buldthensnip/pkg/base/lib_vector.lua

--[[
    This file is part of Ice Lua Components.

    Ice Lua Components is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    Ice Lua Components is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with Ice Lua Components.  If not, see <http://www.gnu.org/licenses/>.
]]

function box_is_clear(x1,y1,z1,x2,y2,z2)
	local x,z,i
	
	x1 = math.floor(x1)
	y1 = math.floor(y1)
	z1 = math.floor(z1)
	x2 = math.floor(x2)
	y2 = math.floor(y2)
	z2 = math.floor(z2)
	
	for z=z1,z2 do
	for x=x1,x2 do
		local l = common.map_pillar_get(x, z)
		i = 1
		while true do
			if y2 < l[i+2] then break end
			if l[i] == 0 then return false end
			i = i + l[i]*4
			if y1 < l[i+3] then return false end
		end
	end
	end
	
	return true
end

function trace_map_box(x1,y1,z1, x2,y2,z2, bx1,by1,bz1, bx2,by2,bz2)
	-- delta
	local dx,dy,dz
	dx = x2-x1
	dy = y2-y1
	dz = z2-z1
	
	-- offsets
	local fx,fy,fz
	if dx < 0 then fx = bx1 else fx = bx2 end
	if dy < 0 then fy = by1 else fy = by2 end
	if dz < 0 then fz = bz1 else fz = bz2 end
	
	-- direction
	local gx,gy,gz
	if dx < 0 then gx = -1 else gx = 1 end
	if dy < 0 then gy = -1 else gy = 1 end
	if dz < 0 then gz = -1 else gz = 1 end
	dx = dx * gx
	dy = dy * gy
	dz = dz * gz
	
	-- combined box size
	local bcx,bcy,bcz
	bcx = (bx2-bx1)
	bcy = (by2-by1)
	bcz = (bz2-bz1)
	
	-- top left offset (note, incorrect name!)
	local tlx,tly,tlz
	if gx >= 0 then tlx = 0.99999 else tlx = 0 end
	if gy >= 0 then tly = 0.99999 else tly = 0 end
	if gz >= 0 then tlz = 0.99999 else tlz = 0 end
	
	-- apply offset
	x1 = x1 + fx
	y1 = y1 + fy
	z1 = z1 + fz
	bx1 = bx1 + fx
	by1 = by1 + fy
	bz1 = bz1 + fz
	bx2 = bx2 + fx
	by2 = by2 + fy
	bz2 = bz2 + fz
	
	-- cell
	local cx,cy,cz
	cx = math.floor(x1)
	cy = math.floor(y1)
	cz = math.floor(z1)
	
	-- sub deltas
	local sx, sy, sz
	sx = math.fmod(x1, 1.0)
	sy = math.fmod(y1, 1.0)
	sz = math.fmod(z1, 1.0)
	if gx >= 0 then sx = 1-sx end
	if gy >= 0 then sy = 1-sy end
	if gz >= 0 then sz = 1-sz end
	
	-- restricted x/y/z
	local rx,ry,rz
	rx = nil
	ry = nil
	rz = nil
	
	-- TODO: unset these when another boundary is crossed
	
	local i
	local iend = (
		  math.abs(math.floor(x2+fx)-cx)
		+ math.abs(math.floor(y2+fy)-cy)
		+ math.abs(math.floor(z2+fz)-cz)
	)
	
	for i=1,iend do
		-- get the time it takes to hit the boundary
		local tx = sx/math.max(dx,0.00001)
		local ty = sy/math.max(dy,0.00001)
		local tz = sz/math.max(dz,0.00001)
		
		local t, d, ck
		
		if tx < ty and tx < tz then
			-- X first
			d = 0
			t = tx
		elseif ty < tx and ty < tz then
			-- Y first
			d = 1
			t = ty
		else
			-- Z first
			d = 2
			t = tz
		end
		
		sx = sx - t*dx
		sy = sy - t*dy
		sz = sz - t*dz
		x1 = rx or x1 + t*dx*gx
		y1 = ry or y1 + t*dy*gy
		z1 = rz or z1 + t*dz*gz
		
		if d == 0 then
			-- X first
			sx = 1.0
			ck = rx or box_is_clear(cx+gx,y1+by1,z1+bz1,cx+gx,y1+by2,z1+bz2)
			if not ck then rx = cx + tlx end
			if not rx then cx = cx + gx end
		elseif d == 1 then
			-- Y first
			sy = 1.0
			ck = ry or box_is_clear(x1+bx1,cy+gy,z1+bz1,x1+bx2,cy+gy,z1+bz2)
			if not ck then ry = cy + tly end
			if not ry then cy = cy + gy end
		else
			-- Z first
			sz = 1.0
			ck = rz or box_is_clear(x1+bx1,y1+by1,cz+gz,x1+bx2,y1+by2,cz+gz)
			if not ck then rz = cz + tlz end
			if not rz then cz = cz + gz end
		end
		
		--if not ck then return x1-bx1, y1-by1, z1-bz1 end
	end
	--
	if rx then rx = rx - fx end
	if ry then ry = ry - fy end
	if rz then rz = rz - fz end
	
	return rx or x2, ry or y2, rz or z2
end