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🕸Fergus Duniho wrote on Wed, Apr 1, 2020 01:02 PM UTC:

I see three problems with your code.

First, you're misspelling origin.

Second, it looks like you are using some operators incorrectly. Operators always take their operands on the right side. This is not like C or PHP, which lets you put operators between operands. To test for equality, put both values you want to compare on the right side of ==.

Third, try doing it backwards from how you're doing it, because it evaluates everything in reverse order. Place the normal King moves at the end. Just before that, include an and that checks a flag value. Before that, include the moves the King is allowed on its first move.

It's important to bear in mind how the logical operators are designed to break out of the function early if given only one operator instead of two. Compare these two lines:

def King or checkleap #0 #1 1 1 checkleap #0 #1 1 0 ;

def King checkleap #0 #1 1 1 or checkleap #0 #1 1 0;

The first one calls checkleap twice everytime, but the second calls checkleap a second time only if it was not a one space orthogonal move. As I mentioned above, operators always go on the right. The second is not an example of placing a logical operator between two operands. It is an example of a logical operator having a single operator on its right side. When or gets a single true value, it exits the function and returns true. This eliminates the need to evaluate checkleap #0 #1 1 1 when checkleap #0 #1 1 0 has already been evaluated as true.

Likewise, and will exit a function and return false if it gets a single false value. Use this to have your function evaluate the first move of a King only on its first move. Design your function so that it breaks out early if it is not a regular King move and the King has already moved. The way your function is currently designed, it does all the calculations for the King's first move everytime the King moves, and that is wasteful.

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Author: Fergus Duniho.

Comments

The Fairychess Include File Tutorial. How to use the fairychess include file to program games for Game Courier.

🕸📝Fergus Duniho wrote on Thu, Apr 11 01:02 AM UTC in reply to Daniel Zacharias from Wed Apr 10 11:51 PM:

I still don't get why the previous way wasn't working since I wasn't changing the pawn subroutine which seems to modify promotion options before the last rank.

The Pawn subroutines are only for actual moves, but nothing was being done to handle variable values of wprom or bprom for potential moves. The stalemated subroutine was supposed to provide a list of all legal moves, but it was omitting moves where someone declines promoting a Pawn. By having functions that dynamically calculate what a piece may promote to, it is now able to provide an accurate list of legal moves for games with variable promotion rules, such as Gross Chess has.

Anyway, this reveals another, but more minor, problem, which is that when a pawn gets to the promotion zone the text in the option selection box is large enough that the lines overlap slightly.

I increased the line-height and made some changes to the borders.

🕸📝Fergus Duniho wrote on Thu, Apr 11 12:33 AM UTC in reply to Fergus Duniho from Wed Apr 10 07:57 PM:

For Obento Chess, you might use functions like these:

def White_Pawn-Promote elem - rank #0 9 ((FP) (FP) (F));
def Black_Pawn-Promote elem rank #0 ((f) (fp) (fp));

That should be this:

def White_Pawn-Promote elem - rank #0 9 ((F P) (F P) (F));
def Black_Pawn-Promote elem rank #0 ((f) (f p) (f p));

Daniel Zacharias wrote on Wed, Apr 10 11:51 PM UTC in reply to Fergus Duniho from 07:57 PM:

Thank you, that does work better; although I still don't get why the previous way wasn't working since I wasn't changing the pawn subroutine which seems to modify promotion options before the last rank.

Anyway, this reveals another, but more minor, problem, which is that when a pawn gets to the promotion zone the text in the option selection box is large enough that the lines overlap slightly.

🕸📝Fergus Duniho wrote on Wed, Apr 10 07:57 PM UTC in reply to Daniel Zacharias from 01:28 PM:

In looking into this, I tested Gross Chess to see if it had the same problem, but before I could tell, I encountered another problem with it. I realized that for a game like Gross Chess it wouldn't do to use bprom and wprom as though they had static values. So I rewrote the fairychess include file and the Gross Chess code to support dynamic values for what a piece is allowed to promote to on a given space.

This makes use of some new functions that end with "-Promote". Here are the default functions for the Pawns:

def White_Pawn-Promote var wprom;
def Black_Pawn-Promote var bprom;

For backwards compatibility with the original way of handling promotions, these just return the value of wprom or bprom. And for additional backwards compatibility, the stalemated subroutine will use these functions only if the piece is not in the promotable array. So, to enable the use of these functions for providing dynamic values for what a piece can promote to, you should unset promotable or set it to an empty array. I added this line to Gross Chess after including the fairychess include file.

unset promotable;

Since the default functions return static values, they need to be rewritten for the particular game they are for. Here are the functions I wrote for Gross Chess:

def White_Pawn-Promote merge intersection var cap elem - rank #0 9 ((B N V W) (B N V W C R S) (B N V W C R S A M Q)) elem - rank #0 9 ((P) (P));
def Black_Pawn-Promote merge intersection var cap elem rank #0 ((b n v w c r s a m q) (b n v w c r s) (b n v w)) elem rank #0 (() (p) (p));

Since what a Pawn may promote to in Gross Chess depends upon the rank it is on, I used the rank value for black (or a value calculated from the rank value for white) as the index for a couple of arrays from which it extracted a particular value. For example, black can promote on ranks 0-2, as they are designated internally. So, this code will return the element of the array with the same index as the rank value:

elem rank #0 ((b n v w c r s a m q) (b n v w c r s) (b n v w))

Since white promotes on ranks 9-11, I subtracted 9 to get a value from 0 to 2 for any rank promotions are allowed on or a number that is out of range for any other rank. So, this works similarly:

elem - rank #0 9 ((B N V W) (B N V W C R S) (B N V W C R S A M Q))

Since the last rank for black is 0, and the last for white is 11, and 11-9 is 2, these list sets of promotion options in the reverse order from each other.

Since promotion options are limited to captured pieces, each function calculates the intersection of the value above with the captured pieces. This looks like this for black:

intersection var cap elem rank #0 ((b n v w c r s a m q) (b n v w c r s) (b n v w))

Finally, I get to the part that is relevant to Obento Chess. Whether it can promote to a Pawn as a way of declining promotion depends on the rank but not on what has been captured. So Pawns were not included in the main lists of promotion options. Instead, it merges the intersection calculated above with the value of another array element. Again, the specific array element is a function of the rank. Here is what it looks like for black:

elem rank #0 (() (p) (p))

Since declining promotion is not an option for black on rank 0, an empty array is provided for the element with an index of 0. This is not necessary for white, as the rank it cannot decline promotion on has a higher index.

elem - rank #0 9 ((P) (P))

For Obento Chess, you might use functions like these:

def White_Pawn-Promote elem - rank #0 9 ((FP) (FP) (F));
def Black_Pawn-Promote elem rank #0 ((f) (fp) (fp));

You could handle promotion for the other promotable pieces with similar functions for each specific piece.

Daniel Zacharias wrote on Wed, Apr 10 01:28 PM UTC in reply to Fergus Duniho from 12:56 PM:

I did copy from Gross chess. The descriptions should be fixed now

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