From: Scott Worley Date: Fri, 21 Dec 2012 06:29:48 +0000 (-0800) Subject: Make extrude's arguments more flexible and powerful X-Git-Url: http://git.scottworley.com/nt3d/commitdiff_plain/08c25ec8473e43e82a1291a528f8332239581483?ds=sidebyside Make extrude's arguments more flexible and powerful --- diff --git a/box_by_extrude.html b/box_by_extrude.html index be95de6..fb1ca2c 100644 --- a/box_by_extrude.html +++ b/box_by_extrude.html @@ -10,8 +10,8 @@ var xy = [size, size, 0]; return nt3d.extrude([[0, 0, 0], [0, 0, 1]], [origin, x, xy, y], - [[0, 0, 1], [0, 0, 1]], - [[1, 0, 0], [1, 0, 0]]); + [0, 0, 1], + [1, 0, 0]); } var params = [["Size", 1]]; diff --git a/nt3d.js b/nt3d.js index a4d3977..9b09b09 100644 --- a/nt3d.js +++ b/nt3d.js @@ -62,6 +62,19 @@ nt3d = { return this.closed_trianglefan([apex].concat(base)).concat( this.trianglefan(base.reverse())); }, + to_function: function(thing, make_indexer) { + // If thing is a point, just yield thing every time. + // If thing is a list of points && make_indexer, index into thing. + // If thing is already a function, just return it. + if (({}).toString.call(thing) === "[object Function]") { + return thing; // Already a function + } + if (make_indexer && Array.isArray(thing[0])) { + // Looks like a list of points. + return function(i) { return thing[i]; } + } + return function() { return thing; } + }, extrude: function(path, shape, shapenormals, pathnormals) { var guts_result = nt3d._extrude_guts(path, shape, shapenormals, pathnormals); @@ -78,40 +91,47 @@ nt3d = { return guts_result.points.concat( nt3d.closed_quadstrip(nt3d.zip(guts_result.first_loop, guts_result.last_loop))); }, - _fix_pathnormals: function(shapenormals, pathnormals) { - // Fix pathnormals[i] to be perfectly perpendicular to - // shapenormals[i]. This lets extrude callers be sloppy - // with pathnormals, which can greatly simplify things. - var fixedpathnormals = []; - for (var i = 0; i < pathnormals.length; i++) { - var proj = this.project(shapenormals[i], pathnormals[i]); - fixedpathnormals[i] = this.sub(pathnormals[i], proj); - } - return fixedpathnormals; - }, _extrude_guts: function(path, shape, shapenormals, pathnormals) { - var fixedpathnormals = this._fix_pathnormals(shapenormals, pathnormals); + var shape_fun = this.to_function(shape, false); + var shapenormal_fun = this.to_function(shapenormals, true); + var pathnormal_fun = this.to_function(pathnormals, true); var result = { points: [] }; var prev_loop; for (var i = 0; i < path.length; i++) { - // loop is shape in 3d with (0,0) at path[i], shape's - // z axis in the direction of shapenormals[i], and - // shape's x axis in the direction of pathnormals[i]. - // We tack [1,0,0] onto the end as a hack to see where - // it ends up after rotation. This is removed later. - var loop = shape.concat([[1,0,0]]); + var shapenormali = shapenormal_fun(i, path[i]); + var pathnormali = pathnormal_fun(i, path[i], shapenormali); + + // Fix pathnormali to be perfectly perpendicular to + // shapenormali. pathnormali must be perpendicular to + // shapenormali or the second rotation will take loop + // back out of the shapenormali plane that the first + // rotation so carefully placed it in. But, letting + // callers be sloppy with the pathnormals can greatly + // simplify generating them -- so much so that you can + // often just pass a constant to use the same value + // along the whole path. + pathnormali = this.project_to_orthogonal(shapenormali, pathnormali); + + var shapei = shape_fun(i, path[i], shapenormali, pathnormali); + + // loop is shapei in 3d with (0,0) at path[i], shape's + // z axis in the direction of shapenormali, and shape's + // x axis in the direction of pathnormali. We tack + // [1,0,0] onto the end as a hack to see where it ends + // up after the first rotation. This is removed later. + var loop = shapei.concat([[1,0,0]]); // This is done in three steps: // 1. Rotate shape out of the xy plane so that [0,0,1] - // becomes shapenormals[i]. This puts the shape in + // becomes shapenormali. This puts the shape in // the correct plane, but does not constrain its - // rotation about shapenormals[i]. - loop = this.rotate_onto(loop, [0,0,1], shapenormals[i]); + // rotation about shapenormali. + loop = this.rotate_onto(loop, [0,0,1], shapenormali); var shapex = loop.pop(); - // 2. Rotate around shapenormals[i] so that [1,0,0] - // becomes fixedpathnormals[i]. - loop = this.rotate_onto(loop, shapex, fixedpathnormals[i]); + // 2. Rotate around shapenormali so that [1,0,0] + // becomes pathnormali. + loop = this.rotate_onto(loop, shapex, pathnormali); // (This would probably be faster and more numerically stable // if the two rotations were applied as one combined operation @@ -172,6 +192,10 @@ nt3d = { var a_magnitude = this.magnitude(a); return this.scale(a, this.dot(a, b) / a_magnitude * a_magnitude); }, + project_to_orthogonal: function(a, b) { + // The nearest thing to b that is orthogonal to a + return this.sub(b, this.project(a, b)); + }, translate: function(points, offset) { var translated = []; for (var i = 0; i < points.length; i++) { diff --git a/torus_by_extrude.html b/torus_by_extrude.html index 69bbdab..c95f821 100644 --- a/torus_by_extrude.html +++ b/torus_by_extrude.html @@ -5,14 +5,11 @@