Add optional azimuth and elevation to initial free camera.

- Add `azimuth` and `elevation` to `visual.global`.
- Add `mjv_defaultFreeCamera`.
- Use `mjv_defaultFreeCamera` in `simulate`.

PiperOrigin-RevId: 465505244
Change-Id: I61e60f14a990d4e2d220958adb75c325001978ee

include/mujoco/mjmodel.h

@@ -418,8 +418,10 @@ typedef struct mjOption_ mjOption;
 
 struct mjVisual_ {                // visualization options
   struct {                        // global parameters
-    float fovy;                   // y-field of view (deg) for free camera
+    float fovy;                   // y-field of view for free camera (degrees)
     float ipd;                    // inter-pupilary distance for free camera
+    float azimuth;                // initial azimuth of free camera (degrees)
+    float elevation;              // initial elevation of free camera (degrees)
     float linewidth;              // line width for wireframe and ray rendering
     float glow;                   // glow coefficient for selected body
     int offwidth;                 // width of offscreen buffer

include/mujoco/mujoco.h

@@ -492,6 +492,9 @@ MJAPI mjtNum mju_raySkin(int nface, int nvert, const int* face, const float* ver
 // Set default camera.
 MJAPI void mjv_defaultCamera(mjvCamera* cam);
 
+// Set default free camera.
+MJAPI void mjv_defaultFreeCamera(const mjModel* m, mjvCamera* cam);
+
 // Set default perturbation.
 MJAPI void mjv_defaultPerturb(mjvPerturb* pert);