Add an Orthogonal Projection option to the Camera Gem (#2414)

* Add an Orthogonal Projection option to the Camera Gem

This adds a check-box to opt into an ortho projection along with a half-width parameter to adjust the size of the visible area. Includes some light tweaks to ensure debug rendering looks OK and that we generate a correct camera state for these non-perspective views.

Known issue: while in "Be this camera" mode in the Editor using an ortho projection manipulators aren't working correctly. This appears to be a downstream issue with CameraState consumers not actually checking the ortho flag.

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Fix some typos

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Account for reversed depth buffer

Signed-off-by: nvsickle <nvsickle@amazon.com>

* Clarify depth reversal for MakeOrthographicMatrixRH

Signed-off-by: nvsickle <nvsickle@amazon.com>

Code/Editor/EditorViewportWidget.cpp

@@ -463,7 +463,7 @@ void EditorViewportWidget::Update()
 
     if (m_updateCameraPositionNextTick)
     {
-        auto cameraState = m_renderViewport->GetCameraState();
+        auto cameraState = GetCameraState();
         AZ::Matrix3x4 matrix;
         matrix.SetBasisAndTranslation(cameraState.m_side, cameraState.m_forward, cameraState.m_up, cameraState.m_position);
         auto m = AZMatrix3x4ToLYMatrix3x4(matrix);
@@ -1138,6 +1138,17 @@ void EditorViewportWidget::OnMenuSelectCurrentCamera()
 
 AzFramework::CameraState EditorViewportWidget::GetCameraState()
 {
+    if (m_viewEntityId.IsValid())
+    {
+        bool cameraStateAcquired = false;
+        AzFramework::CameraState cameraState;
+        Camera::EditorCameraViewRequestBus::BroadcastResult(cameraStateAcquired,
+            &Camera::EditorCameraViewRequestBus::Events::GetCameraState, cameraState);
+        if (cameraStateAcquired)
+        {
+            return cameraState;
+        }
+    }
     return m_renderViewport->GetCameraState();
 }
 

Code/Framework/AzCore/AzCore/Math/MatrixUtils.cpp

@@ -71,7 +71,7 @@ namespace AZ
         return &out;
     }
 
-    Matrix4x4* MakeOrthographicMatrixRH(Matrix4x4& out, float left, float right, float bottom, float top, float nearDist, float farDist)
+    Matrix4x4* MakeOrthographicMatrixRH(Matrix4x4& out, float left, float right, float bottom, float top, float nearDist, float farDist, bool reverseDepth)
     {
         AZ_Assert(right > left, "right should be greater than left");
         // valid to have matrix invert top/bottom and far/near
@@ -83,6 +83,11 @@ namespace AZ
             return nullptr;
         }
 
+        if (reverseDepth)
+        {
+            AZStd::swap(nearDist, farDist);
+        }
+
         out.SetRow(0,   2.f/(right - left), 0.f,                    0.f,                        - (right + left) / (right - left)   );
         out.SetRow(1,   0.f,                2.f / (top - bottom),   0.f,                        - (top + bottom) / (top - bottom)   );
         out.SetRow(2,   0.f,                0.f,                    1 / (nearDist - farDist),   nearDist / (nearDist - farDist)     );

Code/Framework/AzCore/AzCore/Math/MatrixUtils.h

@@ -57,8 +57,9 @@ namespace AZ
     //! @param top The y coordinate of top view-plane
     //! @param near Distance to the near view-plane. Must be no less than zero.
     //! @param far Distance to the far view-plane. Must be greater than zero.
+    //! @param reverseDepth Set to true to reverse depth which means near distance maps to 1 and far distance maps to 0.
     //! @return Pointer of the output matrix
-    Matrix4x4* MakeOrthographicMatrixRH(Matrix4x4& out, float left, float right, float bottom, float top, float nearDist, float farDist);
+    Matrix4x4* MakeOrthographicMatrixRH(Matrix4x4& out, float left, float right, float bottom, float top, float nearDist, float farDist, bool reverseDepth = false);
 
     //! Transforms a position by a matrix. This function can be used with any generic cases which include projection matrices.
     Vector3 MatrixTransformPosition(const Matrix4x4& matrix, const Vector3& inPosition);

Code/Framework/AzFramework/AzFramework/Components/CameraBus.h

@@ -63,6 +63,13 @@ namespace Camera
         //! @return The camera frustum's height
         virtual float GetFrustumHeight() = 0;
 
+        //! Gets whether or not the camera is using an orthographic projection.
+        //! @return True if the camera is using an orthographic projection, or false if the camera is using a perspective projection.
+        virtual bool IsOrthographic() = 0;
+
+        //! @return The half width of the orthographic projection, @see SetOrthographicHalfWidth.
+        virtual float GetOrthographicHalfWidth() = 0;
+
         //! Sets the camera's field of view in degrees between 0 < fov < 180 degrees
         //! @param fov The camera frustum's new field of view in degrees
         virtual void SetFov(float fov)
@@ -95,6 +102,15 @@ namespace Camera
         //! @param height The camera frustum's new height
         virtual void SetFrustumHeight(float height) = 0;
 
+        //! Sets whether or not the camera should use an orthographic projection in place of a perspective projection.
+        //! @param orthographic If true, the camera will use an orthographic projection
+        virtual void SetOrthographic(bool orthographic) = 0;
+
+        //! Sets the half-width of the orthographic projection.
+        //! @params halfWidth Used to calculate the bounds of the projection while in orthographic mode.
+        //! The height is calculated automatically based on the aspect ratio.
+        virtual void SetOrthographicHalfWidth(float halfWidth) = 0;
+
         //! Makes the camera the active view
         virtual void MakeActiveView() = 0;
 

Code/Framework/AzToolsFramework/AzToolsFramework/API/EditorCameraBus.h

@@ -102,7 +102,7 @@ namespace Camera
     using EditorCameraNotificationBus = AZ::EBus<EditorCameraNotifications>;
 
     /**
-     * This bus is for requesting any camera-view-related changes
+     * This bus is for requesting any camera-view-related changes or information
      */
     class EditorCameraViewRequests : public AZ::ComponentBus
     {
@@ -115,6 +115,11 @@ namespace Camera
          * Sets this camera as the active view in the scene, otherwise restores the default editor camera if it was already active
          */
         virtual void ToggleCameraAsActiveView() = 0;
+
+        /**
+        * Gets the camera state associated with this view.
+        */
+        virtual bool GetCameraState(AzFramework::CameraState& cameraState) = 0;
     };
 
     using EditorCameraViewRequestBus = AZ::EBus<EditorCameraViewRequests>;