Hello to everyone, i’ve got a little problem (i hope) in my opengl cad application… i’m using ray picking algho to select meshes from my opengl windows when user clicks on them… the problem is that if i load files from the disk (also plane definition for each object face) it works perfectly but if i try to compute plane from my face data nothing works… here is the code i use

BuildPlaneFromPoly : computes 3 points on the plane, normal and distance

GetHitByRay : returns face hit by the ray (if any)

void BuildPlaneFromPoly(SFACE *sFace)

{

CV3 v1, v2, v3;sFace->vPlanePts[0] = sFace->sFaceVertices[2];

sFace->vPlanePts[1] = sFace->sFaceVertices[1];

sFace->vPlanePts[2] = sFace->sFaceVertices[0];v1 = sFace->vPlanePts[0] - sFace->vPlanePts[1];

v2 = sFace->vPlanePts[1] - sFace->vPlanePts[2];

v3 = sFace->vPlanePts[1];

/*v1 = sFace->vPlanePts[0] - sFace->vPlanePts[1];

v2 = sFace->vPlanePts[2] - sFace->vPlanePts[1];

v3 = sFace->vPlanePts[1];

/v1 = sFace->vPlanePts[1] - sFace->vPlanePts[0];/

v2 = sFace->vPlanePts[2] - sFace->vPlanePts[0];

v3 = sFace->vPlanePts[0];sFace->sFacePlane.vNormal = v1.Cross(v2);

sFace->sFacePlane.vNormal.Normalize();sFace->sFacePlane.fDist = v3.Dot(sFace->sFacePlane.vNormal);

}SFACE *GetHitByRay(CBRUSH *pBrush,CV3 vRay,CV3 vOrigin,CV3 vDir,float &dist)

{

SFACE *retface = NULL;

SFACE *pFace = NULL;float fP1DotPn = 0.0f;

float fP2DotPn = 0.0f;

float frac = 0.0f;CV3 rayPoint1 = vOrigin;

CV3 rayPoint2 = vRay;for (int k = 0; k < pBrush->m_NumFaces; k++)

{

pFace = &pBrush->s_Faces[k];fP1DotPn = rayPoint1.Dot(pFace->sFacePlane.vNormal) - pFace->sFacePlane.fDist;

fP2DotPn = rayPoint2.Dot(pFace->sFacePlane.vNormal) - pFace->sFacePlane.fDist;/*

We dot product the two points from the ray to the poly plane normal

to see if there is an intersection. If fP1DotPn * fP2DotPn is >= 0.0f

then there was no intersection. To optimize calculation a bit, we

check to see if both variables are positive or negative instead of

doing the multiplication

*/

if(fP1DotPn >= 0.0f && fP2DotPn >= 0.0f)

{

dist = 0;

return NULL;

}if(fP1DotPn <= 0.0f && fP2DotPn <= 0.0f)

{

continue;

}

// find intersection point

frac = fP1DotPn / (fP1DotPn - fP2DotPn);

if(fP1DotPn > 0)

{

retface= pFace;rayPoint1.x = rayPoint1.x + frac *(rayPoint2.x - rayPoint1.x);

rayPoint1.y = rayPoint1.y + frac *(rayPoint2.y - rayPoint1.y);

rayPoint1.z = rayPoint1.z + frac *(rayPoint2.z - rayPoint1.z);

}

else

{

rayPoint2.x = rayPoint1.x + frac *(rayPoint2.x - rayPoint1.x);

rayPoint2.y = rayPoint1.y + frac *(rayPoint2.y - rayPoint1.y);

rayPoint2.z = rayPoint1.z + frac *(rayPoint2.z - rayPoint1.z);

}

}// find where ray clipped to poly

rayPoint1 -= vOrigin;

fP1DotPn = rayPoint1.Dot(vDir);dist = fP1DotPn;

return retface;

}