Optimizing 3D Viewport Clipping Distances In Blender
Understanding Clipping Planes in 3D Viewports
3D viewports in Blender utilize clipping planes to determine the boundaries of the visible geometry. The clipping planes include a near clipping plane and a far clipping plane which form an invisible box around the viewport.
Geometry outside these clipping planes is not rendered in the viewport. The near clipping plane determines the closest point the viewer can get to geometry while the far clipping plane determines the furthest point geometry will be rendered.
Adjusting these clipping planes allows optimization of viewport performance. Tight clipping planes around only visible geometry improves rendering speed while wide clipping distances show more scene context.
Purpose of Clipping Planes
Clipping planes serve several key functions in 3D viewports in Blender:
- Improve rendering performance by culling unseen geometry
- Set visible boundaries for the camera’s field of view
- Control depth precision and limit artifacting from exceeding floating point precision limits
- Allow the viewer to get closer to geometry without seeing inside meshes
How Clipping Planes Work
Blender’s clipping planes are defined with a near and far distance value from the camera, creating an invisible box. The near plane is closest to the camera while the far plane stretches out into the distance.
Any geometry in the scene outside these defined clipping planes is culled, or hidden, from view. This improves viewport performance by only drawing visible objects bounded by the clip box.
The closer the clipping planes are to the actual visible geometry, the less excess geometry needs processing while rendering the viewport, thus increasing speed.
Setting Near and Far Clipping Distances
Blender allows manual configuration of the near and far clipping plane distances. Appropriate clipping values are scene-dependent, but following basic guidelines helps optimize most viewports.
Accessing Clipping Plane Settings
The near and far clipping plane distances are set per 3D Viewport. With the desired viewport active, use the following to configure clipping planes:
- Adjust clipping planes interactively in the 3D Viewport Sidebar N panel
- Set clipping values in the View tab of the Properties region
- Change values via Python console commands
Near Clipping Plane Distance
The near clipping distance controls how close the viewer can get to geometry before it is clipped from view. This allows examining objects without seeing inside them.
Values between 0.1 and 1.0 Blender units are ideal for most scenes. Using smaller values allows zooming the view closer to geometry.
Far Clipping Plane Distance
The far clip distance controls how far away from the camera geometry will still be visible. Larger values show more of the scene but reduce performance.
Start with small far clip distances around 10 to 100 Blender units. Increase incrementally as needed to fit required scene visibility.
Optimizing Clipping Planes
Properly constraining visible geometry between tight near and far clip planes can greatly speed up 3D viewport rendering. Follow these guidelines for optimum performance:
- Set near and far clip just outside visible geometry bounds
- Use larger far clip only when more depth is needed
- Minimize volume between clipping planes
- Utilize per-viewport configurations matching each camera
Adjusting Clipping Distances for Different Scenes
Clipping planes will need adjusted on a per scene and per viewport basis to maximize performance. The optimal clip bounds depend on camera position, object distribution, lighting, and other factors.
Camera Position and Angle
As the camera moves through a scene, the visible geometry changes. Track observable object depths and set clipping planes just outside what is drawn.
Likewise each viewport with a different camera angle or lens setting sees different depths. Tune clipping per view to account for the perspective.
Distribution of Scene Geometry
Scenes with objects clustered near the camera can use smaller far clip planes. More distributed geometry like large terrains requires larger far clipping.
Complex particle systems are often grouped in space as well, allowing optimized near and far distances per viewport.
Lighting Needs
Light geometry like spotlights and area lights use attenuated intensities over distance. Using larger far clip planes ensures lights do not get prematurely clipped.
Alternatively, too large a far clip catches excessive light bounce beyond visible surfaces. Restrain distant clipping to optimize performance.
Material and Texture Complexity
Scenes using many high-resolution textures or procedurally generated materials contain large amounts of geometry data.
Clipping planes should isolate just the visible subset. Avoid processing excessive off-screen texture data.
Reducing Clipping Artifacts and Z-Fighting Issues
In some cases issues can occur even with optimized clipping planes resulting in visual artifacts. These most often manifest close to the near and far clip bounds.
Clipping Plane Artifacts
If objects or particles intersect the near or far clip planes directly, you may notice unnatural clipping at geometry edges. This results from rasterization of incomplete primitives.
Try offsetting clipping planes slightly to avoid bisecting complex objects. Increase near clip distance to alleviate near plane clipping.
Z-Fighting Flickering
When surfaces overlap consistently from frame to frame, they can rapidly swap draw order causing distracting flickering.
This z-fighting occurs most often near clip plane boundaries. Modify clip distances to avoid problematic geometry overlap scenarios.
Precision Issues
Extremely large coordinate values close to floating point limits will experience precision issues. This causes animation glitches and bone deformation artifacts.
Constrain the far clip plane to reasonable distances to avoid these exponential value problems.
Clipping Plane Best Practices
Properly setting clipping planes is critical for performant, accurate viewports. Keep these guidelines in mind when configuring near and far clip distances.
- Start with default 0.1 to 1000 initial clip ranges
- Tune clipping planes inward to just fit visible geometry per viewport
- Use larger values only when more depth complexity is needed
- Avoid intersecting complex objects on clip plane boundaries
- Watch for flickering and deformation artifacts near clip edges
- Set per-viewport clip values matching distinct camera views
Checking for clipping indicators like fringing colors and analyzing depth complexity per view are key to optimizing scene visibility.
Example Configurations for Common Use Cases
Certain scene types lend themselves towards typical clip plane configurations that maximize performance.
Interior Scenes
Indoor scenes like building interiors see a limited depth complexity through windows or doorways. Tight clipping planes around these openings contain rendering to essentials.
Typical interior viewports work well in the 0.1 to 100.0 Blender unit clip ranges unless long hallways are shown.
Landscapes
Natural vistas and terrain often stretch to the horizon requiring larger far clip planes. Values from 1000 to 10000 fit distance geometry like mountains.
Lower near clips around 0.5 let the viewer approach foreground objects like trees or rocks while distant peaks remain rendered.
Aerial Views
Top-down perspectives from airborne cameras benefit from asymmetric clipping. The near plane can use a larger 1.0 value while the far plane extends to 5000 or beyond.
This allows focusing on ground details without loading excessive subsurface data.
Particle Simulations
Emission-based particle systems are often grouped spatially. Custom viewports for active particle areas optimize clipping.
Values like 0.1 to 100.0 simplify rendering by culling unused geometry outside localized particle bounds.
