-- TerrainSeamTool.ms
-- 2014 Andy Davis
-- Rockstar London
-- Description: tool snaps terrain seam vertices to adjacent terrain sections

filein (RsConfigGetWildWestDir() + "script/3dsMax/_config_files/Wildwest_header.ms")					--wildwest header
filein (RsConfigGetWildWestDir() + "script/3dsMax/_common_functions/RSL_dotNetUIOps.ms")		--RS_dotNetPreset structure
RsCollectToolUsageData (getThisScriptFilename())
	
global EdgeMatch

struct TerrainSeamTool_SeamVert
(
	obj,
	vertID,
	position
)

struct TerrainSeamTool_SeamEdge
(
	obj1,
	vertids1,
	obj2,
	vertids2,
	axis
)

struct TerrainSeamTool_ObjectSeamData
(
	obj,
	handle,
	minXY,
	maxXY,
	edgeVertIDs = #{},
	northVertIDs = #{},
	southVertIDs = #{},
	westVertIDs = #{},
	eastVertIDs = #{},
	nwVert,
	neVert,
	swVert,
	seVert,
	northEdgeIDs = #{},
	southEdgeIDs = #{},
	eastEdgeIDs = #{},
	westEdgeIDs = #{},
	
	--finds the end vertex on a row of vertices and removes the vertexID from the incoming array
	--used to find corner verts on meshes with non-square edges
	fn GetEndVert obj &vertIDs side =
	(
		vertIDs = vertIDs as array
		local endVert
		local axis
		local numVerts = vertIDs.count
		
		--east and west means looking on the x-axis
		if ((side == #west) or (side == #east)) then
			axis = 1
		else --north and south are y-axis
			axis = 2
		
		--south and west means looking for the minimum values
		if ((side == #west) or (side == #south)) then
		(
			local minValue = obj.verts[vertIDs[1]].position[axis]
			local minID = 1
			
			for i = 2 to numVerts do
			(
				local newValue = obj.verts[vertIDs[i]].position[axis]
				if (newValue < minValue) then
				(
					minValue = newValue
					minID = i
				)
			)
			
			--transfer the found corner vert to the endVert variable, removing it from the vertIDs array
			endVert = vertIDs[minID]
			deleteItem vertIDs minID
		)
		else	--values must be #north or #east
		(
			local maxValue = obj.verts[vertIDs[1]].position[axis]
			local maxID = 1
			
			for i = 2 to numVerts do
			(
				local newValue = obj.verts[vertIDs[i]].position[axis]
				if (newValue > maxValue) then
				(
					maxValue = newValue
					maxID = i
				)				
			)
			
			--transfer the found corner vert to the endVert variable, removing it from the vertIDs array
			endVert = vertIDs[maxID]
			deleteItem vertIDs maxID
		)
		
		return endVert
	),
	
	--run InitData when the obj is set up with a valid geometry object to the obj variable
	fn InitData =
	(
		if obj != undefined then
		(
			local edgeIDs = polyop.getOpenEdges this.obj
			this.edgeVertIDs = polyop.getVertsUsingEdge this.obj edgeIDs
			local tolerance = 0.001
			
			-- find the corner and edge verts based on proximity to bounds
			for id in edgeVertIDs do
			(
				if (abs (obj.verts[id].position.x - obj.min.x) < tolerance) then
				(
					if (abs (obj.verts[id].position.y - obj.min.y) < tolerance) then swVert = id
					else if (abs (obj.verts[id].position.y - obj.max.y) < tolerance) then nwVert = id
					else append westVertIDs id				
				)
				else if (abs (obj.verts[id].position.x - obj.max.x) < tolerance) then
				(
					if (abs (obj.verts[id].position.y - obj.min.y) < tolerance) then seVert = id
					else if (abs (obj.verts[id].position.y - obj.max.y) < tolerance) then neVert = id
					else append eastVertIDs id	
				)
				else if (abs (obj.verts[id].position.y - obj.min.y) < tolerance) then append southVertIDs id
				else if (abs (obj.verts[id].position.y - obj.max.y) < tolerance) then append northVertIDs id
			)
			
			--look for corner verts on meshes with non-square edges
			--if found remove them from the vertID arrays: this is done by GetEndVert()
			--even after these checks, the corner verts may not be found: two adjacent non-square edges will not yield a corner vert
			if (nwVert == undefined) then
			(
				--check north and west vertices for the corner vert
				if ((northVertIDs as array).count > 2) then
					nwVert = GetEndVert obj &northVertIDs #west	--looking for the most west vertex in the north vertices
				else if ((westVertIDs as array).count > 2) then
					nwVert = GetEndVert obj &westVertIDs #north
			)
			
			if (neVert == undefined) then
			(
				--check north and east vertices for the corner vert
				if ((northVertIDs as array).count > 2) then
					neVert = GetEndVert obj &northVertIDs #east
				else if ((eastVertIDs as array).count > 2) then
					neVert = GetEndVert obj &eastVertIDs #north
			)
			
			if (swVert == undefined) then
			(
				--check south and west vertices for the corner vert
				if ((southVertIDs as array).count > 2) then
					swVert = GetEndVert obj &southVertIDs #west
				else if ((westVertIDs as array).count > 2) then
					swVert = GetEndVert obj &westVertIDs #south
			)
			
			if (seVert == undefined) then
			(
				--check south and east vertices for the corner vert
				if ((southVertIDs as array).count > 2) then
					seVert = GetEndVert obj &southVertIDs #east
				else if ((eastVertIDs as array).count > 2) then
					seVert = GetEndVert obj &eastVertIDs #south
			)
			
			--sort the edges
			for id in edgeIDs do
			(
				local vertIDs = (polyop.GetVertsUsingEdge this.obj id) as array
				local edgePosition = (this.obj.verts[vertIDs[1]].position + this.obj.verts[vertIDs[2]].position) / 2
				if (abs (edgePosition.x - obj.min.x) < tolerance) then
					append westEdgeIDs id
				else if (abs (edgePosition.x - obj.max.x) < tolerance) then
					append eastEdgeIDs id
				else if (abs (edgePosition.y - obj.min.y) < tolerance) then
					append southEdgeIDs id
				else if (abs (edgePosition.y - obj.max.y) < tolerance) then
					append northEdgeIDs id
-- 				else
-- 					format "Object % Edge % is not on the periphery\n" this.obj.name id
			)
			
			handle = obj.inode.handle
			minXY = [obj.min.x, obj.min.y]
			maxXY = [obj.max.x, obj.max.y]
-- 			this.FormatData()	--dev
		)
		else
			format "warning: obj is undefined\n"
	),
	
	fn FormatData =
	(
		format "Name: %\t" (MaxOps.GetNodeByHandle this.handle).name
		format "Boundaries: [%,%] [%,%]\n" minXY.x minXY.y maxXY.x maxXY.y
		format "NE vert: %\nNW vert: %\nSE vert: %\nSW vert: %\n" neVert nwVert seVert swVert
		format "--------VERTS----------\n"
		format "North Verts: %\n" northVertIDs
		format "South Verts: %\n" southVertIDs
		format "East Verts: %\n" eastVertIDs
		format "West Verts: %\n" westVertIDs
		format "--------EDGES----------\n"
		format "North Edges: %\n" northEdgeIDs
		format "South Edges: %\n" southEdgeIDs
		format "East Edges: %\n" eastEdgeIDs
		format "West Edges: %\n" westEdgeIDs
		format "\n"
	)
)

struct EdgeMatchStruct
(
	Form,
	ToolTip,
	InfoPanel,
	ApplyButton,
	ProgBar,
	IniFilePath = (RsConfigGetWildWestDir() + "script/3dsMax/_config_files/AD_Tools.ini"),
	ObjectList,					--master array containing all data about object edges
	searchTolerance = 0.5,	--maximum gaps between edge vertices
	edgeTolerance = 0.01,	--maximum gap between edges
	SeamCheckList = #(),	--list of all the object seams to check against each other
	CornerCheckList = #(),	--list of all corners to check against each other
	Progress = 0,
	
	------------------------------------------------------------------------------------------------------------------------------------------
	--GENERAL FUNCTIONS
	------------------------------------------------------------------------------------------------------------------------------------------
	
	fn Apply s e =
	(
		EdgeMatch.Process()
	),
	
	fn UndoClicked s e =
	(
		print "max undo"
		max undo
	),
	
	------------------------------------------------------------------------------------------------------------------------------------------
	--LOAD/SAVE FUNCTIONS
	------------------------------------------------------------------------------------------------------------------------------------------
	
	fn SaveIniFile =
	(
		setINISetting EdgeMatch.IniFilePath "EdgeMatch" "WinLocX" (EdgeMatch.Form.Location.x as string)
		setINISetting EdgeMatch.IniFilePath "EdgeMatch" "WinLocY" (EdgeMatch.Form.Location.y as string)
-- 		setINISetting EdgeMatch.IniFilePath "EdgeMatch" "WinWidth" (EdgeMatch.Form.Width as string)
-- 		setINISetting EdgeMatch.IniFilePath "EdgeMatch" "WinHeight" (EdgeMatch.Form.Height as string)
	),
	
	fn LoadIniFile =
	(
		--default values
		local WinLocX = 100
		local WinLocY = 100
		local WinWidth = 200
		local WinHeight = 200
		
		try
		(
			WinLocX = getINISetting EdgeMatch.IniFilePath "EdgeMatch" "WinLocX" as integer
			WinLocY = getINISetting EdgeMatch.IniFilePath "EdgeMatch" "WinLocY" as integer
-- 			WinWidth = getINISetting EdgeMatch.IniFilePath "EdgeMatch" "WinWidth" as integers
-- 			WinHeight = getINISetting EdgeMatch.IniFilePath "EdgeMatch" "WinHeight" as integer
		)
		
		catch()
		
		EdgeMatch.Form.Location = dotNetObject "system.drawing.point" WinLocX WinLocY
-- 		EdgeMatch.Form.Size = dotNetObject "System.Drawing.Size" WinWidth WinHeight
	),
	
	------------------------------------------------------------------------------------------------------------------------------------------
	--TOOL CODE
	------------------------------------------------------------------------------------------------------------------------------------------
	
	fn GetEdges =
	(
		for item in selection where (this.IsTerrainMesh item) do
		(
			convertToPoly item
			item.WeldThreshold = 0.01
			newTerrainSeamTool_ObjectSeamData = TerrainSeamTool_ObjectSeamData obj:item
			newTerrainSeamTool_ObjectSeamData.InitData()
			append ObjectList newTerrainSeamTool_ObjectSeamData
		)
	),
	
	fn IsTerrainMesh obj =
	(
		IsTerrain = false		
		if classOf obj == Editable_Poly then IsTerrain = true
		if classOf obj == Editable_Mesh then	IsTerrain = true
		if classOf obj == Edit_Poly then	IsTerrain = true
		
		IsTerrain
	),
	
	--returns true if the edges of the two supplied edges line up
	--edge: #north, #south, #east, #west
	fn CheckEdgeOld obj1 obj2 edge =
	(
		--CheckEdge this.ObjectList[i].obj this.ObjectList[j].obj #east FUBAR ARG
		local match = false
		local tolerance = 0.001	--seems to be needed due to innaccuracy with logic testing of Max floats: yes, MAXScript is occasionally shit and annoying
		case edge of
		(
			#north:	--south edge of obj1 to north edge of obj2
			(
				if (abs (obj1.max.Y - obj2.min.Y) <= this.edgeTolerance) and (obj1.min.X + tolerance < obj2.max.X) and (obj1.max.X > obj2.min.X + tolerance) then match = true
				break
			)			
			#south:	--north edge of obj1 to south edge of obj2
			(
				if (abs (obj1.min.Y - obj2.max.Y) <= this.edgeTolerance) and (obj1.min.X + tolerance < obj2.max.X) and (obj1.max.X > obj2.min.X + tolerance) then match = true
				break
			)
			#east:	--west edge of obj1 to east edge of obj2
			(
				if (abs (obj1.max.X - obj2.min.X) <= this.edgeTolerance) and (obj1.min.Y + tolerance < obj2.max.Y) and (obj1.max.Y > obj2.min.Y + tolerance) then match = true
				break
			)
			#west:	--east edge of obj1 to west edge of obj2
			(
				if (abs (obj1.min.X - obj2.max.X) <= this.edgeTolerance) and (obj1.min.Y + tolerance < obj2.max.Y) and (obj1.max.Y > obj2.min.Y + tolerance) then match = true
				break
			)
		)
		
		match
	),
	
	--returns the minimum and maximum values for a set of given vertices along a specific axis
	fn GetMinMax obj vertIDs axis =
	(
		local id
		local numVerts = vertIDs.count
		if (axis == #x) then id = 1
		if (axis == #y) then id = 2
		
		local minValue = obj.verts[vertIDs[1]].position[id]
		local maxValue = obj.verts[vertIDs[1]].position[id]
		
		for i = 2 to numVerts do
		(
			local newValue = obj.verts[vertIDs[i]].position[id]
			if (newValue < minValue) then
				minValue = newValue
			else if (newValue > maxValue) then
				maxValue = newValue
		)
		
		return (dataPair min:minValue max:maxValue)
	),
	
	--returns true if the edges of the two supplied edges line up
	--edge: #north, #south, #east, #west
	fn CheckEdge obj1 obj2 edge =
	(
		local match = false
		local tolerance = 0.1	--seems to be needed due to innaccuracy with logic testing of Max floats: yes, MAXScript is occasionally shit and annoying
		case edge of
		(
			#north:	--south edge of obj1 to north edge of obj2
			(
				if (abs (obj1.obj.max.Y - obj2.obj.min.Y) <= this.edgeTolerance) then
				(
					local obj1_southVertsMinMax = this.GetMinMax obj1.obj (obj1.southVertIDs as array) #x
					local obj2_northVertsMinMax = this.GetMinMax obj2.obj (obj2.northVertIDs as array) #x
					if (obj1_southVertsMinMax.min + tolerance < obj2_northVertsMinMax.max) and (obj1_southVertsMinMax.max > obj2_northVertsMinMax.min + tolerance) then
						match = true
				)
				break
			)
			#south:	--north edge of obj1 to south edge of obj2
			(
				if (abs (obj1.obj.min.Y - obj2.obj.max.Y) <= this.edgeTolerance) then
				(
					local obj1_southVertsMinMax = this.GetMinMax obj1.obj (obj1.southVertIDs as array) #x
					local obj2_northVertsMinMax = this.GetMinMax obj2.obj (obj2.northVertIDs as array) #x
					if (obj1_southVertsMinMax.min + tolerance < obj2_northVertsMinMax.max) and (obj1_southVertsMinMax.max > obj2_northVertsMinMax.min + tolerance) then
						match = true
				)
				break
			)
			#east:	--west edge of obj1 to east edge of obj2
			(
				if (abs (obj1.obj.max.X - obj2.obj.min.X) <= this.edgeTolerance) then
				(
					local obj1_eastVertsMinMax = this.GetMinMax obj1.obj (obj1.eastVertIDs as array) #y
					local obj2_westVertsMinMax = this.GetMinMax obj2.obj (obj2.westVertIDs as array) #y
					if (obj1_eastVertsMinMax.min + tolerance < obj2_westVertsMinMax.max) and (obj1_eastVertsMinMax.max > obj2_westVertsMinMax.min + tolerance) then
						match = true
				)
				break
			)
			#west:	--east edge of obj1 to west edge of obj2
			(
				if (abs (obj1.obj.min.X - obj2.obj.max.X) <= this.edgeTolerance) then
				(
					local obj1_westVertsMinMax = this.GetMinMax obj1.obj (obj1.westVertIDs as array) #y
					local obj2_eastVertsMinMax = this.GetMinMax obj2.obj (obj2.eastVertIDs as array) #y
					if (obj1_westVertsMinMax.min + tolerance < obj2_eastVertsMinMax.max) and (obj1_westVertsMinMax.max > obj2_eastVertsMinMax.min + tolerance) then
						match = true
				)
				break
			)
		)
		match
	),
	
	--qsort function
	fn SortSeamVertsByX a b =
	(
		if a.position[1] < b.position[1] do return -1
		if a.position[1] > b.position[1] do return 1
		return 0
	),
	
	--qsort function
	fn SortSeamVertsByY a b =
	(
		if a.position[2] < b.position[2] do return -1
		if a.position[2] > b.position[2] do return 1
		return 0
	),
	
	--matches the vertices along a pair of matching seam edges
	--target can be used to force which edge stays in place
	--target set to undefined or #obj1 or #obj2
	--targetLocks determines whether unmatched verts move to the closest source vert, or whether new verts are created on the source edge
	fn WeldSeam Seam target: undefined targetLocked: false =
	(
		local minValue, maxValue, axisID
		local obj1 = Seam.obj1
		local obj2 = Seam.obj2
		local vertIDs1 = Seam.vertids1
		local vertIDs2 = Seam.vertids2
		local axis = Seam.axis	
		local matchedTargetVerts = #{}
		local unmatchedVerts
		local SeamVertList1 = for item in vertIDs1 collect (TerrainSeamTool_SeamVert obj:obj1 vertid:item position:obj1.verts[item].position)
		local SeamVertList2 = for item in vertIDs2 collect (TerrainSeamTool_SeamVert obj:obj2 vertid:item position:obj2.verts[item].position)		
		local numVerts = SeamVertList1.count + SeamVertList2.count
		
		--the axisID corresponds to whether we are checking in x or y
		if axis == #x then
		(
			axisID = 1
			QSort SeamVertList1 SortSeamVertsByX
			QSort SeamVertList2 SortSeamVertsByX
		)
		else
		(
			axisID = 2
			QSort SeamVertList1 SortSeamVertsByY
			QSort SeamVertList2 SortSeamVertsByY
		)
		
		--find the minimum and maximum values
		if (SeamVertList1[1].position[1] < SeamVertList2[1].position[axisID]) then
			minValue = SeamVertList1[1].position[axisID]
		else
			minValue = SeamVertList2[1].position[axisID]
		if (SeamVertList1[SeamVertList1.count].position[axisID] > SeamVertList2[SeamVertList2.count].position[1]) then
			maxValue = SeamVertList1[SeamVertList1.count].position[axisID]
		else
			maxValue = SeamVertList2[SeamVertList2.count].position[axisID]
		
		--the list with more verts is matched to the list with fewer
		local SeamListSource, SeamListTarget, SourceVertIDs, SourceObject
		
		--find the target
		case target of
		(
			#obj1:
			(
				SeamListTarget = SeamVertList1
				SeamListSource = SeamVertList2
				SourceVertIDs = vertiDs2
				SourceObject = obj2
				break
			)
			#obj2:
			(
				SeamListTarget = SeamVertList2
				SeamListSource = SeamVertList1
				SourceVertIDs = vertiDs1
				SourceObject = obj1
				break
			)
			default:
			(
				--weld verts on edge with more verts
				if SeamVertList1.count > SeamVertList2.count then
				(
					SeamListSource = SeamVertList1
					SeamListTarget = SeamVertList2
					SourceVertIDs = vertIDs1
					SourceObject = obj1
				)
				else
				(
					SeamListSource = SeamVertList2
					SeamListTarget = SeamVertList1
					SourceVertIDs = vertIDs2
					SourceObject = obj2
				)
				break
			)
		)
		
		for sourceVert in SeamListSource do
		(
			local matchingVert = this.GetMatch sourceVert SeamListTarget axisID			
			sourceVert.obj.verts[sourceVert.vertID].position = SeamListTarget[matchingVert].position
			sourceVert.position = SeamListTarget[matchingVert].position
			append matchedTargetVerts matchingVert
		)
		
		--work out which of the target vertices have not had a corresponding source vert matched
		unmatchedTargetVerts = #{1..SeamListTarget.count} - matchedTargetVerts
		
		--now, what to do about the unmatched target vertices?
		--if targetLocked true: create new verts on the source edge
		--if targetLocked false: move the target verts to match source verts
		if (not targetLocked) then
		(
			for id in unmatchedTargetVerts do
			(
				local targetVert = SeamListTarget[id]
				local matchingVert = this.GetMatch targetVert SeamListSource axisID
				targetVert.obj.verts[targetVert.vertID].position = SeamListSource[matchingVert].position
			)
		)		
	),
	
	--finds the id of the closest edge vert that corresponds to a given vertex position
	fn GetMatch vert SeamVertList axisID =
	(
		local position = vert.position[axisID]	--the x or y postion of the test vertex
		local numVerts = SeamVertList.count
		local foundMatch = false
		local match =SeamVertList[numVerts]
		local gap = (SeamVertList[numVerts].position[axisID] - SeamVertList[1].position[axisID]) * 2
		
		for i = 1 to numVerts where foundMatch == false do
		(
			local newGap = abs (SeamVertList[i].position[axisID] - position)
			if newGap <= gap then
			(
				gap = newGap
				match = i
			)
			else foundMatch = true
		)
		
		match
	),
	
	--generates SeamShcekList and CornerCheckList arrays
	fn ProcessEdges =
	(		
		local numObjects = this.ObjectList.count
		local edgeMatchList = #()		
-- 		for item in this.ObjectList do item.FormatData()	--dev
		
		--find all the edge matches
		for i = 1 to (numObjects - 1) do
		(
			-- fix edges seams and generate CornerCheckList
			for j = (i + 1) to numObjects do
			(
				--check each edge for proximity
				if (CheckEdge this.ObjectList[i] this.ObjectList[j] #north) then
				(
					append edgeMatchList (TerrainSeamTool_SeamEdge obj1:this.ObjectList[i].obj vertids1:this.ObjectList[i].northVertIDs obj2:this.ObjectList[j].obj vertids2:this.ObjectList[j].southVertIDs axis:#x)
-- 					format "Case 1 (south to north): % matched to %\n" edgeMatchList[edgeMatchList.count].obj1.name edgeMatchList[edgeMatchList.count].obj2.name	--dev
				)
				
				if (CheckEdge this.ObjectList[i] this.ObjectList[j] #south) then
				(
					append edgeMatchList (TerrainSeamTool_SeamEdge this.ObjectList[i].obj this.ObjectList[i].southVertIDs this.ObjectList[j].obj this.ObjectList[j].northVertIDs #x)
-- 					format "Case 2 (north to south): % matched to %\n" edgeMatchList[edgeMatchList.count].obj1.name edgeMatchList[edgeMatchList.count].obj2.name	--dev
				)
				
				if (CheckEdge this.ObjectList[i] this.ObjectList[j] #east) then
				(
					append edgeMatchList (TerrainSeamTool_SeamEdge this.ObjectList[i].obj this.ObjectList[i].eastVertIDs this.ObjectList[j].obj this.ObjectList[j].westVertIDs #y)
-- 					format "Case 3 (west to east): % matched to %\n" edgeMatchList[edgeMatchList.count].obj1.name edgeMatchList[edgeMatchList.count].obj2.name	--dev
				)

				if (CheckEdge this.ObjectList[i] this.ObjectList[j] #west) then
				(
					append edgeMatchList (TerrainSeamTool_SeamEdge this.ObjectList[i].obj this.ObjectList[i].westVertIDs this.ObjectList[j].obj this.ObjectList[j].eastVertIDs #y)
-- 					format "Case 4 (east to west): % matched to %\n" edgeMatchList[edgeMatchList.count].obj1.name edgeMatchList[edgeMatchList.count].obj2.name	--dev
				)
			)
		)
		local numEdgeMatches = edgeMatchList.count
		
		--execute the edge matches
		for item in edgeMatchList where (item.vertids1.count > 0) and (item.vertids2.count > 0) do
		(
			this.Progress += (50 / numEdgeMatches)
			this.ProgBar.Value = this.Progress
			WeldSeam item
		)
	),
	
	--move all matching corner points to average positions
	fn ProcessCorners =
	(
		local CornerList = #()		--array of SeamVert objects which describe a vertID with it's corresponding object and position
		for item in this.ObjectList do
		(
-- 			item.FormatData()	--dev
			--add the corners to the corner list but only if they exist
			if item.nwVert != undefined then
				append CornerList (TerrainSeamTool_SeamVert obj:item.obj vertid:item.nwVert position:item.obj.verts[item.nwVert].position)
			if item.neVert != undefined then
				append CornerList (TerrainSeamTool_SeamVert obj:item.obj vertid:item.neVert position:item.obj.verts[item.neVert].position)
			if item.swVert != undefined then
				append CornerList (TerrainSeamTool_SeamVert obj:item.obj vertid:item.swVert position:item.obj.verts[item.swVert].position)
			if item.seVert != undefined then
				append CornerList (TerrainSeamTool_SeamVert obj:item.obj vertid:item.seVert position:item.obj.verts[item.seVert].position)
		)
		
		local initialNumCorners = CornerList.count
		
		while CornerList.count > 1 do
		(
			--iterate through the CornerList looking for matched corner verts
			--note the first item in the list
			local numCorners = CornerList.count
			local refCorner = CornerList[1]
			local matchList = #(refCorner)
			local matchListIDs = #(1)
			local tolerance = 0.001
			local averagePosition = refCorner.position
			
			for i = 2 to numCorners do
			(
				--check the distance between other corners and the refCorner to find matches
				local xgap = abs (CornerList[i].position[1] - refCorner.position[1])
				local ygap = abs (CornerList[i].position[2] - refCorner.position[2])
				if (xgap < tolerance) and (ygap < tolerance) then
				(--match found as vertices are within tolerance distance on x and y axes
					append matchList CornerList[i]
					append matchListIDs i
					averagePosition += CornerList[i].position
				)
			)
			
			local matchListCount = matchList.count
			
			--when a group of matched corners is found, get the average position
			if (matchListCount > 1) then
			(
				averagePosition /= matchList.count
				--move the vertices 
				for item in matchList do
					item.obj.verts[item.vertid].position.z = averagePosition.z	--we only need the vertical, x and y don't change
				--remove these matched corners from the CornerList
				for i = 1 to matchListCount do
					deleteItem CornerList (matchListIDs[matchListCount - i + 1])
			)			
			else --if no match on current item, remove from the CornerList
				deleteItem CornerList 1
			
			this.Progress += (50 * (numCorners - CornerList.count) / initialNumCorners)
			this.ProgBar.Value = this.Progress
		)
	),
	
	fn Process =
	(
		ClearListener()
		--1) Clear data
		this.ObjectList = #()
		this.Progress = 0
		this.ProgBar.Value = 0
		
		--2) Get a list of objects and their edge vertices
		this.GetEdges()
		--3) Check that they are in proximity: generate SeamCheckList and CornerCheckList
		undo on
		(
			this.ProcessEdges()
			--4) Match all the corners
			this.ProcessCorners()
			--5) Process isolated edge vertices
-- 			this.ProcessIsolatedVerts()
			--6) Weld the edge vertices
			for item in this.ObjectList do
				polyop.WeldVertsByThreshold item.obj item.edgeVertIDs
		)
		this.Progress = 0
		this.ProgBar.Value = 0
	),
	
	------------------------------------------------------------------------------------------------------------------------------------------
	--UI
	------------------------------------------------------------------------------------------------------------------------------------------
	
	fn CreateUI =
	(
		-- form setup		
		Form = dotNetObject "maxCustomControls.maxForm"
		Form.Text = "Terrain Seam Tool"
		Form.StartPosition = (dotNetClass "System.Windows.Forms.FormStartPosition").manual
		Form.Location = dotNetObject "system.drawing.point" 0 80
		Form.MaximumSize = dotNetObject "System.Drawing.Size" 1600 1200
		Form.MinimumSize = dotNetObject "System.Drawing.Size" 100 100
		Form.Size = dotNetObject "System.Drawing.Size" 240 230
		Form.FormBorderStyle = RS_dotNetPreset.FB_FixedToolWindow
-- 		Form.FormBorderStyle = RS_dotNetPreset.FB_Sizable
		dotNet.AddEventHandler Form "Load" LoadIniFile
		dotNet.AddEventHandler Form "Closing" SaveIniFile
		
		--content
		ToolTip = dotnetobject "ToolTip"
		Table = dotNetObject "TableLayoutPanel"
		Table.Dock = RS_dotNetPreset.DS_Fill
		Table.RowCount = 4
		Table.RowStyles.add (RS_dotNetObject.rowStyleObject "absolute" 40)	--banner
		Table.RowStyles.add (RS_dotNetObject.rowStyleObject "percent" 100)	--info panel
		Table.RowStyles.add (RS_dotNetObject.rowStyleObject "absolute" 40)	--button
		Table.RowStyles.add (RS_dotNetObject.rowStyleObject "absolute" 16)	--progress bar
		Table.ColumnCount = 1
		Table.ColumnStyles.add (RS_dotNetObject.columnStyleObject "percent" 100)
		Table.Margin = RS_dotNetPreset.Padding_None
		Form.Controls.Add Table
		
		RSBannerPanel	= dotNetObject "System.Windows.Forms.Panel"
		RSBannerPanel.borderstyle	= RS_dotNetClass.borderStyleClass.FixedSingle
		RSBannerPanel.dock = RS_dotNetPreset.DS.Fill
		
		local banner = makeRsBanner dn_Panel:RSBannerPanel width:395 studio:"london" mail:"andy.davis@rockstarlondon.com" wiki:"Terrain Seam Tool"
		banner.setup()
		Table.Controls.Add RSBannerPanel 0 0
		
		InfoPanel = RS_dotNetUI.InitLabel "" RS_dotNetPreset.TA.MiddleLeft
		InfoPanel.Margin = dotNetObject "System.Windows.Forms.Padding" 8
		InfoPanel.Font = dotNetObject "System.Drawing.Font" "Calibri" 10
		InfoPanel.Text = "Select the terrain objects whose seams you want to fix, and hit the button."
		InfoPanel.Text += "This tool moves edge vertices to match adjoining terrain sections and welds vertices where they coincide."
		Table.Controls.Add InfoPanel 0 1
		
		ButtonTable = dotNetObject "TableLayoutPanel"
		ButtonTable.Dock = RS_dotNetPreset.DS_Fill
		ButtonTable.RowCount = 1
		ButtonTable.RowStyles.add (RS_dotNetObject.rowStyleObject "percent" 100)
		ButtonTable.ColumnCount = 2
		ButtonTable.ColumnStyles.add (RS_dotNetObject.columnStyleObject "percent" 50)
		ButtonTable.ColumnStyles.add (RS_dotNetObject.columnStyleObject "percent" 50)
		Table.Controls.Add ButtonTable 0 2

		ApplyButton = RS_dotNetUI.InitButton "Fix Terrain Seam"
		dotNet.AddEventHandler ApplyButton "Click" Apply
		ApplyButton.Font = dotNetObject "System.Drawing.Font" "Arial Black" 11
		ButtonTable.Controls.Add ApplyButton 0 0
		ButtonTable.SetColumnSpan ApplyButton 2
		
		UndoButton = RS_dotNetUI.InitButton "Undo"
		dotNet.AddEventHandler UndoButton "Click" UndoClicked
-- 		ButtonTable.Controls.Add UndoButton 1 0

		ProgBar = dotNetObject "ProgressBar"
		ProgBar.Dock = RS_dotNetPreset.DS_Fill
		Table.Controls.Add ProgBar 0 3
		
		--draw form
		Form.ShowModeless()
		Form
	)
)

-- ClearListener()
if EdgeMatch != undefined then EdgeMatch.Form.Close()
EdgeMatch = EdgeMatchStruct()
EdgeMatch.CreateUI()
-- EdgeMatch.Process()