MCP 3D Printer Server

by DMontgomery40
Verified
/** * SurfaceNets in JavaScript * * Written by Mikola Lysenko (C) 2012 * * MIT License * * Based on: S.F. Gibson, 'Constrained Elastic Surface Nets'. (1998) MERL Tech Report. * from https://github.com/mikolalysenko/isosurface/tree/master * */ let surfaceNet = ( dims, potential, bounds ) => { //Precompute edge table, like Paul Bourke does. // This saves a bit of time when computing the centroid of each boundary cell var cube_edges = new Int32Array(24) , edge_table = new Int32Array(256); (function() { //Initialize the cube_edges table // This is just the vertex number of each cube var k = 0; for(var i=0; i<8; ++i) { for(var j=1; j<=4; j<<=1) { var p = i^j; if(i <= p) { cube_edges[k++] = i; cube_edges[k++] = p; } } } //Initialize the intersection table. // This is a 2^(cube configuration) -> 2^(edge configuration) map // There is one entry for each possible cube configuration, and the output is a 12-bit vector enumerating all edges crossing the 0-level. for(var i=0; i<256; ++i) { var em = 0; for(var j=0; j<24; j+=2) { var a = !!(i & (1<<cube_edges[j])) , b = !!(i & (1<<cube_edges[j+1])); em |= a !== b ? (1 << (j >> 1)) : 0; } edge_table[i] = em; } })(); //Internal buffer, this may get resized at run time var buffer = new Array(4096); (function() { for(var i=0; i<buffer.length; ++i) { buffer[i] = 0; } })(); if(!bounds) { bounds = [[0,0,0],dims]; } var scale = [0,0,0]; var shift = [0,0,0]; for(var i=0; i<3; ++i) { scale[i] = (bounds[1][i] - bounds[0][i]) / dims[i]; shift[i] = bounds[0][i]; } var vertices = [] , faces = [] , n = 0 , x = [0, 0, 0] , R = [1, (dims[0]+1), (dims[0]+1)*(dims[1]+1)] , grid = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0] , buf_no = 1; //Resize buffer if necessary if(R[2] * 2 > buffer.length) { var ol = buffer.length; buffer.length = R[2] * 2; while(ol < buffer.length) { buffer[ol++] = 0; } } //March over the voxel grid for(x[2]=0; x[2]<dims[2]-1; ++x[2], n+=dims[0], buf_no ^= 1, R[2]=-R[2]) { //m is the pointer into the buffer we are going to use. //This is slightly obtuse because javascript does not have good support for packed data structures, so we must use typed arrays :( //The contents of the buffer will be the indices of the vertices on the previous x/y slice of the volume var m = 1 + (dims[0]+1) * (1 + buf_no * (dims[1]+1)); for(x[1]=0; x[1]<dims[1]-1; ++x[1], ++n, m+=2) for(x[0]=0; x[0]<dims[0]-1; ++x[0], ++n, ++m) { //Read in 8 field values around this vertex and store them in an array //Also calculate 8-bit mask, like in marching cubes, so we can speed up sign checks later var mask = 0, g = 0; for(var k=0; k<2; ++k) for(var j=0; j<2; ++j) for(var i=0; i<2; ++i, ++g) { var p = potential( scale[0]*(x[0]+i)+shift[0], scale[1]*(x[1]+j)+shift[1], scale[2]*(x[2]+k)+shift[2]); grid[g] = p; mask |= (p < 0) ? (1<<g) : 0; } //Check for early termination if cell does not intersect boundary if(mask === 0 || mask === 0xff) { continue; } //Sum up edge intersections var edge_mask = edge_table[mask] , v = [0.0,0.0,0.0] , e_count = 0; //For every edge of the cube... for(var i=0; i<12; ++i) { //Use edge mask to check if it is crossed if(!(edge_mask & (1<<i))) { continue; } //If it did, increment number of edge crossings ++e_count; //Now find the point of intersection var e0 = cube_edges[ i<<1 ] //Unpack vertices , e1 = cube_edges[(i<<1)+1] , g0 = grid[e0] //Unpack grid values , g1 = grid[e1] , t = g0 - g1; //Compute point of intersection if(Math.abs(t) > 1e-6) { t = g0 / t; } else { continue; } //Interpolate vertices and add up intersections (this can be done without multiplying) for(var j=0, k=1; j<3; ++j, k<<=1) { var a = e0 & k , b = e1 & k; if(a !== b) { v[j] += a ? 1.0 - t : t; } else { v[j] += a ? 1.0 : 0; } } } //Now we just average the edge intersections and add them to coordinate var s = 1.0 / e_count; for(var i=0; i<3; ++i) { v[i] = scale[i] * (x[i] + s * v[i]) + shift[i]; } //Add vertex to buffer, store pointer to vertex index in buffer buffer[m] = vertices.length; vertices.push(v); //Now we need to add faces together, to do this we just loop over 3 basis components for(var i=0; i<3; ++i) { //The first three entries of the edge_mask count the crossings along the edge if(!(edge_mask & (1<<i)) ) { continue; } // i = axes we are point along. iu, iv = orthogonal axes var iu = (i+1)%3 , iv = (i+2)%3; //If we are on a boundary, skip it if(x[iu] === 0 || x[iv] === 0) { continue; } //Otherwise, look up adjacent edges in buffer var du = R[iu] , dv = R[iv]; //Remember to flip orientation depending on the sign of the corner. if(mask & 1) { faces.push([buffer[m], buffer[m-du], buffer[m-dv]]); faces.push([buffer[m-dv], buffer[m-du], buffer[m-du-dv]]); } else { faces.push([buffer[m], buffer[m-dv], buffer[m-du]]); faces.push([buffer[m-du], buffer[m-dv], buffer[m-du-dv]]); } } } } //All done! Return the result return { positions: vertices, cells: faces }; } export { surfaceNet }