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obj.js
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154 lines (141 loc) · 3.9 KB
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// Copyright 2020, Cem Yuksel, University of Utah
class ObjMesh
{
constructor()
{
this.vpos = []; // vertex positions
this.face = []; // face vertex indices
this.tpos = []; // texture coordinates
this.tfac = []; // face texture coordinate indices
this.norm = []; // surface normals
this.nfac = []; // face surface normal indices
}
// Reads the obj file at the given URL and parses it.
load( url )
{
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
parse( this.responseText );
}
};
xhttp.open("GET", url, true);
xhttp.send();
}
// Parses the contents of an obj file.
parse( objdata )
{
var lines = objdata.split('\n');
for ( var i=0; i<lines.length; ++i ) {
var line = lines[i].trim();
var elem = line.split(/\s+/);
switch ( elem[0][0] ) {
case 'v':
switch ( elem[0].length ) {
case 1:
this.vpos.push( [ parseFloat(elem[1]), parseFloat(elem[2]), parseFloat(elem[3]) ] );
break;
case 2:
switch ( elem[0][1] ) {
case 't':
this.tpos.push( [ parseFloat(elem[1]), parseFloat(elem[2]) ] );
break;
case 'n':
this.norm.push( [ parseFloat(elem[1]), parseFloat(elem[2]), parseFloat(elem[3]) ] );
break;
}
break;
}
break;
case 'f':
var f=[], tf=[], nf=[];
for ( var j=1; j<elem.length; ++j ) {
var ids = elem[j].split('/');
var vid = parseInt(ids[0]);
if ( vid < 0 ) vid = this.vpos.length + vid + 1;
f.push( vid - 1 );
if ( ids.length > 1 && ids[1] !== "" ) {
var tid = parseInt(ids[1]);
if ( tid < 0 ) tid = this.tpos.length + tid + 1;
tf.push( tid - 1 );
}
if ( ids.length > 2 && ids[2] !== "" ) {
var nid = parseInt(ids[2]);
if ( nid < 0 ) nid = this.norm.length + nid + 1;
nf.push( nid - 1 );
}
}
this.face.push(f);
if ( tf.length ) this.tfac.push(tf);
if ( nf.length ) this.nfac.push(nf);
break;
}
}
}
// Returns the bounding box of the object
getBoundingBox()
{
if ( this.vpos.length == 0 ) return null;
var min = [...this.vpos[0]];
var max = [...this.vpos[0]];
for ( var i=1; i<this.vpos.length; ++i ) {
for ( var j=0; j<3; ++j ) {
if ( min[j] > this.vpos[i][j] ) min[j] = this.vpos[i][j];
if ( max[j] < this.vpos[i][j] ) max[j] = this.vpos[i][j];
}
}
return { min: min, max: max };
}
shiftAndScale( shift, scale )
{
for ( var i=0; i<this.vpos.length; ++i ) {
for ( var j=0; j<3; ++j ) {
this.vpos[i][j] = (this.vpos[i][j] + shift[j]) * scale;
}
}
}
addTriangleToBuffers( vBuffer, tBuffer, nBuffer, fi, i, j, k )
{
var f = this.face[fi];
var tf = this.tfac[fi];
var nf = this.nfac[fi];
this.addTriangleToBuffer( vBuffer, this.vpos, f, i, j, k, this.addVertToBuffer3 );
if ( tf ) {
this.addTriangleToBuffer( tBuffer, this.tpos, tf, i, j, k, this.addVertToBuffer2 );
}
if ( nf ) {
this.addTriangleToBuffer( nBuffer, this.norm, nf, i, j, k, this.addVertToBuffer3 );
}
}
addTriangleToBuffer( buffer, v, f, i, j, k, addVert )
{
addVert( buffer, v, f, i );
addVert( buffer, v, f, j );
addVert( buffer, v, f, k );
}
addVertToBuffer3( buffer, v, f, i )
{
buffer.push( v[f[i]][0] );
buffer.push( v[f[i]][1] );
buffer.push( v[f[i]][2] );
}
addVertToBuffer2( buffer, v, f, i )
{
buffer.push( v[f[i]][0] );
buffer.push( v[f[i]][1] );
}
getVertexBuffers()
{
var vBuffer = [];
var tBuffer = [];
var nBuffer = [];
for ( var i=0; i<this.face.length; ++i ) {
if ( this.face[i].length < 3 ) continue;
this.addTriangleToBuffers( vBuffer, tBuffer, nBuffer, i, 0, 1, 2 );
for ( var j=3; j<this.face[i].length; ++j ) {
this.addTriangleToBuffers( vBuffer, tBuffer, nBuffer, i, 0, j-1, j );
}
}
return { positionBuffer: vBuffer, texCoordBuffer: tBuffer, normalBuffer: nBuffer };
}
}