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RAS_texmatrix.cpp

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00001 
00002 
00003 #include "RAS_TexMatrix.h"
00004 
00005 
00006 void RAS_CalcTexMatrix(RAS_TexVert p[3],MT_Point3& origin,MT_Vector3& udir,MT_Vector3& vdir)

00007 {
00008 // precondition: 3 vertices are non-colinear
00009 
00010         MT_Vector3 vec1 = p[1].xyz()-p[0].xyz();
00011         MT_Vector3 vec2 = p[2].xyz()-p[0].xyz();
00012         MT_Vector3 normal = vec1.cross(vec2);
00013         normal.normalize();
00014 
00015         // determine which coordinate we drop, ie. max coordinate in the normal
00016         
00017 
00018         int ZCOORD = normal.closestAxis();
00019         int XCOORD = (ZCOORD+1)%3;
00020         int YCOORD = (ZCOORD+2)%3;
00021                 
00022         // ax+by+cz+d=0
00023         MT_Scalar d = -p[0].xyz().dot(normal);
00024         
00025 
00026         MT_Matrix3x3 mat3(      p[0].getUV1()[0],p[0].getUV1()[1],      1,
00027                                                 p[1].getUV1()[0],p[1].getUV1()[1],      1,
00028                                                 p[2].getUV1()[0],p[2].getUV1()[1],      1);
00029 
00030 
00031         MT_Matrix3x3 mat3inv = mat3.inverse();
00032 
00033         MT_Vector3 p123x(p[0].xyz()[XCOORD],p[1].xyz()[XCOORD],p[2].xyz()[XCOORD]);
00034         MT_Vector3 resultx = mat3inv*p123x;
00035         MT_Vector3 p123y(p[0].xyz()[YCOORD],p[1].xyz()[YCOORD],p[2].xyz()[YCOORD]);
00036         MT_Vector3 resulty = mat3inv*p123y;
00037 
00038         // normal[ZCOORD] is not zero, because it's chosen to be maximal (absolute), and normal has length 1, 
00039         // so at least on of the coords is <> 0
00040 
00041         //droppedvalue udir.dot(normal) =0
00042         MT_Scalar droppedu = -(resultx.x()*normal[XCOORD]+resulty.x()*normal[YCOORD])/normal[ZCOORD];
00043         udir[XCOORD] = resultx.x();
00044         udir[YCOORD] = resulty.x();
00045         udir[ZCOORD] = droppedu;
00046         MT_Scalar droppedv = -(resultx.y()*normal[XCOORD]+resulty.y()*normal[YCOORD])/normal[ZCOORD];
00047         vdir[XCOORD] = resultx.y();
00048         vdir[YCOORD] = resulty.y();
00049         vdir[ZCOORD] = droppedv;
00050         // droppedvalue b = -(ax+cz+d)/y;
00051         MT_Scalar droppedvalue = -((resultx.z()*normal[XCOORD] + resulty.z()*normal[YCOORD]+d))/normal[ZCOORD];
00052         origin[XCOORD] = resultx.z();
00053         origin[YCOORD] = resulty.z();
00054         origin[ZCOORD] = droppedvalue;
00055         
00056 
00057 }
00058 
00059 #ifdef _TEXOWNMAIN
00060 
00061 int main()

00062 {
00063 
00064         MT_Point2 puv0={0,0};
00065         MT_Point3 pxyz0 (0,0,128);
00066 
00067         MT_Scalar puv1[2]={1,0};
00068         MT_Point3 pxyz1(128,0,128);
00069 
00070         MT_Scalar puv2[2]={1,1};
00071         MT_Point3 pxyz2(128,0,0);
00072 
00073         RAS_TexVert p0(pxyz0,puv0);
00074         RAS_TexVert p1(pxyz1,puv1);
00075         RAS_TexVert p2(pxyz2,puv2);
00076 
00077         RAS_TexVert vertices[3] = 
00078         {
00079                 p0,
00080                 p1,
00081                 p2
00082         };
00083 
00084         MT_Vector3 udir,vdir;
00085         MT_Point3 origin;
00086         CalcTexMatrix(vertices,origin,udir,vdir);
00087 
00088         MT_Point3 testpoint(128,32,64);
00089 
00090         MT_Scalar lenu = udir.length2();
00091         MT_Scalar lenv = vdir.length2();
00092 
00093         MT_Scalar testu=((pxyz2-origin).dot(udir))/lenu;
00094         MT_Scalar testv=((pxyz2-origin).dot(vdir))/lenv;
00095 
00096 
00097 
00098 
00099         return 0;
00100 }
00101 
00102 #endif // _TEXOWNMAIN

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