class RenderTarget {
public:
    LPDIRECT3DTEXTURE9 texture; //La textura donde realmente voy a pintar.
    LPDIRECT3DSURFACE9 surface; //La surface de la textura anterior donde se va a pintar realmente.
    LPD3DXRENDERTOSURFACE render_to_surface; //Para gestionar el cambio.
    bool uses_active_zbuffer;
    std::string shader_tech; //Por defecto, "PostProcessTech".
    
    RenderTarget() : texture(NULL), surface(NULL), render_to_surface(NULL), uses_active_zbuffer(false), shader_tech("PostProcessTech") {}
    void init(int, int, bool);
    void beginRender();
    void endRender();
    void renderPostProcess();
    void save(std::string);
    void destroy();
};

void RenderTarget::init(int xres, int yres, bool a_uses_active_zbuffer) {
    uses_active_zbuffer = a_uses_active_zbuffer;
    HRESULT hr = D3DXCreateTexture( g_pd3dDevice, xres, yres, 1, D3DUSAGE_RENDERTARGET, D3DFMT_A8R8G8B8, D3DPOOL_DEFAULT, &texture);
    assert(hr == D3D_OK);
    hr = texture->GetSurfaceLevel(0, &surface);
    assert(hr == D3D_OK);
    hr = D3DXCreateRenderToSurface( g_pd3dDevice, xres, yres, D3DFMT_A8R8G8B8, FALSE, D3DFMT_UNKNOWN, &render_to_surface);
    assert(hr == D3D_OK);
}
void RenderTarget::beginRender() {
    LPDIRECT3DSURFACE9 depth_surface;
    HRESULT hr;
    if(uses_active_zbuffer) {
        hr = g_pd3dDevice->GetDepthStencilSurface(&depth_surface); assert(hr == D3D_OK);
    }
    assert(render_to_surface != NULL);
    hr = render_to_surface->BeginScene(surface, NULL);
    assert(hr == D3D_OK);
    if(uses_active_zbuffer) {
        g_pd3dDevice->SetDepthStencilSurface(depth_surface); assert(hr == D3D_OK);
        depth_surface->Release();
    }
}
void RenderTarget::endRender() {
    assert(render_to_surface != NULL);
    HRESULT hr = render_to_surface->EndScene(0);
    assert(hr == D3D_OK);
}
void RenderTarget::save(std::string file_name) {
    HRESULT hr = D3DXSaveTextureToFile(file_name.c_str(), D3DXIFF_JPG, texture, NULL);
    assert(hr == D3D_OK);
}

void render(float delta_time) {
     renderTarget.beginRender();
     g_pd3dDevice->Clear(0, NULL, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0x80808080, 1.0f, 0);
     renderWorld();  //My scene render.
     renderTarget.endRender();
     
    if( SUCCEEDED( g_pd3dDevice->BeginScene() ) )
     {
          renderTarget.renderPostProcess();      
          g_pd3dDevice->EndScene();
     } 
      g_pd3dDevice->Present( NULL, NULL, NULL, NULL );
}