...
| Info |
|---|
To match Displacement from previous versions of RenderMan, the following conversion may be of use: To get a similar tessellation level, using a shading rate (deprecated) value of X would translate in using a micropolygonlength value of sqrt(X): shading rate = 0.25, micropolygonlength = 0.5 |
Avoiding cracks on polygonal meshes
When displacing a mesh with hard normals, faces can separate and create cracks. Displacement moves vertices in the direction of its normal but adjacent vertices on different sides of a hard edge have different normals and will move is different directions, creating gaps or cracks.
RenderMan has a "polygon:smoothdisplacement" attribute that will create a fully smoothed copy of the normals and use it instead of the original normals.
In RenderMan for Maya, this attribute is enabled by the "Prevent polygon cracking" (rman_preventPolyCracks) check box. It should only be enabled when necessary as it uses a bit more memory.
| Before After Image Slider | ||||||
|---|---|---|---|---|---|---|
|
Notice how the pattern warping happening on the cube has changed its appearance:
| Before After Image Slider | ||||||
|---|---|---|---|---|---|---|
|
You can avoid that effect by inserting additional edges near sharp edges, like so:
| Before After Image Slider | ||||||
|---|---|---|---|---|---|---|
|