R/blocks2vf.R

In ptinpoly: Point-in-Polyhedron Test (2D and 3D)

blocks2vf = function(Block1,Block2,Block3) {
    # Conversion from "block" representation to Vertices-Faces representation:
    # the vertices matrix contains XYZ coordinates of all vertices,
    # while the faces matrix contains integers indicating the three vertices
    # defining each face.

    # Basic checks of Block1 input argument.
    blkDims1 = dim(Block1)
    numFaces = blkDims1[1] ;
    numCols1 = blkDims1[2] ;
    if ( numCols1 != 3 ) {
        print("blocks2vf(): Number of columns in Block1 must be 3!")
        return(0);
    }

    # Basic checks of Block2 input argument.
    blkDims2 = dim(Block2)
    numRows2 = blkDims2[1] ;
    numCols2 = blkDims2[2] ;
    if ( numCols2 != 3 ) {
        print("blocks2vf(): Number of columns in Block2 must be 3!")
        return(0);
    }
    if ( numRows2 != numFaces ) {
        print("blocks2vf(): Number of rows in Block2 must be the same as the number of rows in Block1!")
        return(0);
    }

    # Basic checks of Block3 input argument.
    blkDims3 = dim(Block3)
    numRows3 = blkDims3[1] ;
    numCols3 = blkDims3[2] ;
    if ( numCols3 != 3 ) {
        print("blocks2vf(): Number of columns in Block3 must be 3!")
        return(0);
    }
    if ( numRows3 != numRows2 ) {
        print("blocks2vf(): Number of rows in Block3 must be the same as the number of rows in Block2!")
        return(0);
    }

    # Make sure misc3d is loaded
    # 4/28/2014: commented out -- misc3d is already attached by Depends.
    # if ( ! require("misc3d") ) {
    #     print("blocks2vf(): package misc3d is required but missing!")
    #     return(0);
    # }

    # Use misc3d function to perform the conversion.
    ta    = makeTriangles(Block1,Block2,Block3)
    ve    = ptinpoly_t2ve(ta)
    verts = t(ve$vb)
    faces = t(ve$ib)
    return (list(verts,faces))
}

# The following is from an unexported function T2VE in the misc3d package.
# To avoid name collisions, the name of the function has been modified here.
ptinpoly_t2ve <- function(triangles) 
{
    vb <- rbind(triangles$v1, triangles$v2, triangles$v3)
    vbmin <- min(vb)
    vbmax <- max(vb)
    S <- 10^5
    score <- function(v, d) floor(as.vector(v %*% d))
    scale <- function(v) (1 - 1/S) * (v - vbmin)/(vbmax - vbmin)
    d <- c(S, S^2, S^3)
    scores <- score(scale(vb), d)
    vb <- vb[!duplicated(scores), ]
    scores <- score(scale(vb), d)
    ib <- rbind(match(score(scale(triangles$v1), d), scores), 
        match(score(scale(triangles$v2), d), scores), match(score(scale(triangles$v3), 
            d), scores))
    list(vb = t(vb), ib = ib)
}