Problem making a single array for multiple shape vertices - c++

Question

Here is my code:
#include <iostream>
#include <glad/glad.h>
#include <GLFW/glfw3.h>
const char* vertexShaderSource = "#version 330 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"
"}\0";
const char* fragmentShaderSource = "#version 330 core\n"
"out vec4 FragColor;\n"
"void main()\n"
"{\n"
" FragColor = vec4(0.8f, 0.3f, 0.02f, 1.0f);\n"
"}\n\0";
int main()
{
glfwInit();
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
GLFWwindow* window;
int windowWidth, windowHeight, resAnswer, aspectRatFirst, aspectRatSecond, aspectRatDeformation;
do {
std::cout << "Choose the preset for window resolution:" << std::endl;
std::cout << " 1. 800x800 (1:1)" << std::endl;
std::cout << " 2. 1024x768 (16:9)" << std::endl;
std::cout << "Answer: "; std::cin >> resAnswer;
} while (resAnswer != 1 && resAnswer != 2);
switch (resAnswer)
{
case 1:
windowWidth = 800;
windowHeight = 800;
aspectRatFirst = 1;
aspectRatSecond = 1;
break;
case 2:
windowWidth = 1024;
windowHeight = 768;
aspectRatFirst = 16;
aspectRatSecond = 9;
break;
}
aspectRatDeformation = aspectRatSecond / aspectRatFirst;
int shapeAnswer;
do {
std::cout << std::endl;
std::cout << "Choose your shape:" << std::endl;
std::cout << " 1. Triangle" << std::endl;
std::cout << " 2. Square" << std::endl;
std::cout << "Answer: "; std::cin >> shapeAnswer;
} while (shapeAnswer != 1 && shapeAnswer != 2);
64 GLfloat preVertices[];
if (shapeAnswer == 1) {
preVertices = {
-0.5f, -0.5f * float(sqrt(3)) / 3, 0.0f, //B
0.5f, -0.5f * float(sqrt(3)) / 3, 0.0f, //C
0.0f, 0.5f * float(sqrt(3)) * 2 / 3, 0.0f //A
};
}
else if (shapeAnswer == 2) {
preVertices = {
-0.5f, -0.5f * float(sqrt(3)) / 3, 0.0f, //B
0.5f, -0.5f * float(sqrt(3)) / 3, 0.0f, //C
0.0f, 0.5f * float(sqrt(3)) * 2 / 3, 0.0f //A
};
}
81 GLfloat vertices[] = preVertices;
window = glfwCreateWindow(windowWidth, windowHeight, "OpenGLCourse", NULL, NULL);
if (window == NULL) {
std::cout << "Failed to create GLFW window" << std::endl;
glfwTerminate();
return -1;
}
glfwMakeContextCurrent(window);
gladLoadGL();
glViewport(0, 0, windowWidth, windowHeight);
GLuint vertexShader = glCreateShader(GL_VERTEX_SHADER);
glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
glCompileShader(vertexShader);
GLuint fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
glCompileShader(fragmentShader);
GLuint shaderProgram = glCreateProgram();
glAttachShader(shaderProgram, vertexShader);
glAttachShader(shaderProgram, fragmentShader);
glLinkProgram(shaderProgram);
glDeleteShader(vertexShader);
glDeleteShader(fragmentShader);
GLuint VBO;
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
119 glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glClearColor(0.07f, 0.13f, 0.17f, 1.0f);
glClear(GL_COLOR_BUFFER_BIT);
glfwSwapBuffers(window);
while (!glfwWindowShouldClose(window)) {
glfwPollEvents();
}
glfwDestroyWindow(window);
glfwTerminate();
return 0;
}
My problem is between lines 64-81 and the line 119.
What I am trying to do is to create an array "vertices" for the specified shape vertices coordinates. The problem is that the triangle shape has 3 vertices and the square has 4 vertices, the array tho can only have one number of elements. I have another array "preVertices" just because I tried a lot of things to fix this problem.
The code wasn't working mainly because at line 119 I have to get the size of vertices, and the vertices seems to be undefined (and i think its because its getting defined inside of an if statement, or it was, at first, as i said, i changed a lot of things trying to resolve the problem), now, I think one solution would be just to make two different arrays with the different arrays and actually use an if statement to determine which i need at line 119, but I was wondering if there exists a solution with only one array, cuz I m thinking if there would be 100 different shapes it would be more time consuming to make 100 different arrays and it will also occupy more ram than needed, am I right?