mining lasers: new rayIter function and small particle fix, fixes #163 and closes #247

technic/tools/mining_lasers.lua

@@ -32,64 +32,54 @@ minetest.register_craft({
 	}
 })
 
--- Based on code by Uberi: https://gist.github.com/Uberi/3125280
+local scalar = vector.scalar or vector.dot or function vector.scalar(v1, v2)
+	return v1.x*v2.x + v1.y*v2.y + v1.z*v2.z
+end
+
+local function biggest_of_vec(vec)
+	if vec.x < vec.y then
+		if vec.y < vec.z then
+			return "z"
+		end
+		return "y"
+	end
+	if vec.x < vec.z then
+		return "z"
+	end
+	return "x"
+end
+
 local function rayIter(pos, dir, range)
-	local p = vector.round(pos)
-	local x_step,      y_step,      z_step      = 0, 0, 0
-	local x_component, y_component, z_component = 0, 0, 0
-	local x_intersect, y_intersect, z_intersect = 0, 0, 0
-
-	if dir.x == 0 then
-		x_intersect = math.huge
-	elseif dir.x > 0 then
-		x_step = 1
-		x_component = 1 / dir.x
-		x_intersect = x_component
-	else
-		x_step = -1
-		x_component = 1 / -dir.x
+	-- make a table of possible movements
+	local step = {}
+	for i in pairs(pos) do
+		local v = math.sign(dir[i])
+		if v ~= 0 then
+			step[i] = v
 		end
-	if dir.y == 0 then
-		y_intersect = math.huge
-	elseif dir.y > 0 then
-		y_step = 1
-		y_component = 1 / dir.y
-		y_intersect = y_component
-	else
-		y_step = -1
-		y_component = 1 / -dir.y
-	end
-	if dir.z == 0 then
-		z_intersect = math.huge
-	elseif dir.z > 0 then
-		z_step = 1
-		z_component = 1 / dir.z
-		z_intersect = z_component
-	else
-		z_step = -1
-		z_component = 1 / -dir.z
 	end
 
+	local p
 	return function()
-		if x_intersect < y_intersect then
-			if x_intersect < z_intersect then
-				p.x = p.x + x_step
-				x_intersect = x_intersect + x_component
-			else
-				p.z = p.z + z_step
-				z_intersect = z_intersect + z_component
+		if not p then
+			-- avoid skipping the first position
+			p = vector.round(pos)
+			return vector.new(p)
 		end
-		elseif y_intersect < z_intersect then
-			p.y = p.y + y_step
-			y_intersect = y_intersect + y_component
-		else
-			p.z = p.z + z_step
-			z_intersect = z_intersect + z_component
+
+		-- find the position which has the smallest distance to the line
+		local choose = {}
+		local choosefit = vector.new()
+		for i in pairs(step) do
+			choose[i] = vector.new(p)
+			choose[i][i] = choose[i][i] + step[i]
+			choosefit[i] = scalar(vector.normalize(vector.subtract(choose[i], pos)), dir)
 		end
-		if vector.distance(pos, p) > range then
-			return nil
+		p = choose[biggest_of_vec(choosefit)]
+
+		if vector.distance(pos, p) <= range then
+			return vector.new(p)
 		end
-		return p
 	end
 end
 
@@ -122,11 +112,11 @@ local function laser_shoot(player, range, particle_texture, sound)
 
 	local start_pos = vector.new(player_pos)
 	-- Adjust to head height
-	start_pos.y = start_pos.y + 1.9
+	start_pos.y = start_pos.y + 1.625
 	minetest.add_particle({
-		pos = startpos,
-		vel = dir,
-		acc = vector.multiply(dir, 50),
+		pos = start_pos,
+		velocity = dir,
+		acceleration = vector.multiply(dir, 50),
 		expirationtime = range / 11,
 		size = 1,
 		texture = particle_texture .. "^[transform" .. math.random(0, 7),