Need help texturing triangle strips.

[Einlander]

I'm trying to make a terrain generator, I have the mesh plane generated, but I'm at a total loss at how to generate the uv's for all the triangles.

 

 

This is the code that I currently have. How would I go about programmaticly adding uv's?

 

function Script:MakeTerrain(TerrainSize)

 

local terrain = nil

terrain = Model:Create()

terrain:SetColor(0.5,0.5,0.5)

local surface = terrain:AddSurface()

 

-- add vertexes

System:Print("Generating Vertices")

for TerrainWidth=0 , TerrainSize do

for TerrainDepth=0 , TerrainSize do

surface:AddVertex(TerrainWidth*self.TerrainSquareSize,0,TerrainDepth*self.TerrainSquareSize, 0,1,0)

end

end

-- add triangles

 

 

System:Print("Generating faces")

trianglestrip = 0

System:Print(tostring(surface:CountVertices()))

 

for triangle = 0 , (TerrainSize*TerrainSize)+(TerrainSize-2) do --(surface:CountVertices())/2 do

point1 =trianglestrip

point2 =trianglestrip+(TerrainSize+1)

point3 =trianglestrip+(TerrainSize)-(TerrainSize-1)

point4 = point3+(TerrainSize+1)

System:Print("Bottom:"..tostring(point1+1).."|"..tostring(point2+1).."|"..tostring(point3+1).."["..tostring(point4+1).."]")

System:Print("Top:"..tostring(point2+1).."|"..tostring(point3+1).."|"..tostring(point4+1))

surface:AddTriangle(point1,point3,point2)

surface:AddTriangle(point2,point3,point4)

trianglestrip =point3

end

 

 

-- This is where you would add the uv's

System:Print("Adding UV's")

 

surface:Update(true)

System:Print("")

return terrain

end

[Brutile]

I'd recommend using the default terrain generator. It is a lot easier to setup, but I'm guessing you may want holes and such.

This is the add vertex function from the docs:

 

AddVertex(const Vec3& position, const Vec3& normal=Vec3(0), const Vec2& texcoords0=Vec2(0), const Vec2& texcoords1=Vec2(0), const Vec4& color=Vec4(1))

 

You want something like:

 

surface:AddVertex(Vec3(TerrainWidth*self.TerrainSquareSize,0,TerrainDepth*self.TerrainSquareSize), Vec3(0,1,0), Vec2(TerrainWidth / TerrainSize, TerrainDepth / TerrainSize))

 

The uvs are just a texture mapping for that vertex between 0 and 1 on the x and y, but I'm guessing you know that... maybe

So if you did the xcoord/terrainSize that would get all points between 0 and 1. and the same for the ycoord

[Einlander]

That worked beautifully. I was trying to apply the texture coordinates for every single triangle individually. I also added a scaling feature.

 

The new function for all thoe intrested.

 

function Script:MakeTerrain(TerrainSize,texscale)

--texscale must be => 1

if ( (texscale == nil) == true or (texscale <= 0) == true) then texscale = TerrainSize end

local terrain = nil

terrain = Model:Create()

terrain:SetColor(0.5,0.5,0.5)

local surface = terrain:AddSurface()

-- add vertexes and uv's

System:Print("Generating Vertices")

for TerrainWidth=0 , TerrainSize do

for TerrainDepth=0 , TerrainSize do

surface:AddVertex(Vec3(TerrainWidth*self.TerrainSquareSize,0,TerrainDepth*self.TerrainSquareSize), Vec3(0,1,0),Vec2((TerrainWidth / TerrainSize)*texscale, ((TerrainDepth / TerrainSize)*texscale)*-1))

end

end

-- add triangles

System:Print("Generating faces")

trianglestrip = 0

System:Print(tostring(surface:CountVertices()))

for triangle = 0 , (TerrainSize*TerrainSize)+(TerrainSize-2) do --(surface:CountVertices())/2 do

point1 =trianglestrip

point2 =trianglestrip+(TerrainSize+1)

point3 =trianglestrip+(TerrainSize)-(TerrainSize-1)

point4 = point3+(TerrainSize+1)

--System:Print("Bottom:"..tostring(point1+1).."|"..tostring(point2+1).."|"..tostring(point3+1).."["..tostring(point4+1).."]")

--System:Print("Top:"..tostring(point2+1).."|"..tostring(point3+1).."|"..tostring(point4+1))

surface:AddTriangle(point1,point3,point2)

surface:AddTriangle(point2,point3,point4)

trianglestrip =point3

end

surface:Update(true)

System:Print("")

return terrain

end

 

This isn't quite ready for prime time. I need to swap the direction of the triangles every other row as described here: http://dan.lecocq.us/wordpress/2009/12/25/triangle-strip-for-grids-a-construction/ and that should be easy enough.

 

A last question, Is it possible to change the material for a single polygon as if it were a multi-material mesh?

[Brutile]

You would need add another surface to the mesh and apply the material to it.