chain shape material (#874)

adjusted chain time of impact to improve performance

include/box2d/box2d.h

@@ -708,6 +708,13 @@ B2_API void b2Chain_SetRestitution( b2ChainId chainId, float restitution );
 /// Get the chain restitution
 B2_API float b2Chain_GetRestitution( b2ChainId chainId );
 
+/// Set the chain material
+/// @see b2ChainDef::material
+B2_API void b2Chain_SetMaterial( b2ChainId chainId, int material );
+
+/// Get the chain material
+B2_API int b2Chain_GetMaterial( b2ChainId chainId );
+
 /// Chain identifier validation. Provides validation for up to 64K allocations.
 B2_API bool b2Chain_IsValid( b2ChainId id );
 

include/box2d/types.h

@@ -426,6 +426,10 @@ typedef struct b2ChainDef
 	/// The restitution (elasticity) usually in the range [0,1].
 	float restitution;
 
+	/// User material identifier. This is passed with query results and to friction and restitution
+	/// combining functions. It is not used internally.
+	int material;
+
 	/// Contact filtering data.
 	b2Filter filter;
 

samples/sample_benchmark.cpp

@@ -16,6 +16,7 @@
 #include <vector>
 
 #ifndef NDEBUG
+extern "C" int b2_toiCalls;
 extern "C" int b2_toiHitCount;
 #endif
 
@@ -1476,6 +1477,7 @@ class BenchmarkSpinner : public Sample
 		}
 
 #ifndef NDEBUG
+		b2_toiCalls = 0;
 		b2_toiHitCount = 0;
 #endif
 
@@ -1486,13 +1488,16 @@ class BenchmarkSpinner : public Sample
 	{
 		Sample::Step( settings );
 
-		if ( m_stepCount == 1000 )
+		if ( m_stepCount == 1000 && false )
 		{
-			m_stepCount += 0;
+			// 0.1 : 46544, 25752
+			// 0.25 : 5745, 1947
+			// 0.5 : 2197, 660
+			settings.pause = true;
 		}
+
 #ifndef NDEBUG
-		g_draw.DrawString( 5, m_textLine, "toi hits = %d", b2_toiHitCount );
-		m_textLine += m_textIncrement;
+		DrawTextLine( "toi calls, hits = %d, %d", b2_toiCalls, b2_toiHitCount );
 #endif
 	}
 

samples/sample_continuous.cpp

@@ -330,15 +330,15 @@ class ChainDrop : public Sample
 
 		b2ShapeDef shapeDef = b2DefaultShapeDef();
 
-		//b2Circle circle = { { 0.0f, 0.0f }, 0.5f };
-		//m_shapeId = b2CreateCircleShape( m_bodyId, &shapeDef, &circle );
+		b2Circle circle = { { 0.0f, 0.0f }, 0.5f };
+		m_shapeId = b2CreateCircleShape( m_bodyId, &shapeDef, &circle );
 
 		//b2Capsule capsule = { { -0.5f, 0.0f }, { 0.5f, 0.0 }, 0.25f };
 		//m_shapeId = b2CreateCapsuleShape( m_bodyId, &shapeDef, &capsule );
 
-		float h = 0.5f;
-		b2Polygon box = b2MakeBox( h, h );
-		m_shapeId = b2CreatePolygonShape( m_bodyId, &shapeDef, &box );
+		//float h = 0.5f;
+		//b2Polygon box = b2MakeBox( h, h );
+		//m_shapeId = b2CreatePolygonShape( m_bodyId, &shapeDef, &box );
 	}
 
 	void UpdateUI() override

samples/sample_shapes.cpp

@@ -118,6 +118,7 @@ class ChainShape : public Sample
 		chainDef.customColor = b2_colorSteelBlue;
 		chainDef.isLoop = true;
 		chainDef.friction = 0.2f;
+		chainDef.material = 42;
 
 		b2BodyDef bodyDef = b2DefaultBodyDef();
 		m_groundId = b2CreateBody( m_worldId, &bodyDef );
@@ -210,8 +211,7 @@ class ChainShape : public Sample
 		g_draw.DrawSegment( b2Vec2_zero, { 0.0f, 0.5f }, b2_colorGreen );
 
 #ifndef NDEBUG
-		g_draw.DrawString( 5, m_textLine, "toi calls, hits = %d, %d", b2_toiCalls, b2_toiHitCount );
-		m_textLine += m_textIncrement;
+		DrawTextLine( "toi calls, hits = %d, %d", b2_toiCalls, b2_toiHitCount );
 #endif
 	}
 
@@ -814,7 +814,7 @@ class Restitution : public Sample
 			}
 		}
 
-		b2Circle circle = { };
+		b2Circle circle = {};
 		circle.radius = 0.5f;
 
 		b2Polygon box = b2MakeBox( 0.5f, 0.5f );

src/shape.c

@@ -371,13 +371,15 @@ b2ChainId b2CreateChain( b2BodyId bodyId, const b2ChainDef* def )
 	chainShape->generation += 1;
 	chainShape->friction = def->friction;
 	chainShape->restitution = def->restitution;
+	chainShape->material = def->material;
 
 	body->headChainId = chainId;
 
 	b2ShapeDef shapeDef = b2DefaultShapeDef();
 	shapeDef.userData = def->userData;
-	shapeDef.restitution = def->restitution;
 	shapeDef.friction = def->friction;
+	shapeDef.restitution = def->restitution;
+	shapeDef.material = def->material;
 	shapeDef.filter = def->filter;
 	shapeDef.customColor = def->customColor;
 	shapeDef.enableContactEvents = false;
@@ -1417,6 +1419,34 @@ float b2Chain_GetRestitution( b2ChainId chainId )
 	return chainShape->restitution;
 }
 
+void b2Chain_SetMaterial( b2ChainId chainId, int material )
+{
+	b2World* world = b2GetWorldLocked( chainId.world0 );
+	if ( world == NULL )
+	{
+		return;
+	}
+
+	b2ChainShape* chainShape = b2GetChainShape( world, chainId );
+	chainShape->material = material;
+
+	int count = chainShape->count;
+
+	for ( int i = 0; i < count; ++i )
+	{
+		int shapeId = chainShape->shapeIndices[i];
+		b2Shape* shape = b2ShapeArray_Get( &world->shapes, shapeId );
+		shape->material = material;
+	}
+}
+
+int b2Chain_GetMaterial( b2ChainId chainId )
+{
+	b2World* world = b2GetWorld( chainId.world0 );
+	b2ChainShape* chainShape = b2GetChainShape( world, chainId );
+	return chainShape->material;
+}
+
 int b2Shape_GetContactCapacity( b2ShapeId shapeId )
 {
 	b2World* world = b2GetWorldLocked( shapeId.world0 );

src/shape.h

@@ -57,6 +57,7 @@ typedef struct b2ChainShape
 	int* shapeIndices;
 	float friction;
 	float restitution;
+	int material;
 	uint16_t generation;
 } b2ChainShape;
 

src/solver.c

@@ -289,7 +289,7 @@ static bool b2ContinuousQueryCallback( int proxyId, int shapeId, void* context )
 			b2Vec2 c2 = continuousContext->centroid2;
 			float offset2 = b2Cross( b2Sub( c2, p1 ), e );
 
-			const float allowedFraction = 0.1f;
+			const float allowedFraction = 0.25f;
 			if ( offset1 < 0.0f || offset1 - offset2 < allowedFraction * fastBodySim->minExtent )
 			{
 				// Minimal clipping