SIMD rolling resistance

erincatto · Jan 26, 2025 · bdea14c · bdea14c
1 parent b6984de
commit bdea14c
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Showing 6 changed files with 122 additions and 199 deletions.
diff --git a/samples/car.cpp b/samples/car.cpp
@@ -53,6 +53,7 @@ void Car::Spawn( b2WorldId worldId, b2Vec2 position, float scale, float hertz, f
 
 	shapeDef.density = 2.0f / scale;
 	shapeDef.friction = 1.5f;
+	shapeDef.rollingResistance = 0.1f;
 
 	bodyDef.position = b2Add( { -1.0f * scale, 0.35f * scale }, position );
 	bodyDef.allowFastRotation = true;

diff --git a/samples/sample_benchmark.cpp b/samples/sample_benchmark.cpp
@@ -221,6 +221,7 @@ class BenchmarkBarrel : public Sample
 				{
 					m_bodies[index] = b2CreateBody( m_worldId, &bodyDef );
 					circle.radius = RandomFloatRange( 0.25f, 0.75f );
+					shapeDef.rollingResistance = 0.2f;
 					b2CreateCircleShape( m_bodies[index], &shapeDef, &circle );
 				}
 				else if ( m_shapeType == e_capsuleShape )
@@ -230,6 +231,7 @@ class BenchmarkBarrel : public Sample
 					float length = RandomFloatRange( 0.25f, 1.0f );
 					capsule.center1 = { 0.0f, -0.5f * length };
 					capsule.center2 = { 0.0f, 0.5f * length };
+					shapeDef.rollingResistance = 0.2f;
 					b2CreateCapsuleShape( m_bodies[index], &shapeDef, &capsule );
 				}
 				else if ( m_shapeType == e_mixShape )

diff --git a/samples/sample_joints.cpp b/samples/sample_joints.cpp
@@ -2072,11 +2072,11 @@ class Driving : public Sample
 
 		m_throttle = 0.0f;
 		m_speed = 35.0f;
-		m_torque = 2.5f;
+		m_torque = 5.0f;
 		m_hertz = 5.0f;
 		m_dampingRatio = 0.7f;
 
-		m_car.Spawn( m_worldId, { 0.0f, 0.0f }, 1.0f, m_hertz, m_dampingRatio, m_torque, NULL );
+		m_car.Spawn( m_worldId, { 0.0f, 0.0f }, 1.0f, m_hertz, m_dampingRatio, m_torque, nullptr );
 	}
 
 	void UpdateUI() override
@@ -2103,7 +2103,7 @@ class Driving : public Sample
 			m_car.SetSpeed( m_throttle * m_speed );
 		}
 
-		if ( ImGui::SliderFloat( "Torque", &m_torque, 0.0f, 5.0f, "%.1f" ) )
+		if ( ImGui::SliderFloat( "Torque", &m_torque, 0.0f, 10.0f, "%.1f" ) )
 		{
 			m_car.SetTorque( m_torque );
 		}
@@ -2491,7 +2491,7 @@ class ScissorLift : public Sample
 		m_liftJointId = b2CreateDistanceJoint( m_worldId, &distanceDef );
 
 		Car car;
-		car.Spawn( m_worldId, { 0.0f, y + 2.0f }, 1.0f, 3.0f, 0.7f, 0.0f, NULL );
+		car.Spawn( m_worldId, { 0.0f, y + 2.0f }, 1.0f, 3.0f, 0.7f, 0.0f, nullptr );
 	}
 
 	void UpdateUI() override

diff --git a/samples/sample_shapes.cpp b/samples/sample_shapes.cpp
@@ -967,6 +967,7 @@ class RollingResistance : public Sample
 		}
 
 		m_lift = 0.0f;
+		m_resistScale = 0.02f;
 		CreateScene();
 	}
 
@@ -990,7 +991,7 @@ class RollingResistance : public Sample
 			bodyDef.linearVelocity = { 5.0f, 0.0f };
 
 			b2BodyId bodyId = b2CreateBody( m_worldId, &bodyDef );
-			shapeDef.rollingResistance = 0.1f * i;
+			shapeDef.rollingResistance = m_resistScale * i;
 			b2CreateCircleShape( bodyId, &shapeDef, &circle );
 		}
 	}
@@ -1029,7 +1030,7 @@ class RollingResistance : public Sample
 
 		for ( int i = 0; i < 20; ++i )
 		{
-			g_draw.DrawString( { -41.5f, 2.0f * i + 1.0f }, "%.2f", 0.1f * i );
+			g_draw.DrawString( { -41.5f, 2.0f * i + 1.0f }, "%.2f", m_resistScale * i );
 		}
 	}
 
@@ -1038,6 +1039,7 @@ class RollingResistance : public Sample
 		return new RollingResistance( settings );
 	}
 
+	float m_resistScale;
 	float m_lift;
 };
 

diff --git a/src/constraint_graph.c b/src/constraint_graph.c
@@ -23,7 +23,7 @@
 // cause horrible cache stalls. To make this feasible I would need a way to block these writes.
 
 // This is used for debugging by making all constraints be assigned to overflow.
-#define B2_FORCE_OVERFLOW 1
+#define B2_FORCE_OVERFLOW 0
 
 _Static_assert( B2_GRAPH_COLOR_COUNT == 12, "graph color count assumed to be 12" );