TheGameCreators - CodeBase - Y-rotated box math collision

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Category: Collision

Version: 1.0

Information

Uploaded: 23rd Apr 2004 13:06

Modified: 1st Jan 1970 01:00

Author: Emperor Baal

Summary

This code can check for collision with Y-rotated boxes and pillars.

Full Description

DarkBASIC Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

remstart

--------------------------------------------------------------

Rotated Box Collision

by Emperor-Baal

note:

-This method is not finished, im still tweaking it, but it works.

It also works with sliding collision, which is explained in my tutorial:

http://www.geocities.com/hatesurvivor/MathColl.htm

-This method only works with Y-rotated boxes (x and z size are the same)

-You may alter my code if you want. If you find a better way to check for

collision with rotated boxes then email me at once ;)

geile_teddybeer@msn.com

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remend

rem Use this line to call the function

rem Rotated_Box_Collision( moving object number,  hard object number, hard object size / 1.414)

rem Sets the refresh rate to the maximum

sync on

sync rate 0

rem Lets make the cube that's hard

make object cube 2,10

rem Positions the cube at the center

position object 2,0,0,0

rem Lets make 291 spheres that will move towards the cube

for a=10 to 300

make object sphere a,0.4

position object a,rnd(100)-50,0,rnd(100)-50

point object a,0,0,0

next a

rem Start of the main-loop

rem Check for collision with the spheres, if there's no collision then move the sphere closer.

for a=10 to 300

rem Check if collision is possible, using a position check, if you have a pillar then you should change this

if object position y(a) > object position y(2)-(object size y(2)/2.0)

if object position y(a) < object position y(2)+(object size y(2)/2.0)

rem rotated_box_collision(moving object, hard object, size of object 2 / 1.414

if rotated_box_collision(a,2,object size x(2)/1.414) = 0 then move object a,0.05

endif

next a

rem If the user presses the spacekey, the cube will rotate and every sphere that collides with the cube is repositioned to a random location

if spacekey()=1

yrotate object 2,wrapvalue(object angle y(2)+0.2)

for a=10 to 300

if rotated_box_collision(a,2,10.0) = 1

position object a,rnd(100)-50,0,rnd(100)-50

point object a,0,0,0

endif

next a

endif

position camera 10,30,0

point camera 0, 0,0

sync

loop

function rotated_box_collision(a,b,size#)

rem Get some position values

x# = object position x(a)

y# = object position y(a)

z# = object position z(a)

x2# = object position x(b)

y2# = object position y(b)

z2# = object position z(b)

rem Get the angle for the distance check

ya# = wrapvalue(360-object angle y(b)) + 45.0 + atanfull(x#-x2#,z#-z2#)

rem 0.95 is the magical tweak number, try changing it by steps of 0.1

fla# = (0.95 - cos(45)) / 45.0

rem ---------------------------------------------------

rem Make sure it lies between 0.0 and 90.0

while ya# > 90.0

ya# = ya# - 90.0

endwhile

while ya# < 0.0

ya# = ya# + 90.0

endwhile

rem ---------------------------------------------------

rem This will try to get "real" distance to the cube

if ya# <= 45.0

yb# = 1.0 - (ya# * fla#)

rem Returns a value between 1.0 and 0.7

else

yb# = 1.0 - ((45.0 - (ya# - 45.0))*fla#)

rem Returns a value between 0.7 and 1.0

endif

rem ---------------------------------------------------

rem Reset the result

result = 0

rem Final Distance

superim# = size# * yb#

rem Ordinary distance check using the freshly calculated distance

if SQRT( (x#-x2#)^2 + (z#-z2#)^2 ) < superim# then result = 1

endfunction result

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Author Name:	Emperor Baal
CodeBase Entries:	2

CodeBase - Y-rotated box math collision

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