Sin/cos tutorial+ examples
Blitz3D Forums/Blitz3D Tutorials/Sin/cos tutorial+ examples
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| sin + cos tutorial. This tutorial will work in all versions of blitz. It is aimed at intermediate users, and anyone who does not understand the importance of sin/cos Downloadable link (includes tutorial + examples in 1 .bb file) http://skn3.acsv.net/sourcecode/sincostut.bb NOTE: - When using the Sin/Cos functions, remember that the following - angle values, are equivilant to the following directions, in a 2d world angle#=0 : right angle#=90 : down angle#=180 : left angle#=270 : up NOTE: - Cos returns a horizontal ( in a 2d world ) vector/speed value - Sin returns a vertical ( in a 2d world ) vector/speed value NOTE: - The sin and cos functions will return float numbers ranging from.. -1.0 to 1.0 - This value is directly linked to the direction of the angel passed to it. For example: using the chart above, say we want to use the RIGHT direction, that would be an angle of 0 Xspeed# = cos#(0) = 1 Yspeed# = sin#(0) = 0 - Before you try and understand that, think in your head what the X speed, and Y speed - would be, if you wanted to move in a RIGHT direction. Xspeed# = 1 ( x=x+1 is moving right ) Yspeed# = 0 ( y=y+0 is not moving vertical ) NOTE: - To move faster in a given angle, or to get a larger version of your X,Y speeds - simply multiply by a second number. Xspeed# = cos#(angle) * Multiplier# Yspeed# = sin#(angle) * Multiplier# ;Below are some demos of various uses for sin/cos Graphics 400,400,32,2 SetBuffer BackBuffer() ;#-demo1 ;rotate around a center x,y position, at variable distance angle#=0 pointx#=0 pointy#=0 centerx#=200 centery#=200 distance#=70 Repeat Cls ;get numpad +/- input to change size If KeyDown(74) And distance#>0 distance#=distance#-1 If KeyDown(78) And distance#<150 distance#=distance#+1 ;Update using the sin/cos functions pointx# = centerx# + ( Cos#(angle#) * distance# ) pointy# = centery# + ( Sin#(angle#) * distance# ) ;draw a simple graphic to show the center point Color 255,255,255 Oval centerx#-5,centery#-5,10,10,1 ;draw a simple graphics to show the path the point is travelling Color 255,0,0 Oval centerx#-(distance#),centery#-(distance#),distance#*2,distance#*2,0 ;draw a simple graphics to show the rotating point Color 255,255,255 Oval pointx#-8,pointy#-8,16,16,1 ;update angle angle#=angle#+1 If angle#=360 Then angle#=0 ;draw some status text Color 0,255,0 Text 5,5,"DEMO: rotating around a center point" Color 255,255,255 Text 5,20,"angle: "+angle# Text 5,35,"x speed: "+Cos#(angle#) Text 5,50,"y speed: "+Sin#(angle#) Color 255,0,0 Text 5,65,"press space for next demo" Color 0,0,255 Text 5,80,"use numpad +/- to change the size" Flip Until KeyHit(57) ;#-demo2 ;drawign a sine wave i#=0 angle#=0 pointx#=0 pointy#=0 centerx#=200 centery#=200 multiplier#=70 frequency#=1 Repeat Cls ;get u,d,l,r input If KeyDown(200) And distance#>0 multiplier#=multiplier#-1 If KeyDown(208) And distance#<150 multiplier#=multiplier#+1 If KeyDown(203) And distance#>0 frequency#=frequency#-0.1 If KeyDown(205) frequency#=frequency#+0.1 ;draw sine wave Color 255,255,255 i#=angle# For x=0 To 400 Plot x,200+(Sin#(i#)*multiplier#) i#=i#+frequency# Next angle#=angle#+2 ;draw some status text Color 0,255,0 Text 5,5,"DEMO: a sinewave" Color 255,0,0 Text 5,20,"press space for next demo" Color 0,0,255 Text 5,35,"use u,d keys to change amplitude" Text 5,50,"use l,r keys To change frequency" Flip Until KeyHit(57) ;#-demo3 ;360 degree movement angle#=0 pointx#=200 pointy#=200 xspeed#=0 yspeed#=0 Repeat Cls ;update x,y speeds xspeed#=Cos#(angle#) yspeed#=Sin#(angle#) ;get input from u,d,l,r to move point If KeyDown(200) ;move forwards pointx#=pointx#+xspeed# pointy#=pointy#+yspeed# End If If KeyDown(208) ;move backwards pointx#=pointx#-xspeed# pointy#=pointy#-yspeed# End If If KeyDown(203) ;turn left angle#=angle#-1 If angle#=-1 angle#=359 End If If KeyDown(205) ;turn right angle#=angle#+1 If angle#=360 angle#=0 End If ;draw a simple graphics to show the moving point Color 255,255,255 Oval pointx#-20,pointy#-20,40,40,0 ;draw a simple graphics to show the direction of the point Color 255,0,0 Line pointx#,pointy#,pointx#+(xspeed#*20),pointy#+(yspeed#*20) ;draw some status text Color 0,255,0 Text 5,5,"DEMO: moving in 360 degrees" Color 255,255,255 Text 5,20,"angle: "+angle# Text 5,35,"x speed: "+Cos#(angle#) Text 5,50,"y speed: "+Sin#(angle#) Color 255,0,0 Text 5,65,"press space to exit" Color 0,0,255 Text 5,80,"use u,d keys to move l,r keys to turn" Flip Until KeyHit(57) |
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| The link does not work?? |
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| Link works (for me). |
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| Thanks for the Tut! Nice one :) |
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| thx you a lot skn3[ac] ... this tut rocks ;-) |
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