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Neometron

Member Since 22 Feb 2007
Offline Last Active Nov 26 2014 12:27 PM

Topics I've Started

Floats and Android Devices

05 August 2013 - 09:00 AM

Hello everyone,

Last week I encountered a particular situation dealing with floats in my Android project.  I have two devices, a tablet and a cell phone, that give different results after computations. There is a continuous collision system for a ball and it falls with gravity.  It works perfectly on the tablet device, but on the phone the ball falls through the table. After stepping through the code, the only difference found between devices were the time of impact  ~0.04/s. This caused the ball to be embedded with the surface and falls through.

So in general, what is the difference between accuracy and precision?  Is the terms accuracy and precision one and the same? I know floats don't have that great of precision, but with margin of errors in the hundredth's place?


 


Functions called twice in Blender export script

20 July 2012 - 11:05 AM

I have decided to picked up an old project of mine that I want to finish. It's a DirectX 9 export script for Blender 2.49b using the compiled Python 2.6.2. There is no Python installation on the machine. The issue is that one or possibly more of my class functions are being called twice. However, it does not reflect in my .x file output.

Mesh and MeshFace are functions of class cLayoutManager. For a simple cube with six faces in a mesh, MeshFace is called six times by the Mesh function. But MeshFace is being called 12 times; 6 from Mesh and 6 more for some reason I don't know.

Here is some code:

[source lang="python"]def Mesh(self, ExportMesh = None, ExportArmature = None): # NAMESPACE # EXPORT = self.EXPORT LAYOUT = self TOKEN = self.TOKEN # GET MESH NAME # strMeshName = EXPORT.RESERVED.Verify(ExportMesh.name) # CREATE MESH TAG # LAYOUT.OpenTag("Mesh", strMeshName) # CREATE CURRENT INDENT TOKEN # TIndent = TOKEN.cIndentToken(TOKEN) TOKEN.addToken(TIndent) # GET NUMBER OF VERTS IN MESH # nVerts = len(ExportMesh.verts) # CREATE DWORD TOKEN # LAYOUT.Dword(nVerts) TOKEN.addToken(TOKEN.TNL) # LOOP THROUGH ALL VERT VECTORS # for nIndex in range(0, nVerts): vert = ExportMesh.verts[nIndex] TOKEN.addToken(TIndent) LAYOUT.Vector(vert.co.x, vert.co.y, vert.co.z) if(nIndex != (nVerts-1)): TOKEN.addToken(TOKEN.TComma) TOKEN.addToken(TOKEN.TNL) else: TOKEN.addToken(TOKEN.TSC) TOKEN.addToken(TOKEN.TNL) # END FOR LOOP BLOCK # TOKEN.addToken(TIndent) # GET NUMBER OF FACES IN MESH # nFaces = len(ExportMesh.faces) # CREATE DWORD TOKEN # LAYOUT.Dword(nFaces) #Number of Faces TOKEN.addToken(TOKEN.TNL) # LOOP THROUGH ALL FACES IN MESH # for nIndex in range(0, nFaces): TOKEN.addToken(TIndent) EXPORT.GUI.CONSOLE.Log("LAYOUTMGR.Mesh: Calling LAYOUTMGR.MeshFace", 3) LAYOUT.MeshFace(ExportMesh.faces[nIndex]) if(nIndex != (nFaces-1)): TOKEN.addToken(TOKEN.TComma) TOKEN.addToken(TOKEN.TNL) else: TOKEN.addToken(TOKEN.TSC) TOKEN.addToken(TOKEN.TNL) # END FOR LOOP BLOCK # #TOKEN.addToken(TOKEN.TNL)[/source]

There is more to the Mesh function but this is up to point of calling MeshFace. LAYOUT = self

[source lang="python"]def MeshFace(self, face = None): # NAMESPACE # EXPORT = self.EXPORT LAYOUT = self TOKEN = self.TOKEN EXPORT.GUI.CONSOLE.Log("LAYOUTMGR.MeshFace: Self %s" % self) EXPORT.GUI.CONSOLE.Log("LAYOUTMGR.MeshFace: FACE %s" % face) nMaxVert = len(face.verts) if nMaxVert < 3 or nMaxVert > 4: EXPORT.GUI.CONSOLE.Log("LAYOUTMGR.MeshFace: WARNING - Mesh Inconsistancy: Face has %d vertices" % (nMaxVert)) LAYOUT.Dword(nMaxVert) TOKEN.addToken(TOKEN.TSpace) VertIndexItems = [] for Vert in face.verts: VertIndexItems += [Vert.index] LAYOUT.DwordItems(VertIndexItems, nMaxVert) # UPDATE PROGRESS UI # print "MeshFace Layout" EXPORT.GUI.GIP_Bar.upValue() EXPORT.GUI.MSG.RedrawAllGI() #END cLayoutManager.MeshFace(self, face):[/source]

Sample of my log output:
LAYOUTMGR.Mesh: Calling LAYOUTMGR.MeshFace
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252AC60>
LAYOUTMGR.Mesh: Calling LAYOUTMGR.MeshFace
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252AC88>
LAYOUTMGR.Mesh: Calling LAYOUTMGR.MeshFace
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252ACB0>
LAYOUTMGR.Mesh: Calling LAYOUTMGR.MeshFace
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252ACD8>
LAYOUTMGR.Mesh: Calling LAYOUTMGR.MeshFace
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252AD00>
LAYOUTMGR.Mesh: Calling LAYOUTMGR.MeshFace
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252AD28>
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252AC60>
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252AC88>
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252ACB0>
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252ACD8>
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252AD00>
LAYOUTMGR.MeshFace: Self <__main__.cLayoutManager instance at 0x0C0E92D8>
LAYOUTMGR.MeshFace: FACE <__main__.cFace instance at 0x0252AD28>


Note: Highlighted log entries in red are the extra function calls in question


Here is the .x output of Blender's default startup cube. In the mesh there are 8 verts and 6 faces which the export does correctly.

xof 0303txt 0032
Frame RootFrame
{
FrameTransformMatrix
{
1.000000,0.000000,0.000000,0.000000,
0.000000,1.000000,0.000000,0.000000,
0.000000,0.000000,1.000000,0.000000,
0.000000,0.000000,0.000000,1.000000;;
}

Frame OBJ_Cube
{
FrameTransformMatrix
{
1.000000,0.000000,0.000000,0.000000,
0.000000,1.000000,0.000000,0.000000,
0.000000,0.000000,-1.000000,0.000000,
0.000000,0.000000,0.000000,1.000000;;
}

Mesh
{
8;
1.000000;1.000000;-1.000000;,
1.000000;-1.000000;-1.000000;,
-1.000000;-1.000000;-1.000000;,
-1.000000;1.000000;-1.000000;,
1.000000;0.999999;1.000000;,
0.999999;-1.000001;1.000000;,
-1.000000;-1.000000;1.000000;,
-1.000000;1.000000;1.000000;;
6;

4; 0,3,2,1;,
4; 4,5,6,7;,
4; 0,1,5,4;,
4; 1,2,6,5;,
4; 2,3,7,6;,
4; 4,7,3,0;;

MeshNormals
{
8;
0.577349;0.577349;-0.577349;,
0.577349;-0.577349;-0.577349;,
-0.577349;-0.577349;-0.577349;,
-0.577349;0.577349;-0.577349;,
0.577349;0.577349;0.577349;,
0.577349;-0.577349;0.577349;,
-0.577349;-0.577349;0.577349;,
-0.577349;0.577349;0.577349;;
6;
4; 0,3,2,1;,
4; 4,5,6,7;,
4; 0,1,5,4;,
4; 1,2,6,5;,
4; 2,3,7,6;,
4; 4,7,3,0;;
}
}
}
}


Note: Bold items are the result of function MeshFace


Any clues on why or what is calling MeshFace function six more times?

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