add compile guards for aba spd

CMakeLists.txt

@@ -112,6 +112,15 @@ set(ALL_MODULE ${ALL_MODULE_NO_RENDERER} renderer_glut)
 set(ALL_EXT_LIBS ${PX_LIBS} ${PX_LIBS} ${SYS_LIBS})
 
 
+set(BUILD_SPD_ABA OFF CACHE BOOL "Choose whether to enable linear time SPD controller")
+
+if(${BUILD_SPD_ABA})
+
+    add_compile_definitions(ENABLE_SPD_ABA)
+
+endif()
+
+
 set(BUILD_EXAMPLES ON CACHE BOOL "Choose whether c++ examples should be built")
 
 if(${BUILD_EXAMPLES})

src/articulation/Articulation.cpp

@@ -560,14 +560,15 @@ void Articulation::AddSPDForcesABA(const std::vector<float>& targetPositions, fl
     }
 
     pxArticulation->applyCache(*mainCache, PxArticulationCache::eFORCE);
-
+#ifdef ENABLE_SPD_ABA
     extern float  			g_SPD_Dt;
     extern const float* 	g_SPD_Kd;
     extern const int*		g_SPD_LinkIdCacheIndexMap;
 
     g_SPD_Dt = timeStep;
     g_SPD_Kd = kds.data();
     g_SPD_LinkIdCacheIndexMap = linkIdCacheIndexMap.data();
+#endif
 }
 
 void Articulation::FetchKinematicData() const

wiki/SPDABA.md

@@ -5,6 +5,7 @@
 ### How to Enable 
 * Apply resources/spd-aba.patch to PhysX git repo (not this one).
 * Re-build PhysX (make && make install).
+* Enable `BUILD_SPD_ABA` option when configuring this project.
 * Do a **clean** build for this project. See [Build and set up](wiki/Setup.md) for details.
 * Use AddSPDForcesABA instead of AddSPDForces to use linear time SPD controller