public void raycast3D(float x0, float y0, float z0, float x1, float y1, float z1, RaycastResult result){
    float dx = x1 - x0;
    float dy = y1 - y0;
    float dz = z1 - z0;

    if(dz >= 0){

        int startZ = (int)z0;
        int endZ = (int)Math.ceil(z1);

        float xk = dx / dz;
        float yk = dy / dz;

        for(int z = startZ; z < endZ; z++){
            if(dy >= 0){

                //calculate x, y position of z plane intersections with xk and yk
                //generate startY and endY of the 2D line between two z planes

                for(int y = startY; y < endY; y++){
                    if(dx > 0){

                        //calculate x position of y plane intersections and generate startX and endX

                        for(int x = startX; x < endX; x++){
                           testVoxelCollision(x, y, z);
                        }
                    }else{
                        //Same as above, but loop over x backwards
                    }
                }
            }else{
                 //Loop over y backwards, and then branch for x
            }
        }
    }else{
        //Loop over z backwards, and then branch for y and then x
    }
}

/*
If this isn't eye cancer, I don't know what it is, and this is just around 1/8th of the code I will need to write...
*/