From ea03bb1d323aef010eea00c1709d3dab56c0bf0b Mon Sep 17 00:00:00 2001 From: David Kastrup Date: Thu, 13 Aug 2015 15:30:43 +0200 Subject: [PATCH] Issue 4610: ly:round-filled-polygon: optional parameter `extroversion' `extroversion' specifies where on the specified polygon to draw with the pen of the given thickness. Its default of -1 corresponds to the previous behavior of drawing strictly inside of the given polygon. An extroversion value of 0 draws exactly along the given polygon, and a value of 1 will draw just outside of the given polygon. --- lily/include/lookup.hh | 2 +- lily/lookup.cc | 160 +++++++++++++++++++++++------------------ lily/stencil-scheme.cc | 18 +++-- 3 files changed, 105 insertions(+), 75 deletions(-) diff --git a/lily/include/lookup.hh b/lily/include/lookup.hh index 5b76145316..5fe7404825 100644 --- a/lily/include/lookup.hh +++ b/lily/include/lookup.hh @@ -29,7 +29,7 @@ namespace Lookup Stencil bracket (Axis a, Interval iv, Real thick, Real protrude, Real blot); Stencil circle (Real rad, Real thick, bool filled); Stencil rotated_box (Real slope, Real width, Real thick, Real blot); - Stencil round_filled_polygon (vector const &points, Real blotdiameter); + Stencil round_filled_polygon (vector const &points, Real blotdiameter, Real extroversion = -1.0); Stencil frame (Box b, Real thick, Real blot); Stencil slur (Bezier controls, Real cthick, Real thick, SCM dash_definition); diff --git a/lily/lookup.cc b/lily/lookup.cc index 4f9d0bbbde..bad54405eb 100644 --- a/lily/lookup.cc +++ b/lily/lookup.cc @@ -230,10 +230,18 @@ Lookup::round_filled_box (Box b, Real blotdiameter) * blotdiameter along all edges of the polygon (which is what the * postscript routine in the backend effectively does, but on the * shrinked polygon). --jr + * + * An extra parameter "extroversion" has been added since staying just + * inside of a polygon will reduce its visual size when tracing a + * rounded path. If extroversion is zero, the polygon is just traced + * as-is. If it is -1 (the default) the drawing will stay just within + * the given polygon. If it is 1, the traced line will stay just + * outside of the given polygon. */ Stencil Lookup::round_filled_polygon (vector const &points, - Real blotdiameter) + Real blotdiameter, + Real extroversion) { /* TODO: Maybe print a warning if one of the above limitations applies to the given polygon. However, this is quite complicated @@ -257,101 +265,114 @@ Lookup::round_filled_polygon (vector const &points, return Stencil (); if (points.size () == 1) { - Stencil circ = circle (0.5 * blotdiameter, 0, true); + Stencil circ = circle (0.5 * (1.0 + extroversion) * blotdiameter, 0, true); circ.translate (points[0]); return circ; } if (points.size () == 2) - return Line_interface::make_line (blotdiameter, points[0], points[1]); - - /* shrink polygon in size by 0.5 * blotdiameter */ - - // first we need to determine the orientation of the polygon in - // order to decide whether shrinking means moving the polygon to the - // left or to the right of the outline. We do that by calculating - // (double) the oriented area of the polygon. We first determine the - // center and do the area calculations relative to it. - // Mathematically, the result is not affected by this shift, but - // numerically a lot of cancellation is going on and this keeps its - // effects in check. - - Offset center; - for (vsize i = 0; i < points.size (); i++) - center += points[i]; - center /= points.size (); + return Line_interface::make_line ((1.0 + extroversion) * blotdiameter, points[0], points[1]); - Real area = 0.0; - Offset last = points.back () - center; + vector shrunk_points; - for (vsize i = 0; i < points.size (); i++) + if (extroversion == 0.0) { - Offset here = points[i] - center; - area += cross_product (last, here); - last = here; + shrunk_points = points; } - - bool ccw = area >= 0.0; // true if whole shape is counterclockwise oriented - - vector shrunk_points; - shrunk_points.resize (points.size ()); - - for (vsize i = 0; i < points.size (); i++) + else { - int i0 = i; - int i1 = (i + 1) % points.size (); - int i2 = (i + 2) % points.size (); - Offset p0 = points[i0]; - Offset p1 = points[i1]; - Offset p2 = points[i2]; - Offset p01 = p1 - p0; - Offset p12 = p2 - p1; - Offset inward0 = Offset(-p01[Y_AXIS], p01[X_AXIS]).direction (); - Offset inward2 = Offset(-p12[Y_AXIS], p12[X_AXIS]).direction (); - - if (!ccw) + /* shrink polygon in size by 0.5 * blotdiameter */ + + // first we need to determine the orientation of the polygon in + // order to decide whether shrinking means moving the polygon to the + // left or to the right of the outline. We do that by calculating + // (double) the oriented area of the polygon. We first determine the + // center and do the area calculations relative to it. + // Mathematically, the result is not affected by this shift, but + // numerically a lot of cancellation is going on and this keeps its + // effects in check. + + Offset center; + for (vsize i = 0; i < points.size (); i++) + center += points[i]; + center /= points.size (); + + Real area = 0.0; + Offset last = points.back () - center; + + for (vsize i = 0; i < points.size (); i++) { - inward0 = -inward0; - inward2 = -inward2; + Offset here = points[i] - center; + area += cross_product (last, here); + last = here; } - Offset middle = 0.5*(inward0 + inward2); - - // "middle" now is a vector in the right direction for the - // shrinkage. Its size needs to be large enough that the - // projection on either of the inward vectors has a size of 1. - - Real proj = dot_product (middle, inward0); + bool ccw = area >= 0.0; // true if whole shape is counterclockwise oriented - // What's the size of proj? Assuming that we have a corner - // angle of phi where 0 corresponds to a continuing line, the - // length of middle is 0.5 |(1+cos phi, sin phi)| = cos (phi/2), - // so its projection has length - // cos^2 (phi/2) = 0.5 + 0.5 cos (phi). - // We don't really want to move inwards more than 3 blob - // diameters corresponding to 6 blob radii. So - // cos (phi/2) = 1/6 gives phi ~ 161, meaning that a 20 degree - // corner necessitates moving 3 blob diameters from the corner - // in order to stay inside the lines. Ruler and circle agree. - // 0.03 is close enough to 1/36. Basically we want to keep the - // shape from inverting from pulling too far inward. - // 3 diameters is pretty much a handwaving guess. + shrunk_points.resize (points.size ()); - if (abs (proj) < 0.03) - proj = proj < 0 ? -0.03 : 0.03; + for (vsize i = 0; i < points.size (); i++) + { + int i0 = i; + int i1 = (i + 1) % points.size (); + int i2 = (i + 2) % points.size (); + Offset p0 = points[i0]; + Offset p1 = points[i1]; + Offset p2 = points[i2]; + Offset p01 = p1 - p0; + Offset p12 = p2 - p1; + Offset inward0 = Offset(-p01[Y_AXIS], p01[X_AXIS]).direction (); + Offset inward2 = Offset(-p12[Y_AXIS], p12[X_AXIS]).direction (); + + if (!ccw) + { + inward0 = -inward0; + inward2 = -inward2; + } - shrunk_points[i1] = p1 + (0.5 * blotdiameter / proj) * middle; + Offset middle = 0.5*(inward0 + inward2); + + // "middle" now is a vector in the right direction for the + // shrinkage. Its size needs to be large enough that the + // projection on either of the inward vectors has a size of 1. + + Real proj = dot_product (middle, inward0); + + // What's the size of proj? Assuming that we have a corner + // angle of phi where 0 corresponds to a continuing line, the + // length of middle is 0.5 |(1+cos phi, sin phi)| = cos (phi/2), + // so its projection has length + // cos^2 (phi/2) = 0.5 + 0.5 cos (phi). + // We don't really want to move inwards more than 3 blob + // diameters corresponding to 6 blob radii. So + // cos (phi/2) = 1/6 gives phi ~ 161, meaning that a 20 degree + // corner necessitates moving 3 blob diameters from the corner + // in order to stay inside the lines. Ruler and circle agree. + // 0.03 is close enough to 1/36. Basically we want to keep the + // shape from inverting from pulling too far inward. + // 3 diameters is pretty much a handwaving guess. + + if (abs (proj) < 0.03) + proj = proj < 0 ? -0.03 : 0.03; + + shrunk_points[i1] = p1 - (0.5 * blotdiameter / proj) * middle + * extroversion; + } } /* build scm expression and bounding box */ SCM shrunk_points_scm = SCM_EOL; Box box; + Box shrunk_box; for (vsize i = 0; i < shrunk_points.size (); i++) { SCM x = scm_from_double (shrunk_points[i][X_AXIS]); SCM y = scm_from_double (shrunk_points[i][Y_AXIS]); shrunk_points_scm = scm_cons (x, scm_cons (y, shrunk_points_scm)); box.add_point (points[i]); + shrunk_box.add_point (shrunk_points[i]); } + shrunk_box.widen (0.5*blotdiameter, 0.5*blotdiameter); + box.unite (shrunk_box); SCM polygon_scm = scm_list_n (ly_symbol2scm ("polygon"), ly_quote_scm (shrunk_points_scm), scm_from_double (blotdiameter), @@ -359,7 +380,6 @@ Lookup::round_filled_polygon (vector const &points, SCM_UNDEFINED); Stencil polygon = Stencil (box, polygon_scm); - shrunk_points.clear (); return polygon; } diff --git a/lily/stencil-scheme.cc b/lily/stencil-scheme.cc index e79dda1873..c8d87439d6 100644 --- a/lily/stencil-scheme.cc +++ b/lily/stencil-scheme.cc @@ -413,14 +413,23 @@ LY_DEFINE (ly_round_filled_box, "ly:round-filled-box", } LY_DEFINE (ly_round_filled_polygon, "ly:round-filled-polygon", - 2, 0, 0, - (SCM points, SCM blot), + 2, 1, 0, + (SCM points, SCM blot, SCM extroversion), "Make a @code{Stencil} object that prints a black polygon with" " corners at the points defined by @var{points} (list of coordinate" - " pairs) and roundness @var{blot}.") + " pairs) and roundness @var{blot}. Optional" + "@var{extroversion} shifts the outline outward, with the" + "default of@tie{}@code{-1.0} keeping the outer boundary of" + "the outline just inside of the polygon.") { SCM_ASSERT_TYPE (scm_ilength (points) > 0, points, SCM_ARG1, __FUNCTION__, "list of coordinate pairs"); LY_ASSERT_TYPE (scm_is_number, blot, 2); + Real ext = -1; + if (!SCM_UNBNDP (extroversion)) + { + LY_ASSERT_TYPE (scm_is_number, extroversion, 3); + ext = scm_to_double (extroversion); + } vector pts; for (SCM p = points; scm_is_pair (p); p = scm_cdr (p)) { @@ -434,7 +443,8 @@ LY_DEFINE (ly_round_filled_polygon, "ly:round-filled-polygon", // TODO: Print out warning } } - return Lookup::round_filled_polygon (pts, scm_to_double (blot)).smobbed_copy (); + return Lookup::round_filled_polygon (pts, scm_to_double (blot), ext) + .smobbed_copy (); } LY_DEFINE (ly_register_stencil_expression, "ly:register-stencil-expression", -- 2.39.2