How do I apply pixel shader to specific sprite in XNA 4.0 in a spritesort FrontToBack?

Question

I have a set of sprite drawn in FrontToBack sortmode. In XNA 4.0, the effect must be as an input argument of Begin() function of SpriteBatch. However, If I reinvoke the function, then the sprite sorting is lost. Therefore, I have to find a way to implement the pixel shader within the Begin() and End() for specific texture drawn. I tried to use effect.CurrentTechnique.Passes[0].Apply(), but no pixel was shaded when I invoke this. On the other hand, if I put effect as an argument, then all of the sprites would be effected. Therefore, is there any convenient way to approach this?

By the way, what I am trying to do is to provide an overlay on an isometric tile using some kind of masking. Therefore, I want to draw such masking and programmatically change it to optional color.

Something like this (from final fantasy tactics):

I am not sure if pixel shader is the right way to approach it, but then I have to tackle the fact that I want to be able to specify optional color dynamically. Other than that, I really want it to animate, which I might approach this by creating several grayscale animated masking and saturate it using pixel shader.

Answer 1

Changing effects and effect parameters in a single batch doesn't work unless if you're using the SpriteSortMode.Immediate. This happens because the sprite batch waits until you call spriteBatch.End() before starting the drawing.

It seems like you would like to use the spritebatch because you want to sort the sprites before drawing. If you manually sort the sprites and then draw them all using SortMode.Immediate you can use effect.CurrentTechnique.Passes[0].Apply() anywhere between .Begin() and .End().

Answer 2

This link might help you out with the issue:

http://msdn.microsoft.com/en-us/library/bb313868(v=xnagamestudio.31).aspx