How should I draw the world in a tile-based game? (Slick)

[Zhon]

A long time ago, when I last tried making a game, I used to draw tiles like this.. (pseudo code)

for each tile in the world
if the tile is visible
Image img = tilesheet.getSubImage(a,b,c,d); //to get the tile image from the tilesheet
... //here I use img.setColor(...) for each corner of the img, in order to setup it's colors according to it's light values
img.draw(tile.x, tile.y);

But this is an horrible way to draw things.
I tried using

tilesheet.startUse();
for each tile visible in the world
tilesheet.drawEmebedded(....);
tilesheet.endUse();

This saves me some fps, however, I can't manipulate the colors in order to give lighting to the tiles with this.

Is there a good way to draw tiles from a spritesheet, manipulate light and save as much memory as possible?
Should I try writing a vertex shader? I'm not very familiar to shaders yet.. Specially when it comes to vertex shders.
These are some examples of simple fragment shaders I have written today:

(the background only /\)



But if it happens for vertex shaders being the best decision, I'll do my best to get over it.

Thanks a bunch and sorry for my bad english 

[HeroesGraveDev]

Using shaders will be the easiest way.

And btw, a vertex shader normally goes with a fragment shader.

[davedes]

Depends on what you're trying to achieve. If you can just use images (like a white feathered circle) and tint them, that will be much easier and potentially more performant than shaders (wich Slick at least).

You can tint with myColor.bind() before calling drawEmbedded. More info here:
http://slick.cokeandcode.com/wiki/doku.php?id=performance_memory_tips