DirectX: How to apply an Effect to a texture drawn with ID3DXSprite.Draw(..) - xna

Question

I want to write a very simple Effect for a DirectX program which uses the ID3DXSprite interface to draw a 2D-Hud. In XNA I simply called
spriteBatch.Begin(SpriteBlendMode.AlphaBlend, SpriteSortMode.Immediate, SaveStateMode.None);
effect.Begin();
effect.CurrentTechnique.Passes[0].Begin();
spriteBatch.Draw(texture, new Rectangle(0, 0, 300, 300), Color.White);
effect.CurrentTechnique.Passes[0].End();
effect.End();
spriteBatch.End();
But in C++, nearly the same code doesnt work
pSprite->Begin(D3DXSPRITE_ALPHABLEND | D3DXSPRITE_DONOTSAVESTATE | D3DXSPRITE_SORT_TEXTURE);
anEffect->SetTechnique(technique);
anEffect->Begin(&passes, 0);
anEffect->BeginPass(0);
pSprite->Draw(pTexture, NULL, NULL, &position, 0xFFFFFFFF);
anEffect->EndPass();
anEffect->End();
pSprite->End();
NOTE: The effect is loaded correctly!

Answer 1

Well, first of all the XNA code you have is for XNA 3.1, and it's wrong. This blog post explains how to do it for both XNA 3.1 and 4.0 (the API changes in between).
In XNA 3.1, when using SpriteSortMode.Immediate, SpriteBatch will set up its shaders and other device state in the Begin call, instead of in the End call. This gives you the opportunity to replace parts of the device state before drawing actually takes place (in Draw or End, depending on when it flushes). And then you are supposed to End your effect after you End the sprite batch (so everything gets drawn first).
Now, in DirectX, I would suggest that the same incorrect ordering of your End calls is to blame. Specifically refer to this part of the documentation for the second parameter to ID3DXEffect::Begin
determines if state modified by an effect is saved and restored. The default value 0 specifies that ID3DXEffect::Begin and ID3DXEffect::End will save and restore all state modified by the effect
The upshot is that, when you End the effect, it is resetting the device back to normal sprite drawing, before you call End on the ID3DXSprite, which is what is actually sending your sprite batch to be drawn.
I would guess that the reason your incorrectly-ordered code works on XNA is that XNA is probably doing the equivalent of passing D3DXFX_DONOTSAVESTATE, when beginning the effect, under the hood.

Answer 2

Usage of Sprite with HLSL Effect: (for C++ Game Developers)
Below is the sample code which explains how sprite draw can work with HLSL effect files
Pseudo Code:
ID3DXEffect* g_pEffect = NULL; // D3DX effect interface
void loadTextureEffect() {
D3DXCreateTextureFromFile(gD3dDevice,L"image.png",&gTextureBackdrop);
DWORD dwShaderFlags = D3DXFX_NOT_CLONEABLE;
D3DXCreateEffectFromFile( gD3dDevice, "shader.fx", NULL, NULL, dwShaderFlags,
NULL, &g_pEffect, NULL );
}
void Render()
{
unsigned int passes;
gD3dDevice->Clear(0, 0, D3DCLEAR_TARGET | D3DCLEAR_ZBUFFER, 0x00000000, 1.0f, 0);
gD3dDevice->BeginScene();
gSprite->Begin(0);
g_pEffect->SetTechnique("PostProcess");
g_pEffect->SetTexture( "Tex0", gTextureBackdrop );
float blurFactor = 25;
g_pEffect->SetValue("TextureBlur",&blurFactor ,sizeof(float));
g_pEffect->Begin(&passes, 0);
for(unsigned int pass = 0; pass < passes; ++pass)
{
g_pEffect->BeginPass(pass);
D3DXVECTOR3 spritePos(0.0f, 0.0f, 0.0f);
gD3dDevice->SetTexture(0,gTextureBackdrop);
gSprite->Draw(gTextureBackdrop, 0, 0, &spritePos, 0xffffffff);
gSprite->End();
g_pEffect->CommitChanges();
g_pEffect->EndPass();
}
g_pEffect->End();
gD3dDevice->EndScene();
gD3dDevice->Present(NULL,NULL,NULL,NULL);
}