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[why was deleted ?] Calculating bounding x,y,w,h ?

BlitzMax Forums/BlitzMax Programming/[why was deleted ?] Calculating bounding x,y,w,h ?

skn3(Posted 2006) [#1]
Why was my topic deleted ? .. what rules have I broken ?

For render updates and various other functions I need to know the bounding rectangle of a given entity (the entity is a type in my engine. an engine in blitzmax) at all times.

I havn't really done this type of calculation before so need some advice.

With a given
- x
- y
- width
- height
- scalex
- scaley
- angle
- handlex
- handley

I need to calculate:
- boundingx
- boundingy
- boundingwidth
- boundingheight

Anyone know how to do this ?


Dreamora(Posted 2006) [#2]
Why was it deleted: Assume you posted it to the wrong board as you did yet?
Thats the BM board and BM has no entities.


H&K(Posted 2006) [#3]
Has it been deleted thats stange.

@Dream

"Entity" in English can be taken to mean "thing" so "bounding rectangle of a given entity" can be taken litrally to mean "bounding rectangle of a given Thing".
So what you said might be the reason, but less so then you imply.
(Also and dont take offence, this is ment as help, Yet is normaly used in the negative ie. It hasnt happend yet. In this case you may have ment "Yet again", and even then you would normally only say "as you did again" and only use the Yet verion when it has happened a few times.


skn3(Posted 2006) [#4]
Yeah it is an entity in a bmax project I am creating.

Type acentity extends acpoint



Diablo(Posted 2006) [#5]
Why was my topic deleted ? .. what rules have I broken ?

I assume somthing got broken last night and they had to restore to a previous backup and you post wasnt in the last backup.


puki(Posted 2006) [#6]
LOOKS LIKE THERE WAS A PROBLEM LAST NIGHT - LOOKS LIKE A FEW HOURS OF POSTS HAVE BEEN LOST.


skn3(Posted 2006) [#7]
done it :)

I'll add to code archives

(this is just the function wrapped in a simple 'entity')
Type entity
	Field x:Float
	Field y:Float
	Field width:Float
	Field height:Float
	Field scalex:Float
	Field scaley:Float
	Field angle:Float
	Field handlex:Float
	Field handley:Float
	
	Field boundingx:Float
	Field boundingy:Float
	Field boundingwidth:Float
	Field boundingheight:Float
	
	Method UpdateBounding()	
		'calculate 4 points
		Local oldx1:Float = x
		Local oldy1:Float = y
		Local oldx2:Float = x + width * scalex
		Local oldy2:Float = y
		Local oldx3:Float = x + width * scalex
		Local oldy3:Float = y + height * scaley
		Local oldx4:Float = x
		Local oldy4:Float = y + height * scaley
		
		'calculate center point
		Local centerx:Float = x + (handlex*scalex)
		Local centery:Float = y + (handley*scaley)
		
		'calculate rotated points
		Local x1:Float = x + Cos(angle) * (oldx1 - centerx) - Sin(angle) * (oldy1 - centery)
		Local y1:Float = y + Sin(angle) * (oldx1 - centerx) + Cos(angle) * (oldy1 - centery)
		Local x2:Float = x + Cos(angle) * (oldx2 - centerx) - Sin(angle) * (oldy2 - centery)
		Local y2:Float = y + Sin(angle) * (oldx2 - centerx) + Cos(angle) * (oldy2 - centery)
		Local x3:Float = x + Cos(angle) * (oldx3 - centerx) - Sin(angle) * (oldy3 - centery)
		Local y3:Float = y + Sin(angle) * (oldx3 - centerx) + Cos(angle) * (oldy3 - centery)
		Local x4:Float = x + Cos(angle) * (oldx4 - centerx) - Sin(angle) * (oldy4 - centery)
		Local y4:Float = y + Sin(angle) * (oldx4 - centerx) + Cos(angle) * (oldy4 - centery)
		
		'find order of points
		Local minx:Float = x1
		If x2 < minx minx = x2
		If x3 < minx minx = x3
		If x4 < minx minx = x4
		
		Local miny:Float = y1
		If y2 < miny miny = y2
		If y3 < miny miny = y3
		If y4 < miny miny = y4
		
		Local maxx:Float = x1
		If x2 > maxx maxx = x2
		If x3 > maxx maxx = x3
		If x4 > maxx maxx = x4
		
		Local maxy:Float = y1
		If y2 > maxy maxy = y2
		If y3 > maxy maxy = y3
		If y4 > maxy maxy = y4
		
		'calculate bounding box
		boundingx = minx
		boundingy = miny
		boundingwidth = maxx - minx
		boundingheight = maxy - miny
	End Method
	
	Method Render()
		'draw bounding box
		SetHandle(0,0)
		SetAlpha(0.5)
		SetScale(1,1)
		SetRotation(0)
		SetColor(255,100,100)
		DrawRect(boundingx-3,boundingy-3,boundingwidth+6,boundingheight+6)
		
		'draw box
		SetAlpha(0.5)
		SetHandle(handlex,handley)
		SetScale(scalex,scaley)
		SetRotation(angle)
		SetColor(0,155,0)
		DrawRect(x,y,width,height)
		SetHandle(0,0)
	End Method
End Type

Graphics(640,480,0,0)

Local e:entity = New entity
e.x = 320
e.y = 240
e.width = 40
e.height = 60
e.scalex = 1
e.scaley = 1
e.handlex = 20
e.handley = 30
e.angle = 0

SetBlend(alphablend)
SetClsColor(255,255,255)
Repeat
	Cls
	If KeyDown(KEY_SPACE) e.angle:+0.01
	e.scaley = 1 + MouseY() / 100.0
	e.updatebounding()
	e.render()
	Flip
Until KeyDown(KEY_ESCAPE)