in-progress autotiler

gistfile1.hx

	public inline function rewriteAutoTiling(p : { x:Int, y:Int }, fallback : Int)
	{
		
		// collect the indices for the tile positions.
		
		var idx_tl = result.c21(p.x * 2, p.y * 2);
		var idx_tr = tl + 1;
		var idx_bl = result.c21(p.x * 2, p.y * 2 + 1);
		var idx_br = bl + 1;
		
		// build the mask information
		
		var m_c = defs[c2tSafe(p.x    , p.y    , fallback)].mask;
		
		var m_tl = (defs[c2tSafe(p.x - 1, p.y - 1, fallback)].mask & m_c)>0;
		var m_t  = (defs[c2tSafe(p.x    , p.y - 1, fallback)].mask & m_c)>0;
		var m_tr = (defs[c2tSafe(p.x + 1, p.y - 1, fallback)].mask & m_c)>0;
		var m_l  = (defs[c2tSafe(p.x - 1, p.y    , fallback)].mask & m_c)>0;
		var m_r  = (defs[c2tSafe(p.x + 1, p.y    , fallback)].mask & m_c)>0;
		var m_bl = (defs[c2tSafe(p.x - 1, p.y + 1, fallback)].mask & m_c)>0;
		var m_b  = (defs[c2tSafe(p.x    , p.y + 1, fallback)].mask & m_c)>0;
		var m_br = (defs[c2tSafe(p.x + 1, p.y + 1, fallback)].mask & m_c)>0;
		
		// get the indexes for each subtile.
		
		var si = defs[source.c2t(p.x    , p.y    )].indexes;
		var s0 = si[Autotile.computeMask(m_l, m_t, m_tl, 0)];
		var s1 = si[Autotile.computeMask(m_t, m_r, m_tr, 1)];
		var s3 = si[Autotile.computeMask(m_r, m_b, m_br, 3)];	
		var s2 = si[Autotile.computeMask(m_b, m_l, m_bl, 2)];
		
		// TODO: now we can blit.		
		
	}
	
	// given this arrangement of tiles in a single continuous strip 0-20:
	// /\ -- || \/ **
	// \/ -- || /\ **
	// rewriteAutoTiling does the boilerplate of creating the booleans from the mask defs.
	// computeMask will compute the correct tile index from the mask created by edges a, b, ab and the
	// corner index 0-4, where a is the counterclockwise direction and b is the clockwise direction.
	// then the end of rewriteAutoTiling converts the directives into updates for TileSheetGrid.
	
	public static inline function computeMask(a : Bool, b : Bool, ab : Bool, corner : Int)
	{
		var m = (a ? 1 : 0) + (b ? 2 : 0) + (ab ? 4 : 0);		
		var set = (m & 8) * 2;
		
		if (corner > 1) return set + corner + 8;
		else return set + corner;
	}