How to Fix my Character Controller #984
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Hi, I recently built a project in isolation from my game, I want to use this project to make the character controller feel right. As of right now I am using a As you can see there are various unwanted things that occur with the pure
Do I have any issues with my code which are causing these problems? Here are the relevant files:
The version of this project where the jolt-godot plugin is used feels extremely good out of the box and doesn't have many glaring issues in comparsion. I looked at the godot-jolt and couldn't find any relevant info about a character controller. From what I understand, godot will use their own character controller logic defined here which just sits atop jolt. If these issues are not related to my code, then maybe there's things to learn from the godot implementation? I'd be willing to help contribute if improvements to the character controller (virtual) are in scope. |
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Replies: 2 comments 9 replies
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For an example please look at the CharacterVirtual demo: JoltPhysics/Samples/Tests/Character/CharacterVirtualTest.cpp Lines 37 to 160 in de3517e If you have specific issues, please modify this test to show the problem. |
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It's quite important to have stair stepping turned on. Another thing that I can think of is that you're not using meters as units, the default settings have been tweaked for a character that's roughly 2 m tall. Other than that I don't know what is wrong with your project. I really suggest you find someone with a Windows PC and create a repro in the Samples app. |
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I just went out and bought windows so I can test this myself, I'll see if I can reproduce the behavior over the next week. |
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@jrouwe Now that I can at least run the samples, and have been able to move around the sample map. Just to confirm, if I want to add obstacles to the map such as spiky pyramids to step on I can edit here ? |
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Yes |
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Hi @jrouwe I got around to making a minimal working example for the strange behavior with the virtual character controller. In this implemention I simply use a constant acceleration with friction to move the player around I have no settings set besides the shape and the supporting body. I realize that I could have simply copied many of the the things you use in your default implementation, but my game's movement doesn't work exactly like the one specified in the example. Also I didn't enable very many of the settings/custom logic for the character, because I'd like to be able to understand when and why we need to enable certain settings and what problems they fix. With that knowledge I would like to improve the docs for using the virtual character controller. To test this MWE use this as source for // Jolt Physics Library (https://github.com/jrouwe/JoltPhysics)
// SPDX-FileCopyrightText: 2021 Jorrit Rouwe
// SPDX-License-Identifier: MIT
#include <TestFramework.h>
#include <Tests/Character/CharacterVirtualTest.h>
#include <Jolt/Physics/Collision/Shape/CapsuleShape.h>
#include <Jolt/Physics/Collision/Shape/RotatedTranslatedShape.h>
#include <Layers.h>
#include <Renderer/DebugRendererImp.h>
#include <Application/DebugUI.h>
JPH_IMPLEMENT_RTTI_VIRTUAL(CharacterVirtualTest)
{
JPH_ADD_BASE_CLASS(CharacterVirtualTest, CharacterBaseTest)
}
void CharacterVirtualTest::Initialize()
{
CharacterBaseTest::Initialize();
// Create 'player' character
Ref<CharacterVirtualSettings> settings = new CharacterVirtualSettings();
settings->mShape = mStandingShape;
settings->mSupportingVolume = Plane(Vec3::sAxisY(), -cCharacterRadiusStanding); // Accept contacts that touch the lower sphere of the capsule
mCharacter = new CharacterVirtual(settings, RVec3::sZero(), Quat::sIdentity(), 0, mPhysicsSystem);
mCharacter->SetListener(this);
}
void CharacterVirtualTest::PrePhysicsUpdate(const PreUpdateParams &inParams)
{
CharacterBaseTest::PrePhysicsUpdate(inParams);
// Draw character pre update (the sim is also drawn pre update)
RMat44 com = mCharacter->GetCenterOfMassTransform();
RMat44 world_transform = mCharacter->GetWorldTransform();
#ifdef JPH_DEBUG_RENDERER
mCharacter->GetShape()->Draw(mDebugRenderer, com, Vec3::sReplicate(1.0f), Color::sGreen, false, true);
#endif // JPH_DEBUG_RENDERER
// Draw shape including padding (only implemented for capsules right now)
if (static_cast<const RotatedTranslatedShape *>(mCharacter->GetShape())->GetInnerShape()->GetSubType() == EShapeSubType::Capsule)
{
if (mCharacter->GetShape() == mStandingShape)
mDebugRenderer->DrawCapsule(com, 0.5f * cCharacterHeightStanding, cCharacterRadiusStanding + mCharacter->GetCharacterPadding(), Color::sGrey, DebugRenderer::ECastShadow::Off, DebugRenderer::EDrawMode::Wireframe);
else
mDebugRenderer->DrawCapsule(com, 0.5f * cCharacterHeightCrouching, cCharacterRadiusCrouching + mCharacter->GetCharacterPadding(), Color::sGrey, DebugRenderer::ECastShadow::Off, DebugRenderer::EDrawMode::Wireframe);
}
// Remember old position
RVec3 old_position = mCharacter->GetPosition();
// Settings for our update function
CharacterVirtual::ExtendedUpdateSettings update_settings;
// Update the character position
mCharacter->ExtendedUpdate(inParams.mDeltaTime,
-mCharacter->GetUp() * mPhysicsSystem->GetGravity().Length(),
update_settings,
mPhysicsSystem->GetDefaultBroadPhaseLayerFilter(Layers::MOVING),
mPhysicsSystem->GetDefaultLayerFilter(Layers::MOVING),
{ },
{ },
*mTempAllocator);
// Calculate effective velocity
RVec3 new_position = mCharacter->GetPosition();
Vec3 velocity = Vec3(new_position - old_position) / inParams.mDeltaTime;
// Draw state of character
DrawCharacterState(mCharacter, world_transform, velocity);
// Draw labels on ramp blocks
for (size_t i = 0; i < mRampBlocks.size(); ++i)
mDebugRenderer->DrawText3D(mBodyInterface->GetPosition(mRampBlocks[i]), StringFormat("PushesPlayer: %s\nPushable: %s", (i & 1) != 0? "True" : "False", (i & 2) != 0? "True" : "False"), Color::sWhite, 0.25f);
}
void CharacterVirtualTest::HandleInput(Vec3Arg inMovementDirection, bool inJump, bool inSwitchStance, float inDeltaTime)
{
const int movement_acceleration = 15;
const int jump_impulse_force = 1000;
const float friction = 0.983f;
Vec3 updated_velocity = mCharacter->GetLinearVelocity();
updated_velocity += movement_acceleration * inMovementDirection * inDeltaTime;
updated_velocity *= friction;
updated_velocity += mPhysicsSystem->GetGravity() * inDeltaTime;
if (inJump && mCharacter->GetGroundState() == CharacterVirtual::EGroundState::OnGround) {
updated_velocity += jump_impulse_force * mCharacter->GetUp() * inDeltaTime;
}
mCharacter->SetLinearVelocity(updated_velocity);
}
void CharacterVirtualTest::AddCharacterMovementSettings(DebugUI* inUI, UIElement* inSubMenu)
{
inUI->CreateCheckBox(inSubMenu, "Enable Character Inertia", sEnableCharacterInertia, [](UICheckBox::EState inState) { sEnableCharacterInertia = inState == UICheckBox::STATE_CHECKED; });
}
void CharacterVirtualTest::AddConfigurationSettings(DebugUI *inUI, UIElement *inSubMenu)
{
inUI->CreateComboBox(inSubMenu, "Back Face Mode", { "Ignore", "Collide" }, (int)sBackFaceMode, [=](int inItem) { sBackFaceMode = (EBackFaceMode)inItem; });
inUI->CreateSlider(inSubMenu, "Up Rotation X (degrees)", RadiansToDegrees(sUpRotationX), -90.0f, 90.0f, 1.0f, [](float inValue) { sUpRotationX = DegreesToRadians(inValue); });
inUI->CreateSlider(inSubMenu, "Up Rotation Z (degrees)", RadiansToDegrees(sUpRotationZ), -90.0f, 90.0f, 1.0f, [](float inValue) { sUpRotationZ = DegreesToRadians(inValue); });
inUI->CreateSlider(inSubMenu, "Max Slope Angle (degrees)", RadiansToDegrees(sMaxSlopeAngle), 0.0f, 90.0f, 1.0f, [](float inValue) { sMaxSlopeAngle = DegreesToRadians(inValue); });
inUI->CreateSlider(inSubMenu, "Max Strength (N)", sMaxStrength, 0.0f, 500.0f, 1.0f, [](float inValue) { sMaxStrength = inValue; });
inUI->CreateSlider(inSubMenu, "Character Padding", sCharacterPadding, 0.01f, 0.5f, 0.01f, [](float inValue) { sCharacterPadding = inValue; });
inUI->CreateSlider(inSubMenu, "Penetration Recovery Speed", sPenetrationRecoverySpeed, 0.0f, 1.0f, 0.05f, [](float inValue) { sPenetrationRecoverySpeed = inValue; });
inUI->CreateSlider(inSubMenu, "Predictive Contact Distance", sPredictiveContactDistance, 0.01f, 1.0f, 0.01f, [](float inValue) { sPredictiveContactDistance = inValue; });
inUI->CreateCheckBox(inSubMenu, "Enable Walk Stairs", sEnableWalkStairs, [](UICheckBox::EState inState) { sEnableWalkStairs = inState == UICheckBox::STATE_CHECKED; });
inUI->CreateCheckBox(inSubMenu, "Enable Stick To Floor", sEnableStickToFloor, [](UICheckBox::EState inState) { sEnableStickToFloor = inState == UICheckBox::STATE_CHECKED; });
}
void CharacterVirtualTest::SaveState(StateRecorder &inStream) const
{
CharacterBaseTest::SaveState(inStream);
mCharacter->SaveState(inStream);
bool is_standing = mCharacter->GetShape() == mStandingShape;
inStream.Write(is_standing);
inStream.Write(mAllowSliding);
inStream.Write(mDesiredVelocity);
}
void CharacterVirtualTest::RestoreState(StateRecorder &inStream)
{
CharacterBaseTest::RestoreState(inStream);
mCharacter->RestoreState(inStream);
bool is_standing = mCharacter->GetShape() == mStandingShape; // Initialize variable for validation mode
inStream.Read(is_standing);
mCharacter->SetShape(is_standing? mStandingShape : mCrouchingShape, FLT_MAX, { }, { }, { }, { }, *mTempAllocator);
inStream.Read(mAllowSliding);
inStream.Read(mDesiredVelocity);
}
void CharacterVirtualTest::OnAdjustBodyVelocity(const CharacterVirtual *inCharacter, const Body &inBody2, Vec3 &ioLinearVelocity, Vec3 &ioAngularVelocity)
{
// Apply artificial velocity to the character when standing on the conveyor belt
// if (inBody2.GetID() == mConveyorBeltBody)
// ioLinearVelocity += Vec3(0, 0, 2);
}
void CharacterVirtualTest::OnContactAdded(const CharacterVirtual *inCharacter, const BodyID &inBodyID2, const SubShapeID &inSubShapeID2, RVec3Arg inContactPosition, Vec3Arg inContactNormal, CharacterContactSettings &ioSettings)
{
// Draw a box around the character when it enters the sensor
if (inBodyID2 == mSensorBody)
{
AABox box = inCharacter->GetShape()->GetWorldSpaceBounds(inCharacter->GetCenterOfMassTransform(), Vec3::sReplicate(1.0f));
mDebugRenderer->DrawBox(box, Color::sGreen, DebugRenderer::ECastShadow::Off, DebugRenderer::EDrawMode::Wireframe);
}
// // Dynamic boxes on the ramp go through all permutations
// Array<BodyID>::const_iterator i = find(mRampBlocks.begin(), mRampBlocks.end(), inBodyID2);
// if (i != mRampBlocks.end())
// {
// size_t index = i - mRampBlocks.begin();
// ioSettings.mCanPushCharacter = (index & 1) != 0;
// ioSettings.mCanReceiveImpulses = (index & 2) != 0;
// }
//
// // If we encounter an object that can push us, enable sliding
// if (ioSettings.mCanPushCharacter && mPhysicsSystem->GetBodyInterface().GetMotionType(inBodyID2) != EMotionType::Static)
// mAllowSliding = true;
}
void CharacterVirtualTest::OnContactSolve(const CharacterVirtual *inCharacter, const BodyID &inBodyID2, const SubShapeID &inSubShapeID2, RVec3Arg inContactPosition, Vec3Arg inContactNormal, Vec3Arg inContactVelocity, const PhysicsMaterial *inContactMaterial, Vec3Arg inCharacterVelocity, Vec3 &ioNewCharacterVelocity)
{
// // Don't allow the player to slide down static not-too-steep surfaces when not actively moving and when not on a moving platform
// if (!mAllowSliding && inContactVelocity.IsNearZero() && !inCharacter->IsSlopeTooSteep(inContactNormal))
// ioNewCharacterVelocity = Vec3::sZero();
}With this setup you'll see that the virtual character controller seems to "twitch" around a lot more, especially when it comes to the ramps, when you try to go onto the ramp the character tends to get stuck in a similar way that occurs in my project. |
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Hello, The problem with your solution is that you never reset the vertical velocity of the character (unless you jump). If you add: at the end of
You'll see that moving into this ramp results in a tiny bit of movement towards the ramp and a very large movement towards the floor. So you'll slide down the ramp rather than up. This is why the example separates the velocity in a horizontal and a vertical velocity and resets the vertical velocity when you're moving into the floor. |
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Hey @jrouwe that worked really well, I ended up changing the code to be: void CharacterVirtualTest::HandleInput(Vec3Arg inMovementDirection, bool inJump, bool inSwitchStance, float inDeltaTime)
{
const int movement_acceleration = 15;
const int jump_impulse_force = 1000;
const float friction = 0.983f;
Vec3 updated_velocity = mCharacter->GetLinearVelocity();
updated_velocity += movement_acceleration * inMovementDirection * inDeltaTime;
updated_velocity *= friction;
if (mCharacter->GetGroundState() == CharacterVirtual::EGroundState::OnGround) {
updated_velocity.SetY(0.0f);
if (inJump) {
updated_velocity += jump_impulse_force * mCharacter->GetUp() * inDeltaTime;
}
}
updated_velocity += mPhysicsSystem->GetGravity() * inDeltaTime;
mCharacter->SetLinearVelocity(updated_velocity);
}Would it be within scope to add this code as a minimal working implementation for the |
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No, I think the examples provide a better minimal example. Your code here doesn't take moving platforms into account. If you were to jump on one you'd slide off as if it were ice. Also your code doesn't support surface velocity. |
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Ok, sounds good. |
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Hello,
The problem with your solution is that you never reset the vertical velocity of the character (unless you jump). If you add:
at the end of
CharacterVirtualTest::HandleInputyou'll see that theupdated_velocityvector is ever increasing. If we for example go to the ramp:You'll see that moving into this ramp results in a tiny bit of movement towards the ramp and a very large movement towards the floor. So you'll slide down the ramp rather than up.
This is why the example separates the velocity in a horizontal and a vertical velocity and resets the vertical veloci…