Created attachment 4046 [details]
Comparison of Direct3D renderers with rotated arrow pointing up.

Using the Direct3D 11 render driver, the rotations produced by SDL_RenderCopyEx() seem to be offseted by 180 degrees.

All other renderers that I tested (sofftware, opengl, direct3d) behave like expected.

See forum for more details :
https://discourse.libsdl.org/t/rotation-angle-for-sdl-rendercopyex/26840

Here's a minimum example reproducing the problem :

=====================

#include <SDL.h>
#include <SDL_image.h>
#include <stdio.h>
#include <stdbool.h>

const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;

SDL_Window* gWindow = NULL;
SDL_Renderer* gRenderer = NULL;

SDL_Event e;

SDL_Texture* loadTexture( const char* path )
{
  SDL_Texture* newTexture = NULL;

  SDL_Surface* loadedSurface = IMG_Load(path);
  if( loadedSurface != NULL )
  {
    newTexture = SDL_CreateTextureFromSurface( gRenderer, loadedSurface );
    SDL_FreeSurface( loadedSurface );
  }

  return newTexture;
}


bool Init(void)
{
  bool success = false;

  if(SDL_Init(SDL_INIT_VIDEO) == 0)
  {
    // CHANGE RENDER DRIVER HERE
    char* RenderDriver = "direct3d11"; // software, opengl, direct3d, direct3d11
    SDL_SetHint(SDL_HINT_RENDER_DRIVER, RenderDriver );

    gWindow = SDL_CreateWindow( RenderDriver , SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_WINDOW_SHOWN );
    if( gWindow != NULL )
    {
      gRenderer = SDL_CreateRenderer(gWindow, -1, SDL_RENDERER_ACCELERATED );
      if( gRenderer != NULL )
      {
        success = true;
      }
    }
  }

  return success;
}

void Finit(void)
{
  SDL_DestroyRenderer( gRenderer );
  SDL_DestroyWindow( gWindow );
  SDL_Quit();
}

// ******************************

int main( int argc, char* args[] )
{
  if(!Init())
  {
    printf("Init() failed\n");
  }
  else
  {
    SDL_Texture* arrowTexture = loadTexture(".\\images\\UpArrow.png");
    SDL_Rect destination;

    if(!arrowTexture )
    {
      printf("No texture");
    }
    else
    {
      bool exit = false;
      SDL_QueryTexture(arrowTexture, NULL, NULL, &destination.w, &destination.h);
      destination.x = (SCREEN_WIDTH /2) - (destination.w /2) ;
      destination.y = (SCREEN_HEIGHT /2) - (destination.h /2) ;

      while(!exit)
      {
        SDL_RenderCopyEx(gRenderer, arrowTexture, NULL, &destination, 90.0f, NULL, SDL_FLIP_NONE);
        SDL_RenderPresent(gRenderer);

        while( SDL_PollEvent( &e ) != 0 )
        {
          if( e.type == SDL_QUIT )
          {
            exit = true;
          }
        }
      }
      SDL_DestroyTexture(arrowTexture);
    }
  }

  Finit();
  return 0;
}

=====================