/// <summary>
/// Updates resources associated with a holographic camera's swap chain.
/// The app does not access the swap chain directly, but it does create
/// resource views for the back buffer.
/// </summary>
public void CreateResourcesForBackBuffer(
DeviceResources deviceResources,
ref HolographicCameraRenderingParameters cameraParameters
)
{
var device = deviceResources.D3DDevice;
// Get the WinRT object representing the holographic camera's back buffer.
IDirect3DSurface surface = cameraParameters.Direct3D11BackBuffer;
// Get a DXGI interface for the holographic camera's back buffer.
// Holographic cameras do not provide the DXGI swap chain, which is owned
// by the system. The Direct3D back buffer resource is provided using WinRT
// interop APIs.
InteropStatics.IDirect3DDxgiInterfaceAccess surfaceDxgiInterfaceAccess = surface as InteropStatics.IDirect3DDxgiInterfaceAccess;
IntPtr pResource = surfaceDxgiInterfaceAccess.GetInterface(InteropStatics.ID3D11Resource);
// Determine if the back buffer has changed. If so, ensure that the render target view
// is for the current back buffer.
if ((null == d3dBackBuffer) || (d3dBackBuffer.NativePointer != pResource))
{
// Clean up references to previous resources.
this.RemoveAndDispose(ref d3dBackBuffer);
this.RemoveAndDispose(ref d3dRenderTargetView);
// This can change every frame as the system moves to the next buffer in the
// swap chain. This mode of operation will occur when certain rendering modes
// are activated.
d3dBackBuffer = this.ToDispose(new SharpDX.Direct3D11.Texture2D(pResource));
// Create a render target view of the back buffer.
// Creating this resource is inexpensive, and is better than keeping track of
// the back buffers in order to pre-allocate render target views for each one.
d3dRenderTargetView = this.ToDispose(new RenderTargetView(device, d3dBackBuffer));
// Get the DXGI format for the back buffer.
// This information can be accessed by the app using CameraResources::GetBackBufferDXGIFormat().
Texture2DDescription backBufferDesc = BackBufferTexture2D.Description;
dxgiFormat = backBufferDesc.Format;
// Check for render target size changes.
Size currentSize = holographicCamera.RenderTargetSize;
if (d3dRenderTargetSize != currentSize)
{
// Set render target size.
d3dRenderTargetSize = HolographicCamera.RenderTargetSize;
// A new depth stencil view is also needed.
this.RemoveAndDispose(ref d3dDepthStencilView);
}
}
// We took a reference to a COM interface when we got the native pointer; here, we
// release that reference.
Marshal.Release(pResource);
// Refresh depth stencil resources, if needed.
if (null == DepthStencilView)
{
// Create a depth stencil view for use with 3D rendering if needed.
var depthStencilDesc = new Texture2DDescription
{
Format = SharpDX.DXGI.Format.D16_UNorm,
Width = (int)RenderTargetSize.Width,
Height = (int)RenderTargetSize.Height,
ArraySize = IsRenderingStereoscopic ? 2 : 1, // Create two textures when rendering in stereo.
MipLevels = 1, // Use a single mipmap level.
BindFlags = BindFlags.DepthStencil,
SampleDescription = new SharpDX.DXGI.SampleDescription(1, 0)
};
using (var depthStencil = new Texture2D(device, depthStencilDesc))
{
var depthStencilViewDesc = new DepthStencilViewDescription();
depthStencilViewDesc.Dimension = IsRenderingStereoscopic ? DepthStencilViewDimension.Texture2DArray : DepthStencilViewDimension.Texture2D;
depthStencilViewDesc.Texture2DArray.ArraySize = IsRenderingStereoscopic ? 2 : 0;
d3dDepthStencilView = this.ToDispose(new DepthStencilView(device, depthStencil, depthStencilViewDesc));
}
}
// Create the constant buffer, if needed.
if (null == viewProjectionConstantBuffer)
{
// Create a constant buffer to store view and projection matrices for the camera.
ViewProjectionConstantBuffer viewProjectionConstantBufferData = new ViewProjectionConstantBuffer();
viewProjectionConstantBuffer = this.ToDispose(SharpDX.Direct3D11.Buffer.Create(
device,
BindFlags.ConstantBuffer,
ref viewProjectionConstantBufferData));
}
}
/// <summary>
/// Updates the constant buffer for the display with view and projection
/// matrices for the current frame.
/// </summary>
public void UpdateViewProjectionBuffer(
DeviceResources deviceResources,
HolographicCameraPose cameraPose,
SpatialCoordinateSystem coordinateSystem
)
{
// The system changes the viewport on a per-frame basis for system optimizations.
d3dViewport.X = (float)cameraPose.Viewport.Left;
d3dViewport.Y = (float)cameraPose.Viewport.Top;
d3dViewport.Width = (float)cameraPose.Viewport.Width;
d3dViewport.Height = (float)cameraPose.Viewport.Height;
d3dViewport.MinDepth = 0;
d3dViewport.MaxDepth = 1;
// The projection transform for each frame is provided by the HolographicCameraPose.
HolographicStereoTransform cameraProjectionTransform = cameraPose.ProjectionTransform;
// Get a container object with the view and projection matrices for the given
// pose in the given coordinate system.
HolographicStereoTransform?viewTransformContainer = cameraPose.TryGetViewTransform(coordinateSystem);
// If TryGetViewTransform returns null, that means the pose and coordinate system
// cannot be understood relative to one another; content cannot be rendered in this
// coordinate system for the duration of the current frame.
// This usually means that positional tracking is not active for the current frame, in
// which case it is possible to use a SpatialLocatorAttachedFrameOfReference to render
// content that is not world-locked instead.
ViewProjectionConstantBuffer viewProjectionConstantBufferData = new ViewProjectionConstantBuffer();
bool viewTransformAcquired = viewTransformContainer.HasValue;
if (viewTransformAcquired)
{
// Otherwise, the set of view transforms can be retrieved.
HolographicStereoTransform viewCoordinateSystemTransform = viewTransformContainer.Value;
// Update the view matrices. Holographic cameras (such as Microsoft HoloLens) are
// constantly moving relative to the world. The view matrices need to be updated
// every frame.
viewProjectionConstantBufferData.viewProjectionLeft = Matrix4x4.Transpose(
viewCoordinateSystemTransform.Left * cameraProjectionTransform.Left
);
viewProjectionConstantBufferData.viewProjectionRight = Matrix4x4.Transpose(
viewCoordinateSystemTransform.Right * cameraProjectionTransform.Right
);
}
// Use the D3D device context to update Direct3D device-based resources.
var context = deviceResources.D3DDeviceContext;
// Loading is asynchronous. Resources must be created before they can be updated.
if (context == null || viewProjectionConstantBuffer == null || !viewTransformAcquired)
{
framePending = false;
}
else
{
// Update the view and projection matrices.
context.UpdateSubresource(ref viewProjectionConstantBufferData, viewProjectionConstantBuffer);
framePending = true;
}
}