How to draw many shapes efficiently?

[Piorjade]

Soo I'm currently developing a "virtual retro-like computer" to get into SFML and C/C++.
The problem currently is though that I want to draw pseudo-pixels (basically just many small rectangles that the user can manipulate, just like pixels) and if I go to a resolution of 200x80 (~16k pseudo-pixels) the performance drops to 60FPS (with a resolution of 51x19 I had about 400-500).

Is there any way that I can improve the performance? Or is it as fast as it can get with 16k shapes?

I also wanted to make the user decide what the resolution is via configuration file but if 200x80 gets to 55-60FPS (with a GTX 960, 16GB RAM and a FX-8350) I'll probably hard-code that..

Also, the way how I store these pixels is that the pixels are objects containing information about their color and their actual shape object and they are all stored in a 2-dimensional array, which gets iterated through to draw every pixel each frame, if that is of any meaning.

[eXpl0it3r]

Use std::vector<sf::Vertex> (or sf::VertexArray) and draw quads. So you need four vertices per quad.
That way you'll end up with one draw call.

[Piorjade]

And this vector should store every pixel?
So I'll basically just push_back 4 vertices per pixel into that one vector, right?

Thanks for your reply btw

[eXpl0it3r]

Yes. Instead of having a rectangle shape, you just define each point of the rectangle yourself in the right order and add it to the vector, which you then can draw with one draw call (check the documentation).

To get familiar with the concept you should also read the official tutorial on vertex arrays.

[Piorjade]

Alright, thanks dude! 

EDIT: Yeah I got up to 1500-2000FPS now, thank you very much!

Guess I shouldn't be so scared of more lower-level stuff

[eXpl0it3r]

Glad it worked out