From 54e86b7307b6571edc165246d09e09dc7717d5b8 Mon Sep 17 00:00:00 2001
From: Joseph Lenox <lenox.joseph@gmail.com>
Date: Fri, 5 Jan 2018 20:02:54 -0600
Subject: [PATCH] Reduce bounds on auto width again (the math likes to go very
 wide which is not feasible if your nozzle isn't really big).

Should address #4212
---
 xs/src/libslic3r/Flow.cpp | 10 +++++-----
 xs/src/libslic3r/Flow.hpp |  3 ++-
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/xs/src/libslic3r/Flow.cpp b/xs/src/libslic3r/Flow.cpp
index cc87ec0bb..c3346e82b 100644
--- a/xs/src/libslic3r/Flow.cpp
+++ b/xs/src/libslic3r/Flow.cpp
@@ -90,18 +90,18 @@ Flow::_bridge_width(float nozzle_diameter, float bridge_flow_ratio) {
 
 /* This static method returns a sane extrusion width default. */
 float
-Flow::_auto_width(FlowRole role, float nozzle_diameter, float height) {
+Flow::_auto_width(FlowRole role, float nozzle_diameter, float height) const {
     // here we calculate a sane default by matching the flow speed (at the nozzle) and the feed rate
     // shape: rectangle with semicircles at the ends
     float width = ((nozzle_diameter*nozzle_diameter) * PI + (height*height) * (4.0 - PI)) / (4.0 * height);
     
     float min = nozzle_diameter * 1.05;
-    float max = nozzle_diameter * 3; // cap width to 3x nozzle diameter
+    float max = nozzle_diameter * 1.25; // cap width to 1.25x nozzle diameter
     if (role == frExternalPerimeter || role == frSupportMaterial || role == frSupportMaterialInterface) {
-        min = max = nozzle_diameter;
+        min = max = nozzle_diameter*1.1;
     } else if (role != frInfill) {
-        // do not limit width for sparse infill so that we use full native flow for it
-        max = nozzle_diameter * 1.7;
+        // limit width a bit for sparse infill to avoid unwanted overextrusion.
+        max = nozzle_diameter * 1.4;
     }
     if (width > max) width = max;
     if (width < min) width = min;
diff --git a/xs/src/libslic3r/Flow.hpp b/xs/src/libslic3r/Flow.hpp
index 5f2467d54..85fa5be85 100644
--- a/xs/src/libslic3r/Flow.hpp
+++ b/xs/src/libslic3r/Flow.hpp
@@ -69,7 +69,8 @@ class Flow
     static float _bridge_width(float nozzle_diameter, float bridge_flow_ratio);
     /// Calculate a relatively sane extrusion width, based on height and nozzle diameter.
     /// Algorithm used does not play nice with layer heights < 0.1mm. 
-    static float _auto_width(FlowRole role, float nozzle_diameter, float height);
+    /// To avoid extra headaches, min and max are capped at 105% and 125% of nozzle diameter.
+    static float _auto_width(FlowRole role, float nozzle_diameter, float height) const;
     static float _width_from_spacing(float spacing, float nozzle_diameter, float height, bool bridge);
 };