TheGameCreators - CodeBase - Using Catmull Rom Splines

Category: 3D Maths

Version: 1.0

Information

Uploaded: 19th Apr 2004 10:48

Modified: 12th May 2004 14:14

Author: Hamish McHaggis

Summary

This is a demontration of how to use vector2 commands to create a smooth curve between 2D points, using catmull rom splines.

Full Description

This is a demontration of how to use vector2 commands to create a smooth curve between 2D points, using catmull rom splines. Catmull rom splines use 4 control points, but by stringing lots together you can get a long smooth curve between points.<br /> <br /> The same can be done with vector3, just use 3D coords not 2D ones.

DarkBASIC Professional Source Code

` This code was downloaded from The Game Creators

` It is reproduced here with full permission

` http://www.thegamecreators.com

`2D Catmull Rom Splines in DBPro

`By Joseph Thomson

`18/04/04

randomize timer()

set display mode 800,600,32

type pointType

x as integer

y as integer

endtype

`Maximum number of points

maxPoints as integer = 100

dim points(maxPoints) as pointType

`Number of starting points (has to be at least 4)

numPoints as integer = 4

`Number of points between main points (displaying the curve)

numSections as integer = 50

pointSelected as integer

mouseHold as integer

spaceHold as integer

`Randomize the starting points coordinates

points(1).x = rnd(600)+100

points(1).y = rnd(400)+100

points(2).x = rnd(600)+100

points(2).y = rnd(400)+100

points(3).x = rnd(600)+100

points(3).y = rnd(400)+100

points(4).x = rnd(600)+100

points(4).y = rnd(400)+100

`Create the vectors 1 to 5

tmp = make vector2(1)

tmp = make vector2(2)

tmp = make vector2(3)

tmp = make vector2(4)

tmp = make vector2(5)

sync on

sync rate 0

`Control addition of points

if mouseclick() = 2 and numPoints < maxPoints and mouseHold = 0

inc numPoints

points(numPoints).x = mousex()

points(numPoints).y = mousey()

endif

`Control deletion of points

if spacekey() = 1

if numPoints > 4 and spaceHold = 0

dec numPoints

endif

spaceHold = 1

else

spaceHold = 0

endif

ink rgb(255,255,0),0

`Loop through all points

for x = 1 to numPoints

if mouseclick() = 1

if mousex() >= points(x).x-3 and mousex() <= points(x).x+3 and mousey() >= points(x).y-3 and mousey() <= points(x).y+3 and mouseHold = 0

pointSelected = x

endif

box points(x).x-2,points(x).y-2,points(x).x+2,points(x).y+2

next x

`Allow one click selection

if mouseclick() <> 0

mouseHold = 1

endif

`Move selected point if there is one

if pointSelected <> 0

points(pointSelected).x = mousex()

points(pointSelected).y = mousey()

endif

ink rgb(255,255,255),0

`Loop through all active points

for x = 3 to numPoints-1

`Fill vectors with point coordinates

set vector2 1,points(x-2).x,points(x-2).y

set vector2 2,points(x-1).x,points(x-1).y

set vector2 3,points(x).x,points(x).y

set vector2 4,points(x+1).x,points(x+1).y

`Loop through the sections between points

for y = 1 to numSections-1

`Work out point on catmull rom spline (filledVector,pointA,pointB,pointC,pointD,value (0.0 = beginning of curve, 1.0 = end of curve, 0.5 = half way down curve))

catmullrom vector2 5,1,2,3,4,1.0/numSections*y

`Draw point

dot x vector2(5),y vector2(5)

next y

next x

`Draw lines between end points and 2nd end points

ink rgb(0,0,255),0

line points(1).x,points(1).y,points(2).x,points(2).y

ink rgb(0,255,0),0

line points(numPoints-1).x,points(numPoints-1).y,points(numPoints).x,points(numPoints).y

`Reset one click variable and point selected if no mouse is clicked

if mouseclick() = 0

mouseHold = 0

pointSelected = 0

endif

`Info

ink rgb(255,255,255),0

text 10,10,"2D Catmull Rom Splines"

text 10,25,"By Joseph Thomson 18/04/04"

text 10,45,"LMB to move points"

text 10,60,"RMB to add a point"

text 10,75,"Space bar to delete the last point"

sync

cls

loop

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Author Name:	Hamish McHaggis
CodeBase Entries:	14

CodeBase - Using Catmull Rom Splines

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