Rewrite

math/bs3.lua

@@ -0,0 +1,145 @@
+--- 3D bounding sphere
+local bs3
+
+local v3 = require((...):match("^(.*)bs3$").."v3")
+
+-- bs3 methods
+-- Unless specified otherwise, all operations are done in place and do not create a bounding sphere.
+local bs3_mt = {
+	-- Clone the bounding sphere. Returns a new bounding sphere.
+	clone = function(self)
+		return bs3(self.center:clone(), self.radius)
+	end,
+
+	-- Set bounding sphere
+	set = function(self, center, radius)
+		self.center:set(center)
+		self.radius = radius
+		return self
+	end,
+
+	-- Retrieve center vectors and radius
+	unpack = function(self)
+		return self.center, self.radius
+	end,
+
+	-- Test if the bounding sphere collide with another bounding sphere, bounding box or point
+	collide = function(self, other)
+		if other.radius then -- bs3
+			return (self.center[1] - other.center[1]) * (self.center[1] - other.center[1]) +
+			       (self.center[2] - other.center[2]) * (self.center[2] - other.center[2]) +
+			       (self.center[3] - other.center[3]) * (self.center[3] - other.center[3])
+			       <= (self.radius + other.radius) * (self.radius + other.radius)
+		elseif other.min then -- bb3
+			local x = math.max(other.min[1], math.min(self.center[1], other.max[1]))
+			local y = math.max(other.min[2], math.min(self.center[2], other.max[2]))
+			local z = math.max(other.min[3], math.min(self.center[3], other.max[3]))
+			return (self.center[1] - x) * (self.center[1] - x) +
+			       (self.center[2] - y) * (self.center[2] - y) +
+			       (self.center[3] - z) * (self.center[3] - z)
+			       <= self.radius * self.radius
+		else -- v3
+			return (self.center[1] - other[1]) * (self.center[1] - other[1]) +
+			       (self.center[2] - other[2]) * (self.center[2] - other[2]) +
+			       (self.center[3] - other[3]) * (self.center[3] - other[3])
+			       <= self.radius * self.radius
+		end
+	end,
+
+	-- Extend the bounding sphere by v (number)
+	extend = function(self, v)
+		self.radius = self.radius + v
+		return self
+	end,
+
+	-- Modify the bounding sphere so that it include v (v3 or bs3)
+	include = function(self, v)
+		if v.min then -- bounding sphere
+			self.radius = (self.center:distance(v.center) + self.radius + v.radius) / 2
+			self.center = v.center + (self.center - v.center):normalize() * (self.radius - v.radius)
+		else -- vector
+			self.radius = (self.center:distance(v) + self.radius) / 2
+			self.center = v + (self.center - v):normalize() * self.radius
+		end
+		return self
+	end,
+
+	-- Common operations with vectors. Returns a new bounding box.
+	__sub = function(self, other)
+		return bs3(self.center - other, self.radius)
+	end,
+	__add = function(self, other)
+		return bs3(self.center + other, self.radius)
+	end,
+	__unm = function(self)
+		return bs3(-self.center, self.radius)
+	end,
+	__div = function(self, other)
+		return bs3(self.center, self.radius / other)
+	end,
+	__mul = function(self, other)
+		return bs3(self.center, self.radius * other)
+	end,
+
+	__tostring = function(self)
+		return ("bs3(%s,%s)"):format(self.center, self.radius)
+	end
+}
+bs3_mt.__index = bs3_mt
+
+bs3 = setmetatable({
+	-- Calculate the mesh's bounding sphere. Returns a new bounding sphere.
+	fromMesh = function(mesh, tr)
+		local bs
+
+		-- 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
+			bs = bs3(v:clone(),0)
+			for i=min+1, max do
+				v = v3(mesh:getVertexAttribute(vmap[i], iposition))
+				if tr then v:transform(tr) end
+				bs: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
+			bs = bs3(v:clone(),0)
+			for i=min+1, max do
+				v = v3(mesh:getVertexAttribute(i, iposition))
+				if tr then v:transform(tr) end
+				bs:include(v)
+			end
+		end
+
+		return bs
+	end
+}, {
+	-- center will not be copied.
+	__call = function(self, center, radius)
+		return setmetatable({ center = v3(center), radius = radius }, bs3_mt)
+	end
+})
+
+return bs3