far_tutorial_2_2.cpp
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.. code:: c++
//------------------------------------------------------------------------------
// Tutorial description:
//
// Building on tutorial 0, this example shows how to instantiate a simple mesh,
// refine it uniformly and then interpolate both 'vertex' and 'face-varying'
// primvar data.
// The resulting interpolated data is output as an 'obj' file, with the
// 'face-varying' data recorded in the uv texture layout.
//
#include <opensubdiv/far/topologyDescriptor.h>
#include <opensubdiv/far/primvarRefiner.h>
#include <cstdio>
//------------------------------------------------------------------------------
// Face-varying implementation.
//
//
struct Vertex {
// Minimal required interface ----------------------
Vertex() { }
Vertex(Vertex const & src) {
_position[0] = src._position[0];
_position[1] = src._position[1];
_position[2] = src._position[2];
}
void Clear( void * =0 ) {
_position[0]=_position[1]=_position[2]=0.0f;
}
void AddWithWeight(Vertex const & src, float weight) {
_position[0]+=weight*src._position[0];
_position[1]+=weight*src._position[1];
_position[2]+=weight*src._position[2];
}
// Public interface ------------------------------------
void SetPosition(float x, float y, float z) {
_position[0]=x;
_position[1]=y;
_position[2]=z;
}
const float * GetPosition() const {
return _position;
}
private:
float _position[3];
};
//------------------------------------------------------------------------------
// Face-varying container implementation.
//
// We are using a uv texture layout as a 'face-varying' primitive variable
// attribute. Because face-varying data is specified 'per-face-per-vertex',
// we cannot use the same container that we use for 'vertex' or 'varying'
// data. We specify a new container, which only carries (u,v) coordinates.
// Similarly to our 'Vertex' container, we add a minimalistic interpolation
// interface with a 'Clear()' and 'AddWithWeight()' methods.
//
struct FVarVertexUV {
// Minimal required interface ----------------------
void Clear() {
u=v=0.0f;
}
void AddWithWeight(FVarVertexUV const & src, float weight) {
u += weight * src.u;
v += weight * src.v;
}
// Basic 'uv' layout channel
float u,v;
};
struct FVarVertexColor {
// Minimal required interface ----------------------
void Clear() {
r=g=b=a=0.0f;
}
void AddWithWeight(FVarVertexColor const & src, float weight) {
r += weight * src.r;
g += weight * src.g;
b += weight * src.b;
a += weight * src.a;
}
// Basic 'color' layout channel
float r,g,b,a;
};
//------------------------------------------------------------------------------
// Cube geometry from catmark_cube.h
// 'vertex' primitive variable data & topology
static float g_verts[8][3] = {{ -0.5f, -0.5f, 0.5f },
{ 0.5f, -0.5f, 0.5f },
{ -0.5f, 0.5f, 0.5f },
{ 0.5f, 0.5f, 0.5f },
{ -0.5f, 0.5f, -0.5f },
{ 0.5f, 0.5f, -0.5f },
{ -0.5f, -0.5f, -0.5f },
{ 0.5f, -0.5f, -0.5f }};
static int g_nverts = 8,
g_nfaces = 6;
static int g_vertsperface[6] = { 4, 4, 4, 4, 4, 4 };
static int g_vertIndices[24] = { 0, 1, 3, 2,
2, 3, 5, 4,
4, 5, 7, 6,
6, 7, 1, 0,
1, 7, 5, 3,
6, 0, 2, 4 };
// 'face-varying' primitive variable data & topology for UVs
static float g_uvs[14][2] = {{ 0.375, 0.00 },
{ 0.625, 0.00 },
{ 0.375, 0.25 },
{ 0.625, 0.25 },
{ 0.375, 0.50 },
{ 0.625, 0.50 },
{ 0.375, 0.75 },
{ 0.625, 0.75 },
{ 0.375, 1.00 },
{ 0.625, 1.00 },
{ 0.875, 0.00 },
{ 0.875, 0.25 },
{ 0.125, 0.00 },
{ 0.125, 0.25 }};
static int g_nuvs = 14;
static int g_uvIndices[24] = { 0, 1, 3, 2,
2, 3, 5, 4,
4, 5, 7, 6,
6, 7, 9, 8,
1, 10, 11, 3,
12, 0, 2, 13 };
// 'face-varying' primitive variable data & topology for color
static float g_colors[24][4] = {{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 0.0, 0.0, 1.0},
{1.0, 0.0, 0.0, 1.0},
{1.0, 0.0, 0.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0},
{1.0, 1.0, 1.0, 1.0}};
static int g_ncolors = 24;
static int g_colorIndices[24] = { 0, 3, 9, 6,
7, 10, 15, 12,
13, 16, 21, 18,
19, 22, 4, 1,
5, 23, 17, 11,
20, 2, 8, 14 };
using namespace OpenSubdiv;
//------------------------------------------------------------------------------
int main(int, char **) {
int maxlevel = 3;
typedef Far::TopologyDescriptor Descriptor;
Sdc::SchemeType type = OpenSubdiv::Sdc::SCHEME_CATMARK;
Sdc::Options options;
options.SetVtxBoundaryInterpolation(Sdc::Options::VTX_BOUNDARY_EDGE_ONLY);
options.SetFVarLinearInterpolation(Sdc::Options::FVAR_LINEAR_NONE);
// Populate a topology descriptor with our raw data
Descriptor desc;
desc.numVertices = g_nverts;
desc.numFaces = g_nfaces;
desc.numVertsPerFace = g_vertsperface;
desc.vertIndicesPerFace = g_vertIndices;
int channelUV = 0;
int channelColor = 1;
// Create a face-varying channel descriptor
Descriptor::FVarChannel channels[2];
channels[channelUV].numValues = g_nuvs;
channels[channelUV].valueIndices = g_uvIndices;
channels[channelColor].numValues = g_ncolors;
channels[channelColor].valueIndices = g_colorIndices;
// Add the channel topology to the main descriptor
desc.numFVarChannels = 2;
desc.fvarChannels = channels;
// Instantiate a Far::TopologyRefiner from the descriptor
Far::TopologyRefiner * refiner =
Far::TopologyRefinerFactory<Descriptor>::Create(desc,
Far::TopologyRefinerFactory<Descriptor>::Options(type, options));
// Uniformly refine the topology up to 'maxlevel'
// note: fullTopologyInLastLevel must be true to work with face-varying data
{
Far::TopologyRefiner::UniformOptions refineOptions(maxlevel);
refineOptions.fullTopologyInLastLevel = true;
refiner->RefineUniform(refineOptions);
}
// Allocate and initialize the 'vertex' primvar data (see tutorial 2 for
// more details).
std::vector<Vertex> vbuffer(refiner->GetNumVerticesTotal());
Vertex * verts = &vbuffer[0];
for (int i=0; i<g_nverts; ++i) {
verts[i].SetPosition(g_verts[i][0], g_verts[i][1], g_verts[i][2]);
}
// Allocate and initialize the first channel of 'face-varying' primvar data (UVs)
std::vector<FVarVertexUV> fvBufferUV(refiner->GetNumFVarValuesTotal(channelUV));
FVarVertexUV * fvVertsUV = &fvBufferUV[0];
for (int i=0; i<g_nuvs; ++i) {
fvVertsUV[i].u = g_uvs[i][0];
fvVertsUV[i].v = g_uvs[i][1];
}
// Allocate & interpolate the 'face-varying' primvar data (colors)
std::vector<FVarVertexColor> fvBufferColor(refiner->GetNumFVarValuesTotal(channelColor));
FVarVertexColor * fvVertsColor = &fvBufferColor[0];
for (int i=0; i<g_ncolors; ++i) {
fvVertsColor[i].r = g_colors[i][0];
fvVertsColor[i].g = g_colors[i][1];
fvVertsColor[i].b = g_colors[i][2];
fvVertsColor[i].a = g_colors[i][3];
}
// Interpolate both vertex and face-varying primvar data
Far::PrimvarRefiner primvarRefiner(*refiner);
Vertex * srcVert = verts;
FVarVertexUV * srcFVarUV = fvVertsUV;
FVarVertexColor * srcFVarColor = fvVertsColor;
for (int level = 1; level <= maxlevel; ++level) {
Vertex * dstVert = srcVert + refiner->GetLevel(level-1).GetNumVertices();
FVarVertexUV * dstFVarUV = srcFVarUV + refiner->GetLevel(level-1).GetNumFVarValues(channelUV);
FVarVertexColor * dstFVarColor = srcFVarColor + refiner->GetLevel(level-1).GetNumFVarValues(channelColor);
primvarRefiner.Interpolate(level, srcVert, dstVert);
primvarRefiner.InterpolateFaceVarying(level, srcFVarUV, dstFVarUV, channelUV);
primvarRefiner.InterpolateFaceVarying(level, srcFVarColor, dstFVarColor, channelColor);
srcVert = dstVert;
srcFVarUV = dstFVarUV;
srcFVarColor = dstFVarColor;
}
{ // Output OBJ of the highest level refined -----------
Far::TopologyLevel const & refLastLevel = refiner->GetLevel(maxlevel);
int nverts = refLastLevel.GetNumVertices();
int nuvs = refLastLevel.GetNumFVarValues(channelUV);
int ncolors= refLastLevel.GetNumFVarValues(channelColor);
int nfaces = refLastLevel.GetNumFaces();
// Print vertex positions
int firstOfLastVerts = refiner->GetNumVerticesTotal() - nverts;
for (int vert = 0; vert < nverts; ++vert) {
float const * pos = verts[firstOfLastVerts + vert].GetPosition();
printf("v %f %f %f\n", pos[0], pos[1], pos[2]);
}
// Print uvs
int firstOfLastUvs = refiner->GetNumFVarValuesTotal(channelUV) - nuvs;
for (int fvvert = 0; fvvert < nuvs; ++fvvert) {
FVarVertexUV const & uv = fvVertsUV[firstOfLastUvs + fvvert];
printf("vt %f %f\n", uv.u, uv.v);
}
// Print colors
int firstOfLastColors = refiner->GetNumFVarValuesTotal(channelColor) - ncolors;
for (int fvvert = 0; fvvert < ncolors; ++fvvert) {
FVarVertexColor const & c = fvVertsColor[firstOfLastColors + fvvert];
printf("c %f %f %f %f\n", c.r, c.g, c.b, c.a);
}
// Print faces
for (int face = 0; face < nfaces; ++face) {
Far::ConstIndexArray fverts = refLastLevel.GetFaceVertices(face);
Far::ConstIndexArray fuvs = refLastLevel.GetFaceFVarValues(face, channelUV);
// all refined Catmark faces should be quads
assert(fverts.size()==4 && fuvs.size()==4);
printf("f ");
for (int vert=0; vert<fverts.size(); ++vert) {
// OBJ uses 1-based arrays...
printf("%d/%d ", fverts[vert]+1, fuvs[vert]+1);
}
printf("\n");
}
}
delete refiner;
return EXIT_SUCCESS;
}
//------------------------------------------------------------------------------
Generated on: 2025-09-03 12:43 UTC.
