Module noddybox.glflag

ModuleInfo "Framework: Simple Open GL Backdrop flag"
ModuleInfo "Copyright: Public Domain"
ModuleInfo "Author: Ian Cowburn"
ModuleInfo "Version: $Revision$"

' $Id$

Import brl.Basic
Import pub.OpenGL

Strict

Type GLFlag

	' These are considered private
	'
	Const THRESHOLD:Float=0.0001
	Field v:GLFlagVertex[,]
	Field width:Int
	Field height:Int
	Field txt:Int
	Field zpos:Float

	' Creates a new flag
	'	
	' texture		- Flag texture
	' horiz		- Number of horizontal vertices
	' vert		- Number of vertical vertices
	' size		- Size of each square
	' tile		- Whether the texture is tiled or not
	' z			- Distance of flag (flags always created in the XY plane)
	'
	' Returns null for invalid parameters.
	'
	Function Create:GLFlag(texture:Int, horiz:Int, vert:Int, size:Float, tile:Int, z:Float)
		Local o:GLFlag
		
		If (horiz<2 Or vert<2)
			Return Null
		EndIf
		
		o=New GLFlag
		
		o.txt=texture
		o.zpos=z
		o.width=horiz
		o.height=vert
		o.v=New GLFlagVertex[horiz,vert]
		
		Local ox:Float
		Local oy:Float
		
		ox=-(size*horiz)/2
		oy=-(size*horiz)/2
		
		For Local x=0 Until horiz
			For Local y=0 Until vert
				Local v:GLFlagVertex=New GLFlagVertex
				v.Set(ox+x*size,oy+y*size,0)
				
				If (tile)
					v.u=(x&1)
					v.v=(y&1)
				Else
					v.u=1.0/(horiz-1)*x
					v.v=1.0/(vert-1)*(vert-1-y)
				EndIf

				o.v[x,y]=v
			Next
		Next
		
		Return o
	End Function

	' Call to render the flag
	'	
	' dampen		- Scale to dampen movements by when bouncing movement
	' friction	- Scale to slow down movements
	'	
	Method Render(dampen:Float=1.0, friction:Float=0.95)
		glPushMatrix()
		glTranslatef(0,0,zpos)
		glBindTexture(GL_TEXTURE_2D,txt)
		
		For Local vert:GLFlagVertex=EachIn v
			If (vert.xi<>0 Or vert.yi<>0 Or vert.zi<>0)
				Local s:Float
				
				s=Sgn(vert.xi)
				vert.xi:*friction
				If (Abs(vert.xi)<THRESHOLD)
					vert.initxi=vert.initxi*dampen
					If (vert.initxi<THRESHOLD)
						vert.xi=0
						vert.x=vert.initx
					Else
						vert.xi=-s*vert.initxi*2
					EndIf
				Else
					vert.x:+vert.xi
				EndIf

				s=Sgn(vert.yi)
				vert.yi:*friction
				If (Abs(vert.yi)<THRESHOLD)
					vert.inityi=vert.inityi*dampen
					If (vert.inityi<THRESHOLD)
						vert.yi=0
						vert.y=vert.inity
					Else
						vert.yi=-s*vert.inityi*2
					EndIf
				Else
					vert.y:+vert.yi
				EndIf

				s=Sgn(vert.zi)
				vert.zi:*friction
				If (Abs(vert.zi)<THRESHOLD)
					vert.initzi=vert.initzi*dampen
					If (vert.initzi<THRESHOLD)
						vert.zi=0
						vert.z=vert.initx
					Else
						vert.zi=-s*vert.initzi*2
					EndIf
				Else
					vert.z:+vert.zi
				EndIf
			EndIf
		Next

		For Local x:Int=0 Until width-1
			glBegin(GL_TRIANGLE_STRIP)
			For Local y:Int=0 Until height
				glTexCoord2f(v[x,y].u,v[x,y].v)
				glVertex3f(v[x,y].x,v[x,y].y,v[x,y].z)
				glTexCoord2f(v[x+1,y].u,v[x+1,y].v)
				glVertex3f(v[x+1,y].x,v[x+1,y].y,v[x+1,y].z)
			Next
			glEnd()
		Next
		glPopMatrix()
	End Method
	
	' Sets the movements for a vertex
	'
	' x			- The X co-ord of the vertex
	' y			- The Y co-ord of the vertex
	' xi			- The X movement
	' yi			- The Y movement
	' zi			- The Z movement
	'
	Method Nudge(x:Int, y:Int, xi:Float, yi:Float, zi:Float)
		v[x,y].initxi=Abs(xi)
		v[x,y].inityi=Abs(yi)
		v[x,y].initzi=Abs(zi)
		v[x,y].xi=xi
		v[x,y].yi=yi
		v[x,y].zi=zi
	End Method
	
End Type

Type GLFlagVertex
	Field x#,y#,z#
	Field u#,v#
	Field initx#,inity#,initz#
	Field initxi#,inityi#,initzi#
	Field xi#,yi#,zi#
	
	Method New()
		x=0
		y=0
		z=0
		initx=0
		inity=0
		initz=0
		initxi=0
		inityi=0
		initzi=0
		xi=0
		yi=0
		zi=0
	End Method
	
	Method Set(xc:Float, yc:Float, zc:Float)
		x=xc
		initx=xc
		y=yc
		inity=yc
		z=zc
		initz=zc
	End Method
End Type