z-bar-qt/Plugins/ZShell/Blobs/blobrect.cpp

#include "blobrect.hpp"
#include "blobgroup.hpp"

#include <algorithm>
#include <cmath>

BlobRect::BlobRect(QQuickItem* parent)
	: BlobShape(parent) {
}

BlobRect::~BlobRect() {
	if (m_group)
		m_group->removeShape(this);
}

void BlobRect::updatePolish() {
	BlobShape::updatePolish();

	if (m_physicsActive) {
		// Check if deformation is visually imperceptible
		float totalDelta = std::abs(m_dm00 - 1.0f) + std::abs(m_dm01) + std::abs(m_dm11 - 1.0f);
		float totalVel = std::abs(m_dmVel00) + std::abs(m_dmVel01) + std::abs(m_dmVel11);

		if (totalDelta < 0.004f && totalVel < 0.05f) {
			// Snap to rest, no visible deformation
			m_dm00 = 1.0f;
			m_dm01 = 0.0f;
			m_dm11 = 1.0f;
			m_dmVel00 = m_dmVel01 = m_dmVel11 = 0.0f;
			m_deformMatrix = QMatrix4x4();
			emit rawDeformMatrixChanged();
			updateCenteredDeformMatrix();
			m_physicsActive = false;
		} else {
			QMetaObject::invokeMethod(
				this,
				[this]() {
				if (m_physicsActive && m_group)
					m_group->markDirty();
			},
				Qt::QueuedConnection);
		}
	}
}

void BlobRect::updatePhysics() {
	const QPointF scenePos = mapToScene(QPointF(width() / 2.0, height() / 2.0));

	if (!m_hasPrevPos) {
		m_prevScenePos = scenePos;
		m_elapsed.start();
		m_hasPrevPos = true;
		return;
	}

	const float dt = static_cast<float>(m_elapsed.restart()) / 1000.0f;
	if (dt > 0.1f || dt < 0.001f) {
		m_prevScenePos = scenePos;
		// Still check atRest on skipped frames to avoid getting stuck
		if (m_physicsActive)
			checkAtRest(0.0f);
		return;
	}

	const float velX = static_cast<float>(scenePos.x() - m_prevScenePos.x()) / dt;
	const float velY = static_cast<float>(scenePos.y() - m_prevScenePos.y()) / dt;
	m_prevScenePos = scenePos;

	const float speed = std::sqrt(velX * velX + velY * velY);

	if (!m_physicsActive) {
		if (speed < 5.0f)
			return;
		m_physicsActive = true;
	}

	// Compute target deformation matrix from velocity
	// R(θ) * diag(stretch, compress) * R(θ)^T
	const float kStretchFactor = static_cast<float>(m_deformScale);
	constexpr float kMaxStretch = 0.35f;

	float target00 = 1.0f;
	float target01 = 0.0f;
	float target11 = 1.0f;

	if (speed > 5.0f) {
		const float targetStretch = 1.0f + std::min(speed * kStretchFactor, kMaxStretch);
		const float targetCompress = 1.0f / targetStretch;

		const float cosA = velX / speed;
		const float sinA = velY / speed;
		const float cos2 = cosA * cosA;
		const float sin2 = sinA * sinA;
		const float cs = cosA * sinA;

		target00 = targetStretch * cos2 + targetCompress * sin2;
		target01 = (targetStretch - targetCompress) * cs;
		target11 = targetStretch * sin2 + targetCompress * cos2;
	}

	// Underdamped spring on each matrix component
	const float kStiffness = static_cast<float>(m_stiffness);
	const float kDamping = static_cast<float>(m_damping);

	const float accel00 = -kStiffness * (m_dm00 - target00) - kDamping * m_dmVel00;
	m_dmVel00 += accel00 * dt;
	m_dm00 += m_dmVel00 * dt;

	const float accel01 = -kStiffness * (m_dm01 - target01) - kDamping * m_dmVel01;
	m_dmVel01 += accel01 * dt;
	m_dm01 += m_dmVel01 * dt;

	const float accel11 = -kStiffness * (m_dm11 - target11) - kDamping * m_dmVel11;
	m_dmVel11 += accel11 * dt;
	m_dm11 += m_dmVel11 * dt;

	m_deformMatrix = QMatrix4x4(m_dm00, m_dm01, 0, 0, m_dm01, m_dm11, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1);
	emit rawDeformMatrixChanged();
	updateCenteredDeformMatrix();

	checkAtRest(speed);
}

void BlobRect::setTopLeftRadius(qreal r) {
	if (!qFuzzyCompare(m_topLeftRadius, r)) {
		m_topLeftRadius = r;
		emit topLeftRadiusChanged();
		if (m_group)
			m_group->markDirty();
	}
}

void BlobRect::setTopRightRadius(qreal r) {
	if (!qFuzzyCompare(m_topRightRadius, r)) {
		m_topRightRadius = r;
		emit topRightRadiusChanged();
		if (m_group)
			m_group->markDirty();
	}
}

void BlobRect::setBottomLeftRadius(qreal r) {
	if (!qFuzzyCompare(m_bottomLeftRadius, r)) {
		m_bottomLeftRadius = r;
		emit bottomLeftRadiusChanged();
		if (m_group)
			m_group->markDirty();
	}
}

void BlobRect::setBottomRightRadius(qreal r) {
	if (!qFuzzyCompare(m_bottomRightRadius, r)) {
		m_bottomRightRadius = r;
		emit bottomRightRadiusChanged();
		if (m_group)
			m_group->markDirty();
	}
}

void BlobRect::cornerRadii(float out[4]) const {
	const auto base = static_cast<float>(m_radius);
	out[0] = m_topRightRadius >= 0 ? static_cast<float>(m_topRightRadius) : base;
	out[1] = m_bottomRightRadius >= 0 ? static_cast<float>(m_bottomRightRadius) : base;
	out[2] = m_bottomLeftRadius >= 0 ? static_cast<float>(m_bottomLeftRadius) : base;
	out[3] = m_topLeftRadius >= 0 ? static_cast<float>(m_topLeftRadius) : base;
}

bool BlobRect::isExcluded(const BlobShape* other) const {
	for (const auto& ptr : m_exclude) {
		if (ptr == other)
			return true;
	}
	return false;
}

QQmlListProperty<BlobRect> BlobRect::exclude() {
	return QQmlListProperty<BlobRect>(
		this, nullptr, &excludeAppend, &excludeCount, &excludeAt, &excludeClear, &excludeReplace, &excludeRemoveLast);
}

void BlobRect::excludeAppend(QQmlListProperty<BlobRect>* prop, BlobRect* rect) {
	auto* self = static_cast<BlobRect*>(prop->object);
	self->m_exclude.append(rect);
	if (self->m_group)
		self->m_group->markDirty();
	emit self->excludeChanged();
}

qsizetype BlobRect::excludeCount(QQmlListProperty<BlobRect>* prop) {
	auto* self = static_cast<BlobRect*>(prop->object);
	return self->m_exclude.size();
}

BlobRect* BlobRect::excludeAt(QQmlListProperty<BlobRect>* prop, qsizetype index) {
	auto* self = static_cast<BlobRect*>(prop->object);
	return self->m_exclude.at(index);
}

void BlobRect::excludeClear(QQmlListProperty<BlobRect>* prop) {
	auto* self = static_cast<BlobRect*>(prop->object);
	if (self->m_exclude.isEmpty())
		return;
	self->m_exclude.clear();
	if (self->m_group)
		self->m_group->markDirty();
	emit self->excludeChanged();
}

void BlobRect::excludeReplace(QQmlListProperty<BlobRect>* prop, qsizetype index, BlobRect* rect) {
	auto* self = static_cast<BlobRect*>(prop->object);
	self->m_exclude[index] = rect;
	if (self->m_group)
		self->m_group->markDirty();
	emit self->excludeChanged();
}

void BlobRect::excludeRemoveLast(QQmlListProperty<BlobRect>* prop) {
	auto* self = static_cast<BlobRect*>(prop->object);
	if (self->m_exclude.isEmpty())
		return;
	self->m_exclude.removeLast();
	if (self->m_group)
		self->m_group->markDirty();
	emit self->excludeChanged();
}

void BlobRect::checkAtRest(float speed) {
	constexpr float kEpsilon = 0.002f;
	const bool atRest = std::abs(m_dm00 - 1.0f) < kEpsilon && std::abs(m_dm01) < kEpsilon &&
	                    std::abs(m_dm11 - 1.0f) < kEpsilon && std::abs(m_dmVel00) < kEpsilon &&
	                    std::abs(m_dmVel01) < kEpsilon && std::abs(m_dmVel11) < kEpsilon && speed < 5.0f;

	if (atRest) {
		m_dm00 = 1.0f;
		m_dm01 = 0.0f;
		m_dm11 = 1.0f;
		m_dmVel00 = 0.0f;
		m_dmVel01 = 0.0f;
		m_dmVel11 = 0.0f;
		m_deformMatrix = QMatrix4x4(); // identity
		emit rawDeformMatrixChanged();
		updateCenteredDeformMatrix();
		m_physicsActive = false;
	}
}