OpenGL - tell vertex shader that VBO has changed - c++

Question

I am currently writing a program that requires updating my VBO data constantly.
However, I found out that if I call glBindBuffer(GL_ARRAY_BUFFER, 0) after I initialize my buffer, the window closed itself somehow.
Below is my code snippet:
glGenBuffers(1, &vertex_buffer);
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(pts[0]) * pts.size(), NULL, GL_DYNAMIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
vertex_shader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertex_shader, 1, &vertex_shader_text, NULL);
glCompileShader(vertex_shader);
fragment_shader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragment_shader, 1, &fragment_shader_text, NULL);
glCompileShader(fragment_shader);
program = glCreateProgram();
glAttachShader(program, vertex_shader);
glAttachShader(program, fragment_shader);
glLinkProgram(program);
mvp_location = glGetUniformLocation(program, "MVP");
vpos_location = glGetAttribLocation(program, "vPos");
glEnableVertexAttribArray(vpos_location);
glVertexAttribPointer(vpos_location, 3, GL_FLOAT, GL_FALSE,
sizeof(float) * 3, (void*) 0);
while(!glfwWindowShouldClose(window)) {
glUseProgram(program);
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(pts[0]) * pts.size(), &pts);
glBindBuffer(GL_ARRAY_BUFFER, 0);
mat4x4_mul(mvp, m, p);
glUniformMatrix4fv(mvp_location, 1, GL_FALSE, (const GLfloat*) mvp);
glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer);
glDrawArrays(GL_POINTS, 0, pts.size());
glBindBuffer(GL_ARRAY_BUFFER, 0);
glfwSwapBuffers(window);
glfwPollEvents();
}
FYI: pts is constantly updated.
IS there a way to tell vertex shader that the VBO data is updated?
Edit: updated the code snippet
Edit: I am supposed to draw pts.size() number of vertices each time but there is only one point appeared on the screen

Answer 1

Right before your draw call there where you have glBindBuffer(GL_ARRAY_BUFFER, vertex_buffer); you need to actually set the attrib pointer(glVertexAttribPointer()). A secondary note is that GlVertexAttribPointer() binds GL_ARRAY_BUFFER to the specified attribute pointer. Where you call it at the moment there is nothing bound to GL_ARRAY_BUFFER.
For reference GLEnum error = glGetError() will return an the error state of openGL and is a powerful debugging tool. If you're using glew, glewGetErrorString() will get a string for any non-zero error code which explains the error in more detail.
p.s. sorry for my poor writing skills.