Tile WipeTower2 purge rows contiguously across toolchange blocks

Without ramming, each purge block reserved one wipe pitch more than its
rows occupy (ceil+1 rounding plus the ram-geometry start offset), and the
wipe began a full pitch inside the block, leaving a blank band of exactly
two pitches between adjacent blocks. Plan the block as whole wipe rows,
start the first row so the row lattice continues across the block
boundary, and fill the reserved box instead of stopping at the ordered
volume, mirroring how the BBL WipeTower keeps planned depth identical to
printed rows. Ram-printing toolchanges (SEMM with ramming enabled,
multitool ramming) are unchanged.

src/libslic3r/GCode/WipeTower2.cpp

@@ -1673,6 +1673,11 @@ WipeTower::ToolChangeResult WipeTower2::tool_change(size_t tool)
 
     // Ram the hot material out of the melt zone, retract the filament into the cooling tubes and let it cool.
     if (tool != (unsigned int)-1){ 			// This is not the last change.
+        // Without a ram the box was planned as whole wipe rows; the wipe then fills it
+        // completely so adjacent purge blocks stay contiguous. Uses the old tool
+        // (m_current_tool before toolchange_Change), same condition as
+        // toolchange_Unload()'s do_ramming.
+        const bool fill_box = !((m_semm && m_enable_filament_ramming) || m_filpar[m_current_tool].multitool_ramming);
         auto new_tool_temp = is_first_layer() ? m_filpar[tool].first_layer_temperature : m_filpar[tool].temperature;
         toolchange_Unload(writer, cleaning_box, m_filpar[m_current_tool].material,
                           (is_first_layer() ? m_filpar[m_current_tool].first_layer_temperature : m_filpar[m_current_tool].temperature),
@@ -1695,7 +1700,7 @@ WipeTower::ToolChangeResult WipeTower2::tool_change(size_t tool)
                 writer.extrude_explicit(target_x, writer.y(), pre_len, 600.f);
             }
         }
-        toolchange_Wipe(writer, cleaning_box, wipe_volume, interface_layer);     // Wipe the newly loaded filament until the end of the assigned wipe area.
+        toolchange_Wipe(writer, cleaning_box, wipe_volume, interface_layer, false, fill_box);     // Wipe the newly loaded filament until the end of the assigned wipe area.
         if (interface_layer) {
             int interface_temp = m_filpar[tool].interface_print_temperature;
             if (!m_enable_tower_interface_cooldown_during_tower && interface_temp > 0 && interface_temp != base_temp)
@@ -1933,8 +1938,18 @@ void WipeTower2::toolchange_Unload(
     Vec2f pos = Vec2f(end_of_ramming.x(), end_of_ramming.y() + (y_step/m_extra_spacing_ramming-m_perimeter_width) / 2.f + m_perimeter_width);
     if (do_ramming)
         writer.travel(pos, 2400.f);
-    else
-        writer.set_position(pos);
+    else {
+        // Orca: with no ram printed there is no ramming geometry to align with. Start the
+        // first wipe row so the purge row lattice continues across the block boundary
+        // (previous box's last row top edge sits at its box top): with the planned depth
+        // of rows * dy, the last row's top edge then lands exactly on this box's top and
+        // no blank band is left between adjacent purge blocks. Mirrors dy/line_width in
+        // toolchange_Wipe().
+        const float wipe_dy         = (is_first_layer() ? m_extra_flow : m_extra_spacing_wipe) * m_perimeter_width;
+        const float wipe_line_width = m_perimeter_width * m_extra_flow;
+        writer.set_position(Vec2f(end_of_ramming.x(),
+            cleaning_box.ld.y() + m_depth_traversed + wipe_dy - (m_perimeter_width + wipe_line_width) / 2.f + m_perimeter_width));
+    }
 
     writer.resume_preview()
           .flush_planner_queue();
@@ -2014,7 +2029,8 @@ void WipeTower2::toolchange_Wipe(
 	const WipeTower::box_coordinates  &cleaning_box,
 	float wipe_volume,
     bool interface_layer,
-    bool priming)
+    bool priming,
+    bool fill_box)
 {
 	// Increase flow on first layer, slow down print.
     writer.set_extrusion_flow(m_extrusion_flow * (is_first_layer() ? 1.18f : 1.f))
@@ -2092,7 +2108,10 @@ void WipeTower2::toolchange_Wipe(
 
 		traversed_x -= writer.x();
         x_to_wipe -= std::abs(traversed_x);
-		if (x_to_wipe < WT_EPSILON) {
+        // Orca: with no ram printed the box was planned as whole wipe rows; fill it
+        // completely (quantizing the purge up to the planned rows) so the next block
+        // can start right above it without a blank band in between.
+        if (!fill_box && x_to_wipe < WT_EPSILON) {
             writer.travel(m_left_to_right ? xl + 1.5f*line_width : xr - 1.5f*line_width, writer.y(), 7200);
 			break;
 		}
@@ -2346,14 +2365,6 @@ void WipeTower2::plan_toolchange(float z_par, float layer_height_par, unsigned i
     m_plan.back().tool_changes.push_back(set_toolchange(old_tool, new_tool, layer_height_par, wipe_volume, first_layer_plan));
 }
 
-float WipeTower2::wipe_start_depth_offset(size_t old_tool) const
-{
-    const bool do_ramming = (m_semm && m_enable_filament_ramming) || m_filpar[old_tool].multitool_ramming;
-    if (do_ramming)
-        return 0.f;
-    return 0.5f * m_perimeter_width * m_filpar[old_tool].ramming_line_width_multiplicator * m_filpar[old_tool].ramming_step_multiplicator * m_extra_spacing_ramming;
-}
-
 WipeTower2::WipeTowerInfo::ToolChange WipeTower2::set_toolchange(size_t old_tool, size_t new_tool, float layer_height, float wipe_volume, bool first_layer_plan)
 {
     float width = m_wipe_tower_width - 3*m_perimeter_width;
@@ -2381,8 +2392,7 @@ WipeTower2::WipeTowerInfo::ToolChange WipeTower2::set_toolchange(size_t old_tool
     // ORCA: and first-layer purge segments do not leave visible gaps.
     const float planning_spacing = first_layer_plan ? m_extra_flow : m_extra_spacing_wipe;
 
-    float wiping_depth = get_wipe_depth(wipe_volume - first_wipe_volume, layer_height, m_perimeter_width, m_extra_flow, planning_spacing, width)
-                       + wipe_start_depth_offset(old_tool);
+    float wiping_depth = get_wipe_depth(wipe_volume - first_wipe_volume, layer_height, m_perimeter_width, m_extra_flow, planning_spacing, width);
 
 	return WipeTowerInfo::ToolChange(old_tool, new_tool, ramming_depth + wiping_depth, ramming_depth, first_wipe_line, wipe_volume);
 }
@@ -2444,8 +2454,7 @@ void WipeTower2::save_on_last_wipe()
             const bool first_layer_plan = size_t(m_layer_info - m_plan.begin()) == m_first_layer_idx;
             const float planning_spacing = first_layer_plan ? m_extra_flow : m_extra_spacing_wipe;
 
-            float depth_to_wipe = get_wipe_depth(volume_we_need_depth_for, m_layer_info->height, m_perimeter_width, m_extra_flow, planning_spacing, width)
-                                + wipe_start_depth_offset(toolchange.old_tool);
+            float depth_to_wipe = get_wipe_depth(volume_we_need_depth_for, m_layer_info->height, m_perimeter_width, m_extra_flow, planning_spacing, width);
 
             toolchange.required_depth = toolchange.ramming_depth + depth_to_wipe;
             toolchange.wipe_volume = volume_left_to_wipe;

src/libslic3r/GCode/WipeTower2.hpp

@@ -362,7 +362,8 @@ private:
 		const WipeTower::box_coordinates  &cleaning_box,
 		float wipe_volume,
         bool interface_layer,
-        bool priming = false);
+        bool priming = false,
+        bool fill_box = false);
 
 
     Polygon generate_support_rib_wall(WipeTowerWriter2&                 writer,
@@ -387,11 +388,6 @@ private:
     // Computes the depth reserved for a toolchange (shared by plan_toolchange() and the
     // rib-wall square-tower replanning in generate()).
     WipeTowerInfo::ToolChange set_toolchange(size_t old_tool, size_t new_tool, float layer_height, float wipe_volume, bool first_layer_plan);
-
-    // Depth consumed before the first wipe row when no ramming is printed (the wipe
-    // still starts y_step/2 into the box, see toolchange_Unload()); 0 with ramming,
-    // whose planned rows already carry the slack for it.
-    float wipe_start_depth_offset(size_t old_tool) const;
 };