TheGameCreators - CodeBase - [Tier 1] Tile based line of sight

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Category: Basic 2D

Version: 1.0

Information

Uploaded: 20th Feb 2013 17:48

Modified: 20th Feb 2013 17:50

Author: Cliff Mellangard 3DEGS

Summary

I have only converted this from dbp by another author todd riggins.

Full Description

I neaded this for my dungeon game and converted it.<br /> Simply change the map array to the array name you use.<br /> My map used true as a open segment while the original used false.

AGK Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

FUNCTION LOS(StartX,StartY,EndX,EndY) `returns BOOL

IF StartX=EndX then if StartY=EndY THEN EXITFUNCTION 1

dx = StartX - EndX

dy = StartY - EndY

ax = ABS(dx)*2

ay = ABS(dy)*2

sx = losSGN(dx)

sy = losSGN(dy)

x = EndX

y = EndY

rem The following if statement checks to see if the line

rem is x dominate or y dominate and loops accordingly

IF ax > ay

rem X dominate loop

t = ay - (ax/2)

REPEAT

IF t >= 0

y = y+sy

t = t-ax

ENDIF

x = x+sx

t = t+ay

rem check to see if we are at the player's position

IF (x=StartX) AND (y=StartY)

rem return that the player can see the specified map location

EXITFUNCTION 1

ENDIF

rem keep looping until the specified map location is blocked

rem by an object at the updated x,y coord

UNTIL GridMap[x,y].BlockType=0

rem  Unable to see map location

EXITFUNCTION 0

ELSE

rem Y dominate loop

t = ax - (ay/2)

REPEAT

IF t >= 0

x = x+sx

t = t-ay

ENDIF

y = y+sy

t = t+ax

IF (x=StartX) AND (y=StartY)

EXITFUNCTION 1

ENDIF

UNTIL GridMap[x,y].BlockType=0

EXITFUNCTION 0

ENDIF

ENDFUNCTION 0

FUNCTION losSGN(a)

IF a<0 THEN EXITFUNCTION -1

ENDFUNCTION 1

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Author Name:	Cliff Mellangard 3DEGS
CodeBase Entries:	15

CodeBase - [Tier 1] Tile based line of sight

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AGK Source Code

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