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I have a voxel game where I want to know which block the players camera is facing. To do this I have a line the distance allowed for the player to interact with the world cast from the center of the camera with its two rotations. How do I divide the line Point : (ROX, ROY, ROZ) to Point : (CPX, CPY, CPZ) by a certain amount of divisions held by a variable named LineDivisions.

Since I don't know how to divide the line i've attempted to cast a ray that changes length in front of the camera. To do this I used the following two formulas.

Rotate in X axis

X' = X

Y' = Ycos(theta) - Zsin (theta)

Z' = Ysin(theta) + Zcos(theta)

Rotate in Y axis

X' = Zsin(theta) + Xcos(theta)

Y' = Y

Z' = Zcos(theta) - Xsin(theta)

I put them in this for loop in this function below.

void DBPB()
{
   DB = 0;
   DBIZ = 0;
   //if(XR < 0){XR = 360;}
   //if(XR > 360){XR = 0;}
   //if(YR < 0){YR = 360;}
   //if(YR > 360){YR = 0;}
   //if(ZR < 0){ ZR = 360;}
   //if(ZR > 360){ZR = 0;}

   //Convert current rotation values into Radian
   XRa = (RayXr / 180 * PI);
   YRa = (RayYr / 180 * PI);
   //ZRa = (ZR / 180 * PI);
   //The origin is set to zero and the line that is in the correct axis for the camera is added. 
   TDX = 0;
   TDY = 0;
   TDZ = RayLength;
   //Raycast
   for(RayLength = 0; RayLength > -7; RayLength -= .1)
   {
      //Rotate in X axis
      ROX = TDX;
      ROY = (TDY*cos(XRa)) - (TDZ*sin(XRa));
      ROZ = (TDY*sin(XRa)) + (TDZ*cos(XRa));

      //Rotate in Y axis
      RTX = (ROZ*sin(YRa)) + (ROX*cos(YRa));
      RTY = ROY;
      RTZ = (ROZ*cos(YRa)) -  (ROX*sin(YRa));

      //Rotate in Z axis(Not used)
      //X = X*cos(theta) - y*sin(theta)
      //Y = X*Sin(theta) + y*cos(theta)
      //Z = Z
      //std::cout << "Rotated X :" << RTX << " Y:" << RTY << " Z :" << RTZ << std::endl;
      CPX = static_cast<int>(RTX+PX);
      CPY = static_cast<int>(RTY+PY);
      CPZ = static_cast<int>(RTZ+PZ);
      //When not inside a block in creative
      //This will hold the position of the block
      //before the selected block.
      if(DB == 0 && DBIZ == 0)
      {
         PBX = CPX;
         PBY = CPY;
         PBZ = CPZ;
      }
  
      if(Blocks[CPX][CPY][CPZ] != 0 && Blocks[CPX][CPY][CPZ] != NULL && DB == 0)
      {
         //Toggle bool DB
         std::cout << "Collided X :" << CPX << " Y:" << CPY << " Z :" << CPZ << std::endl;
         //Detected Collision at BBX, BBY, BBZ
         BBX = CPX;
         BBY = CPY;
         BBZ = CPZ;
         RayLength = -7;
         DB = 1;
         DBIZ = 1;
      }
   }
}

The vertex its at jumps in circles but sometimes looks right, Does anyone have resources I can read about doing this?

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    \$\begingroup\$ Are you looking for help determining the first solid voxel your view ray intersects? \$\endgroup\$ Commented Jul 9 at 5:28
  • \$\begingroup\$ Yes im trying to figure out how to divide the line or rotate a ray to check the vertexs for intersection. \$\endgroup\$ Commented Jul 10 at 23:15
  • \$\begingroup\$ We usually would not check for intersection that way. It's not necessary to divide the line into small steps - we can march it through the voxel grid directly using the technique described at the link above. That guarantees we don't accidentally skip past the corner of a voxel by choosing the wrong division. We automatically check only the places where the ray intersects a new voxel. \$\endgroup\$ Commented Jul 11 at 0:46
  • \$\begingroup\$ Im looking for a C++ example I don't quite understand how the algorithm works. \$\endgroup\$ Commented Jul 11 at 1:58
  • \$\begingroup\$ If you only want answers in C++, then you should probably add the c++ tag to your question. Right now, it says nothing about that requirement. You can also try asking a clarifying question: what's one part of the algorithm you don't understand? We're happy to help, we just need to know what parts you need help with. \$\endgroup\$ Commented Jul 11 at 10:49

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