Faster island split

include/box2d/base.h

@@ -113,14 +113,9 @@ B2_API b2Version b2GetVersion( void );
 #endif
 
 #if !defined( NDEBUG ) || defined( B2_ENABLE_ASSERT )
-B2_API int b2InternalAssertFcn( const char* condition, const char* fileName, int lineNumber );
+B2_API int b2InternalAssert( const char* condition, const char* fileName, int lineNumber );
 #define B2_ASSERT( condition )                                                                                                   \
-	do                                                                                                                           \
-	{                                                                                                                            \
-		if ( !( condition ) && b2InternalAssertFcn( #condition, __FILE__, (int)__LINE__ ) )                                      \
-			B2_BREAKPOINT;                                                                                                       \
-	}                                                                                                                            \
-	while ( 0 )
+	( (void)( ( !!( condition ) ) || ( b2InternalAssert( #condition, __FILE__, (int)( __LINE__ ) ), 0 ) ) )
 #else
 #define B2_ASSERT( ... ) ( (void)0 )
 #endif

samples/CMakeLists.txt

@@ -67,6 +67,20 @@ set(JSMN_DIR ${CMAKE_SOURCE_DIR}/extern/jsmn)
 add_library(jsmn INTERFACE ${JSMN_DIR}/jsmn.h)
 target_include_directories(jsmn INTERFACE ${JSMN_DIR})
 
+# implot for drawing real time plots
+set(IMPLOT_DIR ${CMAKE_SOURCE_DIR}/extern/implot)
+
+add_library(
+	implot STATIC
+	${IMPLOT_DIR}/implot_demo.cpp
+	${IMPLOT_DIR}/implot.cpp
+	${IMPLOT_DIR}/implot_items.cpp
+	${IMPLOT_DIR}/implot_internal.h
+	${IMPLOT_DIR}/implot.h
+)
+target_link_libraries(implot PUBLIC imgui)
+target_include_directories(implot PUBLIC ${IMPLOT_DIR})
+
 set(BOX2D_SAMPLE_FILES
 	car.cpp
 	car.h
@@ -114,7 +128,7 @@ if (BOX2D_COMPILE_WARNING_AS_ERROR)
 endif()
 
 target_include_directories(samples PRIVATE ${CMAKE_CURRENT_SOURCE_DIR} ${JSMN_DIR})
-target_link_libraries(samples PUBLIC box2d shared imgui glfw glad enkiTS)
+target_link_libraries(samples PUBLIC box2d shared imgui implot glfw glad enkiTS)
 
 # target_compile_definitions(samples PRIVATE "$<$<CONFIG:DEBUG>:SAMPLES_DEBUG>")
 # message(STATUS "runtime = ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}")

samples/main.cpp

@@ -26,6 +26,7 @@
 #include "imgui.h"
 #include "imgui_impl_glfw.h"
 #include "imgui_impl_opengl3.h"
+#include "implot.h"
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -135,6 +136,7 @@ static void CreateUI( GLFWwindow* window, const char* glslVersion )
 {
 	IMGUI_CHECKVERSION();
 	ImGui::CreateContext();
+	ImPlot::CreateContext();
 
 	bool success = ImGui_ImplGlfw_InitForOpenGL( window, false );
 	if ( success == false )
@@ -182,6 +184,7 @@ static void DestroyUI()
 {
 	ImGui_ImplOpenGL3_Shutdown();
 	ImGui_ImplGlfw_Shutdown();
+	ImPlot::DestroyContext();
 	ImGui::DestroyContext();
 }
 
@@ -438,7 +441,7 @@ static void UpdateUI()
 				ImGui::Checkbox( "Islands", &s_context.debugDraw.drawIslands );
 				ImGui::Checkbox( "Counters", &s_context.drawCounters );
 				ImGui::Checkbox( "Profile", &s_context.drawProfile );
-				ImGui::Separator();
+				ImGui::Checkbox( "Frame Time", &s_context.frameTime );
 
 				ImGui::Separator();
 

samples/sample.cpp

@@ -10,6 +10,7 @@
 #include "TaskScheduler.h"
 #include "draw.h"
 #include "imgui.h"
+#include "implot.h"
 #include "random.h"
 
 // consider using https://github.com/skeeto/pdjson
@@ -301,11 +302,17 @@ Sample::Sample( SampleContext* context )
 	m_mouseJointId = b2_nullJointId;
 
 	m_stepCount = 0;
+	m_didStep = false;
 
 	m_mouseBodyId = b2_nullBodyId;
 	m_mousePoint = {};
 	m_mouseForceScale = 100.0f;
 
+	memset( m_profiles, 0, sizeof( m_profiles ) );
+	m_currentProfileIndex = 0;
+	m_profileReadIndex = 0;
+	m_profileWriteIndex = 0;
+
 	m_maxProfile = {};
 	m_totalProfile = {};
 
@@ -499,6 +506,8 @@ void Sample::ResetProfile()
 
 void Sample::Step()
 {
+	m_didStep = false;
+
 	float timeStep = m_context->hertz > 0.0f ? 1.0f / m_context->hertz : 0.0f;
 
 	if ( m_context->pause )
@@ -561,7 +570,18 @@ void Sample::Step()
 
 	if ( timeStep > 0.0f )
 	{
-		++m_stepCount;
+		m_stepCount += 1;
+		m_didStep = true;
+
+		if ( m_profileWriteIndex - m_profileReadIndex == m_profileCapacity )
+		{
+			m_profileReadIndex += 1;
+		}
+
+		m_currentProfileIndex = m_profileWriteIndex & ( m_profileCapacity - 1 );
+		m_profiles[m_currentProfileIndex] = b2World_GetProfile( m_worldId );
+
+		m_profileWriteIndex += 1;
 	}
 
 	if ( m_context->drawCounters )
@@ -590,8 +610,9 @@ void Sample::Step()
 	}
 
 	// Track maximum profile times
+	if (m_didStep)
 	{
-		b2Profile p = b2World_GetProfile( m_worldId );
+		b2Profile p = m_profiles[m_currentProfileIndex];
 		m_maxProfile.step = b2MaxFloat( m_maxProfile.step, p.step );
 		m_maxProfile.pairs = b2MaxFloat( m_maxProfile.pairs, p.pairs );
 		m_maxProfile.collide = b2MaxFloat( m_maxProfile.collide, p.collide );
@@ -641,8 +662,6 @@ void Sample::Step()
 
 	if ( m_context->drawProfile )
 	{
-		b2Profile p = b2World_GetProfile( m_worldId );
-
 		b2Profile aveProfile = {};
 		if ( m_stepCount > 0 )
 		{
@@ -671,6 +690,7 @@ void Sample::Step()
 			aveProfile.sensors = scale * m_totalProfile.sensors;
 		}
 
+		const b2Profile& p = m_profiles[m_currentProfileIndex];
 		DrawTextLine( "step [ave] (max) = %5.2f [%6.2f] (%6.2f)", p.step, aveProfile.step, m_maxProfile.step );
 		DrawTextLine( "pairs [ave] (max) = %5.2f [%6.2f] (%6.2f)", p.pairs, aveProfile.pairs, m_maxProfile.pairs );
 		DrawTextLine( "collide [ave] (max) = %5.2f [%6.2f] (%6.2f)", p.collide, aveProfile.collide, m_maxProfile.collide );
@@ -711,6 +731,53 @@ void Sample::Step()
 	}
 }
 
+void Sample::UpdateGui()
+{
+	if ( m_context->frameTime )
+	{
+		float frameTimeHeight = 400.0f;
+		float frameTimeWidth = 800.0f;
+
+		ImGui::SetNextWindowPos( { 30.0f, 30.0f }, ImGuiCond_FirstUseEver );
+		ImGui::SetNextWindowSize( { frameTimeWidth, frameTimeHeight }, ImGuiCond_FirstUseEver );
+
+		ImGui::Begin( "Frame Time", nullptr, ImGuiWindowFlags_NoCollapse );
+
+		ImGui::PushItemWidth( ImGui::GetWindowWidth() - 20.0f );
+
+		float maxValue = 0.0f;
+		float times[m_profileCapacity];
+		float stepTimes[m_profileCapacity];
+		float collideTimes[m_profileCapacity];
+		float solveTimes[m_profileCapacity];
+		int count = m_profileWriteIndex - m_profileReadIndex;
+		for ( int i = 0; i < count; ++i )
+		{
+			int index = ( m_profileReadIndex + i ) & ( m_profileCapacity - 1 );
+			times[i] = i / 60.0f;
+			stepTimes[i] = m_profiles[index].step;
+			collideTimes[i] = m_profiles[index].collide;
+			solveTimes[i] = m_profiles[index].solve;
+			maxValue = b2MaxFloat( stepTimes[i], maxValue );
+		}
+
+		// This is the pixel size, not the range.
+		ImVec2 plotSize = { -1, 22.0f * ImGui::GetTextLineHeight() };
+		if ( ImPlot::BeginPlot( "Profile", plotSize, ImPlotFlags_NoTitle ) )
+		{
+			ImPlot::SetupAxes( "t", "ms" );
+			ImPlot::SetupAxesLimits( 0, m_profileCapacity / 60.0, 0.0, maxValue, ImPlotCond_Always );
+			ImPlot::PlotLine( "step", times, stepTimes, count );
+			ImPlot::PlotLine( "collide", times, collideTimes, count );
+			ImPlot::PlotLine( "solve", times, solveTimes, count );
+			ImPlot::EndPlot();
+		}
+
+		ImGui::PopItemWidth();
+		ImGui::End();
+	}
+}
+
 void Sample::ShiftOrigin( b2Vec2 newOrigin )
 {
 	// m_world->ShiftOrigin(newOrigin);

samples/sample.h

@@ -38,6 +38,7 @@ struct SampleContext
 	bool enableRecycling = true;
 	bool enableSleep = true;
 	bool showUI = true;
+	bool frameTime = false;
 
 	// These are persisted
 	int sampleIndex = 0;
@@ -58,9 +59,7 @@ class Sample
 
 	void ResetText();
 	virtual void Step( );
-	virtual void UpdateGui()
-	{
-	}
+	virtual void UpdateGui();
 	virtual void Keyboard( int )
 	{
 	}
@@ -81,6 +80,7 @@ class Sample
 
 	static constexpr int m_maxTasks = 64;
 	static constexpr int m_maxThreads = 64;
+	static constexpr int m_profileCapacity = 512;
 
 #ifdef NDEBUG
 	static constexpr bool m_isDebug = false;
@@ -104,12 +104,18 @@ class Sample
 	b2Vec2 m_mousePoint;
 	float m_mouseForceScale;
 	int m_stepCount;
+	int m_textLine;
+	int m_textIncrement;
+
+	b2Profile m_profiles[m_profileCapacity];
+	int m_currentProfileIndex;
+	int m_profileReadIndex;
+	int m_profileWriteIndex;
+
 	b2Profile m_maxProfile;
 	b2Profile m_totalProfile;
 
-private:
-	int m_textLine;
-	int m_textIncrement;
+	bool m_didStep;
 };
 
 typedef Sample* SampleCreateFcn( SampleContext* context );

samples/sample_benchmark.cpp

@@ -310,6 +310,8 @@ class BenchmarkBarrel : public Sample
 
 	void UpdateGui() override
 	{
+		Sample::UpdateGui();
+
 		float fontSize = ImGui::GetFontSize();
 		float height = 6.0f * fontSize;
 		ImGui::SetNextWindowPos( ImVec2( 0.5f * fontSize, m_camera->height - height - 2.0f * fontSize ), ImGuiCond_Once );

src/CMakeLists.txt

@@ -20,6 +20,7 @@ set(BOX2D_SOURCE_FILES
 	contact.h
 	contact_solver.c
 	contact_solver.h
+	container.h
 	core.c
 	core.h
 	ctz.h

src/body.c

@@ -84,77 +84,45 @@ b2BodyState* b2GetBodyState( b2World* world, b2Body* body )
 static void b2CreateIslandForBody( b2World* world, int setIndex, b2Body* body )
 {
 	B2_ASSERT( body->islandId == B2_NULL_INDEX );
-	B2_ASSERT( body->islandPrev == B2_NULL_INDEX );
-	B2_ASSERT( body->islandNext == B2_NULL_INDEX );
 	B2_ASSERT( setIndex != b2_disabledSet );
 
 	b2Island* island = b2CreateIsland( world, setIndex );
-
+	b2Array_Push( island->bodies, body->id );
 	body->islandId = island->islandId;
-	island->headBody = body->id;
-	island->tailBody = body->id;
-	island->bodyCount = 1;
+	body->islandIndex = 0;
+
+	b2ValidateIsland( world, island->islandId );
 }
 
 static void b2RemoveBodyFromIsland( b2World* world, b2Body* body )
 {
 	if ( body->islandId == B2_NULL_INDEX )
 	{
-		B2_ASSERT( body->islandPrev == B2_NULL_INDEX );
-		B2_ASSERT( body->islandNext == B2_NULL_INDEX );
+		B2_ASSERT( body->islandIndex == B2_NULL_INDEX );
 		return;
 	}
 
 	int islandId = body->islandId;
-	b2Island* island = b2IslandArray_Get( &world->islands, islandId );
-
-	// Fix the island's linked list of sims
-	if ( body->islandPrev != B2_NULL_INDEX )
-	{
-		b2Body* prevBody = b2BodyArray_Get( &world->bodies, body->islandPrev );
-		prevBody->islandNext = body->islandNext;
-	}
-
-	if ( body->islandNext != B2_NULL_INDEX )
-	{
-		b2Body* nextBody = b2BodyArray_Get( &world->bodies, body->islandNext );
-		nextBody->islandPrev = body->islandPrev;
-	}
+	b2Island* island = b2Array_Get( world->islands, islandId );
 
-	B2_ASSERT( island->bodyCount > 0 );
-	island->bodyCount -= 1;
-	bool islandDestroyed = false;
+	b2RemoveUpdate( island->bodies, world->bodies, body->id, islandIndex );
 
-	if ( island->headBody == body->id )
+	if (island->bodies.count == 0)
 	{
-		island->headBody = body->islandNext;
+		// Destroy empty island
+		B2_ASSERT( island->contactCount == 0 );
+		B2_ASSERT( island->jointCount == 0 );
 
-		if ( island->headBody == B2_NULL_INDEX )
-		{
-			// Destroy empty island
-			B2_ASSERT( island->tailBody == body->id );
-			B2_ASSERT( island->bodyCount == 0 );
-			B2_ASSERT( island->contactCount == 0 );
-			B2_ASSERT( island->jointCount == 0 );
-
-			// Free the island
-			b2DestroyIsland( world, island->islandId );
-			islandDestroyed = true;
-		}
+		// Free the island
+		b2DestroyIsland( world, island->islandId );
 	}
-	else if ( island->tailBody == body->id )
-	{
-		island->tailBody = body->islandPrev;
-	}
-
-	if ( islandDestroyed == false )
+	else
 	{
 		b2ValidateIsland( world, islandId );
 	}
 
 	body->islandId = B2_NULL_INDEX;
-	body->islandPrev = B2_NULL_INDEX;
-	body->islandNext = B2_NULL_INDEX;
+	body->islandIndex = B2_NULL_INDEX;
 }
 
 static void b2DestroyBodyContacts( b2World* world, b2Body* body, bool wakeBodies )
@@ -311,8 +279,7 @@ b2BodyId b2CreateBody( b2WorldId worldId, const b2BodyDef* def )
 	body->headJointKey = B2_NULL_INDEX;
 	body->jointCount = 0;
 	body->islandId = B2_NULL_INDEX;
-	body->islandPrev = B2_NULL_INDEX;
-	body->islandNext = B2_NULL_INDEX;
+	body->islandIndex = B2_NULL_INDEX;
 	body->bodyMoveIndex = B2_NULL_INDEX;
 	body->id = bodyId;
 	body->mass = 0.0f;
@@ -1541,7 +1508,7 @@ void b2Body_SetAwake( b2BodyId bodyId, bool awake )
 	}
 	else if ( awake == false && body->setIndex == b2_awakeSet )
 	{
-		b2Island* island = b2IslandArray_Get( &world->islands, body->islandId );
+		b2Island* island = b2Array_Get( world->islands, body->islandId );
 		if ( island->constraintRemoveCount > 0 )
 		{
 			// Must split the island before sleeping. This is expensive.