c++ - Filling a cube (back-face culling algorithm)? -


i want fill cube. found back-face culling algorithm. can explain me how works? have 8 points in vector:

check here

maybe know easier algorithm or explain me should back-face culling?

(wallx[0] - point 0; wallx[1] - point 1; wallx[2] - point 2 image)

code fist wall:

x1[0]=wallx[1]-wallx[0]; y1[0]=wally[1]-wally[0]; z1[0]=wallz[1]-wallz[0];  x2[0]=wallx[2]-wallx[0]; y2[0]=wally[2]-wally[0]; z2[0]=wallz[2]-wallz[0];  x3[0]=0; y3[0]=0; z3[0]=1000;  wall1={y2[0]*z1[0]-z2[0]*y1[0], z2[0]*x1[0]-x2[0]*z1[0], x2[0]*y1[0]-y2[0]*x1[0]}; wall1*={x3, y3, z3}; if(wall1[2]>0) cout<<"wall watching"<<endl;

presumably, want render cube opaque solid.

this indeed done painting faces, in such way see faces closer viewer.

i assume that

  • you have polygon painting algorithm,
  • you able compute color/shading assign every face.

you can resort 2 methods:

  • the painter's algorithm, i.e. painting faces front. can achieve sorting faces on depth coordinate of closest vertex of each face. easy little inefficient paint 6 faces when 3 enough.

  • backface culling, i.e. ignoring faces have depth component of normal vector pointing rear. little of vector calculus.


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