Rewrite

math/bb3.lua

@@ -0,0 +1,146 @@
+--- Axis aligned 3D bounding box
+local bb3
+
+local v3 = require((...):match("^(.*)bb3$").."v3")
+
+-- bb3 methods
+-- Unless specified otherwise, all operations are done in place and do not create a bounding box.
+local bb3_mt = {
+	-- Clone the bounding box. Returns a new bounding box.
+	clone = function(self)
+		return bb3(self.min:clone(), self.max:clone())
+	end,
+
+	-- Set bounding box
+	set = function(self, min, max)
+		self.min, self.max = v3(min), v3(max)
+		return self
+	end,
+
+	-- Retrieve min and max vectors
+	unpack = function(self)
+		return self.min, self.max
+	end,
+
+	-- Test if the bounding box collide with another bounding box, bounding sphere or point
+	collide = function(self, other)
+		if other.min then -- bb3
+			return self.min[1] <= other.max[1] and self.max[1] >= other.min[1] and
+			       self.min[2] <= other.max[2] and self.max[2] >= other.min[2] and
+			       self.min[3] <= other.max[3] and self.max[3] >= other.min[3]
+		elseif other.radius then -- bs3
+			return other:collide(self)
+		else -- v3
+			return self.min[1] <= other[1] and self.max[1] >= other[1] and
+			       self.min[2] <= other[2] and self.max[2] >= other[2] and
+			       self.min[3] <= other[3] and self.max[3] >= other[3]
+		end
+	end,
+
+	-- Extend the bounding box by v:
+	-- * number: extend by a certain distance from the center
+	-- * v3: extend each axis by the associated vector coordinate
+	extend = function(self, v)
+		if type(v) == "number" then
+			self.min = self.min - { v, v, v }
+			self.max = self.max + { v, v, v }
+		else
+			self.min = self.min - v
+			self.max = self.max + v
+		end
+		return self
+	end,
+
+	-- Modify the bounding box so that it include v (v3 or bb3)
+	include = function(self, v)
+		if v.min then -- bounding box
+			self.min[1] = math.min(self.min[1], v.min[1])
+			self.min[2] = math.min(self.min[2], v.min[2])
+			self.min[3] = math.min(self.min[3], v.min[3])
+			self.max[1] = math.max(self.max[1], v.max[1])
+			self.max[2] = math.max(self.max[2], v.max[2])
+			self.max[3] = math.max(self.max[3], v.max[3])
+		else -- vector
+			self.min[1] = math.min(self.min[1], v[1])
+			self.min[2] = math.min(self.min[2], v[2])
+			self.min[3] = math.min(self.min[3], v[3])
+			self.max[1] = math.max(self.max[1], v[1])
+			self.max[2] = math.max(self.max[2], v[2])
+			self.max[3] = math.max(self.max[3], v[3])
+		end
+		return self
+	end,
+
+	-- Common operations with vectors. Returns a new bounding box.
+	__sub = function(self, other)
+		return bb3(self.min - other, self.max - other)
+	end,
+	__add = function(self, other)
+		return bb3(self.min + other, self.max + other)
+	end,
+	__unm = function(self)
+		return bb3(-self.min, -self.max)
+	end,
+
+	__tostring = function(self)
+		return ("bb3(%s,%s)"):format(self.min, self.max)
+	end
+}
+bb3_mt.__index = bb3_mt
+
+bb3 = setmetatable({
+	-- Calculate the mesh's bounding box. Returns a new bounding box.
+	fromMesh = function(mesh, tr)
+		local bb
+
+		-- Get VertexPosition attribute index in vertex data
+		local iposition
+		for i, t in ipairs(mesh:getVertexFormat()) do
+			if t[1] == "VertexPosition" then
+				if t[3] ~= 3 then error("mesh vertices don't have a 3 dimensional position") end
+				iposition = i
+				break
+			end
+		end
+		if not iposition then error("mesh doesn't have VertexPosition attributes") end
+
+		-- Retrieve vertices
+		local vmap = mesh:getVertexMap()
+		if vmap then
+			local min, max = mesh:getDrawRange()
+			if not min then
+				min, max = 1, #vmap
+			end
+			local v = v3(mesh:getVertexAttribute(vmap[min], iposition))
+			if tr then v:transform(tr) end
+			bb = bb3(v:clone(),v:clone())
+			for i=min+1, max do
+				v = v3(mesh:getVertexAttribute(vmap[i], iposition))
+				if tr then v:transform(tr) end
+				bb:include(v)
+			end
+		else
+			local min, max = mesh:getDrawRange()
+			if not min then
+				min, max = 1, mesh:getVertexCount()
+			end
+			local v = v3(mesh:getVertexAttribute(min, iposition))
+			if tr then v:transform(tr) end
+			bb = bb3(v:clone(),v:clone())
+			for i=min+1, max do
+				v = v3(mesh:getVertexAttribute(i, iposition))
+				if tr then v:transform(tr) end
+				bb:include(v)
+			end
+		end
+
+		return bb
+	end
+}, {
+	-- min and max will not be copied.
+	__call = function(self, min, max)
+		return setmetatable({ min = v3(min), max = v3(max) }, bb3_mt)
+	end
+})
+
+return bb3