From a092c486428ad78b0d8a7830df56babb867cf4c8 Mon Sep 17 00:00:00 2001
From: "xun.zhang" <xun.zhang@bambulab.com>
Date: Wed, 2 Jul 2025 14:54:07 +0800
Subject: [PATCH] FIX: find the first layer with enough space to extrude

1. Sometimes the first layer is too small and does not have enough space to extrude.That will make first layer extruders empty

jira: STUDIO-13030

Signed-off-by: xun.zhang <xun.zhang@bambulab.com>
Change-Id: I69b99ab74101c772f4c91e955060e403988bb91c
(cherry picked from commit 9699397858c6d52d027e79e91041a9dac7280bba)
---
 src/libslic3r/GCode/ToolOrdering.cpp | 44 +++++++++++++++++++++++++---
 1 file changed, 40 insertions(+), 4 deletions(-)

diff --git a/src/libslic3r/GCode/ToolOrdering.cpp b/src/libslic3r/GCode/ToolOrdering.cpp
index b60cd55734..e6347e3fb0 100644
--- a/src/libslic3r/GCode/ToolOrdering.cpp
+++ b/src/libslic3r/GCode/ToolOrdering.cpp
@@ -479,8 +479,26 @@ std::vector<unsigned int> ToolOrdering::generate_first_layer_tool_order(const Pr
     std::map<int, double> min_areas_per_extruder;
 
     for (auto object : print.objects()) {
-        auto first_layer = object->get_layer(0);
-        for (auto layerm : first_layer->regions()) {
+        const Layer* target_layer = nullptr;
+        for(auto layer : object->layers()){
+            for(auto layerm : layer->regions()){
+                for(auto& expoly : layerm->raw_slices){
+                    if (!offset_ex(expoly, -0.2 * scale_(print.config().initial_layer_line_width)).empty()) {
+                        target_layer = layer;
+                        break;
+                    }
+                }
+                if(target_layer)
+                    break;
+            }
+            if(target_layer)
+                break;
+        }
+
+        if(!target_layer)
+            return tool_order;
+
+        for (auto layerm : target_layer->regions()) {
             int extruder_id = layerm->region().config().option("wall_filament")->getInt();
 
             for (auto expoly : layerm->raw_slices) {
@@ -525,8 +543,26 @@ std::vector<unsigned int> ToolOrdering::generate_first_layer_tool_order(const Pr
     std::vector<unsigned int> tool_order;
     int initial_extruder_id = -1;
     std::map<int, double> min_areas_per_extruder;
-    auto first_layer = object.get_layer(0);
-    for (auto layerm : first_layer->regions()) {
+    const Layer* target_layer = nullptr;
+    for(auto layer : object.layers()){
+        for(auto layerm : layer->regions()){
+            for(auto& expoly : layerm->raw_slices){
+                if (!offset_ex(expoly, -0.2 * scale_(object.config().line_width)).empty()) {
+                    target_layer = layer;
+                    break;
+                }
+            }
+            if(target_layer)
+                break;
+        }
+        if(target_layer)
+            break;
+    }
+
+    if(!target_layer)
+        return tool_order;
+
+    for (auto layerm : target_layer->regions()) {
         int extruder_id = layerm->region().config().option("wall_filament")->getInt();
         for (auto expoly : layerm->raw_slices) {
             const double nozzle_diameter = object.print()->config().nozzle_diameter.get_at(0);