plumb URDF/SDF audio_source into PhysicsServerCommandProcessor, allow to play sounds on collision !

See also https://youtu.be/eppOjTfx5Jg for a first test, and this modified URDF how to add sounds:
https://github.com/bulletphysics/bullet3/blob/master/data/plane_with_collision_audio.urdf
Add the --audio flag to enable sound in pybullet/Bullet-C-API

examples/Importers/ImportURDFDemo/BulletUrdfImporter.cpp

@@ -1134,9 +1134,9 @@ bool BulletURDFImporter::getLinkColor(int linkIndex, btVector4& colorRGBA) const
 	return false;
 }
 
-bool BulletURDFImporter::getLinkContactInfo(int linkIndex, URDFLinkContactInfo& contactInfo ) const
+bool BulletURDFImporter::getLinkContactInfo(int urdflinkIndex, URDFLinkContactInfo& contactInfo ) const
 {
-	UrdfLink* const* linkPtr = m_data->m_urdfParser.getModel().m_links.getAtIndex(linkIndex);
+	UrdfLink* const* linkPtr = m_data->m_urdfParser.getModel().m_links.getAtIndex(urdflinkIndex);
 	if (linkPtr)
 	{
 		const UrdfLink* link = *linkPtr;
@@ -1146,6 +1146,22 @@ bool BulletURDFImporter::getLinkContactInfo(int linkIndex, URDFLinkContactInfo&
 	return false;
 }
 
+bool BulletURDFImporter::getLinkAudioSource(int linkIndex, SDFAudioSource& audioSource) const
+{
+	UrdfLink* const* linkPtr = m_data->m_urdfParser.getModel().m_links.getAtIndex(linkIndex);
+	if (linkPtr)
+	{
+		const UrdfLink* link = *linkPtr;
+		if (link->m_audioSource.m_flags & SDFAudioSource::SDFAudioSourceValid)
+		{
+			audioSource = link->m_audioSource;
+			return true;
+		}
+	}
+	return false;
+}
+
+
 void BulletURDFImporter::convertLinkVisualShapes2(int linkIndex, int urdfIndex, const char* pathPrefix, const btTransform& localInertiaFrame, class btCollisionObject* colObj, int bodyUniqueId) const
 {
   	if (m_data->m_customVisualShapesConverter)

examples/Importers/ImportURDFDemo/BulletUrdfImporter.h

@@ -41,8 +41,10 @@ public:
 
 	virtual bool getLinkColor(int linkIndex, btVector4& colorRGBA) const;
 
-	virtual bool getLinkContactInfo(int linkIndex, URDFLinkContactInfo& contactInfo ) const;
+	virtual bool getLinkContactInfo(int urdflinkIndex, URDFLinkContactInfo& contactInfo ) const;
 	
+	virtual bool getLinkAudioSource(int linkIndex, SDFAudioSource& audioSource) const;
+
     virtual std::string getJointName(int linkIndex) const;
     
     virtual void  getMassAndInertia(int linkIndex, btScalar& mass,btVector3& localInertiaDiagonal, btTransform& inertialFrame) const;

examples/Importers/ImportURDFDemo/MyMultiBodyCreator.h

@@ -4,6 +4,7 @@
 
 #include "MultiBodyCreationInterface.h"
 #include "LinearMath/btAlignedObjectArray.h"
+#include "LinearMath/btHashMap.h"
 
 struct GUIHelperInterface;
 class btMultiBody;
@@ -28,7 +29,6 @@ protected:
     
 	struct GUIHelperInterface* m_guiHelper;
 
-	
 	btAlignedObjectArray<btGeneric6DofSpring2Constraint*> m_6DofConstraints;
 
 public:

examples/Importers/ImportURDFDemo/SDFAudioTypes.h

@@ -0,0 +1,46 @@
+#ifndef SDF_AUDIO_TYPES_H
+#define SDF_AUDIO_TYPES_H
+
+#include <string>
+
+
+
+///See audio_source element in http://sdformat.org/spec?ver=1.6&elem=link
+struct SDFAudioSource
+{
+	enum
+	{
+		SDFAudioSourceValid=1,
+		SDFAudioSourceLooping=2,
+	};
+
+	int m_flags;	//repeat mode (0 = no repeat, 1 = loop forever)
+
+	std::string	m_uri;	//media filename of the sound, .wav file
+	double m_pitch;	//1 = regular rate, -1 play in reverse
+	double m_gain;	//normalized volume in range [0..1] where 0 is silent, 1 is most loud
+
+	double m_attackRate;
+	double m_decayRate;
+	double m_sustainLevel;
+	double m_releaseRate;
+
+	double m_collisionForceThreshold;	//force that will trigger the audio, in Newton. If < 0, audio source is invalid
+	
+	int m_userIndex;
+
+	SDFAudioSource()
+	:	m_flags(0),
+		m_pitch(1),
+		m_gain(1),
+		m_attackRate(0.0001),
+		m_decayRate(0.00001),
+		m_sustainLevel(0.5),
+		m_releaseRate(0.0005),
+		m_collisionForceThreshold(0.5),
+		m_userIndex(-1)
+		{
+		}
+};
+
+#endif //SDF_AUDIO_TYPES_H

examples/Importers/ImportURDFDemo/URDFImporterInterface.h

@@ -5,7 +5,7 @@
 #include "LinearMath/btAlignedObjectArray.h"
 #include "LinearMath/btTransform.h"
 #include "URDFJointTypes.h"
-
+#include "SDFAudioTypes.h"
 
 class URDFImporterInterface
 {
@@ -40,6 +40,8 @@ public:
 	///this API will likely change, don't override it!
 	virtual bool getLinkContactInfo(int linkIndex, URDFLinkContactInfo& contactInfo ) const  { return false;}
     
+	virtual bool getLinkAudioSource(int linkIndex, SDFAudioSource& audioSource) const { return false;}
+
     virtual std::string getJointName(int linkIndex) const = 0;
 
     //fill mass and inertial data. If inertial data is missing, please initialize mass, inertia to sensitive values, and inertialFrame to identity.

examples/Importers/ImportURDFDemo/UrdfParser.cpp

@@ -663,6 +663,82 @@ bool UrdfParser::parseLink(UrdfModel& model, UrdfLink& link, TiXmlElement *confi
         }
     }
 
+	{
+		//optional 'audio_source' parameters
+		//modified version of SDF audio_source specification in //http://sdformat.org/spec?ver=1.6&elem=link
+		#if 0
+		<audio_source>
+          <uri>file://media/audio/cheer.mp3</uri>
+          <pitch>2.0</pitch>
+          <gain>1.0</gain>
+          <loop>false</loop>
+          <contact>
+            <collision>collision</collision>
+          </contact>
+        </audio_source>
+		#endif
+		TiXmlElement* ci = config->FirstChildElement("audio_source");
+		if (ci)
+		{
+			link.m_audioSource.m_flags |= SDFAudioSource::SDFAudioSourceValid;
+			
+			const char* fn = ci->Attribute("filename");
+			if (fn)
+			{
+				link.m_audioSource.m_uri = fn;
+			} else
+			{
+				if (TiXmlElement* filename_xml = ci->FirstChildElement("uri"))
+				{
+					link.m_audioSource.m_uri = filename_xml->GetText();
+				}
+			}
+			if (TiXmlElement* pitch_xml = ci->FirstChildElement("pitch"))
+			{
+				link.m_audioSource.m_pitch = urdfLexicalCast<double>(pitch_xml->GetText());
+			}
+			if (TiXmlElement* gain_xml = ci->FirstChildElement("gain"))
+			{
+				link.m_audioSource.m_gain = urdfLexicalCast<double>(gain_xml->GetText());
+			}
+
+			if (TiXmlElement* attack_rate_xml = ci->FirstChildElement("attack_rate"))
+			{
+				link.m_audioSource.m_attackRate = urdfLexicalCast<double>(attack_rate_xml->GetText());
+			}
+
+			if (TiXmlElement* decay_rate_xml = ci->FirstChildElement("decay_rate"))
+			{
+				link.m_audioSource.m_decayRate = urdfLexicalCast<double>(decay_rate_xml->GetText());
+			}
+
+			if (TiXmlElement* sustain_level_xml = ci->FirstChildElement("sustain_level"))
+			{
+				link.m_audioSource.m_sustainLevel = urdfLexicalCast<double>(sustain_level_xml->GetText());
+			}
+
+			if (TiXmlElement* release_rate_xml = ci->FirstChildElement("release_rate"))
+			{
+				link.m_audioSource.m_releaseRate = urdfLexicalCast<double>(release_rate_xml->GetText());
+			}
+
+			if (TiXmlElement* loop_xml = ci->FirstChildElement("loop"))
+			{
+				std::string looptxt = loop_xml->GetText();
+				if (looptxt == "true")
+				{
+					link.m_audioSource.m_flags |= SDFAudioSource::SDFAudioSourceLooping;
+				}
+			}
+			if (TiXmlElement* forceThreshold_xml = ci->FirstChildElement("collision_force_threshold"))
+			{
+				link.m_audioSource.m_collisionForceThreshold= urdfLexicalCast<double>(forceThreshold_xml->GetText());
+			}
+			//todo: see other audio_source children
+			//pitch, gain, loop, contact
+			
+		}
+	}
 	{
 		//optional 'contact' parameters
 	 TiXmlElement* ci = config->FirstChildElement("contact");

examples/Importers/ImportURDFDemo/UrdfParser.h

@@ -5,6 +5,7 @@
 #include "LinearMath/btAlignedObjectArray.h"
 #include "LinearMath/btHashMap.h"
 #include "URDFJointTypes.h"
+#include "SDFAudioTypes.h"
 
 #define btArray btAlignedObjectArray
 #include <string>
@@ -140,6 +141,8 @@ struct UrdfLink
 	
 	URDFLinkContactInfo m_contactInfo;
 
+	SDFAudioSource m_audioSource;
+
 	UrdfLink()
 		:m_parentLink(0),
 		m_parentJoint(0)