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Implemented a custom physics engine #316

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direnbharwani merged 95 commits from SHPhysics into main 2023-01-23 15:55:45 +08:00
Conversation 0 Commits 95 Files Changed 144 +49 -47
9 changed files with 49 additions and 47 deletions
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19
Assets/Scenes/PhysicsSandbox.shade
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@ -45,9 +45,9 @@
NumberOfChildren: 0
Components:
Camera Component:
Position: {x: -0.5, y: 10, z: -3}
Position: {x: 0, y: 0, z: 7}
Pitch: 0
Yaw: 180
Yaw: 0
Roll: 0
Width: 1920
Height: 1080
@ -71,7 +71,7 @@
Auto Mass: false
Mass: 10
Drag: 0.00999999978
Angular Drag: 0.00999999978
Angular Drag: 0
Use Gravity: true
Gravity Scale: 1
Interpolate: true
@ -95,15 +95,6 @@
Density: 1
Position Offset: {x: 0, y: 0, z: 0}
Rotation Offset: {x: 0, y: 0, z: 0}
- Is Trigger: true
Collision Tag: 1
Type: Sphere
Radius: 0.5
Friction: 0.400000006
Bounciness: 0
Density: 1
Position Offset: {x: 0.75, y: 0.5, z: 0}
Rotation Offset: {x: 0, y: 0, z: 0}
IsActive: true
Scripts:
- Type: PhysicsTestObj
@ -280,7 +271,7 @@
NumberOfChildren: 0
Components:
Transform Component:
Translate: {x: 0.524352431, y: 13.5, z: 0.0463808179}
Translate: {x: 1, y: 2, z: 3}
Rotate: {x: -0, y: 0.785398066, z: 0.785398185}
Scale: {x: 0.999999821, y: 0.999999821, z: 0.999999881}
IsActive: true
@ -321,7 +312,7 @@
NumberOfChildren: 0
Components:
Transform Component:
Translate: {x: -0.5, y: 10, z: 0}
Translate: {x: 0, y: 0, z: 3}
Rotate: {x: -0, y: 0, z: -0}
Scale: {x: 1, y: 1, z: 1}
IsActive: true

2
SHADE_Engine/src/Physics/Collision/Broadphase/SHDynamicAABBTree.cpp
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@ -337,7 +337,7 @@ namespace SHADE
{
SHASSERT(index >= 0 && index < capacity, "Trying to free an invalid AABB Tree node!")
nodes[index].next = NULL_NODE;
nodes[index].next = freeList;
nodes[index].height = NULL_NODE;
// Put it back on the free list

14
SHADE_Engine/src/Physics/Collision/Contacts/SHContact.h
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@ -31,22 +31,16 @@ namespace SHADE
/* Type Definit */
/*---------------------------------------------------------------------------------*/
enum class Type : uint8_t
{
VERTEX = 0
, FACE = 1
};
/*---------------------------------------------------------------------------------*/
/* Data Members */
/*---------------------------------------------------------------------------------*/
struct
{
uint8_t indexA;
uint8_t indexB;
uint8_t typeA;
uint8_t typeB;
uint8_t inI;
uint8_t outI;
uint8_t inR;
uint8_t outR;
};
uint32_t key = std::numeric_limits<uint32_t>::max();

1
SHADE_Engine/src/Physics/Collision/Narrowphase/SHCollision.h
View File

@ -82,6 +82,7 @@ namespace SHADE
{
int32_t halfEdgeA = -1;
int32_t halfEdgeB = -1;
int32_t axis = -1;
float bestDistance = std::numeric_limits<float>::lowest();
};

25
SHADE_Engine/src/Physics/Collision/Narrowphase/SHConvexVsConvex.cpp
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@ -48,7 +48,8 @@ namespace SHADE
bool SHCollision::ConvexVsConvex(SHManifold& manifold, const SHCollisionShape& A, const SHCollisionShape& B) noexcept
{
static constexpr float TOLERANCE = 0.1f + SHPHYSICS_LINEAR_SLOP;
static constexpr float ABSOLUTE_TOLERANCE = 0.01f;
static constexpr float RELATIVE_TOLERANCE = 0.95f;
const SHConvexPolyhedron& POLY_A = dynamic_cast<const SHConvexPolyhedron&>(A);
const SHConvexPolyhedron& POLY_B = dynamic_cast<const SHConvexPolyhedron&>(B);
@ -72,7 +73,7 @@ namespace SHADE
const SHConvexPolyhedron* incidentPoly = nullptr;
FaceQuery minFaceQuery;
if (FACE_QUERY_A.bestDistance + TOLERANCE > FACE_QUERY_B.bestDistance)
if (FACE_QUERY_A.bestDistance + ABSOLUTE_TOLERANCE > FACE_QUERY_B.bestDistance * RELATIVE_TOLERANCE)
{
minFaceQuery = FACE_QUERY_A;
referencePoly = &POLY_A;
@ -91,7 +92,7 @@ namespace SHADE
// If an edge pair contains the closest distance,vwe ignore any face queries and find the closest points on
// each edge and use that as the contact point.
if (EDGE_QUERY.bestDistance > minFaceQuery.bestDistance + TOLERANCE)
if (EDGE_QUERY.bestDistance * RELATIVE_TOLERANCE > minFaceQuery.bestDistance + ABSOLUTE_TOLERANCE)
{
const SHHalfEdgeStructure::HalfEdge& HALF_EDGE_A = POLY_A.GetHalfEdge(EDGE_QUERY.halfEdgeA);
const SHHalfEdgeStructure::HalfEdge& HALF_EDGE_B = POLY_B.GetHalfEdge(EDGE_QUERY.halfEdgeB);
@ -111,13 +112,9 @@ namespace SHADE
// In this scenario, we only have one contact
SHContact contact;
contact.featurePair.typeA = SHUtilities::ConvertEnum(SHContactFeatures::Type::VERTEX);
contact.featurePair.indexA = HALF_EDGE_A.tailVertexIndex;
contact.featurePair.typeB = SHUtilities::ConvertEnum(SHContactFeatures::Type::VERTEX);
contact.featurePair.indexB = HALF_EDGE_B.tailVertexIndex;
contact.position = findClosestPointBetweenEdges(POLY_A, POLY_B, EDGE_QUERY.halfEdgeA, EDGE_QUERY.halfEdgeB);
contact.penetration = EDGE_QUERY.bestDistance;
contact.featurePair.key = EDGE_QUERY.axis;
contact.position = findClosestPointBetweenEdges(POLY_A, POLY_B, EDGE_QUERY.halfEdgeA, EDGE_QUERY.halfEdgeB);
contact.penetration = EDGE_QUERY.bestDistance;
manifold.contacts[numContacts++] = contact;
manifold.numContacts = numContacts;
@ -188,6 +185,7 @@ namespace SHADE
const int32_t EDGE_COUNT_A = A.GetHalfEdgeCount();
const int32_t EDGE_COUNT_B = B.GetHalfEdgeCount();
int32_t axis = -1;
for (int32_t i = 0; i < EDGE_COUNT_A; i += 2)
{
for (int32_t j = 0; j < EDGE_COUNT_B; j += 2)
@ -196,12 +194,15 @@ namespace SHADE
if (!IS_MINKOWSKI_FACE)
continue;
++axis;
const float SEPARATION = distanceBetweenEdges(A, B, i, j);
if (SEPARATION > edgeQuery.bestDistance)
{
edgeQuery.bestDistance = SEPARATION;
edgeQuery.halfEdgeA = i;
edgeQuery.halfEdgeB = j;
edgeQuery.axis = axis;
}
}
}
@ -321,10 +322,10 @@ namespace SHADE
* R = (c1a2 / a1 - c2) / ( b2 - a2b1/a1 )
*/
const float A2_OVER_A1 = VB_DOT_VB / VB_DOT_VA;
const float A2_OVER_A1 = VB_DOT_VA == 0.0f ? 0.0f : VB_DOT_VB / VB_DOT_VA;
const float NUMERATOR = C_DOT_VA * A2_OVER_A1 - C_DOT_VB;
const float DENOMINATOR = AV_DOT_VB - AV_DOT_VA * A2_OVER_A1;
const float R = NUMERATOR / DENOMINATOR;
const float R = DENOMINATOR == 0.0f ? NUMERATOR : NUMERATOR / DENOMINATOR;
// Just take a point from A since it's A -> B
return TAIL_A + R * VA;

14
SHADE_Engine/src/Physics/Collision/Narrowphase/SHSphereVsConvex.cpp
View File

@ -179,7 +179,13 @@ namespace SHADE
bool SHCollision::ConvexVsSphere(SHManifold& manifold, const SHCollisionShape& A, const SHCollisionShape& B) noexcept
{
return SphereVsConvex(manifold, B, A);
if (SphereVsConvex(manifold, B, A))
{
manifold.normal = -manifold.normal;
return true;
};
return false;
}
/*-----------------------------------------------------------------------------------*/
@ -326,7 +332,13 @@ namespace SHADE
// Face to vertex is in the opposite direction of any tangent.
const float PROJECTION = SHVec3::Dot(FACE_TO_CENTER, tangent1);
if (PROJECTION < 0)
{
const float DISTANCE_SQUARED = SHVec3::DistanceSquared(faceVertex, CENTER);
if (DISTANCE_SQUARED > RADIUS * RADIUS)
return 0;
return 3;
}
// Belongs in region D by default
return 4;

4
SHADE_Engine/src/Physics/Dynamics/SHContactManager.cpp
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@ -238,6 +238,8 @@ namespace SHADE
void SHContactManager::updateManifold(SHManifold& manifold, const SHManifold& oldManifold) noexcept
{
static const float SQRT_ONE_THIRD = std::sqrtf(1.0f / 3.0f);
// Early out since exiting a collision does not require an update beyond updating the state
if (manifold.state == SHCollisionState::EXIT)
return;
@ -250,7 +252,7 @@ namespace SHADE
const SHVec3& OLD_TANGENT_1 = oldManifold.tangents[1];
// Compute tangents
if (std::fabs(NORMAL.x) >= SHMath::EULER_CONSTANT)
if (std::fabs(NORMAL.x) >= SQRT_ONE_THIRD)
tangent0 = SHVec3{ NORMAL.y, -NORMAL.x, 0.0f };
else
tangent0 = SHVec3{ 0.0f, NORMAL.z, -NORMAL.y };

15
SHADE_Engine/src/Physics/Dynamics/SHContactSolver.cpp
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@ -187,14 +187,7 @@ namespace SHADE
* restituion bias = restitution * (relative velocity /dot normal)
*/
const SHVec3 RV_A = vA + SHVec3::Cross(wA, contact.rA);
const SHVec3 RV_B = vB + SHVec3::Cross(wB, contact.rB);
const float RV_N = SHVec3::Dot(RV_B - RV_A, constraint.normal);
const float ERROR_BIAS = SHPHYSICS_BAUMGARTE * INV_DT * std::min(0.0f, -contact.penetration + SHPHYSICS_LINEAR_SLOP);
const float RESTITUTION_BIAS = std::fabs(RV_N) > SHPHYSICS_RESTITUTION_THRESHOLD ? -constraint.restitution * RV_N : 0.0f;
contact.bias = ERROR_BIAS + RESTITUTION_BIAS;
// Warm starting
// Compute impulses
@ -208,6 +201,14 @@ namespace SHADE
vB += impulse * constraint.invMassB * LINEAR_LOCK_B;
wB += constraint.invInertiaB * SHVec3::Cross(contact.rB, impulse) * ANGULAR_LOCK_B;
const SHVec3 RV_A = vA + SHVec3::Cross(wA, contact.rA);
const SHVec3 RV_B = vB + SHVec3::Cross(wB, contact.rB);
const float RV_N = SHVec3::Dot(RV_B - RV_A, constraint.normal);
const float RESTITUTION_BIAS = std::fabs(RV_N) > SHPHYSICS_RESTITUTION_THRESHOLD ? -constraint.restitution * RV_N : 0.0f;
contact.bias = ERROR_BIAS + RESTITUTION_BIAS;
}
velocityStateA.LinearVelocity = vA;

2
SHADE_Engine/src/Physics/SHPhysicsConstants.h
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@ -26,7 +26,7 @@ namespace SHADE
* @brief
* Linear Collision & Constraint tolerance.
*/
static constexpr float SHPHYSICS_LINEAR_SLOP = 0.005f * SHPHYSICS_LENGTHS_PER_UNIT_METER;
static constexpr float SHPHYSICS_LINEAR_SLOP = 0.05f * SHPHYSICS_LENGTHS_PER_UNIT_METER;
/**
* @brief