[bb] Convert BlitzTerrain To Mesh by _PJ_ [ 1+ years ago ]

Started by BlitzBot, June 29, 2017, 00:28:42

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June 29, 2017, 00:28:42
Title : Convert BlitzTerrain To Mesh
Author : _PJ_
Posted : 1+ years ago

Description : Currently converts the topography and UV Coordinates of a BlitzTerrain to Mesh surface triangles.

I hope to include textures and hopefully cope with rotated Terrains.
This basic example shows the conversion:

Code Select
Graphics3D 1024,768,32
SetBuffer BackBuffer()

Const TSize=64

AmbientLight 127,127,127
Global sun=CreateLight()

Global cam=CreateCamera()
MoveEntity cam,0,10,-20
TurnEntity cam,0,-35,0

Local terrain=CreateTerrain(TSize)
TerrainShading terrain,True

Local X#
Local Y#
Local Z#

;(Randomiseterrain)
For Z#= 0 To TSize-1
For X#=0 To TSize-1
ModifyTerrain(terrain,X#,Z#,Rnd(0,1))
Next
Next
ScaleEntity terrain,1,Rand(2,8),1

;EFFECTS
EntityFX terrain,16
EntityAlpha terrain,0.5
EntityColor terrain,255,0,0

Local Mesh=ConvertTerrainToMesh(terrain)

;MESH EFFECTS
EntityFX Mesh,16
EntityAlpha Mesh,0.5
EntityColor Mesh,0,255,0

;EXAMPLE
Local SH

While Not KeyDown(1)

If(KeyHit(57))
SH=1-SH

If SH
ShowEntity terrain
HideEntity Mesh
Else
ShowEntity Mesh
HideEntity terrain
End If
End If

TurnEntity terrain,0,1,0
TurnEntity Mesh,0,1,0


UpdateWorld
RenderWorld
Flip
Wend

Code :
Code (blitzbasic) Select
Function h3d_MESH_GenerateMeshFromTerrain(Terrain,StartX=0,StartZ=0,MeshSize=0)
;TERRAIN MUST NOT BE ROTATED (Might do this later but it's really complicated... Maybe require TFormPoint or something with the Entitypitch and Yaw values)
; No need to know SCALE factor - Mesh is generated to current actual scaled size of terrain

;Establish Parameters
Local Size=TerrainSize(Terrain)

Local XOffset#=EntityX(Terrain,True)
Local YOffset#=EntityY(Terrain,True)
Local ZOffset#=EntityZ(Terrain,True)

Local UVRatio#=1.0/Size

;Declare locals

Local U#
Local V#
Local W#

Local X#
Local Y#
Local Z#

Local TX#
Local TY#
Local TZ#

Local v0
Local v1
Local v2
Local v3

Local Mesh=CreateMesh()
Local Surface=CreateSurface(Mesh)

For Z=0 To MeshSize-1
For X=0 To MeshSize-1

;Adjust for position
TX=StartX+X+XOffset
TZ=StartZ+Z+ZOffset

;Vertex0
Y#=GetRelativeTerrainHeight(Terrain,TX+1,TZ,YOffset)

U#=(X+1)*UVRatio
V#=1-(Z*UVRatio)
W=(Z*UVRatio)

v0=AddVertex(Surface,X+1,Y,Z,U,V,W)

;Vertex1
Y#=GetRelativeTerrainHeight(Terrain,TX,TZ,YOffset)

U#=X*UVRatio
V#=1-(Z*UVRatio)
W=Z*UVRatio

v1=AddVertex(Surface,X,Y,Z,U,V,W)

;Vertex2
Y#=GetRelativeTerrainHeight(Terrain,TX+1,TZ+1,YOffset)

U#=(X+1)*UVRatio
V#=1-((Z+1)*UVRatio)
W=(Z+1)*UVRatio

v2=AddVertex(Surface,X+1,Y,Z+1,U,V,W)

;Vertex3
Y#=GetRelativeTerrainHeight(Terrain,TX,TZ+1,YOffset)

U#=X*UVRatio
V#=1-((Z+1)*UVRatio)
W=(Z+1)*UVRatio

v3=AddVertex(Surface,X,Y,Z+1,U,V,W)

;Create Surface Polys

AddTriangle(Surface,v0,v1,v2)
AddTriangle(Surface,v1,v3,v2)

Next
Next

UpdateNormals Mesh

PositionEntity Mesh,XOffset+StartX,YOffset,ZOffset+StartZ,True

Return Mesh

End Function

Function GetRelativeTerrainHeight#(Terrain,X#,Z#,YOffset#)
;Converts absolute value to relative
Local AbsoluteHeight#=TerrainY(Terrain,X,0,Z)
Return AbsoluteHeight#-YOffset
End Function

Comments :


_PJ_(Posted 1+ years ago)

 Updated to include StartX StartZ and MeshSize parameters.This means that portions of a large terrain can be split into multiple meshes.Necessary for Terrain sizes greater than around 64 units which exceed the polycount limit for mesh surfaces.
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