Messages

1

Graphics / Re: Error when trying to scale texture with dimensions that are not divisible by 8

« on: August 01, 2023, 04:16:26 am »

Turning Vsync on solved the issue. It was a matter of just adding

window.setVerticalSyncEnabled(true);
 

and the texture scaled up perfectly without taring, which makes a lot of sense, considering Vsync's job in the first place.

Thanks a million!

2

Graphics / Error when trying to scale texture with dimensions that are not divisible by 8

« on: July 31, 2023, 08:23:02 pm »

Hi!

For the last while I've been experiencing with updating textures from pixels in order to create a canvas library. So far everything has worked as expected except one really annoying thing; Say I created a 16x9 texture with a corresponding pixel array to match it. Displaying this array is really straightforward using array->texture->sprite->draw. But it obviously would display it by its real size. I want the texture to fill the window as much as possible without it being stretched, so I tried to use a view and a [letterbox effect function I found][https://github.com/SFML/SFML/wiki/Source%3A-Letterbox-effect-using-a-view]  and while it initially worked, every time I wanted to update the texture fast (say randomize it) I would get really weird visual glitches. After playing around with it for a while I found that textures with a (16x9) multiplied by some multiple of 8 would work perfectly well.

Here's the simplified code:

#include <SFML/Graphics/Texture.hpp>
#include <SFML/Window/Event.hpp>
#include <SFML/Window/WindowStyle.hpp>
#include <SFML/Graphics.hpp>


const int window_width = 854, window_h = 480;
const int cell_size = 4;
const int mul = 1;
const int canvas_width = 16 * mul, canvas_height = 9 * mul;



using sf::Uint8;
Uint8* pixels;


int get_power(int value);
void randomize();
sf::View getLetterboxView(sf::View view, int windowWidth, int windowHeight);

int main() {
    sf::RenderWindow window(sf::VideoMode(window_width, window_h), "Hello World SFML Window",  sf::Style::Default | sf::Style::Resize);

    pixels = new Uint8[canvas_width * canvas_height * cell_size];

    sf::View view;
    view.setCenter((float)canvas_width /2.0f, (float)canvas_height / 2.0f);
    view.setSize((float)canvas_width, (float)canvas_height);
    view = getLetterboxView(view, window_width, window_h);

    for (int i = 0; i <= canvas_width * canvas_height * cell_size; i++)
        pixels[i] = 0;

    sf::Texture texture;
    if (!texture.create(canvas_width, canvas_height)) { return -1; };

   

    while (window.isOpen()) {

        sf::Event e;
        while (window.pollEvent(e)) {
            switch (e.type) {
                case sf::Event::EventType::Closed:
                    window.close();
                    break;
                case sf::Event::EventType::Resized:
                    view = getLetterboxView(view, e.size.width, e.size.height);
                default: {}; break;
            }
        }

        window.clear();
        randomize();
        texture.update(pixels);
        sf::Sprite s(texture);

        window.setView(view);
        window.draw(s);
        window.display();
    }

    delete [] pixels;
}


void randomize() {
    for (int i =0; i < canvas_width * canvas_height * cell_size; i++)
    {
        pixels[i] = (i % cell_size == cell_size - 1) ? 255 : rand() % 255;
    }
}

 

   



And as you can see, the pixel scale up extremely distorted, I also encountered the same glitch when trying to just scale up the sprite to the exact window screen.

Any help would be greatly appreciated, thanks!