Creating a cube in SDL

Hello,

So I’m trying to switch this cool SFML project to SDL and I’m not exactly sure if it’s possible. https://github.com/xSnapi/Isometric-Terrain

All I’m trying to do at the moment is just make an isometric cube. I thought I could do it using SDL_Vertex and SDL_RenderGeometry, but I’m not sure if I can do it without OpenGL.

Here is where I started.

void AddCube(Vector2f position, float size, SDL_Color color, Vector2f texCoords) {
    size /= 2.0f;

   SDL_Vertex v[6] =
    {
     { SDL_FPoint{-size, 0.0f} + position,         color, SDL_FPoint(texCoords.x, texCoords.y) },
     { SDL_FPoint{size, 0.0f} + position,         color, SDL_FPoint(texCoords.x,   texCoords.y) },
     { SDL_FPoint{size, size * 2.0f} + position,         color, SDL_FPoint(texCoords.x,   texCoords.y)   },
                                         
     { SDL_FPoint{-size, 0.0f} + position,         color, SDL_FPoint(texCoords.x, texCoords.y) },
     { SDL_FPoint{-size, size * 2.0f} + position,         color, SDL_FPoint(texCoords.x, texCoords.y)	 },
     { SDL_FPoint{size, size * 2.0f} + position,         color, SDL_FPoint(texCoords.x,   texCoords.y)	 },
    };

   for (uint32_t i = 0; i < 6; i++) {
       m_Vertices.push_back(v[i]);
   }
}

...
   SDL_SetRenderDrawColor(renderer, 0, 0, 0, SDL_ALPHA_OPAQUE);
        SDL_RenderClear(renderer);

    
        SDL_RenderGeometry(renderer, nullptr, m_Vertices.data(), m_Vertices.size(), nullptr, 0);
        SDL_RenderPresent(renderer);

PS: All I get is a red square.