Documentation for shadow volumes, DLSS, FidelityFx upscaling

Author: mlavik1

Documentation/Documentation.md

@@ -5,6 +5,7 @@
 - [Importing datasets](General/Importing/ImportingDatasets.md)
 - [Using the imported datasets](General/VolumeRendering/GameObjectManipulation.md)
 - [Changing the appearance](General/VolumeRendering/VolumeRenderingSettings.md)
+- [Shadow volumes](General/VolumeRendering/ShadowVolumes.md)
 - [Transfer Functions](General/TransferFunctions/TransferFunctions.md)
 - [Cross section tools](General/CrossSectionTools/CrossSectionTools.md)
 - [Slice renderer](General/SliceRenderer/SliceRenderer.md)

Documentation/General/VolumeRendering/ShadowVolumes.md

@@ -0,0 +1,25 @@
+# Shadow volumes
+
+To get more realistic rendering, you can optionally enable shadow volumes.
+
+<img src="../../../Screenshots/shadow-volume.jpg" width="300px">
+
+This can be enabled from the VolumeRenderedObject inspector in the editor, or by adding a `ShadowVolumeManager` component:
+
+<img src="../../../Screenshots/volume-inspector-settings.jpg" width="300px">
+
+## How it works
+
+A shadow volume 3D texture is generated for the whole dataset.
+A compute shader is repsonsible for updating the shadow volume, by casting rays from the light source through the dataset, and storing information about shadows.
+Since this can take a long time, and async compute is not available on all platforms, the shadow volume manager divides the shadow volume into smaller chunks, and updates one chunk every frame.
+
+## Performance
+
+Because of the extra work of computing the shadow volume (compute shader) and the extra texture lookups during volume rendreing, this can have a bad impact on performance.
+
+There are luckily some ways to work around this, at least on desktop applications (Windows, Linux, etc.).
+- If you're using HDRP: [Enable DLSS](https://docs.unity3d.com/Packages/[email protected]/manual/deep-learning-super-sampling-in-hdrp.html) and reduce the render scale.
+- If you're using URP: [Enable FidelityFX Super Resolution](https://forum.unity.com/threads/amd-fidelityfx-super-resolution-fsr-preview-now-available.1141495/) and reduce the [render scale](https://docs.unity3d.com/Packages/[email protected]/manual/universalrp-asset.html).
+
+This works by rendering to a smaller render target (which is usually the bottleneck during volume rendering) and then doing "magic" upscaling on the rendered image.

Documentation/General/VolumeRendering/VolumeRenderingSettings.md

@@ -3,10 +3,11 @@
 **Table of contents:**
 <!-- TOC -->
 
-- [Cross section tools](#cross-section-tools)
-    - [Cross section plane](#cross-section-plane)
-    - [Box cutout](#box-cutout)
-    - [Sphere cutout](#sphere-cutout)
+- [Render Mode](#render-mode)
+- [Lighting](#lighting)
+- [Shadow volumes](#shadow-volumes)
+- [Cubic interpolation](#cubic-interpolation)
+- [Early ray termination](#early-ray-termination)
 
 <!-- /TOC -->
 
@@ -33,6 +34,11 @@ This comes at a cost, and performance may suffer (both memory and rendering spee
 
 To apply lighting to the volume rendering, we calculate the gradient at each voxel and use this to calculate a normal, which we use to apply phong lighting.
 
+## Shadow volumes
+
+Improve the rendered image by using shadow volumes.
+This is expensive, but there are ways to still get good performance with this enabled. See [shadow volume documentation](ShadowVolumes.md)
+
 ## Cubic interpolation
 
 <img src="cubic-interpolation.png" width="300px">

README.md

@@ -84,6 +84,7 @@ There are 3 render modes:
 
 There are also some other settings that you can adjust:
 - "Enable lighting": Enable lighting calculations during volume rendering.
+- "Enable shadow volume": Expensive, but may look much better!
 - Enable early ray termination: Optimisation (you usually want this on). Requires the above setting to be disabled.
 - Enable cubic interpolation: Use cubic interpolation of the 3D volume texture and gradient texture.
 
@@ -161,14 +162,18 @@ Yes, it's free even for commercial projects. The license ([MIT](https://chooseal
 
 ## How can I make it look better?
 - Try [enabling cubic sampling](https://github.com/mlavik1/UnityVolumeRendering/pull/121#issuecomment-1281289885) in the inspector.
+- Try [enabling shadow volumes](Documentation/General/VolumeRendering/ShadowVolumes.md) in the inspector.
 - Try increasing the value of "MAX_NUM_STEPS" in the [DirectVolumeRenderingShader.shader](https://github.com/mlavik1/UnityVolumeRendering/blob/master/Assets/Shaders/DirectVolumeRenderingShader.shader)
 
+## How can I get better rendering performance with lighting enabled?
+If you're on a platform that supports it (Windows, etc.), try [enabling DLSS (HDRP)](https://docs.unity3d.com/Packages/[email protected]/manual/deep-learning-super-sampling-in-hdrp.html) or [FidelityFX Super Resolution (URP)](https://forum.unity.com/threads/amd-fidelityfx-super-resolution-fsr-preview-now-available.1141495/) and reduce the render scale.
+
 ## How can I raycast the scene to find an intersection?
 - See the [VolumeRaycasting documentation](Documentation/Scripting/VolumeRaycasting.md).
 
 ## I'm stuck! How can I get help?
 [Create an issue](https://github.com/mlavik1/UnityVolumeRendering/issues).
-You can also reach me on [Mastodon](https://floss.social/@sigsegv).
+You can also reach me on [the fediverse](https://nattomaki.social/@matias).
 
 # Contributing
 See [CONTRIBUTING.md](CONTRIBUTING.md) for how to contribute.