基于网格的2D照明问题

Question

I am aware this question has been asked before, but unfortunately I am new to the language, so the complicated explanations I've found do not help me in the least.

I need a lighting engine for my game, and I've tried some procedural lighting systems. This method works the best:

if (light[xx - 1, yy] > light[xx, yy]) light[xx, yy] = light[xx - 1, yy] - lightPass;
if (light[xx, yy - 1] > light[xx, yy]) light[xx, yy] = light[xx, yy - 1] - lightPass;
if (light[xx + 1, yy] > light[xx, yy]) light[xx, yy] = light[xx + 1, yy] - lightPass;
if (light[xx, yy + 1] > light[xx, yy]) light[xx, yy] = light[xx, yy + 1] - lightPass;

(Subtracts adjacent values by 'lightPass' variable if they are more bright) (It's in a for() loop)

This is all fine and dandy except for a couple obvious reasons:

1. The system favors whatever comes first, in this case the value to the left (x - 1)
2. The system cannot replace lighter values with darker values when a light source is deleted

This is what the above code looks like applied to my game:

If I could get some help on creating a new procedural or otherwise lighting system I would really appreciate it!

Answer 1

First off, I love your art style :)

Grid based lighting was a tough one I was searching for, eventually I found a method of doing this. Basically each block has a Light value, how much light it emits. and an Absorb value, how much light it absorbs.

A blank block, during day, may have:

Light = 1; (Or Color.White for color)
Absorb = 15; //Light flows for 15 blocks through blank tiles

A dirt block, will have:

Light = 0; (Or Color.Black for color) //Emits nothing
Absorb = 6; //Light flows for 6 blocks

With this you can easily configure any block. For this example I will assume you have a tile array of some sort of class, say Tile , which contains a Block , with Light and Absorb

I will also say, that each frame you must RESET all of the lighting to its default values (Blank to 1, dirt to 0) before you recalculate the lighting (Unless nothing has changed of course, this skip the reset and lighting)

Before I show the code, let me explain the steps needed to do this:

Basically what we do is loop through all the tiles, starting from the top, if a tile is blank, set the CurrentLight variable to max brightness, if we find a solid tile, set it as the CurrentLight variable and subtract an "absorbsion" amount from the CurrentLight . This way, on our next solid tile, when we set the tile to the CurrentLight value, it will be slightly less. This process is repeated until the array is iterated.

Now that will create a top to bottom lighting effect, the loop must be repeated, right to left, left to right, and bottom to top.

The code used for each tile on the loop is:

if (tile.Light > CurrentLight) //If this tile is brighter than the last, set the current light to the tiles light
     CurrentLightR = tile.Light;
else if (CurrentLight != 0f) //If it is less, and isn't dark, then set the tile to the current light
     tile.Light = CurLightR;
if (tile.Light == CurLightR) //If it is the same, subtract absorb values
     CurrentLight -= tile.Absorb;

You can also see how I made "smooth" lighting, here :