SUN AND SHADOW EFFECTS IN THE SAME SPRITES

My idea is to darken botton-left and lighten top-right of every sprite onscreen, but how to do it?

I got a paralax 0,0 layer on the Z-top. Now i don't know how to add the effects, nor how to setup my configuration of botton it, top that...

Help, please.

<img src="" border="0" />

I'm thinking to keep one of these re-sized and pinned in every single player/enemie sprite of my game.

If you are reading this and have any other idea that gonna consume less, please reply.

[edit]Seems that I cant post images on the forum, but it is a square of gradient color from top-right-white to bottom-left-black.

This is a good idea, but, I think the extra VRAM, that is needed, would ruin game play.

[EDIT]

Back to your question at hand. You would have to take every sprite you plan on using shadows with and open then in Photoshop. Then make all the gradients in exact same size/shape as your sprite in an above layer. After you load all those new sprites in you would then simply use one set of sprites if NightTime is true or the other set if DayTime is true.

[EDIT 2]

I was thinking there might be a way to use the Additive/Screen effects on a layer with a gradient but this wouldn't line up properly with each sprite. Who knows! >.<

Tekniko, thanks for you help, but my player/enemies right now are about 2 images each and have angles. I would have to add lots of new content.

I tryed to imagine it even with 2 additive screen, but i would need that each one get only half(or less) of each sprite. And here we are. Do you have any idea how to create effects for c2?