VertexArray not drawing onto screen

Question

I'm currently learning about VertexArray and I'm currently struggling to fix the issue I am having. The issue is that the VertexArray would not draw to the screen. I have tested the code with sprites, and the sprite was drawn to screen successfully.

#include <SFML/Graphics.hpp>
#include <string>
#include <iostream>
#include <ctime>
#include <cstdlib>

int main()
{
    sf::Vector2i screenDimensions(800,600);
    sf::Vector2i blockDimensions(10,10);

    srand(time(0));

    sf::RenderWindow Window;
    Window.create(sf::VideoMode(screenDimensions.x,screenDimensions.y),"My first SFML game!");

    while(Window.isOpen())
    {
        sf::Event Evnt;
        while(Window.pollEvent(Evnt))
        {
            switch(Evnt.type)
            {
                case(sf::Event::Closed):
                    Window.close();
                    break;
            }
        }
        for(int i=0; i< screenDimensions.x/blockDimensions.x; i++)
        {
            for(int j=0; j<screenDimensions.y/blockDimensions.y;j++)
            {
                sf::VertexArray vArray;
                vArray[0].position = sf::Vector2f(i*blockDimensions.x,j*blockDimensions.y);
                vArray[1].position = sf::Vector2f(i*blockDimensions.x + blockDimensions.x, j*blockDimensions.y);
                vArray[2].position = sf::Vector2f(i*blockDimensions.x + blockDimensions.x, j*blockDimensions.y + blockDimensions.y);
                vArray[3].position = sf::Vector2f(i*blockDimensions.x,j*blockDimensions.y + blockDimensions.y);

                for(int k=0;k<4;k++)
                {
                    int red = rand() % 255;
                    int green = rand() % 255;
                    int blue = rand() % 255;

                    vArray[k].color = sf::Color(red,green,blue);
                }
                Window.draw(vArray);
            }
        }

        Window.clear();
        Window.display();
    }

}

Here's the simple code that draws random color inside quads onto a screen. The tutorial I was following was this one by CodingMadeEasy. Thanks in advance everyone!

Answer 1

First of all you created an empty vertex array. Create one with a type and an initial number of vertices sf::VertexArray vArray (sf::Quads, 4);

And you cleared the window before you actually drawn it, Window.display(); goes before Window.clear();.

Here is the working code:

#include <SFML/Graphics.hpp>
#include <string>
#include <iostream>
#include <ctime>
#include <cstdlib>

int main()
{
    sf::Vector2i screenDimensions(800,600);
    sf::Vector2i blockDimensions(10,10);

    srand(time(0));

    sf::RenderWindow Window;
    Window.create(sf::VideoMode(screenDimensions.x,screenDimensions.y),"My first SFML game!");

    while(Window.isOpen())
    {
        sf::Event Evnt;
        while(Window.pollEvent(Evnt))
        {
            switch(Evnt.type)
            {
                case(sf::Event::Closed):
                    Window.close();
                    break;
            }
        }
        for(int i=0; i< screenDimensions.x/blockDimensions.x; i++)
        {
            for(int j=0; j<screenDimensions.y/blockDimensions.y;j++)
            {
                sf::VertexArray vArray (sf::Quads, 4);
                vArray[0].position = sf::Vector2f(i*blockDimensions.x,j*blockDimensions.y);
                vArray[1].position = sf::Vector2f(i*blockDimensions.x + blockDimensions.x, j*blockDimensions.y);
                vArray[2].position = sf::Vector2f(i*blockDimensions.x + blockDimensions.x, j*blockDimensions.y + blockDimensions.y);
                vArray[3].position = sf::Vector2f(i*blockDimensions.x,j*blockDimensions.y + blockDimensions.y);

                for(int k=0;k<4;k++)
                {
                    int red = rand() % 255;
                    int green = rand() % 255;
                    int blue = rand() % 255;

                    vArray[k].color = sf::Color(red,green,blue);
                }
                Window.draw(vArray);
            }
        }

        Window.display();
        Window.clear();
    }

}