Topics

1

General / SFML CMake error

« on: November 10, 2019, 06:18:19 pm »

I'm trying to build SFML with CMake using this tutorial.

Now I've managed to make the makefile with CMake.

However if I tried to build SFML using the "mingw32-make install" command I get this error.

Code: [Select]

[  1%] Building CXX object src/SFML/System/CMakeFiles/sfml-system.dir/Clock.cpp.
obj
'C:\PROGRA~1\MinGW\MINGW' is not recognized as an internal or external command,
operable program or batch file.
src\SFML\System\CMakeFiles\sfml-system.dir\build.make:62: recipe for target 'src
/SFML/System/CMakeFiles/sfml-system.dir/Clock.cpp.obj' failed
mingw32-make[2]: *** [src/SFML/System/CMakeFiles/sfml-system.dir/Clock.cpp.obj]
Error 1
CMakeFiles\Makefile2:215: recipe for target 'src/SFML/System/CMakeFiles/sfml-sys
tem.dir/all' failed
mingw32-make[1]: *** [src/SFML/System/CMakeFiles/sfml-system.dir/all] Error 2
Makefile:128: recipe for target 'all' failed
mingw32-make: *** [all] Error 2


2

General discussions / SFML Book order

« on: August 29, 2019, 12:20:57 am »

Hello, I would like to know which SFML book should I read first, and which order should I read them.

3

Graphics / A single draw call severely slows thing down

« on: July 30, 2019, 10:46:38 pm »

I'm currently trying to make a simple bullet hell game, and I've noticed that a single draw call slows things down a lot if there's a lot of vertices, and I'm not sure how to fix it.

I've made this simple sample version, to illustrate the issue.

#include <SFML/Graphics.hpp>
#include <SFML/Window.hpp>
#include <chrono>
#include <iostream>
#include <memory>
static const sf::IntRect rect = {0,0,64,64};
static const sf::Vector2f initPos = {400,150};
class Bullet {
public:
    Bullet(sf::Vector2f vel_) : velocity{vel_} {
        vertices[0].texCoords = sf::Vector2f{0,0};
        vertices[1].texCoords = sf::Vector2f{64,0};
        vertices[2].texCoords = sf::Vector2f{64,64};
        vertices[3].texCoords = sf::Vector2f{0,64};
        for(size_t i=0; i<4; ++i)
            vertices[i].position = initPos + vertices[i].texCoords;
        vertices[4] = vertices[0];
        vertices[5] = vertices[2];
    }
    void update() {
        for(size_t i=0; i<6; ++i) {
            vertices[i].position += velocity;
        }
    }
    sf::Vertex* getVertices() {
        return vertices;
    }
private:
    sf::Vertex vertices[6];
    sf::Vector2f velocity;
};
int main() {
    constexpr size_t TOTAL_BULLETS = 20000;
    constexpr float pi = 4*std::atan(1);
    std::unique_ptr<Bullet> bullets[TOTAL_BULLETS];
    sf::VertexArray bulletVertices{sf::Triangles,TOTAL_BULLETS*6};
    sf::Texture tex;
    //tex.loadFromFile("bullets.png");
    for(size_t i=0; i<TOTAL_BULLETS; ++i) {
        float angle = 2*pi * static_cast<float>(i)/TOTAL_BULLETS;
        auto vel = sf::Vector2f{std::cos(angle),std::sin(angle)} * 1.0f;
        bullets[i] = std::make_unique<Bullet>(vel);
    }
    sf::RenderWindow window(sf::VideoMode(800,600), "Test");
    while( window.isOpen() ) {
        auto tp = std::chrono::steady_clock::now();
        sf::Event event;
        while( window.pollEvent(event) ) {
            switch(event.type) {
            case sf::Event::Closed:
                window.close();
            break;
            default:
            break;
            }
        }
        for(size_t j=0; j<TOTAL_BULLETS; ++j) {
            bullets[j]->update();
            auto vertice = bullets[j]->getVertices();
            for(size_t i=0; i<6; ++i)
                bulletVertices[j*6+i] = vertice[i];
        }
        window.clear();
        window.draw(bulletVertices,&tex); //This line slows things down a lot
        window.display();
        auto dur = std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::steady_clock::now()-tp);
        std::cout<<"Frame takes: "<< dur.count() <<"microseconds.\n";
    }
    return 0;
}
 

The main point of interest is line 64, which is:

window.draw(bulletVertices,&tex); //This line slows things down a lot
 

This draws 120,000 vertices, or 40,000 triangles. By commenting it out, I've noticed that the program becomes a lot faster. (When uncommented, the frame time is about 45,000 microseconds, and commenting makes it becomes about 5,000 microseconds.)