerspective(eye_angle, dim_ratio, cam_len, 500.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();
    camera = camera_new();
    camera.pitch = 10;

}

void draw() {
    camera_update(&camera);
    glBegin(GL_TRIANGLES);
        glVertex3f(0.0,2.0,-5.0);
        glVertex3f(-2.0,-2.0,-5.0);
        glVertex3f(2.0,-2.0,-5.0);
    glEnd();

}

void cb_keyboard(GLFWwindow *window, int key, int scancode, int action, int mods) {
    if (key == GLFW_KEY_W && action == GLFW_PRESS)
        camera.z += 1;
    else if (key == GLFW_KEY_S && action == GLFW_PRESS)
        camera.z -= 1;
    camera_update(&camera);
}

int main() {
    GLFWwindow *window;
    if (!glfwInit())
        return 1;
    window = glfwCreateWindow(640, 480, "Ethan's 3D Engine", NULL, NULL);
    if (!window) {
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);
    glfwSetKeyCallback(window, &cb_keyboard);

    init();

    while (!glfwWindowShouldClose(window)) {
        glClear(GL_COLOR_BUFFER_BIT);
        glPushMatrix();
        draw();
        glfwSwapBuffers(window);
        glPopMatrix();
        glfwPollEvents();
    }
    glfwTerminate();
    return 0;
}