From b2281883dd8f772d8937868853eb650a7df28390 Mon Sep 17 00:00:00 2001
From: Yuval Tassa <tassa@google.com>
Date: Mon, 20 Apr 2026 08:53:28 -0700
Subject: [PATCH] Improve slider precision and range clamping, fixes #3206

Add clamping to slider values in both ImGui widgets and mjUI to ensure they remain within the defined min/max ranges, preventing potential floating point inaccuracies from causing values to slightly exceed the bounds.

PiperOrigin-RevId: 902660458
Change-Id: Ia153ae7907f07b890f2b5ac2e3a4be93ecae7bd3
---
 simulate/simulate.cc                          | 4 ++--
 src/experimental/platform/ux/imgui_widgets.cc | 2 +-
 src/ui/ui_main.c                              | 5 +++--
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/simulate/simulate.cc b/simulate/simulate.cc
index 522404b9..b4e29e35 100644
--- a/simulate/simulate.cc
+++ b/simulate/simulate.cc
@@ -1192,7 +1192,7 @@ void MakeJointSection(mj::Simulate* sim) {
 
       // set range
       if (sim->jnt_range_[i].has_value())
-        mju::sprintf_arr(defSlider[0].other, "%.4g %.4g",
+        mju::sprintf_arr(defSlider[0].other, "%.17g %.17g",
                          sim->jnt_range_[i]->first, sim->jnt_range_[i]->second);
       else if (sim->jnt_type_[i]==mjJNT_SLIDE) {
         mju::strcpy_arr(defSlider[0].other, "-1 1");
@@ -1251,7 +1251,7 @@ void MakeControlSection(mj::Simulate* sim) {
 
     // set range
     if (sim->actuator_ctrlrange_[i].has_value())
-      mju::sprintf_arr(defSlider[0].other, "%.4g %.4g",
+      mju::sprintf_arr(defSlider[0].other, "%.17g %.17g",
                        sim->actuator_ctrlrange_[i]->first, sim->actuator_ctrlrange_[i]->second);
     else {
       mju::strcpy_arr(defSlider[0].other, "-1 1");
diff --git a/src/experimental/platform/ux/imgui_widgets.cc b/src/experimental/platform/ux/imgui_widgets.cc
index 9ffbbe3e..61d2989a 100644
--- a/src/experimental/platform/ux/imgui_widgets.cc
+++ b/src/experimental/platform/ux/imgui_widgets.cc
@@ -321,7 +321,7 @@ bool ImGui_Slider(const char* name, mjtNum* value, mjtNum min, mjtNum max) {
   float f = *value;
   const bool res = ImGui::SliderFloat(name, &f, min, max);
   if (res) {
-    *value = f;
+    *value = mju_clip(f, min, max);
   }
   return res;
 }
diff --git a/src/ui/ui_main.c b/src/ui/ui_main.c
index ffc2fca2..14f588f1 100644
--- a/src/ui/ui_main.c
+++ b/src/ui/ui_main.c
@@ -849,8 +849,9 @@ static void setslider(mjuiItem* it, mjUI* ui,
   rx = mju_round(rx * it->slider.divisions) / mjMAX(1, it->slider.divisions);
   rx = mjMAX(0, mjMIN(1, rx));
 
-  // compute value
-  mjtNum val = (mjtNum)(it->slider.range[0]*(1-rx) + it->slider.range[1]*rx);
+  // compute value, clamp to range
+  mjtNum val = mju_clip(it->slider.range[0]*(1-rx) + it->slider.range[1]*rx,
+                        it->slider.range[0], it->slider.range[1]);
 
   // set slider position
   if (it->type == mjITEM_SLIDERINT) {