diff options
Diffstat (limited to 'src/dyna-draw-context.cpp')
| -rw-r--r-- | src/dyna-draw-context.cpp | 36 |
1 files changed, 32 insertions, 4 deletions
diff --git a/src/dyna-draw-context.cpp b/src/dyna-draw-context.cpp index 7fd7bfe72..303573c46 100644 --- a/src/dyna-draw-context.cpp +++ b/src/dyna-draw-context.cpp @@ -226,6 +226,7 @@ sp_dyna_draw_context_setup(SPEventContext *ec) sp_event_context_read(ec, "angle"); sp_event_context_read(ec, "width"); sp_event_context_read(ec, "thinning"); + sp_event_context_read(ec, "tremor"); sp_event_context_read(ec, "flatness"); sp_event_context_read(ec, "usepressure"); sp_event_context_read(ec, "usetilt"); @@ -255,6 +256,9 @@ sp_dyna_draw_context_set(SPEventContext *ec, gchar const *key, gchar const *val) } else if (!strcmp(key, "thinning")) { double const dval = ( val ? g_ascii_strtod (val, NULL) : 0.1 ); ddc->vel_thin = CLAMP(dval, -1.0, 1.0); + } else if (!strcmp(key, "tremor")) { + double const dval = ( val ? g_ascii_strtod (val, NULL) : 0.0 ); + ddc->tremor = CLAMP(dval, 0.0, 1.0); } else if (!strcmp(key, "flatness")) { double const dval = ( val ? g_ascii_strtod (val, NULL) : 1.0 ); ddc->flatness = CLAMP(dval, 0, 1.0); @@ -422,16 +426,40 @@ sp_dyna_draw_brush(SPDynaDrawContext *dc) double pressure_thick = (dc->usepressure ? dc->pressure : 1.0); double width = ( pressure_thick - vel_thin * NR::L2(dc->vel) ) * dc->width; + + double tremble_left = 0, tremble_right = 0; + if (dc->tremor > 0) { + // obtain two normally distributed random variables, using polar Box-Muller transform + double x1, x2, w, y1, y2; + do { + x1 = 2.0 * g_random_double_range(0,1) - 1.0; + x2 = 2.0 * g_random_double_range(0,1) - 1.0; + w = x1 * x1 + x2 * x2; + } while ( w >= 1.0 ); + w = sqrt( (-2.0 * log( w ) ) / w ); + y1 = x1 * w; + y2 = x2 * w; + + // deflect both left and right edges randomly and independently, so that: + // (1) dc->tremor=1 corresponds to sigma=1, decreasing dc->tremor narrows the bell curve; + // (2) deflection depends on width, but is upped for small widths for better visual uniformity across widths; + // (3) deflection somewhat depends on speed, to prevent fast strokes looking + // comparatively smooth and slow ones excessively jittery + tremble_left = (y1)*dc->tremor * (0.15 + 0.8*width) * (0.35 + 14*NR::L2(dc->vel)); + tremble_right = (y2)*dc->tremor * (0.15 + 0.8*width) * (0.35 + 14*NR::L2(dc->vel)); + } + if ( width < 0.02 * dc->width ) { width = 0.02 * dc->width; } - NR::Point del = 0.05 * width * dc->ang; + NR::Point del_left = 0.05 * (width + tremble_left) * dc->ang; + NR::Point del_right = 0.05 * (width + tremble_right) * dc->ang; - dc->point1[dc->npoints] = sp_dyna_draw_get_vpoint(dc, dc->cur + del); - dc->point2[dc->npoints] = sp_dyna_draw_get_vpoint(dc, dc->cur - del); + dc->point1[dc->npoints] = sp_dyna_draw_get_vpoint(dc, dc->cur + del_left); + dc->point2[dc->npoints] = sp_dyna_draw_get_vpoint(dc, dc->cur - del_right); - dc->del = del; + dc->del = 0.5*(del_left + del_right); } else { dc->point1[dc->npoints] = sp_dyna_draw_get_curr_vpoint(dc); } |