Add focus camera and custom camera input (#4493)

* add focus camera and custom camera input Signed-off-by: hultonha <hultonha@amazon.co.uk> * very minor tidy before publishing PR Signed-off-by: hultonha <hultonha@amazon.co.uk> * small updates after PR feedback Signed-off-by: hultonha <hultonha@amazon.co.uk>
2021-10-06 14:52:59 +01:00
parent 5cee9b43b7
commit a40af98394
8 changed files with 198 additions and 20 deletions
@@ -623,15 +623,24 @@ namespace AzFramework
    {
        Camera nextCamera = targetCamera;

-        const auto pivotDirection = targetCamera.m_offset.GetNormalized();
-        nextCamera.m_offset -= pivotDirection * delta;
-        const auto pivotDot = targetCamera.m_offset.Dot(nextCamera.m_offset);
-        const auto distance = nextCamera.m_offset.GetLength() * AZ::GetSign(pivotDot);
-
-        const auto minDistance = 0.01f;
-        if (distance < minDistance || pivotDot < 0.0f)
+        // handle case where pivot and offset may be the same to begin with
+        // choose negative y-axis for offset to default to moving the camera backwards from the pivot (standard centered pivot behavior)
+        const auto pivotDirection = [&targetCamera]
        {
-            nextCamera.m_offset = pivotDirection * minDistance;
+            if (const auto offsetLength = targetCamera.m_offset.GetLength(); AZ::IsCloseMag(offsetLength, 0.0f))
+            {
+                return -AZ::Vector3::CreateAxisY();
+            }
+            else
+            {
+                return targetCamera.m_offset / offsetLength;
+            }
+        }();
+
+        nextCamera.m_offset -= pivotDirection * delta;
+        if (pivotDirection.Dot(nextCamera.m_offset) < 0.0f)
+        {
+            nextCamera.m_offset = pivotDirection * 0.001f;
        }

        return nextCamera;
@@ -771,6 +780,73 @@ namespace AzFramework
        return camera;
    }

+    FocusCameraInput::FocusCameraInput(const InputChannelId& focusChannelId, FocusOffsetFn offsetFn)
+        : m_focusChannelId(focusChannelId)
+        , m_offsetFn(offsetFn)
+    {
+    }
+
+    bool FocusCameraInput::HandleEvents(
+        const InputEvent& event, [[maybe_unused]] const ScreenVector& cursorDelta, [[maybe_unused]] float scrollDelta)
+    {
+        if (const auto* input = AZStd::get_if<DiscreteInputEvent>(&event))
+        {
+            if (input->m_channelId == m_focusChannelId && input->m_state == InputChannel::State::Began)
+            {
+                BeginActivation();
+            }
+        }
+
+        return !Idle();
+    }
+
+    Camera FocusCameraInput::StepCamera(
+        const Camera& targetCamera,
+        [[maybe_unused]] const ScreenVector& cursorDelta,
+        [[maybe_unused]] float scrollDelta,
+        [[maybe_unused]] float deltaTime)
+    {
+        if (Beginning())
+        {
+            // as the camera starts, record the camera we would like to end up as
+            m_nextCamera.m_offset = m_offsetFn(m_pivotFn().GetDistance(targetCamera.Translation()));
+            const auto angles =
+                EulerAngles(AZ::Matrix3x3::CreateFromMatrix3x4(AZ::Matrix3x4::CreateLookAt(targetCamera.Translation(), m_pivotFn())));
+            m_nextCamera.m_pitch = angles.GetX();
+            m_nextCamera.m_yaw = angles.GetZ();
+            m_nextCamera.m_pivot = targetCamera.m_pivot;
+        }
+
+        // end the behavior when the camera is in alignment
+        if (AZ::IsCloseMag(targetCamera.m_pitch, m_nextCamera.m_pitch) && AZ::IsCloseMag(targetCamera.m_yaw, m_nextCamera.m_yaw))
+        {
+            EndActivation();
+        }
+
+        return m_nextCamera;
+    }
+
+    void FocusCameraInput::SetPivotFn(PivotFn pivotFn)
+    {
+        m_pivotFn = AZStd::move(pivotFn);
+    }
+
+    void FocusCameraInput::SetFocusInputChannelId(const InputChannelId& focusChannelId)
+    {
+        m_focusChannelId = focusChannelId;
+    }
+
+    bool CustomCameraInput::HandleEvents(const InputEvent& event, const ScreenVector& cursorDelta, const float scrollDelta)
+    {
+        return m_handleEventsFn(*this, event, cursorDelta, scrollDelta);
+    }
+
+    Camera CustomCameraInput::StepCamera(
+        const Camera& targetCamera, const ScreenVector& cursorDelta, const float scrollDelta, const float deltaTime)
+    {
+        return m_stepCameraFn(*this, targetCamera, cursorDelta, scrollDelta, deltaTime);
+    }
+
    InputEvent BuildInputEvent(const InputChannel& inputChannel, const WindowSize& windowSize)
    {
        const auto& inputChannelId = inputChannel.GetInputChannelId();
@@ -617,6 +617,60 @@ namespace AzFramework
        return true;
    }

+    //! Callback to use for FocusCameraInput when a free look camera is being used.
+    //! @note This is when offset is zero.
+    inline AZ::Vector3 FocusLook(float)
+    {
+        return AZ::Vector3::CreateZero();
+    }
+
+    //! Callback to use for FocusCameraInput when a pivot camera is being used.
+    //! @note This is when offset is non zero.
+    inline AZ::Vector3 FocusPivot(const float length)
+    {
+        return AZ::Vector3::CreateAxisY(-length);
+    }
+
+    using FocusOffsetFn = AZStd::function<AZ::Vector3(float)>;
+
+    //! A focus behavior to align the camera view to the position returned by the pivot function.
+    //! @note This only alters the camera orientation, the translation is unaffected.
+    class FocusCameraInput : public CameraInput
+    {
+    public:
+        using PivotFn = AZStd::function<AZ::Vector3()>;
+
+        FocusCameraInput(const InputChannelId& focusChannelId, FocusOffsetFn offsetFn);
+
+        // CameraInput overrides ...
+        bool HandleEvents(const InputEvent& event, const ScreenVector& cursorDelta, float scrollDelta) override;
+        Camera StepCamera(const Camera& targetCamera, const ScreenVector& cursorDelta, float scrollDelta, float deltaTime) override;
+
+        //! Override the default behavior for how a pivot point is calculated.
+        void SetPivotFn(PivotFn pivotFn);
+
+        void SetFocusInputChannelId(const InputChannelId& focusChannelId);
+
+    private:
+        InputChannelId m_focusChannelId; //!< Input channel to begin the focus camera input.
+        Camera m_nextCamera;
+        PivotFn m_pivotFn;
+        FocusOffsetFn m_offsetFn;
+    };
+
+    //! Provides a CameraInput type that can be implemented without needing to create a new type deriving from CameraInput.
+    //! This can be very useful for specific use cases that are less generally applicable.
+    class CustomCameraInput : public CameraInput
+    {
+    public:
+        // CameraInput overrides ...
+        bool HandleEvents(const InputEvent& event, const ScreenVector& cursorDelta, float scrollDelta) override;
+        Camera StepCamera(const Camera& targetCamera, const ScreenVector& cursorDelta, float scrollDelta, float deltaTime) override;
+
+        AZStd::function<bool(CameraInput&, const InputEvent&, const ScreenVector&, float)> m_handleEventsFn;
+        AZStd::function<Camera(CameraInput&, const Camera&, const ScreenVector&, float, float)> m_stepCameraFn;
+    };
+
    //! Map from a generic InputChannel event to a camera specific InputEvent.
    InputEvent BuildInputEvent(const InputChannel& inputChannel, const WindowSize& windowSize);
 } // namespace AzFramework