Trying to mimic Blender's Catmull-Clark

[Kalen White]

Hi,

I just found this amazing library and implemented using example from far_tutorial_1_1.

I have a simple unit Quad I am computing, just 2.0 in scale, centered on 0, so -1.0 to +1.0 on X and Y.  I expect to get something close to Blender's Catmull-Clark as this would be importing an artist's design as exported from Blender.

Here is reference from Blender

Subdivision Panel (these are default settings):

Top Left Vert Selected after Applying Modifier:

Top Vertex on Edge:

The values I get after 1 iteration are 0.75 for the Corners and 1.0 for the Edges.

Are any of these options applicable to a 'Use Limit Surface' option in Blender? 

enum VtxBoundaryInterpolation {

VTX_BOUNDARY_NONE = 0, ///< no boundary interpolation, except where

///< boundary edges were explicitly sharpened

VTX_BOUNDARY_EDGE_ONLY, ///< all boundary edges sharpened and interpolated

VTX_BOUNDARY_EDGE_AND_CORNER ///< all boundary edges and corner vertices

///< sharpened and interpolated

};

enum FVarLinearInterpolation {

FVAR_LINEAR_NONE = 0, ///< smooth everywhere ("edge only")

FVAR_LINEAR_CORNERS_ONLY, ///< sharpen corners only

FVAR_LINEAR_CORNERS_PLUS1, ///< ("edge corner")

FVAR_LINEAR_CORNERS_PLUS2, ///< ("edge and corner + propagate corner")

FVAR_LINEAR_BOUNDARIES, ///< sharpen all boundaries ("always sharp")

FVAR_LINEAR_ALL ///< bilinear interpolation ("bilinear")

};

enum CreasingMethod {

CREASE_UNIFORM = 0, ///< Catmark rule

CREASE_CHAIKIN ///< Chaikin rule

};

enum TriangleSubdivision {

TRI_SUB_CATMARK = 0, ///< Catmark weights (Catmark scheme only)

TRI_SUB_SMOOTH ///< "smooth triangle" weights (Catmark scheme only)

};

I tried a variety of the options for the different option types and did not get a change in output.

Thanks for this great library!  I am actually curious if you would be interested in getting a Dawn/WebGL shader implementation to go along with the GLSL/DX12/Metal.  For now I just need to reproduce what Blender does on CPU.

Kalen White

[Kalen White]

I meant WebGPU compute shader, I apologize for typo.