Add realtime parameter to visual global.

PiperOrigin-RevId: 478775714
Change-Id: Ic2d178a5c57d298d005215219ce8470392c4651b

doc/APIreference.rst

@@ -1237,6 +1237,7 @@ mjVisual
            float ipd;                  // inter-pupilary distance for free camera
            float linewidth;            // line width for wireframe and ray rendering
            float glow;                 // glow coefficient for selected body
+           float realtime;             // initial real-time factor (1: real time)
            int offwidth;               // width of offscreen buffer
            int offheight;              // height of offscreen buffer
        } global;

doc/XMLreference.rst

@@ -592,6 +592,9 @@ is effectively a miscellaneous subsection.
 :at:`glow`: :at-val:`real, "0.3"`
    The value of this attribute is added to the emission coefficient of all geoms attached to the selected body. As a
    result, the selected body appears to glow.
+:at:`realtime`: :at-val:`real, "1"`
+   This value sets the initial real-time factor of the model, when loaded in `simulate`. 1: real time. Less than 1:
+   slower than real time. Must be greater than 0.
 :at:`offwidth`: :at-val:`int, "640"`
    This and the next attribute specify the size in pixels of the off-screen OpenGL rendering buffer. This attribute
    specifies the width of the buffer. The size of this buffer can also be adjusted at runtime, but it is usually more

doc/changelog.rst

@@ -50,6 +50,8 @@ General
 - Added :at:`assetdir` compiler option, which sets the values of both :at:`meshdir` and :at:`texturedir`. Values in
   the latter attributes take precedence over :at:`assetdir`.
 
+- Added :at:`realtime` option to :ref:`visual` for starting a simulation at a slower speed.
+
 Python bindings
 ^^^^^^^^^^^^^^^
 

include/mujoco/mjmodel.h

@@ -429,6 +429,7 @@ struct mjVisual_ {                // visualization options
     float elevation;              // initial elevation of free camera (degrees)
     float linewidth;              // line width for wireframe and ray rendering
     float glow;                   // glow coefficient for selected body
+    float realtime;               // initial real-time factor (1: real time)
     int offwidth;                 // width of offscreen buffer
     int offheight;                // height of offscreen buffer
   } global;

simulate/simulate.cc

@@ -1648,6 +1648,18 @@ void Simulate::loadmodel() {
   // clear request
   this->loadrequest = 0;
   cond_loadrequest.notify_all();
+
+  // set real time index
+  int numclicks = sizeof(this->percentRealTime) / sizeof(this->percentRealTime[0]);
+  float min_error = 1e6;
+  float desired = mju_log(100*this->m->vis.global.realtime);
+  for (int click=0; click<numclicks; click++) {
+    float error = mju_abs(mju_log(this->percentRealTime[click]) - desired);
+    if (error < min_error) {
+      min_error = error;
+      this->realTimeIndex = click;
+    }
+  }
 }
 
 

simulate/simulate.h

@@ -125,7 +125,7 @@ class MJSIMULATEAPI Simulate {
   char previous_filename[kMaxFilenameLength] = "";
 
   // time synchronization
-  int realTimeIndex = 0;
+  int realTimeIndex;
   bool speedChanged = true;
   float measuredSlowdown = 1.0;
   // logarithmically spaced realtime slow-down coefficients (percent)

src/engine/engine_io.c

@@ -160,6 +160,7 @@ void mj_defaultVisual(mjVisual* vis) {
   vis->global.glow                = 0.3;
   vis->global.offwidth            = 640;
   vis->global.offheight           = 480;
+  vis->global.realtime            = 1.0;
 
   // rendering quality
   vis->quality.shadowsize         = 4096;

src/xml/xml_native_reader.cc

@@ -109,8 +109,8 @@ static const char* MJCF[nMJCF][mjXATTRNUM] = {
 
     {"visual", "*", "0"},
     {"<"},
-        {"global", "?", "8", "fovy", "ipd", "azimuth", "elevation", "linewidth", "glow", "offwidth",
-            "offheight"},
+        {"global", "?", "9", "fovy", "ipd", "azimuth", "elevation", "linewidth", "glow", "offwidth",
+            "offheight", "realtime"},
         {"quality", "?", "5", "shadowsize", "offsamples", "numslices", "numstacks",
             "numquads"},
         {"headlight", "?", "4", "ambient", "diffuse", "specular", "active"},
@@ -2172,6 +2172,10 @@ void mjXReader::Visual(XMLElement* section) {
       ReadAttr(elem,    "glow",      1, &vis->global.glow,      text);
       ReadAttrInt(elem, "offwidth",     &vis->global.offwidth);
       ReadAttrInt(elem, "offheight",    &vis->global.offheight);
+      if (ReadAttr(elem, "realtime", 1, &vis->global.realtime, text))
+        if (vis->global.realtime<=0) {
+          throw mjXError(elem, "realtime must be greater than 0");
+        }
     }
 
     // quality sub-element

src/xml/xml_native_writer.cc

@@ -868,6 +868,7 @@ void mjXWriter::Visual(XMLElement* root) {
   WriteAttr(elem,    "elevation", 1,   &vis->global.elevation,  &visdef.global.elevation);
   WriteAttr(elem,    "linewidth", 1,   &vis->global.linewidth,  &visdef.global.linewidth);
   WriteAttr(elem,    "glow",      1,   &vis->global.glow,       &visdef.global.glow);
+  WriteAttr(elem,    "realtime",  1,   &vis->global.realtime,   &visdef.global.realtime);
   WriteAttrInt(elem, "offwidth",       vis->global.offwidth,    visdef.global.offwidth);
   WriteAttrInt(elem, "offheight",      vis->global.offheight,   visdef.global.offheight);
   if (!elem->FirstAttribute()) {

unity/Runtime/Bindings/MujocoBindings.cs

@@ -1749,6 +1749,7 @@ public unsafe struct global {
   public float elevation;
   public float linewidth;
   public float glow;
+  public float realtime;
   public int offwidth;
   public int offheight;
 }