demos/painter_path_test: add sweep-gradient

demos/painter_path_test/main.cpp

@@ -205,6 +205,7 @@ class PerPath
 
   vec2 m_gradient_p0, m_gradient_p1;
   float m_gradient_r0, m_gradient_r1;
+  float m_sweep_repeat_factor;
   bool m_repeat_gradient;
 
   bool m_repeat_window;
@@ -237,6 +238,7 @@ class painter_stroke_test:public sdl_painter_demo
       draw_no_gradient,
       draw_linear_gradient,
       draw_radial_gradient,
+      draw_sweep_gradient,
 
       number_gradient_draw_modes
     };
@@ -370,6 +372,12 @@ class painter_stroke_test:public sdl_painter_demo
     return m_paths[m_selected_path].m_gradient_r1;
   }
 
+  float&
+  sweep_repeat_factor(void)
+  {
+    return m_paths[m_selected_path].m_sweep_repeat_factor;
+  }
+
   bool&
   repeat_gradient(void)
   {
@@ -434,6 +442,7 @@ class painter_stroke_test:public sdl_painter_demo
   command_line_argument_value<float> m_change_stroke_width_rate;
   command_line_argument_value<float> m_window_change_rate;
   command_line_argument_value<float> m_radial_gradient_change_rate;
+  command_line_argument_value<float> m_sweep_factor_gradient_change_rate;
   command_line_list<std::string> m_path_file_list;
   DashPatternList m_dash_pattern_files;
   command_line_argument_value<bool> m_print_path;
@@ -585,6 +594,8 @@ PerPath(const Path &path, const std::string &label, int w, int h, bool from_gylp
   m_gradient_r0 = 0.0f;
   m_gradient_r1 = 200.0f / m_path_zoomer.transformation().scale();
 
+  m_sweep_repeat_factor = 1.0f;
+
   m_repeat_xy = vec2(0.0f, 0.0f);
   m_repeat_wh = m_path.tessellation()->bounding_box_max() - m_path.tessellation()->bounding_box_min();
 
@@ -613,6 +624,9 @@ painter_stroke_test(void):
   m_radial_gradient_change_rate(0.1f, "change_rate_brush_radial_gradient",
                                 "rate of change in pixels/sec when changing the radial gradient radius",
                                 *this),
+  m_sweep_factor_gradient_change_rate(0.05f, "change_rate_brush_sweep_factor_gradient",
+                                      "rate of change in units/sec when changing the sweep factor",
+                                      *this),
   m_path_file_list("add_path_file",
                    "add a path read from file to path list; if path list is empty then "
                    "a default path will be used to render ",
@@ -741,6 +755,7 @@ painter_stroke_test(void):
   m_gradient_mode_labels[draw_no_gradient] = "draw_no_gradient";
   m_gradient_mode_labels[draw_linear_gradient] = "draw_linear_gradient";
   m_gradient_mode_labels[draw_radial_gradient] = "draw_radial_gradient";
+  m_gradient_mode_labels[draw_sweep_gradient] = "draw_sweep_gradient";
 
   m_join_labels[Painter::no_joins] = "no_joins";
   m_join_labels[Painter::rounded_joins] = "rounded_joins";
@@ -932,17 +947,16 @@ update_cts_params(void)
           gradient_r0() -= delta;
           gradient_r0() = fastuidraw::t_max(0.0f, gradient_r0());
         }
-
       if (keyboard_state[SDL_SCANCODE_2])
         {
           gradient_r0() += delta;
         }
+
       if (keyboard_state[SDL_SCANCODE_3])
         {
           gradient_r1() -= delta;
           gradient_r1() = fastuidraw::t_max(0.0f, gradient_r1());
         }
-
       if (keyboard_state[SDL_SCANCODE_4])
         {
           gradient_r1() += delta;
@@ -956,6 +970,26 @@ update_cts_params(void)
         }
     }
 
+  if (m_gradient_draw_mode == draw_sweep_gradient)
+    {
+      float delta;
+
+      delta = m_sweep_factor_gradient_change_rate.value();
+      if (keyboard_state[SDL_SCANCODE_1])
+        {
+          sweep_repeat_factor() -= delta;
+        }
+      if (keyboard_state[SDL_SCANCODE_2])
+        {
+          sweep_repeat_factor() += delta;
+        }
+
+      if (keyboard_state[SDL_SCANCODE_1] || keyboard_state[SDL_SCANCODE_2])
+        {
+          std::cout << "Sweep Repeat factor set to: "
+                    << sweep_repeat_factor() << "\n";
+        }
+    }
 
   if (is_miter_join_style(m_join_style) && m_have_miter_limit)
     {
@@ -1574,16 +1608,6 @@ void
 painter_stroke_test::
 construct_color_stops(void)
 {
-  ColorStopSequence S;
-  reference_counted_ptr<ColorStopSequenceOnAtlas> h;
-
-  S.add(ColorStop(u8vec4(0, 255, 0, 255), 0.0f));
-  S.add(ColorStop(u8vec4(0, 255, 255, 255), 0.33f));
-  S.add(ColorStop(u8vec4(255, 255, 0, 255), 0.66f));
-  S.add(ColorStop(u8vec4(255, 0, 0, 255), 1.0f));
-  h = FASTUIDRAWnew ColorStopSequenceOnAtlas(S, m_painter->colorstop_atlas(), 8);
-  m_color_stops.push_back(named_color_stop("Default ColorStop Sequence", h));
-
   for(color_stop_arguments::hoard::const_iterator
         iter = m_color_stop_args.values().begin(),
         end = m_color_stop_args.values().end();
@@ -1595,6 +1619,19 @@ construct_color_stops(void)
                                                  iter->second->m_discretization);
       m_color_stops.push_back(named_color_stop(iter->first, h));
     }
+
+  if (m_color_stops.empty())
+    {
+      ColorStopSequence S;
+      reference_counted_ptr<ColorStopSequenceOnAtlas> h;
+
+      S.add(ColorStop(u8vec4(0, 255, 0, 255), 0.0f));
+      S.add(ColorStop(u8vec4(0, 255, 255, 255), 0.33f));
+      S.add(ColorStop(u8vec4(255, 255, 0, 255), 0.66f));
+      S.add(ColorStop(u8vec4(255, 0, 0, 255), 1.0f));
+      h = FASTUIDRAWnew ColorStopSequenceOnAtlas(S, m_painter->colorstop_atlas(), 8);
+      m_color_stops.push_back(named_color_stop("Default ColorStop Sequence", h));
+    }
 }
 
 void
@@ -1731,6 +1768,16 @@ draw_scene(bool drawing_wire_frame)
                                      gradient_p1(), gradient_r1(),
                                      repeat_gradient());
         }
+      else if (m_gradient_draw_mode == draw_sweep_gradient)
+        {
+          vec2 d;
+          d = gradient_p1() - gradient_p0();
+          fill_brush.sweep_gradient(m_color_stops[m_active_color_stop].second,
+                                    gradient_p0(), t_atan2(d.y(), d.x()),
+                                    Painter::y_increases_downwards,
+                                    Painter::clockwise, sweep_repeat_factor(),
+                                    repeat_gradient());
+        }
       else
         {
           fill_brush.no_gradient();