is this a bug?

Monkey Forums/Monkey Programming/is this a bug?

slenkar

(Posted 2011) [#1]

Strict
Import mojo

Global time:Int
Global anim_interval:Int=300
Global tor:body_part
Global leg1:body_part
Global leg2:body_part
Global shin1:body_part
Global shin2:body_part

Class body_part
Field angle:Float
Field child_list:List<body_part>
Field parent:body_part
Field matrix:Float[]
Field x:Int
Field y:Int
Field globalx:Int
Field globaly:Int

End Class

Class imgtest Extends App


Method OnUpdate:Int()
time=Millisecs()
If KeyDown(KEY_W)
tor.y=tor.y-10
Endif
If KeyDown(KEY_LEFT)
leg1.angle=leg1.angle-1
Endif
If KeyDown(KEY_RIGHT)
leg1.angle=leg1.angle+1
Endif
If KeyDown(KEY_UP)
shin1.angle=shin1.angle+1
Endif
If KeyDown(KEY_DOWN)
shin1.angle=shin1.angle-1
Endif

Return 0

End Method

Method OnRender:Int()

Cls
PushMatrix

Local gx1:Int
Local gy1:Int
Local gx2:Int
Local gy2:Int
Translate(tor.x,tor.y)
Rotate(tor.angle)
DrawCircle (0,0,30)
tor.matrix=GetMatrix()
For Local b:body_part=Eachin tor.child_list
SetMatrix(tor.matrix)
Translate(b.x,b.y)
Rotate(b.angle)
DrawRect(0,0,10,40)
b.matrix=GetMatrix()
b.globalx=b.matrix[4]
b.globaly=b.matrix[5]

For Local bo:body_part=Eachin b.child_list
SetMatrix(b.matrix)
Translate(bo.x,bo.y)
Rotate bo.angle
DrawRect(0,0,10,40)
bo.matrix=GetMatrix()
If bo=shin1
bo.globalx=bo.matrix[4]
bo.globaly=bo.matrix[5]
Endif
If bo=shin2
bo.globalx=bo.matrix[4]
bo.globaly=bo.matrix[5]
Endif




Next

Next

PopMatrix
PushMatrix
DrawLine(shin1.globalx,shin1.globaly,shin2.globalx,shin2.globaly)
PopMatrix

Return 0
End Method

Method OnCreate:Int()
SetUpdateRate 60
tor=New body_part
tor.x=200
tor.y=300
tor.child_list=New List<body_part>

leg1=New body_part
leg1.x=40
leg1.y=40
tor.child_list.AddLast(leg1)
leg1.child_list=New List<body_part>

shin1=New body_part
shin1.x=0
shin1.y=40
leg1.child_list.AddLast(shin1)


leg2=New body_part
leg2.x=-40
leg2.y=40
tor.child_list.AddLast(leg2)
leg2.child_list=New List<body_part>

shin2=New body_part
shin2.x=0
shin2.y=40
leg2.child_list.AddLast(shin2)


Return 0
End Method

End Class

Function Main:Int()
New imgtest
Return 0
End Function

if you press the arrow keys you move the limbs and the line will be drawn between the two legs

in this next version the line is being drawn in between the push and popmatrix and is drawn off the screen (ie the wrong place)


Strict
Import mojo

Global time:Int
Global anim_interval:Int=300
Global tor:body_part
Global leg1:body_part
Global leg2:body_part
Global shin1:body_part
Global shin2:body_part

Class body_part
Field angle:Float
Field child_list:List<body_part>
Field parent:body_part
Field matrix:Float[]
Field x:Int
Field y:Int
Field globalx:Int
Field globaly:Int

End Class

Class imgtest Extends App


Method OnUpdate:Int()
time=Millisecs()
If KeyDown(KEY_W)
tor.y=tor.y-10
Endif
If KeyDown(KEY_LEFT)
leg1.angle=leg1.angle-1
Endif
If KeyDown(KEY_RIGHT)
leg1.angle=leg1.angle+1
Endif
If KeyDown(KEY_UP)
shin1.angle=shin1.angle+1
Endif
If KeyDown(KEY_DOWN)
shin1.angle=shin1.angle-1
Endif

Return 0

End Method

Method OnRender:Int()

Cls
PushMatrix

Local gx1:Int
Local gy1:Int
Local gx2:Int
Local gy2:Int
Translate(tor.x,tor.y)
Rotate(tor.angle)
DrawCircle (0,0,30)
tor.matrix=GetMatrix()
For Local b:body_part=Eachin tor.child_list
SetMatrix(tor.matrix)
Translate(b.x,b.y)
Rotate(b.angle)
DrawRect(0,0,10,40)
b.matrix=GetMatrix()
b.globalx=b.matrix[4]
b.globaly=b.matrix[5]

For Local bo:body_part=Eachin b.child_list
SetMatrix(b.matrix)
Translate(bo.x,bo.y)
Rotate bo.angle
DrawRect(0,0,10,40)
bo.matrix=GetMatrix()
If bo=shin1
bo.globalx=bo.matrix[4]
bo.globaly=bo.matrix[5]
Endif
If bo=shin2
bo.globalx=bo.matrix[4]
bo.globaly=bo.matrix[5]
Endif




Next

Next
PushMatrix
DrawLine(shin1.globalx,shin1.globaly,shin2.globalx,shin2.globaly)
PopMatrix

PopMatrix

Return 0
End Method

Method OnCreate:Int()
SetUpdateRate 60
tor=New body_part
tor.x=200
tor.y=300
tor.child_list=New List<body_part>

leg1=New body_part
leg1.x=40
leg1.y=40
tor.child_list.AddLast(leg1)
leg1.child_list=New List<body_part>

shin1=New body_part
shin1.x=0
shin1.y=40
leg1.child_list.AddLast(shin1)


leg2=New body_part
leg2.x=-40
leg2.y=40
tor.child_list.AddLast(leg2)
leg2.child_list=New List<body_part>

shin2=New body_part
shin2.x=0
shin2.y=40
leg2.child_list.AddLast(shin2)


Return 0
End Method

End Class

Function Main:Int()
New imgtest
Return 0
End Function

if I understand correctly arent the push and pop matrix commands supposed to push an identity stack onto the matrix and then pop it off?
the line is being drawn as if I never used push and pop at all (in the second example)

AdamRedwoods

(Posted 2011) [#2]

PushMatrix() PopMatrix()
Push and pop the currently used matrix on/off the stack, not necessarily the identity matrix.

The identity matrix is:
SetMatrix(1,0,0,1,0,0)

slenkar

(Posted 2011) [#3]

im a little confused now about the matrix stack
thanks for the identity matrix idea

Goodlookinguy

(Posted 2011) [#4]

The matrix stack is really pretty simple. Mojo draws objects based on the values ix, iy, jx, jy, tx, and ty, stored in the global context variable. When you push the stack, it takes those variables and stores them in the matrix, but continues using them to draw objects to a position. So when you Translate, Rotate, or Scale, all it does is add to those variables values. When it "Pops", it takes the matrix saved during the push and puts them in the ix, iy, jx, jy, tx, and ty variables.

From mojo.graphics

Function SetMatrix( ix#,iy#,jx#,jy#,tx#,ty# )
	context.ix=ix
	context.iy=iy
	context.jx=jx
	context.jy=jy
	context.tx=tx
	context.ty=ty
	context.tformed=(ix<>1 Or iy<>0 Or jx<>0 Or jy<>1 Or tx<>0 Or ty<>0)
	context.matDirty=1
End

Function GetMatrix#[]()
	Return [context.ix,context.iy,context.jx,context.jy,context.tx,context.ty]
End

Function PushMatrix()
	Local sp=context.matrixSp
	context.matrixStack[sp+0]=context.ix
	context.matrixStack[sp+1]=context.iy
	context.matrixStack[sp+2]=context.jx
	context.matrixStack[sp+3]=context.jy
	context.matrixStack[sp+4]=context.tx
	context.matrixStack[sp+5]=context.ty
	context.matrixSp=sp+6
End

Function PopMatrix()
	Local sp=context.matrixSp-6
	SetMatrix context.matrixStack[sp+0],context.matrixStack[sp+1],
	context.matrixStack[sp+2],context.matrixStack[sp+3],
	context.matrixStack[sp+4],context.matrixStack[sp+5]
	context.matrixSp=sp
End

Function Transform( ix#,iy#,jx#,jy#,tx#,ty# )
	Local ix2#=ix*context.ix+iy*context.jx
	Local iy2#=ix*context.iy+iy*context.jy
	Local jx2#=jx*context.ix+jy*context.jx
	Local jy2#=jx*context.iy+jy*context.jy
	Local tx2#=tx*context.ix+ty*context.jx+context.tx
	Local ty2#=tx*context.iy+ty*context.jy+context.ty
	SetMatrix ix2,iy2,jx2,jy2,tx2,ty2
End

slenkar

(Posted 2011) [#5]

ah ok, I was thinking that the top of the stack was used, but its actually something seperate that gets rendered, i fixed the problem now thanks