Maximize WPF 3D Performance
As you use the Windows Presentation Foundation (WPF) to build 3D controls and include 3D scenes in your applications, it is important to consider performance optimization. This topic provides a list of 3D classes and properties that have performance implications for your application, along with recommendations for optimizing performance when you use them.
This topic assumes an advanced understanding of Windows Presentation Foundation (WPF) 3D features. The suggestions in this document apply to "rendering tier 2"—roughly defined as hardware that supports pixel shader version 2.0 and vertex shader version 2.0. For more details, see Graphics Rendering Tiers.
Brush speed (fastest to slowest):
Set Viewport3D.ClipToBounds to false whenever you do not need to have Windows Presentation Foundation (WPF) explicitly clip the content of a Viewport3D to the Viewport3D’s rectangle. Windows Presentation Foundation (WPF) antialiased clipping can be very slow, and ClipToBounds is enabled (slow) by default on Viewport3D.
Set Viewport3D.IsHitTestVisible to false whenever you do not need Windows Presentation Foundation (WPF) to consider the content of a Viewport3D when performing mouse hit testing. Hit testing 3D content is done in software and can be slow with large meshes. IsHitTestVisible is enabled (slow) by default on Viewport3D.
Create different models only when they require different Materials or Transforms. Otherwise, try to coalesce many GeometryModel3D instances with the same Materials and Transforms into a few larger GeometryModel3D and MeshGeometry3D instances.
Mesh animation—changing the individual vertices of a mesh on a per-frame basis—is not always efficient in Windows Presentation Foundation (WPF). To minimize the performance impact of change notifications when each vertex is modified, detach the mesh from the visual tree before performing per-vertex modification. Once the mesh has been modified, reattach it to the visual tree. Also, try to minimize the size of meshes that will be animated in this way.
To increase rendering speed, disable multisampling on a Viewport3D by setting the attached property EdgeMode to Aliased. By default, 3D antialiasing is disabled on Microsoft Windows XP and enabled on Windows Vista with 4 samples per pixel.
If you must use a VisualBrush or a DrawingBrush in a 3D scene because the brush’s content is not static, try caching the brush (setting the attached property CachingHint to Cache). Set the minimum and maximum scale invalidation thresholds (with the attached properties CacheInvalidationThresholdMinimum and CacheInvalidationThresholdMaximum) so that the cached brushes won’t be regenerated too frequently, while still maintaining your desired level of quality. By default, DrawingBrush and VisualBrush are not cached, meaning that every time something painted with the brush has to be re-rendered, the entire content of the brush must first be re-rendered to an intermediate surface.
When a mesh is defined as abutting triangles with shared vertices and those vertices have the same position, normal, and texture coordinates, define each shared vertex only once and then define your triangles by index with TriangleIndices.
Try to minimize texture sizes when you have explicit control over the size (when you’re using a RenderTargetBitmap and/or an ImageBrush). Note that lower resolution textures can decrease visual quality, so try to find the right balance between quality and performance.
When rendering translucent 3D content (such as reflections), use the opacity properties on brushes or materials (via Opacity or Color) instead of creating a separate translucent Viewport3D by setting Viewport3D.Opacity to a value less than 1.
Minimize the number of Viewport3D objects you’re using in a scene. Put many 3D models in the same Viewport3D rather than creating separate Viewport3D instances for each model.
Call the Freeze method on Freezables when their properties will remain unchanged in your application. Freezing can decrease working set and increase speed.
Light speed (fastest to slowest):
Try to keep mesh sizes under these limits:
Material speed (fastest to slowest):
Windows Presentation Foundation (WPF) 3D doesn't opt out of invisible brushes (black ambient brushes, clear brushes, etc.) in a consistent way. Consider omitting these from your scene.
Each Material in a MaterialGroup causes another rendering pass, so including many materials, even simple materials, can dramatically increase the fill demands on your GPU. Minimize the number of materials in your MaterialGroup.
When you don’t need animation or data binding, instead of using a transform group containing multiple transforms, use a single MatrixTransform3D, setting it to be the product of all the transforms that would otherwise exist independently in the transform group.
Minimize the number of lights in your scene. Too many lights in a scene will force Windows Presentation Foundation (WPF) to fall back to software rendering. The limits are roughly 110 DirectionalLight objects, 70 PointLight objects, or 40 SpotLight objects.
Separate moving objects from static objects by putting them in separate ModelVisual3D instances. ModelVisual3D is "heavier" than GeometryModel3D because it caches transformed bounds. GeometryModel3D is optimized to be a model; ModelVisual3D is optimized to be a scene node. Use ModelVisual3D to put shared instances of GeometryModel3D into the scene.
Minimize the number of times you change the number of lights in the scene. Each change of light count forces a shader regeneration and recompilation unless that configuration has existed previously (and thus had its shader cached).
Black lights won’t be visible, but they will add to render time; consider omitting them.
To minimize the construction time of large collections in Windows Presentation Foundation (WPF), such as a MeshGeometry3D’s Positions, Normals, TextureCoordinates, and TriangleIndices, pre-size the collections before value population. If possible, pass the collections’ constructors prepopulated data structures such as arrays or Lists.