Look at the rectangle in the screen shoot. The corners are brighter than I expected them to be.
I scale up with:
SDL_SetWindowSize(_window, _width*(int)_scale, _heigth*(int)_scale);
SDL_SetWindowPosition(_window, SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED);
SDL_RenderSetScale(_renderer, (float)_scale, (float)_scale);
I set the color with
SDL_SetRenderDrawColor(game->_renderer, 255, 0, 0, 128);
and I draw with
SDL_RenderDrawRect(game->_renderer, &rect);
I am running on Windows 10 with the newest packaged nuget can give me.
This is a plain screen shoot with the scale up in the C++ code.