Wavefront (OBJ) Loader

Here you will find various resources to help you create 3D games and apps in Gideros Studio.

note: you may have to provide your own assets (fonts, gfx, …).

Wavefront (OBJ) Loader

Import your Wavefront OBJ models in Gideros.

--[[
Load meshes from a wavefront .obj file
Usage:
sprite = loadObj(path, file) : load the file located at path/file

Returned sprite has a few specific attributes:
- objs: table referencing all objects within the loaded file
]]
local function Split(str, delim, maxNb)
	-- Eliminate bad cases...
	if string.find(str, delim) ==	nil then
		return { str }
	end
	if maxNb ==	nil or maxNb < 1 then
		maxNb = 0 -- no limit
	end
	local result = {}
	local pat = "(.-)" .. delim .. "()"
	local nb = 0
	local lastPos
	for part, pos in string.gfind(str, pat) do
		nb +=	1
		result[nb] = part
		lastPos = pos
		if nb ==	maxNb then break end
	end
	-- Handle the last field
	if nb ~= maxNb then
		result[nb + 1] = string.sub(str, lastPos)
	end

	return result
end

local function parsemtl(mtls, path, file, texture_replacements, texture_folder, texture)
	local mtl = { texturew = 0, textureh = 0 }

	for line in io.lines(path.."/"..file) do
		fld = Split(line," ",6)
		for i = 1,#fld, 1 do
			fld[i] = string.gsub(fld[i], "\r", "")
		end

		if (fld[2] ~= nil) then
			fld[2] = string.gsub(fld[2], "\r", "")
		end

		if fld[1] == "newmtl" then
			--print("DM",fld[2])
			mtl = {texturew = 0, textureh = 0}
			mtls[fld[2]] = mtl
		elseif fld[1] == "Kd" then
			mtl.kd = {fld[2],fld[3],fld[4],1.0}
		elseif fld[1] == "map_Kd" then
			table.remove(fld, 1)
			local f = table.concat(fld," ")
			--print("Texture:.. ["..path.."/"..f.."]")
			if texture_replacements then
				for i = 1, #texture_replacements do
					if texture_replacements[i][1] ==	f then
						f = texture_replacements[i][2] -- .. " "
					end
				end
			end
			if texture then
				mtl.texture = texture
				--print("Applying existing texture to material.")
			elseif texture_folder then
				mtl.texture = Texture.new(texture_folder.."/"..f, true,{ wrap = TextureBase.REPEAT })
			else
				mtl.texture = Texture.new(path.."/"..f, true,{ wrap = TextureBase.REPEAT })
			end
			mtl.texturew = mtl.texture:getWidth()
			mtl.textureh = mtl.texture:getHeight()
		elseif fld[1] == "map_Bump" then
			table.remove(fld, 1)
			local f = table.concat(fld," ")
			--print("Texture:.. ["..path.."/"..f.."]")
			mtl.normalMap = Texture.new(path.."/"..f, true,{ wrap = TextureBase.REPEAT })
			mtl.normalMapW = mtl.normalMap:getWidth()
			mtl.normalMapH = mtl.normalMap:getHeight()
		end

	end
end

function string.starts(String, Start)
	return string.sub(String, 1, string.len(Start)) == Start
end

function string.ends(String, End)
	return End == '' or string.sub(String, -string.len(End)) ==	End
end

function loadObj(path, file, texture_replacements, texture_folder, texture)
	local spr = Sprite.new()
	v = {}
	imap = nil
	vt = {}
	vn = {}
	mtls = {}
	mtl = nil
	spr.min = {1000000, 1000000, 1000000}
	spr.max = {-1000000,-1000000,-1000000}
	spr.objs = {}
	oname = nil

	local function buildObject()
		local m = nil
		if (imap ~= nil) then
			for _, vm in pairs(imap.vngmap) do
				local nx, ny, nz = 0, 0, 0
				for _, vn in ipairs(vm) do
					nx = nx+imap.lvn[vn+1]
					ny = ny+imap.lvn[vn+2]
					nz = nz+imap.lvn[vn+3]
				end
				local nl = math.sqrt(nx*nx+ny*ny+nz*nz)
				nx = nx/nl
				ny = ny/nl
				nz = nz/nl
				for _, vn in ipairs(vm) do
					imap.lvn[vn+1] = nx
					imap.lvn[vn+2] = ny
					imap.lvn[vn+3] = nz
				end
			end
			m = Mesh.new(true)
			m:setVertexArray(imap.lv)
			m:setIndexArray(imap.i)
			--m:setColorArray(c)

			if (mtl.texture ~= nil) then
				m:setTextureCoordinateArray(imap.lvt)
				m:setTexture(mtl.texture)
				m.hasTexture = true
			end
			if (mtl.normalMap ~= nil) then
				m:setTexture(mtl.normalMap, 1)
				m.hasNormalMap = true
			end
			if mtl.kd then
				m:setColorTransform(mtl.kd[1],mtl.kd[2],mtl.kd[3],mtl.kd[4])
			end
			if #imap.lvn > 0 then
				m.hasNormals = true
				m:setGenericArray(3, Shader.DFLOAT, 3,#imap.lvn/3, imap.lvn)
			end

			local sobj = spr.objs[oname]
			if sobj == nil then
				sobj = Sprite.new()
				spr:addChild(sobj)
				spr.objs[oname] = sobj
				sobj.min = {1000000, 1000000, 1000000}
				sobj.max = {-1000000,-1000000,-1000000}
			end
			sobj:addChild(m)

			local minx, miny, minz = 100000, 100000, 100000
			local maxx, maxy, maxz = -100000,-100000,-100000
			for i = 1,#imap.lv-2, 3 do
				local x, y, z = imap.lv[i],imap.lv[i+1],imap.lv[i+2]
				minx = math.min(minx, x)
				miny = math.min(miny, y)
				minz = math.min(minz, z)
				maxx = math.max(maxx, x)
				maxy = math.max(maxy, y)
				maxz = math.max(maxz, z)
			end
			m.min = {minx, miny, minz}
			m.max = {maxx, maxy, maxz}
			m.center = {(m.max[1]+m.min[1])/2,(m.max[2]+m.min[2])/2,(m.max[3]+m.min[3])/2}
			sobj.min = {math.min(sobj.min[1],m.min[1]),math.min(sobj.min[2],m.min[2]),math.min(sobj.min[3],m.min[3])}
			sobj.max = {math.max(sobj.max[1],m.max[1]),math.max(sobj.max[2],m.max[2]),math.max(sobj.max[3],m.max[3])}
			spr.min = {math.min(spr.min[1],m.min[1]),math.min(spr.min[2],m.min[2]),math.min(spr.min[3],m.min[3])}
			spr.max = {math.max(spr.max[1],m.max[1]),math.max(spr.max[2],m.max[2]),math.max(spr.max[3],m.max[3])}
			m.name = oname
			--[[print(oname, m.min[1],m.min[2],m.min[3],m.max[1],m.max[2],m.max[3])
			if string.starts(oname,"light") then
				lightPosX, lightPosY, lightPosZ = m.center[1],m.center[2],m.center[3]
				lightRef = m
			end]]
			imap = nil
		end

		return m
	end

	for line in io.lines(path.."/"..file) do
		fld = Split(line," ")
		for i = 1,#fld, 1 do
			fld[i] = string.gsub(fld[i], "\r", "")
		end

		if fld[1] == "v" then
			table.insert(v, tonumber(fld[2]))
			table.insert(v, tonumber(fld[3]))
			table.insert(v, tonumber(fld[4]))
		elseif fld[1] == "vn" then
			table.insert(vn, tonumber(fld[2]))
			table.insert(vn, tonumber(fld[3]))
			table.insert(vn, tonumber(fld[4]))
		elseif fld[1] == "vt" then
			table.insert(vt, tonumber(fld[2]))
			table.insert(vt, tonumber(fld[3]))
		elseif fld[1] == "f" then

			if imap == nil then
				imap = {}
				imap.alloc = function(self, ifld, facenm)
					local ifl = Split(ifld,"/",3)
					local iv = tonumber(ifl[1])
					if (iv<0) then iv = (#v/3+1+iv) end
					iv = iv-1
					local it = tonumber(ifl[2])
					if (it == nil) then
						it = -1
					else
						if (it<0) then it = (#vt / 2) + it + 1 end
						it -= 1
					end

					local inm = tonumber(ifl[3])
					if (inm == nil) then
						inm = -1
					else
						if (inm<0) then
							inm = (#vn / 3) + inm + 1
						end
						inm -= 1
					end
					if inm == -1 then inm = facenm.code end

					local ms = iv..":"..it..":"..inm
					if self.vmap[ms] == nil then
						ni = self.ni + 1
						self.ni = ni
						table.insert(facenm.lvi,#self.lv)
						table.insert(self.lv, v[iv*3+1])
						table.insert(self.lv, v[iv*3+2])
						table.insert(self.lv, v[iv*3+3])
						if it >= 0 then
							table.insert(self.lvt, vt[it*2+1]*mtl.texturew)
							table.insert(self.lvt, vt[it*2+2]*mtl.textureh)
						end
						if inm >= 0 then
							table.insert(self.lvn, vn[inm*3+1])
							table.insert(self.lvn, vn[inm*3+2])
							table.insert(self.lvn, vn[inm*3+3])
						else
							local vngmap = self.vngmap[iv] or { }
							self.vngmap[iv] = vngmap
							table.insert(vngmap,#self.lvn)
							table.insert(facenm.lvni,#self.lvn)
							table.insert(self.lvn, 0)
							table.insert(self.lvn, 0)
							table.insert(self.lvn, 0)
						end
						self.vmap[ms] = ni
					end

					return self.vmap[ms]
				end
				imap.i = {}
				imap.ni = 0
				imap.lv = {}
				imap.lvt = {}
				imap.lvn = {}
				imap.vmap = {}
				imap.vngmap = {}
				imap.gnorm = -2
			end
			local itab = {}
			local normtab = { code = imap.gnorm, lvi = {}, lvni = {} }
			for ii = 2,#fld, 1 do
				if (fld[ii] ~= nil) and (fld[ii] ~= "") then
					table.insert(itab, imap:alloc(fld[ii],normtab))
				end
			end
			imap.gnorm = imap.gnorm-1
			if (#itab >= 3) then
				if #normtab.lvni > 0 then -- Gen normals
					local ux = imap.lv[normtab.lvi[2]+1]-imap.lv[normtab.lvi[1]+1]
					local uy = imap.lv[normtab.lvi[2]+2]-imap.lv[normtab.lvi[1]+2]
					local uz = imap.lv[normtab.lvi[2]+3]-imap.lv[normtab.lvi[1]+3]
					local vx = imap.lv[normtab.lvi[3]+1]-imap.lv[normtab.lvi[1]+1]
					local vy = imap.lv[normtab.lvi[3]+2]-imap.lv[normtab.lvi[1]+2]
					local vz = imap.lv[normtab.lvi[3]+3]-imap.lv[normtab.lvi[1]+3]
					local nx = uy*vz-uz*vy
					local ny = uz*vx-ux*vz
					local nz = ux*vy-uy*vx
					local nl = math.sqrt(nx * nx + ny * ny + nz * nz)
					nx = nx/nl
					ny = ny/nl
					nz = nz/nl
					for _, vni in ipairs(normtab.lvni) do
						imap.lvn[vni+1] = nx
						imap.lvn[vni+2] = ny
						imap.lvn[vni+3] = nz
					end
				end

				for ii = 3,#itab, 1 do
					table.insert(imap.i, itab[1])
					table.insert(imap.i, itab[ii-1])
					table.insert(imap.i, itab[ii])
				end
			end

		elseif fld[1] == "o" or fld[1] == "g" then
			buildObject()
			--print(line)
			oname = fld[2]
		elseif fld[1] == "mtllib" then
			table.remove(fld, 1)
			parsemtl(mtls, path, table.concat(fld," "), texture_replacements, texture_folder, texture)
		elseif fld[1] == "usemtl" then
			buildObject()
			mtl = mtls[fld[2]]
		end

	end

	--spr:setColorTransform(1.0, 0, 0, 1.0)
	buildObject() --If any in progress
	spr.center = {(spr.max[1]+spr.min[1])/2,(spr.max[2]+spr.min[2])/2,(spr.max[3]+spr.min[3])/2}

	return spr
end