Grass demo

Looking the AGore's GrassDemo.bb located in the samples directory of Blitz3D I didn't understand anything about the following piece of code:

CameraProject(camera,EntityX(flare,1),EntityY(flare,1),EntityZ(flare,1))
	
vx# = ProjectedX() - (gwidth/2)
vy# = ProjectedY() - (gheight/2)
sx = vx + (gwidth/2) : sy = vy + (gheight/2)
PositionEntity s1,SpriteX(sx,sy,128),SpriteY(sx,sy,128),SpriteZ(sx,sy,128)
	sx = -vx/2 + (gwidth/2) : sy = -vy/2 + (gheight/2)
	PositionEntity s2,SpriteX(sx,sy,128),SpriteY(sx,sy,128),SpriteZ(sx,sy,128)
	sx = -vx/5 + (gwidth/2) : sy = -vy/5 + (gheight/2)
	PositionEntity s3,SpriteX(sx,sy,128),SpriteY(sx,sy,128),SpriteZ(sx,sy,128)
	sx = -vx/1.2 + (gwidth/2) : sy = -vy/1.2 + (gheight/2)
	PositionEntity s4,SpriteX(sx,sy,128),SpriteY(sx,sy,128),SpriteZ(sx,sy,128)
	
	RotateSprite s1,-EntityYaw(camera)
EntityAlpha s1,ProjectedZ()
EntityAlpha s2,1-(Abs(vx)/(gwidth/2))
EntityAlpha s3,1-(Abs(vx)/(gwidth/2))
EntityAlpha s4,1-(Abs(vx)/(gwidth/2))

I removed the lines above but I didn't notice a difference.
Does anyone knows what they do?

Thanks

This piece of code is used to display the lens flare
sprite position and alpha.

But there is no difference in the output if you remove these lines...

There is if you look at the sun.

I am sorry, I was a little bit harry. I had to turn the camera several degrees in order to see the difference

Thanks both!