Add SDF functions to public API.

PiperOrigin-RevId: 757829339
Change-Id: I81ee7c3f33acf234835bf34cbb632e23cb9e284e

include/mujoco/mjmodel.h

@@ -407,6 +407,14 @@ typedef enum mjtFlexSelf_ {       // mode for flex selfcollide
 } mjtFlexSelf;
 
 
+typedef enum mjtSDFType_ {        // signed distance function (SDF) type
+  mjSDFTYPE_SINGLE     = 0,       // single SDF
+  mjSDFTYPE_INTERSECTION,         // max(A, B)
+  mjSDFTYPE_MIDSURFACE,           // A - B
+  mjSDFTYPE_COLLISION,            // A + B + abs(max(A, B))
+} mjtSDFType;
+
+
 //---------------------------------- mjLROpt -------------------------------------------------------
 
 struct mjLROpt_ {                 // options for mj_setLengthRange()

include/mujoco/mjplugin.h

@@ -135,6 +135,16 @@ struct mjpPlugin_ {
 };
 typedef struct mjpPlugin_ mjpPlugin;
 
+struct mjSDF_ {
+  const mjpPlugin** plugin;
+  int* id;
+  mjtSDFType type;
+  mjtNum* relpos;
+  mjtNum* relmat;
+  mjtGeom* geomtype;
+};
+typedef struct mjSDF_ mjSDF;
+
 #if defined(__has_attribute)
 
   #if __has_attribute(constructor)

include/mujoco/mujoco.h

@@ -1308,6 +1308,19 @@ MJAPI char* mju_strncpy(char *dst, const char *src, int n);
 MJAPI mjtNum mju_sigmoid(mjtNum x);
 
 
+//---------------------------------- Signed Distance Function --------------------------------------
+
+// get sdf from geom id
+MJAPI const mjpPlugin* mjc_getSDF(const mjModel* m, int id);
+
+// signed distance function
+MJAPI mjtNum mjc_distance(const mjModel* m, const mjData* d, const mjSDF* s, const mjtNum x[3]);
+
+// gradient of sdf
+MJAPI void mjc_gradient(const mjModel* m, const mjData* d, const mjSDF* s, mjtNum gradient[3],
+                        const mjtNum x[3]);
+
+
 //---------------------------------- Derivatives ---------------------------------------------------
 
 // Finite differenced transition matrices (control theory notation)