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Posted 09 October 2012 - 11:12 PM
Posted 09 October 2012 - 11:56 PM
I could write the algorithm to do this myself if I took the time to work it out, but I wanted to see if someone else has done it first.
I'm working on a voxel engine for a game that I'm working on, and I need to trace a ray from the camera's position out a certain distance to try to find the nearest intersection. I was thinking of just taking the cell that the camera is in, then taking the direction, figuring out at what point the ray leaves the cell, then figure out what the next cell is that it will enter. I would keep doing this until I find an intersection.
Does anyone have experience with this? Maybe you have an algorithm that can do just that?
CurrentCell = GetCell(Ray.Start); //we start in the current cell EndCell = GetCell(Ray.End); //we mark the last cell so we know where to stop. while(CurrentCell!=EndCell){ //we only need to check at most 3 faces depending on the direction of the ray(since we obviously can't hit faces we're not heading towards) Vector3 Result; //Store ray point. int Faces[3]; Faces[0] = Ray.Direction.x<0.0f?LEFT:(Ray.Direction.x>0.0f?Right:-1); //if direction.x == 0 then no need to test the face; Faces[1] = Ray.Direction.y<0.0f?BOTTOM:(Ray.Direction.y>0.0f?TOP:-1); //" " Faces[2] = Ray.Direction.z<0.0f?BACK:(Ray.Drection.z>0.0f?FRONT:-1); //" " for(int i=0;i<3;i++){ if(Faces[i]==-1) continue; if(CheckPlanexRay(CurrentCell.VoxelPlane[Faces[i]], Ray, &Result)){ //we need the point that intersects this cell. if(CurrentCell.CheckPointInVoxel(Result)){ CurrentCell = CurrentCell.GetNeighbor(Faces[i]); if(CurrentCell.isClosed()) return Result, CurrentCell;. break; } } } return null; }
Edited by slicer4ever, 09 October 2012 - 11:59 PM.
Posted 10 October 2012 - 01:59 AM
Posted 10 October 2012 - 05:39 AM
For simplicity, since my voxels are 1x1x1 in size, I decided I could just move the ray by 1 unit, then get the cell that the ray is in, then check collision within that cell. Then I just keep incrementing it until I either reach my max length, or I find collision. Now I just need to remember how to collide a 3D ray with a 3D quad.
Posted 11 October 2012 - 12:56 AM
Posted 11 October 2012 - 01:09 AM
Edited by luca-deltodesco, 11 October 2012 - 01:10 AM.
Posted 11 October 2012 - 01:26 AM
You should really just look up the DDA algorithm as previously suggested, it is 'far' simpler implementation than what you have described.
int sign = Math.Sign(direction) float distance; if(sign == 1) { distance = 1 - value; } else if(sign == -1) { distance = -value; } else { distance = infinity; }
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