// Copyright (C) 2019 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only

#include "qquick3dfrustumcamera_p.h"

#include <QtQuick3DRuntimeRender/private/qssgrendercamera_p.h>

#include <QtMath>
#include <QtQuick3DUtils/private/qssgutils_p.h>

#include "qquick3dutils_p.h"

#include "qquick3dnode_p_p.h"

QT_BEGIN_NAMESPACE

/*!
    \qmltype FrustumCamera
    \inherits PerspectiveCamera
    \inqmlmodule QtQuick3D
    \brief Defines a PerspectiveCamera with a custom frustum.

    A \l Camera defines how the content of the 3D scene is projected onto a 2D surface,
    such as a View3D. A scene needs at least one \l Camera in order to visualize its
    contents.

    It is possible to position and rotate the \l Camera like any other spatial \l{QtQuick3D::Node}{Node} in
    the scene. The \l{QtQuick3D::Node}{Node}'s location and orientation determines where the \l Camera is in
    the scene, and what direction it is facing. The default orientation of the \l Camera
    has its forward vector pointing along the negative Z axis and its up vector along
    the positive Y axis.

    The FrustumCamera type provides a PerspectiveCamera where the frustum bounds can be
    customized. This can be useful for creating asymmetrical frustums.

    The following example creates a FrustumCamera at [0, 0, 100] in the scene.
    The \l {PerspectiveCamera::clipNear}{near plane} is placed 100 units in front of the camera at the origin.
    The intersection of the frustum and the near plane is then given by the rectangle that has a bottom left corner at [-5, -5],
    and a top right corner at [5, 5], and continues until it intersect the
    \l {PerspectiveCamera::clipFar}{far plane}, which is located 1000 units from the camera at [0, 0, -900].

    \note The \l{PerspectiveCamera::fieldOfViewOrientation}{vertical field of view} angle is
    a product of the distance between the camera, the \l {PerspectiveCamera::clipNear}{near plane}
    and the length between the \c top and \c bottom of the near plane.

    \note If the top and bottom, or left right, values are asymmetric,
    the apex of the frustum will be shifted, effectively offsetting the camera from its location.

    \code
    FrustumCamera {
        position: Qt.vector3d(0, 0, 100)
        clipNear: 100
        clipFar: 1000
        top: 5
        bottom: -5
        left: -5
        right: 5
    }
    \endcode

    \sa PerspectiveCamera, OrthographicCamera, CustomCamera
*/

/*!
 * \internal
 */
QQuick3DFrustumCamera::QQuick3DFrustumCamera(QQuick3DNode *parent)
    : QQuick3DPerspectiveCamera(*(new QQuick3DNodePrivate(QQuick3DNodePrivate::Type::CustomFrustumCamera)), parent)
{}

/*!
    \qmlproperty real FrustumCamera::top

    The \c top value specifies the top of the \l{PerspectiveCamera::clipNear}{near clip plane},
    relative to the camera's position in local coordinates.
*/
float QQuick3DFrustumCamera::top() const
{
    return m_top;
}

/*!
    \qmlproperty real FrustumCamera::bottom

    The \c bottom value specifies the bottom of the \l{PerspectiveCamera::clipNear}{near clip plane},
    relative to the camera's position in local coordinates.
*/
float QQuick3DFrustumCamera::bottom() const
{
    return m_bottom;
}

/*!
    \qmlproperty real FrustumCamera::right

    The \c right value specifies the right of the \l{PerspectiveCamera::clipNear}{near clip plane},
    relative to the camera's position in local coordinates.
*/
float QQuick3DFrustumCamera::right() const
{
    return m_right;
}

/*!
    \qmlproperty real FrustumCamera::left

    The \c left value specifies the left of the \l{PerspectiveCamera::clipNear}{near clip plane},
    relative to the camera's position in local coordinates.
*/
float QQuick3DFrustumCamera::left() const
{
    return m_left;
}

void QQuick3DFrustumCamera::setTop(float top)
{
    if (qFuzzyCompare(m_top, top))
        return;

    m_top = top;
    emit topChanged();
    update();
}

void QQuick3DFrustumCamera::setBottom(float bottom)
{
    if (qFuzzyCompare(m_bottom, bottom))
        return;

    m_bottom = bottom;
    emit bottomChanged();
    update();
}

void QQuick3DFrustumCamera::setRight(float right)
{
    if (qFuzzyCompare(m_right, right))
        return;

    m_right = right;
    emit rightChanged();
    update();
}

void QQuick3DFrustumCamera::setLeft(float left)
{
    if (qFuzzyCompare(m_left, left))
        return;

    m_left = left;
    emit leftChanged();
    update();
}

QSSGRenderGraphObject *QQuick3DFrustumCamera::updateSpatialNode(QSSGRenderGraphObject *node)
{
    // NOTE: The frustum camera extends the perspective camera!
    QSSGRenderCamera *camera = static_cast<QSSGRenderCamera *>(QQuick3DPerspectiveCamera::updateSpatialNode(node));
    if (camera) {
        const bool changed = ((int(qUpdateIfNeeded(camera->customFrustum, { m_top, m_bottom, m_left, m_right }))) != 0);
        if (changed)
            camera->markDirty(QSSGRenderCamera::DirtyFlag::CameraDirty);
    }

    return camera;
}

QT_END_NAMESPACE
