Finally I cracked it! 2D rotatable objects with vertices

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Libervurto

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Posted: 23rd Jan 2008 02:32 Edited at: 23rd Jan 2008 02:34

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Ok so you can't add an image or anything fancy like that but now I can make a gta style game with DBC! ehem, I mean like Asteroids

+ Code Snippet

`--------------------
` 2D Rotating Points
` Speedometer
` By OBese87
`--------------------

hide mouse
sync on : sync rate 40

rem v=vertex, a=angle from centre, d=distance from centre
DIM v(4,1)
a=0:d=1
`plot vertices
v(1,a)=0 : v(1,d)=10
v(2,a)=90 : v(2,d)=10
v(3,a)=180 : v(3,d)=100
v(4,a)=270 : v(4,d)=10

`square root data
mina=0 : maxa=170
angle=mina : x=320 : y=240

DO
   if spacekey()=1
      inc angle,6
      if angle>maxa then angle=maxa-20
   else
      dec angle,4
      if angle<mina then angle=mina
   endif

   for vt = 1 to 4
      if vt<4 then add=1 else add=-3
      sx = x + cos(angle+v(vt,a))*v(vt,d)
      sy = y + sin(angle+v(vt,a))*v(vt,d)
      ex = x + cos(angle+v(vt+add,a))*v(vt+add,d)
      ey = y + sin(angle+v(vt+add,a))*v(vt+add,d)
      line sx,sy,ex,ey
   next vt

   sync:cls
LOOP

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Latch

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Posted: 23rd Jan 2008 08:29

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Pretty Smooth!

Enjoy your day.

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demons breath

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Location: Surrey, UK

Posted: 23rd Jan 2008 15:19 Edited at: 23rd Jan 2008 15:19

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That's pretty cool!

I just use newxvalue and newzvalue, like this:

dim pos(5,1)
pos(5,0)=60 : pos(5,1)=80
maxspeed=10
speed#=0

do

gosub moveship
gosub drawship

sync
cls
set cursor 600,15 : print rot
set cursor 600,30 : print speed#
loop

moveship:
if rightkey()=1 then rot=wrapvalue(rot+3)
if leftkey()=1 then rot=wrapvalue(rot-3)

if upkey()=1
	if speed#<maxspeed then speed#=speed#+0.5
else
	if speed#>0 then speed#=speed#-0.2
endif

if speed#>maxspeed then speed#=maxspeed
if speed#<0 then speed#=0

if speed#>0
	pos(5,0)=WRAPVALUE(newxvalue(pos(5,0),rot,speed#))
	pos(5,1)=WRAPVALUE(newzvalue(pos(5,1),rot,speed#))
endif

pos(0,0)=(pos(5,0)*1.7)+14
pos(0,1)=(pos(5,1)*1.1)+12
return

drawship:
pos(1,0)=newxvalue(pos(0,0),rot,35)
pos(1,1)=newzvalue(pos(0,1),rot,35)
pos(2,0)=newxvalue(pos(0,0),rot+120,20)
pos(2,1)=newzvalue(pos(0,1),rot+120,20)
pos(3,0)=newxvalue(pos(0,0),rot+240,20)
pos(3,1)=newzvalue(pos(0,1),rot+240,20)
pos(4,0)=newxvalue(pos(0,0),rot+180,1)
pos(4,1)=newzvalue(pos(0,1),rot+180,1)

line pos(2,0),pos(2,1),pos(1,0),pos(1,1)
line pos(3,0),pos(3,1),pos(1,0),pos(1,1)
line pos(2,0),pos(2,1),pos(4,0),pos(4,1)
line pos(3,0),pos(3,1),pos(4,0),pos(4,1)
return

+ Code Snippet

dim pos(5,1)
pos(5,0)=60 : pos(5,1)=80
maxspeed=10
speed#=0

do

gosub moveship
gosub drawship

sync
cls
set cursor 600,15 : print rot
set cursor 600,30 : print speed#
loop


moveship:
if rightkey()=1 then rot=wrapvalue(rot+3)
if leftkey()=1 then rot=wrapvalue(rot-3)

if upkey()=1
	if speed#<maxspeed then speed#=speed#+0.5
else
	if speed#>0 then speed#=speed#-0.2
endif

if speed#>maxspeed then speed#=maxspeed
if speed#<0 then speed#=0

if speed#>0
	pos(5,0)=WRAPVALUE(newxvalue(pos(5,0),rot,speed#))
	pos(5,1)=WRAPVALUE(newzvalue(pos(5,1),rot,speed#))
endif

pos(0,0)=(pos(5,0)*1.7)+14
pos(0,1)=(pos(5,1)*1.1)+12
return

drawship:
pos(1,0)=newxvalue(pos(0,0),rot,35)
pos(1,1)=newzvalue(pos(0,1),rot,35)
pos(2,0)=newxvalue(pos(0,0),rot+120,20)
pos(2,1)=newzvalue(pos(0,1),rot+120,20)
pos(3,0)=newxvalue(pos(0,0),rot+240,20)
pos(3,1)=newzvalue(pos(0,1),rot+240,20)
pos(4,0)=newxvalue(pos(0,0),rot+180,1)
pos(4,1)=newzvalue(pos(0,1),rot+180,1)

line pos(2,0),pos(2,1),pos(1,0),pos(1,1)
line pos(3,0),pos(3,1),pos(1,0),pos(1,1)
line pos(2,0),pos(2,1),pos(4,0),pos(4,1)
line pos(3,0),pos(3,1),pos(4,0),pos(4,1)
return

that's part of what I have for some asteroids clone I'm trying to make; I find it much easier than fiddling about with vertices (don't understand them)...

Hopefully I should learn how to use vertices soon 'cos they're the next topic in my maths course so once I have the basics I'll give them a whirl, I'm just too lazy to learn anything new unless it's absolutely necessary...

"A West Texas girl, just like me"
-Bush

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Libervurto

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Joined: 30th Jun 2006

Location: On Toast

Posted: 23rd Jan 2008 17:50 Edited at: 23rd Jan 2008 23:35

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@DB
I've never used newvalue, now I see they are useful

I'm sure there are benefits from doing it the hard way like, ermm...

[edit]
Here's my next project
If I can make this in 2D I can make anything!

I'll have to position 63 vertices!

Can you guess what it is yet?

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Latch

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Joined: 23rd Jul 2006

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Posted: 24th Jan 2008 00:06

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I remeber doing a benchmark once and newxvalue etc were faster than sin and cos.

But you can squeeze a little more speed out of cos and sin that should leave sin() and cos() functions in the dust (newx etc too). Create lookup tables for sine and cosine. Here's a quick benchmark of sin() vs sine#() lookup:

+ Code Snippet

sync on
sync rate 0

trig_lookup:
print "Creating lookup tables..."
wait 0
   dim sine#(360)
   dim cosine#(360)
   for ang=0 to 360
      sine#(ang)=sin(ang)
      cosine#(ang)=cos(ang)
   next ang
sync

rem test speed
print "Running through 100000 iterations (may take a while)"
wait 0
tim=timer()
for n=1 to 100000
   for ang=0 to 360
      value#=sin(ang)
   next ang
next n
sync
print "regular sin took ";timer()-tim;" ms"
sync

print "Running through 100000 iterations (may take a while)"
wait 0
tim=timer()
for n=1 to 100000
   for ang=0 to 360
      value#=sine#(ang)
   next ang
next n
sync
print "lookup sin took ";timer()-tim;" ms"
sync

It's about 200% faster on my computer. This only returns whole number angle ratios, but that should suffice.

Enjoy your day.

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Libervurto

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Joined: 30th Jun 2006

Location: On Toast

Posted: 24th Jan 2008 01:58 Edited at: 24th Jan 2008 02:10

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I took your advice but it's getting a bit messy.
This example also shows that all vertices no longer have to be connected.

`--------------------
` 2D Rotating Points
` Speedometer
` By OBese87
`--------------------

hide mouse
sync on : sync rate 40

gosub LookupTables

rem v=vertex, a=angle from centre, d=distance from centre, vc=vertex connected to
maxv=7
DIM v(maxv,2)
a=0:d=1:vc=2
`plot vertices
v(1,a)=0   : v(1,d)=10  : v(1,vc)=4
v(2,a)=90  : v(2,d)=10  : v(2,vc)=1
v(3,a)=180 : v(3,d)=100 : v(3,vc)=2
v(4,a)=270 : v(4,d)=10  : v(4,vc)=3
`inner triangle
v(5,a)=180 : v(5,d)=60  : v(5,vc)=6
v(6,a)=270 : v(6,d)=4  : v(6,vc)=7
v(7,a)=90 : v(7,d)=4  : v(7,vc)=5

`square root data
mina=0 : maxa=170
angle=mina : x=320 : y=240

DO
   if spacekey()=1
      inc angle,6
      if angle>maxa then angle=maxa-20
   else
      dec angle,4
      if angle<mina then angle=mina
   endif

for vt = 1 to maxv
      AngleS = wrapvalue(angle+v(vt,a))
      DistS = v(vt,d)
      sx = x + cosine#(AngleS)*DistS
      sy = y + sine#(AngleS)*DistS

AngleE = wrapvalue(angle+v(v(vt,vc),a))
      DistE = v(v(vt,vc),d)
      ex = x + cosine#(AngleE)*DistE
      ey = y + sine#(AngleE)*DistE

line sx,sy,ex,ey
   next vt

sync:cls
LOOP

`------------
` Gosubs
`------------
LookupTables:
   dim sine#(360)
   dim cosine#(360)
   for n = 0 to 359
      sine#(n)=sin(n)
      cosine#(n)=cos(n)
   next n
Return

+ Code Snippet

`--------------------
` 2D Rotating Points
` Speedometer
` By OBese87
`--------------------

hide mouse
sync on : sync rate 40

gosub LookupTables

rem v=vertex, a=angle from centre, d=distance from centre, vc=vertex connected to
maxv=7
DIM v(maxv,2)
a=0:d=1:vc=2
`plot vertices
v(1,a)=0   : v(1,d)=10  : v(1,vc)=4
v(2,a)=90  : v(2,d)=10  : v(2,vc)=1
v(3,a)=180 : v(3,d)=100 : v(3,vc)=2
v(4,a)=270 : v(4,d)=10  : v(4,vc)=3
`inner triangle
v(5,a)=180 : v(5,d)=60  : v(5,vc)=6
v(6,a)=270 : v(6,d)=4  : v(6,vc)=7
v(7,a)=90 : v(7,d)=4  : v(7,vc)=5

`square root data
mina=0 : maxa=170
angle=mina : x=320 : y=240

DO
   if spacekey()=1
      inc angle,6
      if angle>maxa then angle=maxa-20
   else
      dec angle,4
      if angle<mina then angle=mina
   endif

   for vt = 1 to maxv
      AngleS = wrapvalue(angle+v(vt,a))
      DistS = v(vt,d)
      sx = x + cosine#(AngleS)*DistS
      sy = y + sine#(AngleS)*DistS

      AngleE = wrapvalue(angle+v(v(vt,vc),a))
      DistE = v(v(vt,vc),d)
      ex = x + cosine#(AngleE)*DistE
      ey = y + sine#(AngleE)*DistE

      line sx,sy,ex,ey
   next vt

   sync:cls
LOOP

`------------
` Gosubs
`------------
LookupTables:
   dim sine#(360)
   dim cosine#(360)
   for n = 0 to 359
      sine#(n)=sin(n)
      cosine#(n)=cos(n)
   next n
Return

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demons breath

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Location: Surrey, UK

Posted: 24th Jan 2008 20:46

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@OBese: looking good, but it tends to spasm uncontrollably when it reaches the limit...

"A West Texas girl, just like me"
-Bush

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Libervurto

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Posted: 24th Jan 2008 22:24

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Yeah it's supposed to never actually seen that in real life but it happens in computer games

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Link102

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Posted: 25th Jan 2008 12:18

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instead of angle and distance, why don't you do xoffset and yoffset. That's how 3d objects work.

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Libervurto

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Posted: 25th Jan 2008 19:24

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@link
Then I'd have to calculate the offset as the object rotates, but it would mean that when the object wasn't rotating I wouldn't have to calculate anything.
X and Y positions would also make it easier to detect collisions, maybe I'll try it.

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