Walking on slopes

BlitzMax Forums/BlitzMax Beginners Area/Walking on slopes

deps	(Posted 2006) [#1]

Hi, time for yet another question.

Working on a tilemap engine and I want to add slopes.
I'm having some problems when the player walks on them:
Sometimes he cannot climb from one slope up to another (But he can go back to where he came from), and he can also fall between sloped tiles if one of the sloped tiles doesn't have a solid tile under it.

Here is the collision code I have for the moment. It's called after applying gravity and when the player moves left/right

	Method check_collision()
		Local my:Int = y / Tsize ' Where in the map is the player?
		Local mx:Int = x / Tsize
		
                ' Check for a collision on layer 0
		Local coll:Int = map_get_collision( mx,my,0 )
		
		Select coll
		
			Case COLL_BOX
				y = oldy ' Cannot walk here at all. reset movement
				x = oldx
				Return True
				
			Case COLL_USLOPE ' Walking on a up / slope
				Local slope_y:Int = (x Mod Tsize) + 1
				
				Local pos:Int = (my*Tsize)+Tsize-slope_y-1
				
				If y > pos Then y = pos
				
				Return True
				
			Case COLL_DSLOPE ' Walking on a down \ slope
				Local slope_y:Int = (x Mod Tsize) + 1
				
				Local pos:Int = (my*Tsize)+slope_y-1
				
				If y > pos Then y = pos
				
				Return True
								
		EndSelect
		
		Return False ' No collision at all
	
	EndMethod

x and y are floats and is not limited to anything. Therefore I use things like ( x Mod Tsize ) to get the offset in the current tile. Is this right?
What else am I doing wrong? Anyone got any nice codesnippets showing how to walk on slopes with less bugs?

Thankfull for any help.