add kinematic rigid body ground example.

examples/ExampleBrowser/CMakeLists.txt

@@ -384,6 +384,7 @@ SET(BulletExampleBrowser_SRCS
   ../MultiBody/MultiDofDemo.cpp
   ../MultiBody/MultiDofDemo.h
   ../RigidBody/RigidBodySoftContact.cpp
+  ../RigidBody/KinematicRigidBodyExample.cpp
   ../Constraints/TestHingeTorque.cpp
   ../Constraints/TestHingeTorque.h
   ../Constraints/ConstraintDemo.cpp

examples/ExampleBrowser/ExampleEntries.cpp

@@ -35,6 +35,7 @@
 #include "../MultiBody/InvertedPendulumPDControl.h"
 
 #include "../RigidBody/RigidBodySoftContact.h"
+#include "../RigidBody/KinematicRigidBodyExample.h"
 #include "../VoronoiFracture/VoronoiFractureDemo.h"
 #include "../SoftDemo/SoftDemo.h"
 #include "../Constraints/ConstraintDemo.h"
@@ -145,6 +146,7 @@ static ExampleEntry gDefaultExamples[] =
 		ExampleEntry(1, "Gyroscopic", "Show the Dzhanibekov effect using various settings of the gyroscopic term. You can select the gyroscopic term computation using btRigidBody::setFlags, with arguments BT_ENABLE_GYROSCOPIC_FORCE_EXPLICIT (using explicit integration, which adds energy and can lead to explosions), BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_WORLD, BT_ENABLE_GYROSCOPIC_FORCE_IMPLICIT_BODY. If you don't set any of these flags, there is no gyroscopic term used.", GyroscopicCreateFunc),
 
 		ExampleEntry(1, "Soft Contact", "Using the error correction parameter (ERP) and constraint force mixing (CFM) values for contacts to simulate compliant contact.", RigidBodySoftContactCreateFunc),
+    ExampleEntry(1, "Kinematic Body", "Let the user set the transform, the physics engine computes the velocity for one-way contact and friction interaction.", KinematicRigidBodyExampleCreateFunc),
 
 		ExampleEntry(0, "MultiBody"),
 		ExampleEntry(1, "MultiDof", "Create a basic btMultiBody with 3-DOF spherical joints (mobilizers). The demo uses a fixed base or a floating base at restart.", MultiDofCreateFunc),

examples/ExampleBrowser/premake4.lua

@@ -197,6 +197,7 @@ project "App_BulletExampleBrowser"
 		"../MultiBody/MultiBodyConstraintFeedback.cpp",
 		"../MultiBody/InvertedPendulumPDControl.cpp",
 		"../RigidBody/RigidBodySoftContact.cpp",
+		"../RigidBody/KinematicRigidBodyExample.cpp",
 		"../ThirdPartyLibs/stb_image/stb_image.cpp",
 		"../ThirdPartyLibs/Wavefront/tiny_obj_loader.*",
 		"../GyroscopicDemo/GyroscopicSetup.cpp",

examples/RigidBody/KinematicRigidBodyExample.cpp

@@ -0,0 +1,234 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2015 Google Inc. http://bulletphysics.org
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+#include "KinematicRigidBodyExample.h"
+//#define USE_MOTIONSTATE 1
+#include "btBulletDynamicsCommon.h"
+#include "LinearMath/btTransformUtil.h"
+#define ARRAY_SIZE_Y 5
+#define ARRAY_SIZE_X 5
+#define ARRAY_SIZE_Z 5
+
+#include "LinearMath/btVector3.h"
+#include "LinearMath/btAlignedObjectArray.h"
+#include "../OpenGLWindow/ShapeData.h"
+
+#include "../CommonInterfaces/CommonRigidBodyBase.h"
+
+
+void kinematicPreTickCallback(btDynamicsWorld* world, btScalar deltaTime)
+{
+	btRigidBody* groundBody = (btRigidBody*)world->getWorldUserInfo();
+	btTransform predictedTrans;
+	btVector3 linearVelocity(0, 0, 0);
+	btVector3 angularVelocity(0, 0.1, 0);
+	btTransformUtil::integrateTransform(groundBody->getWorldTransform(), linearVelocity, angularVelocity, deltaTime, predictedTrans);
+#ifdef USE_MOTIONSTATE
+	groundBody->getMotionState()->setWorldTransform(predictedTrans);
+#else
+	m_groundBody->setWorldTransform(predictedTrans);
+#endif
+}
+
+struct KinematicRigidBodyExample : public CommonRigidBodyBase
+{
+	btRigidBody* m_groundBody;
+
+	KinematicRigidBodyExample(struct GUIHelperInterface* helper)
+		: CommonRigidBodyBase(helper),
+		  m_groundBody(0)
+	{
+	}
+
+	virtual void stepSimulation(float deltaTime)
+	{
+		if (m_dynamicsWorld)
+		{
+			m_dynamicsWorld->stepSimulation(deltaTime);
+		}
+	}
+
+	virtual ~KinematicRigidBodyExample() {}
+	virtual void initPhysics();
+	virtual void renderScene();
+	void resetCamera()
+	{
+		float dist = 4;
+		float pitch = -30;
+		float yaw = 50;
+		float targetPos[3] = {0, 0, 0};
+		m_guiHelper->resetCamera(dist, yaw, pitch, targetPos[0], targetPos[1], targetPos[2]);
+	}
+};
+
+void KinematicRigidBodyExample::initPhysics()
+{
+	m_guiHelper->setUpAxis(1);
+
+	createEmptyDynamicsWorld();
+	m_guiHelper->createPhysicsDebugDrawer(m_dynamicsWorld);
+
+	if (m_dynamicsWorld->getDebugDrawer())
+		m_dynamicsWorld->getDebugDrawer()->setDebugMode(btIDebugDraw::DBG_DrawWireframe + btIDebugDraw::DBG_DrawContactPoints);
+
+	///create a few basic rigid bodies
+	btScalar halfExtentsX = 10.0;
+	btScalar halfExtentsY = 0.1;
+	btScalar halfExtentsZ = 10.0;
+
+	btBoxShape* groundShape = createBoxShape(btVector3(btScalar(10.), btScalar(0.1), btScalar(10.)));
+	btTransform groundTransform;
+	groundTransform.setIdentity();
+	groundTransform.setOrigin(btVector3(0, -halfExtentsY, 0));
+	m_collisionShapes.push_back(groundShape);
+
+
+
+	{
+		btScalar mass(0.);
+		//rigidbody is dynamic if and only if mass is non zero, otherwise static
+		bool isDynamic = (mass != 0.f);
+
+		btVector3 localInertia(0, 0, 0);
+
+#ifdef USE_MOTIONSTATE
+		btDefaultMotionState* myMotionState = new btDefaultMotionState(groundTransform);
+		btRigidBody::btRigidBodyConstructionInfo cInfo(mass, myMotionState, groundShape, localInertia);
+		m_groundBody = new btRigidBody(cInfo);
+#else
+		m_groundBody = new btRigidBody(mass, 0, shape, localInertia);
+		m_groundBody->setWorldTransform(startTransform);
+#endif  //
+
+		m_groundBody->setUserIndex(-1);
+		
+		m_groundBody->forceActivationState(DISABLE_DEACTIVATION);
+		m_groundBody->setCollisionFlags(btCollisionObject::CF_KINEMATIC_OBJECT | btCollisionObject::CF_STATIC_OBJECT);
+		m_dynamicsWorld->addRigidBody(m_groundBody);
+		
+	}
+	m_dynamicsWorld->setInternalTickCallback(kinematicPreTickCallback, m_groundBody, true);
+	{
+		int strideInBytes = 9 * sizeof(float);
+		int numVertices = sizeof(cube_vertices_textured) / strideInBytes;
+		int numIndices = sizeof(cube_indices) / sizeof(int);
+		btScalar textureScaling = 40.0;
+		btAlignedObjectArray<GfxVertexFormat1> verts;
+		verts.resize(numVertices);
+		for (int i = 0; i < numVertices; i++)
+		{
+			verts[i].x = halfExtentsX * cube_vertices_textured[i * 9];
+			verts[i].y = halfExtentsY * cube_vertices_textured[i * 9 + 1];
+			verts[i].z = halfExtentsZ * cube_vertices_textured[i * 9 + 2];
+			verts[i].w = cube_vertices_textured[i * 9 + 3];
+			verts[i].nx = cube_vertices_textured[i * 9 + 4];
+			verts[i].ny = cube_vertices_textured[i * 9 + 5];
+			verts[i].nz = cube_vertices_textured[i * 9 + 6];
+			verts[i].u = cube_vertices_textured[i * 9 + 7] * textureScaling;
+			verts[i].v = cube_vertices_textured[i * 9 + 8] * textureScaling;
+		}
+
+		int red = 173;
+		int green = 199;
+		int blue = 255;
+		btAlignedObjectArray<unsigned char> rgbaTexture;
+		int textureWidth = 256;
+		int textureHeight = 256;
+		rgbaTexture.resize(textureWidth * textureHeight * 3);
+
+		for (int i = 0; i < textureWidth * textureHeight * 3; i++)
+			rgbaTexture[i] = 255;
+		for (int i = 0; i < textureWidth; i++)
+		{
+			for (int j = 0; j < textureHeight; j++)
+			{
+				int a = i < textureWidth / 2 ? 1 : 0;
+				int b = j < textureWidth / 2 ? 1 : 0;
+
+				if (a == b)
+				{
+					rgbaTexture[(i + j * textureWidth) * 3 + 0] = red;
+					rgbaTexture[(i + j * textureWidth) * 3 + 1] = green;
+					rgbaTexture[(i + j * textureWidth) * 3 + 2] = blue;
+				}
+			}
+		}
+		bool flipPixelsY = false;
+		int textureIndex = m_guiHelper->getRenderInterface()->registerTexture(&rgbaTexture[0], textureWidth, textureHeight, flipPixelsY);
+		int shapeId = m_guiHelper->getRenderInterface()->registerShape(&verts[0].x, numVertices, cube_indices, numIndices, B3_GL_TRIANGLES, textureIndex);
+		btVector3 scaling(1, 1, 1);
+		btVector4 color(1, 1, 1, 1);
+		btQuaternion orn;
+		groundTransform.getBasis().getRotation(orn);
+		int graphicsInstanceId = m_guiHelper->getRenderInterface()->registerGraphicsInstance(shapeId, groundTransform.getOrigin(), orn, color, scaling);
+		groundShape->setUserIndex(shapeId);
+		m_groundBody->setUserIndex(graphicsInstanceId);
+	
+	}
+
+	if (1)
+	{
+		//create a few dynamic rigidbodies
+		// Re-using the same collision is better for memory usage and performance
+
+		btBoxShape* colShape = createBoxShape(btVector3(.1, .1, .1));
+
+		//btCollisionShape* colShape = new btSphereShape(btScalar(1.));
+		m_collisionShapes.push_back(colShape);
+
+		/// Create Dynamic Objects
+		btTransform startTransform;
+		startTransform.setIdentity();
+
+		btScalar mass(1.f);
+
+		//rigidbody is dynamic if and only if mass is non zero, otherwise static
+		bool isDynamic = (mass != 0.f);
+
+		btVector3 localInertia(0, 0, 0);
+		if (isDynamic)
+			colShape->calculateLocalInertia(mass, localInertia);
+
+		for (int k = 0; k < ARRAY_SIZE_Y; k++)
+		{
+			for (int i = 0; i < ARRAY_SIZE_X; i++)
+			{
+				for (int j = 0; j < ARRAY_SIZE_Z; j++)
+				{
+					startTransform.setOrigin(btVector3(
+						btScalar(0.2 * i),
+						btScalar(2 + .2 * k),
+						btScalar(0.2 * j)));
+
+					createRigidBody(mass, startTransform, colShape);
+				}
+			}
+		}
+	}
+
+	m_guiHelper->autogenerateGraphicsObjects(m_dynamicsWorld);
+}
+
+void KinematicRigidBodyExample::renderScene()
+{
+	CommonRigidBodyBase::renderScene();
+}
+
+CommonExampleInterface* KinematicRigidBodyExampleCreateFunc(CommonExampleOptions& options)
+{
+	return new KinematicRigidBodyExample(options.m_guiHelper);
+}
+
+B3_STANDALONE_EXAMPLE(KinematicRigidBodyExampleCreateFunc)

examples/RigidBody/KinematicRigidBodyExample.h

@@ -0,0 +1,21 @@
+/*
+Bullet Continuous Collision Detection and Physics Library
+Copyright (c) 2015 Google Inc. http://bulletphysics.org
+
+This software is provided 'as-is', without any express or implied warranty.
+In no event will the authors be held liable for any damages arising from the use of this software.
+Permission is granted to anyone to use this software for any purpose, 
+including commercial applications, and to alter it and redistribute it freely, 
+subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required.
+2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
+3. This notice may not be removed or altered from any source distribution.
+*/
+
+#ifndef KINEMATIC_RIGID_BODY_EXAMPLE_H
+#define KINEMATIC_RIGID_BODY_EXAMPLE_H
+
+class CommonExampleInterface* KinematicRigidBodyExampleCreateFunc(struct CommonExampleOptions& options);
+
+#endif  //KINEMATIC_RIGID_BODY_EXAMPLE_H