Camera.h

/*
 * Copyright (C) 2014 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef CAMERA_H
#define CAMERA_H

#include <QMatrix4x4>
#include <QPointF>
#include <QQuickItem>
#include <QSGNode>
#include <memory>

class Camera : public QQuickItem {
    Q_OBJECT

    Q_PROPERTY(float fov READ getFov WRITE setFov NOTIFY fovChanged)
    Q_PROPERTY(QPointF lookAt READ getLookAt WRITE setLookAt NOTIFY lookAtChanged)
    Q_PROPERTY(float aspectRatio READ getAspectRatio)

public:
    explicit Camera(QQuickItem* parent = 0);
    virtual ~Camera();

    float getFov() const { return mFov; }
    void setFov(float fov);
    QPointF getLookAt() const { return mLookAt; }
    void setLookAt(const QPointF& lookAt);
    float getAspectRatio() const;

    QPointF getParallaxOrigin() const { return mParallaxOrigin; }
    void setParallaxOrigin(const QPointF& value);
    QPointF getParallaxOffset() const { return mParallaxOffset; }
    const QMatrix4x4& getOpenGLViewMatrix() const { return mAppliedGlViewMatrix; }
    const QRectF& getViewportWorldBounds() const { return mViewportWorldBounds; }
    const QRectF& getWorldCullBounds() const { return mWorldCullBounds; }

    void updateTransform();
    void applyTransform();

signals:
    void fovChanged();
    void lookAtChanged();
    void transformApplied();

protected:
    virtual QSGNode* updatePaintNode(QSGNode* oldNode, UpdatePaintNodeData* data) override;

private:
    QPointF toWorldSpace(const QPointF& point) const;
    void updateOpenGLViewMatrix();

    float mFov = 1.0f;
    QPointF mLookAt = QPointF(0.0f, 0.0f);
    float mTransformScale = 1.0f;
    QPointF mTransformTranslate;
    QPointF mParallaxOrigin;
    QPointF mParallaxOffset;
    QRectF mViewportWorldBounds;
    QRectF mWorldCullBounds;
    QMatrix4x4 mGlViewMatrix;
    QMatrix4x4 mAppliedGlViewMatrix;
    std::unique_ptr<QSGNode> mPaintNode;

    // The distance, in world coordinates, from the edges of the camera that objects should be
    // culled.
    constexpr static const float VIEWPORT_CULL_PADDING = 0.5f;
};
Q_DECLARE_METATYPE(Camera*)

#endif // CAMERA_H