Seeking to understand how to use SDL2 in the render-to-texture mode, I found this nice, crisp example from the answer to this question and tried it. It builds, it executes without reporting any error and runs for 8 seconds as specified, but no window appears. Changing the position to SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED doesn’t make a difference.

Has something changed in SDL2 in 10 years that would invalidate this example? Or are there special issues on Mac?

Running on Mac OS 14.2.1 on an Apple silicon computer, with a recently downloaded SDL2. Here is the precise code I’m running:

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <SDL2/SDL.h>

// Compile: gcc test.c -I/usr/local/include/SDL2 -L/usr/local/lib -lSDL2


void putPixel(SDL_Renderer *renderer, int x, int y)
{
    SDL_SetRenderDrawColor(renderer, 255,255,255,255);
    SDL_RenderDrawPoint(renderer, x, y);
}

int main(int argc, char* argv[]) {

    int width = 640;
    int height = 480;

    SDL_Window *window = SDL_CreateWindow("Test", 0,0,width,height, 0);
    if (window == NULL)
    {
        return -1;
    }
    SDL_Renderer *renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_TARGETTEXTURE);
    if (renderer == NULL)
    {
        return -2;
    }

    SDL_SetRenderDrawBlendMode(renderer,SDL_BLENDMODE_BLEND);

    /* Create texture for display */
    SDL_Texture *display = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGBA8888, SDL_TEXTUREACCESS_TARGET, width, height);

    SDL_SetRenderTarget(renderer, display);

    SDL_SetRenderDrawColor(renderer, 0, 0, 0, 255);
    SDL_RenderClear(renderer);

    for(int x=0;x<8;x++)
    {
        SDL_SetRenderTarget(renderer, display);

        for(int y=0;y<10;y++)
        {
            putPixel(renderer,40+x*10,50+y);
        }

        SDL_SetRenderTarget(renderer, NULL);
        SDL_RenderCopy(renderer, display, NULL, NULL);
        SDL_RenderPresent(renderer);
        sleep(1);
    }


    SDL_Quit();
    return 0;
}