   Lesson 27
  I have a problem with it not showing shadows after modifing it.  counter=0;counter2 = 0;// second pass, stencil operation increases stencil valueglFrontFace(GL_CCW);glStencilOp(GL_KEEP,GL_KEEP, GL_DECR);//MessageBox(NULL,"Start Pass2","Layer2",MB_OK);for (i=0; i<nPlanes;i++){if (planes[i].visible)for (j=0;j<3;j++){k = planes[i].neigh[j];if ((!k) || (!planes[k-1].visible)){// here we have an edge, we must draw a polygonp1 = planes[i].p[j];jj = (j+1)%3;p2 = planes[i].p[jj];//calculate the length of the vectorv1.x = (points[p1].x - lp[0])*100;v1.y = (points[p1].y - lp[1])*100;v1.z = (points[p1].z - lp[2])*100;v2.x = (points[p2].x - lp[0])*100;v2.y = (points[p2].y - lp[1])*100;v2.z = (points[p2].z - lp[2])*100;//draw the polygon//glEnable(GL_CULL_FACE);vbuffer[counter] = points[p1].x; counter++;vbuffer[counter] = points[p1].y; counter++;vbuffer[counter] = points[p1].z; counter++;elements[counter2]= counter2;counter2++;vbuffer[counter] = points[p1].x+v1.x; counter++;vbuffer[counter] = points[p1].y+v1.y; counter++;vbuffer[counter] = points[p1].z+v1.z; counter++;   elements[counter2]= counter2;counter2++;  vbuffer[counter] = points[p2].x; counter++;vbuffer[counter] = points[p2].y; counter++;vbuffer[counter] = points[p2].z; counter++;elements[counter2]= counter2;counter2++;vbuffer[counter] = points[p1].x+v1.x; counter++;vbuffer[counter] = points[p1].y+v1.y; counter++;vbuffer[counter] = points[p1].z+v1.z; counter++;elements[counter2]= counter2;counter2++;vbuffer[counter] = points[p2].x; counter++;vbuffer[counter] = points[p2].y; counter++;vbuffer[counter] = points[p2].z; counter++;elements[counter2]= counter2;counter2++;vbuffer[counter] = points[p2].x + v2.x; counter++;vbuffer[counter] = points[p2].y + v2.y; counter++;vbuffer[counter] = points[p2].z + v2.z; counter++; elements[counter2]= counter2;counter2++;//glDisable(GL_CULL_FACE);}}}I had to change facing for the model. Disabling the second pass (which is above) looks fine, but when i re-enable it. i get nothing til i move. then i get a stationary black clone of the model.Anyone?Bobby 
  Ehr... if it did show shadows fine before you modified it, why did you modify it, to begin with? You should try to understand each step first before messing around with it. And, instead of posting the modified code only, it''d be a little more helpfull if you could post something like ''I had this'' - ''I turned it into that'' (line by line! Not two large chunks of code). Would make it easier for people to tell what changes you have done, and what exactly the consequences of those change are.  ;  i went through everything with culling, looked up trianglestrip for even is like n+1,n,n+2.as for the black clone, erasing stencil buffer did help.:Sso now, i use a model with two shadowing lightpoints.vsync off ranging from 240 to 400 fps.though, the scene is not complex. Bobby 