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OpenSubdiv/opensubdiv/osd/hlslPatchCommon.hlsl
George ElKoura c34cc0a7fe A few minor fixes for Gregory Patches in DirectX 
- Make sure to initialize all structs properly when using gregory
patches

- Rename a loop variable to avoid shader compiler warning.
2019-04-01 00:22:11 -07:00

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//
// Copyright 2013 Pixar
//
// Licensed under the Apache License, Version 2.0 (the "Apache License")
// with the following modification; you may not use this file except in
// compliance with the Apache License and the following modification to it:
// Section 6. Trademarks. is deleted and replaced with:
//
// 6. Trademarks. This License does not grant permission to use the trade
// names, trademarks, service marks, or product names of the Licensor
// and its affiliates, except as required to comply with Section 4(c) of
// the License and to reproduce the content of the NOTICE file.
//
// You may obtain a copy of the Apache License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the Apache License with the above modification is
// distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the Apache License for the specific
// language governing permissions and limitations under the Apache License.
//
//----------------------------------------------------------
// Patches.Common
//----------------------------------------------------------
// For now, fractional spacing is supported only with screen space tessellation
#ifndef OSD_ENABLE_SCREENSPACE_TESSELLATION
#undef OSD_FRACTIONAL_EVEN_SPACING
#undef OSD_FRACTIONAL_ODD_SPACING
#endif
#if defined OSD_FRACTIONAL_EVEN_SPACING
#define OSD_PARTITIONING "fractional_even"
#elif defined OSD_FRACTIONAL_ODD_SPACING
#define OSD_PARTITIONING "fractional_odd"
#else
#define OSD_PARTITIONING "integer"
#endif
#define M_PI 3.14159265359f
struct InputVertex {
float4 position : POSITION;
float3 normal : NORMAL;
};
struct HullVertex {
float4 position : POSITION;
#ifdef OSD_ENABLE_PATCH_CULL
int3 clipFlag : CLIPFLAG;
#endif
};
// XXXdyu all downstream data can be handled by client code
struct OutputVertex {
float4 positionOut : SV_Position;
float4 position : POSITION1;
float3 normal : NORMAL;
float3 tangent : TANGENT;
float3 bitangent : TANGENT1;
float4 patchCoord : PATCHCOORD; // u, v, faceLevel, faceId
noperspective float4 edgeDistance : EDGEDISTANCE;
#if defined(OSD_COMPUTE_NORMAL_DERIVATIVES)
float3 Nu : TANGENT2;
float3 Nv : TANGENT3;
#endif
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
float2 vSegments : VSEGMENTS;
#endif
};
struct HS_CONSTANT_FUNC_OUT {
float tessLevelInner[2] : SV_InsideTessFactor;
float tessLevelOuter[4] : SV_TessFactor;
float4 tessOuterLo : TRANSITIONLO;
float4 tessOuterHi : TRANSITIONHI;
};
// osd shaders need following functions defined
float4x4 OsdModelViewMatrix();
float4x4 OsdProjectionMatrix();
float4x4 OsdModelViewProjectionMatrix();
float OsdTessLevel();
int OsdGregoryQuadOffsetBase();
int OsdPrimitiveIdBase();
int OsdBaseVertex();
#ifndef OSD_DISPLACEMENT_CALLBACK
#define OSD_DISPLACEMENT_CALLBACK
#endif
// ----------------------------------------------------------------------------
// Patch Parameters
// ----------------------------------------------------------------------------
//
// Each patch has a corresponding patchParam. This is a set of three values
// specifying additional information about the patch:
//
// faceId -- topological face identifier (e.g. Ptex FaceId)
// bitfield -- refinement-level, non-quad, boundary, transition, uv-offset
// sharpness -- crease sharpness for single-crease patches
//
// These are stored in OsdPatchParamBuffer indexed by the value returned
// from OsdGetPatchIndex() which is a function of the current PrimitiveID
// along with an optional client provided offset.
//
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
Buffer<uint3> OsdPatchParamBuffer : register( t0 );
#else
Buffer<uint2> OsdPatchParamBuffer : register( t0 );
#endif
int OsdGetPatchIndex(int primitiveId)
{
return (primitiveId + OsdPrimitiveIdBase());
}
int3 OsdGetPatchParam(int patchIndex)
{
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
return OsdPatchParamBuffer[patchIndex].xyz;
#else
uint2 p = OsdPatchParamBuffer[patchIndex].xy;
return int3(p.x, p.y, 0);
#endif
}
int OsdGetPatchFaceId(int3 patchParam)
{
return (patchParam.x & 0xfffffff);
}
int OsdGetPatchFaceLevel(int3 patchParam)
{
return (1 << ((patchParam.y & 0xf) - ((patchParam.y >> 4) & 1)));
}
int OsdGetPatchRefinementLevel(int3 patchParam)
{
return (patchParam.y & 0xf);
}
int OsdGetPatchBoundaryMask(int3 patchParam)
{
return ((patchParam.y >> 7) & 0x1f);
}
int OsdGetPatchTransitionMask(int3 patchParam)
{
return ((patchParam.x >> 28) & 0xf);
}
int2 OsdGetPatchFaceUV(int3 patchParam)
{
int u = (patchParam.y >> 22) & 0x3ff;
int v = (patchParam.y >> 12) & 0x3ff;
return int2(u,v);
}
bool OsdGetPatchIsRegular(int3 patchParam)
{
return ((patchParam.y >> 5) & 0x1) != 0;
}
float OsdGetPatchSharpness(int3 patchParam)
{
return asfloat(patchParam.z);
}
float OsdGetPatchSingleCreaseSegmentParameter(int3 patchParam, float2 uv)
{
int boundaryMask = OsdGetPatchBoundaryMask(patchParam);
float s = 0;
if ((boundaryMask & 1) != 0) {
s = 1 - uv.y;
} else if ((boundaryMask & 2) != 0) {
s = uv.x;
} else if ((boundaryMask & 4) != 0) {
s = uv.y;
} else if ((boundaryMask & 8) != 0) {
s = 1 - uv.x;
}
return s;
}
int4 OsdGetPatchCoord(int3 patchParam)
{
int faceId = OsdGetPatchFaceId(patchParam);
int faceLevel = OsdGetPatchFaceLevel(patchParam);
int2 faceUV = OsdGetPatchFaceUV(patchParam);
return int4(faceUV.x, faceUV.y, faceLevel, faceId);
}
float4 OsdInterpolatePatchCoord(float2 localUV, int3 patchParam)
{
int4 perPrimPatchCoord = OsdGetPatchCoord(patchParam);
int faceId = perPrimPatchCoord.w;
int faceLevel = perPrimPatchCoord.z;
float2 faceUV = float2(perPrimPatchCoord.x, perPrimPatchCoord.y);
float2 uv = localUV/faceLevel + faceUV/faceLevel;
// add 0.5 to integer values for more robust interpolation
return float4(uv.x, uv.y, faceLevel+0.5, faceId+0.5);
}
// ----------------------------------------------------------------------------
// patch culling
// ----------------------------------------------------------------------------
#ifdef OSD_ENABLE_PATCH_CULL
#define OSD_PATCH_CULL_COMPUTE_CLIPFLAGS(P) \
float4 clipPos = mul(OsdModelViewProjectionMatrix(), P); \
int3 clip0 = int3(clipPos.x < clipPos.w, \
clipPos.y < clipPos.w, \
clipPos.z < clipPos.w); \
int3 clip1 = int3(clipPos.x > -clipPos.w, \
clipPos.y > -clipPos.w, \
clipPos.z > -clipPos.w); \
output.clipFlag = int3(clip0) + 2*int3(clip1); \
#define OSD_PATCH_CULL(N) \
int3 clipFlag = int3(0,0,0); \
for(int i = 0; i < N; ++i) { \
clipFlag |= patch[i].clipFlag; \
} \
if (any(clipFlag != int3(3,3,3))) { \
output.tessLevelInner[0] = 0; \
output.tessLevelInner[1] = 0; \
output.tessLevelOuter[0] = 0; \
output.tessLevelOuter[1] = 0; \
output.tessLevelOuter[2] = 0; \
output.tessLevelOuter[3] = 0; \
output.tessOuterLo = float4(0,0,0,0); \
output.tessOuterHi = float4(0,0,0,0); \
return output; \
}
#else
#define OSD_PATCH_CULL_COMPUTE_CLIPFLAGS(P)
#define OSD_PATCH_CULL(N)
#endif
// ----------------------------------------------------------------------------
void
OsdUnivar4x4(in float u, out float B[4], out float D[4])
{
float t = u;
float s = 1.0f - u;
float A0 = s * s;
float A1 = 2 * s * t;
float A2 = t * t;
B[0] = s * A0;
B[1] = t * A0 + s * A1;
B[2] = t * A1 + s * A2;
B[3] = t * A2;
D[0] = - A0;
D[1] = A0 - A1;
D[2] = A1 - A2;
D[3] = A2;
}
void
OsdUnivar4x4(in float u, out float B[4], out float D[4], out float C[4])
{
float t = u;
float s = 1.0f - u;
float A0 = s * s;
float A1 = 2 * s * t;
float A2 = t * t;
B[0] = s * A0;
B[1] = t * A0 + s * A1;
B[2] = t * A1 + s * A2;
B[3] = t * A2;
D[0] = - A0;
D[1] = A0 - A1;
D[2] = A1 - A2;
D[3] = A2;
A0 = - s;
A1 = s - t;
A2 = t;
C[0] = - A0;
C[1] = A0 - A1;
C[2] = A1 - A2;
C[3] = A2;
}
// ----------------------------------------------------------------------------
struct OsdPerPatchVertexBezier {
int3 patchParam : PATCHPARAM;
float3 P : POSITION;
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
float3 P1 : POSITION1;
float3 P2 : POSITION2;
float2 vSegments : VSEGMENTS;
#endif
};
float3
OsdEvalBezier(float3 cp[16], float2 uv)
{
float3 BUCP[4] = {float3(0,0,0),float3(0,0,0),float3(0,0,0),float3(0,0,0)};
float B[4], D[4];
OsdUnivar4x4(uv.x, B, D);
for (int i=0; i<4; ++i) {
for (int j=0; j<4; ++j) {
float3 A = cp[4*i + j];
BUCP[i] += A * B[j];
}
}
float3 P = float3(0,0,0);
OsdUnivar4x4(uv.y, B, D);
for (int k=0; k<4; ++k) {
P += B[k] * BUCP[k];
}
return P;
}
// When OSD_PATCH_ENABLE_SINGLE_CREASE is defined,
// this function evaluates single-crease patch, which is segmented into
// 3 parts in the v-direction.
//
// v=0 vSegment.x vSegment.y v=1
// +------------------+-------------------+------------------+
// | cp 0 | cp 1 | cp 2 |
// | (infinite sharp) | (floor sharpness) | (ceil sharpness) |
// +------------------+-------------------+------------------+
//
float3
OsdEvalBezier(OsdPerPatchVertexBezier cp[16], int3 patchParam, float2 uv)
{
float3 BUCP[4] = {float3(0,0,0),float3(0,0,0),float3(0,0,0),float3(0,0,0)};
float B[4], D[4];
float s = OsdGetPatchSingleCreaseSegmentParameter(patchParam, uv);
OsdUnivar4x4(uv.x, B, D);
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
float2 vSegments = cp[0].vSegments;
if (s <= vSegments.x) {
for (int i=0; i<4; ++i) {
for (int j=0; j<4; ++j) {
float3 A = cp[4*i + j].P;
BUCP[i] += A * B[j];
}
}
} else if (s <= vSegments.y) {
for (int i=0; i<4; ++i) {
for (int j=0; j<4; ++j) {
float3 A = cp[4*i + j].P1;
BUCP[i] += A * B[j];
}
}
} else {
for (int i=0; i<4; ++i) {
for (int j=0; j<4; ++j) {
float3 A = cp[4*i + j].P2;
BUCP[i] += A * B[j];
}
}
}
#else
for (int i=0; i<4; ++i) {
for (int j=0; j<4; ++j) {
float3 A = cp[4*i + j].P;
BUCP[i] += A * B[j];
}
}
#endif
float3 P = float3(0,0,0);
OsdUnivar4x4(uv.y, B, D);
for (int k=0; k<4; ++k) {
P += B[k] * BUCP[k];
}
return P;
}
// ----------------------------------------------------------------------------
// Boundary Interpolation
// ----------------------------------------------------------------------------
void
OsdComputeBSplineBoundaryPoints(inout float3 cpt[16], int3 patchParam)
{
int boundaryMask = OsdGetPatchBoundaryMask(patchParam);
if ((boundaryMask & 1) != 0) {
cpt[0] = 2*cpt[4] - cpt[8];
cpt[1] = 2*cpt[5] - cpt[9];
cpt[2] = 2*cpt[6] - cpt[10];
cpt[3] = 2*cpt[7] - cpt[11];
}
if ((boundaryMask & 2) != 0) {
cpt[3] = 2*cpt[2] - cpt[1];
cpt[7] = 2*cpt[6] - cpt[5];
cpt[11] = 2*cpt[10] - cpt[9];
cpt[15] = 2*cpt[14] - cpt[13];
}
if ((boundaryMask & 4) != 0) {
cpt[12] = 2*cpt[8] - cpt[4];
cpt[13] = 2*cpt[9] - cpt[5];
cpt[14] = 2*cpt[10] - cpt[6];
cpt[15] = 2*cpt[11] - cpt[7];
}
if ((boundaryMask & 8) != 0) {
cpt[0] = 2*cpt[1] - cpt[2];
cpt[4] = 2*cpt[5] - cpt[6];
cpt[8] = 2*cpt[9] - cpt[10];
cpt[12] = 2*cpt[13] - cpt[14];
}
}
// ----------------------------------------------------------------------------
// Tessellation
// ----------------------------------------------------------------------------
//
// Organization of B-spline and Bezier control points.
//
// Each patch is defined by 16 control points (labeled 0-15).
//
// The patch will be evaluated across the domain from (0,0) at
// the lower-left to (1,1) at the upper-right. When computing
// adaptive tessellation metrics, we consider refined vertex-vertex
// and edge-vertex points along the transition edges of the patch
// (labeled vv* and ev* respectively).
//
// The two segments of each transition edge are labeled Lo and Hi,
// with the Lo segment occurring before the Hi segment along the
// transition edge's domain parameterization. These Lo and Hi segment
// tessellation levels determine how domain evaluation coordinates
// are remapped along transition edges. The Hi segment value will
// be zero for a non-transition edge.
//
// (0,1) (1,1)
//
// vv3 ev23 vv2
// | Lo3 | Hi3 |
// --O-----------O-----+-----O-----------O--
// | 12 | 13 14 | 15 |
// | | | |
// | | | |
// Hi0 | | | | Hi2
// | | | |
// O-----------O-----------O-----------O
// | 8 | 9 10 | 11 |
// | | | |
// ev03 --+ | | +-- ev12
// | | | |
// | 4 | 5 6 | 7 |
// O-----------O-----------O-----------O
// | | | |
// Lo0 | | | | Lo2
// | | | |
// | | | |
// | 0 | 1 2 | 3 |
// --O-----------O-----+-----O-----------O--
// | Lo1 | Hi1 |
// vv0 ev01 vv1
//
// (0,0) (1,0)
//
#define OSD_MAX_TESS_LEVEL 64
float OsdComputePostProjectionSphereExtent(float3 center, float diameter)
{
float4 p = mul(OsdProjectionMatrix(), float4(center, 1.0));
return abs(diameter * OsdProjectionMatrix()[1][1] / p.w);
}
float OsdComputeTessLevel(float3 p0, float3 p1)
{
// Adaptive factor can be any computation that depends only on arg values.
// Project the diameter of the edge's bounding sphere instead of using the
// length of the projected edge itself to avoid problems near silhouettes.
p0 = mul(OsdModelViewMatrix(), float4(p0, 1.0)).xyz;
p1 = mul(OsdModelViewMatrix(), float4(p1, 1.0)).xyz;
float3 center = (p0 + p1) / 2.0;
float diameter = distance(p0, p1);
float projLength = OsdComputePostProjectionSphereExtent(center, diameter);
float tessLevel = max(1.0, OsdTessLevel() * projLength);
// We restrict adaptive tessellation levels to half of the device
// supported maximum because transition edges are split into two
// halves and the sum of the two corresponding levels must not exceed
// the device maximum. We impose this limit even for non-transition
// edges because a non-transition edge must be able to match up with
// one half of the transition edge of an adjacent transition patch.
return min(tessLevel, OSD_MAX_TESS_LEVEL / 2);
}
void
OsdGetTessLevelsUniform(int3 patchParam,
out float4 tessOuterLo, out float4 tessOuterHi)
{
// Uniform factors are simple powers of two for each level.
// The maximum here can be increased if we know the maximum
// refinement level of the mesh:
// min(OSD_MAX_TESS_LEVEL, pow(2, MaximumRefinementLevel-1)
int refinementLevel = OsdGetPatchRefinementLevel(patchParam);
float tessLevel = min(OsdTessLevel(), OSD_MAX_TESS_LEVEL) /
pow(2, refinementLevel-1);
// tessLevels of transition edge should be clamped to 2.
int transitionMask = OsdGetPatchTransitionMask(patchParam);
float4 tessLevelMin = float4(1,1,1,1)
+ float4(((transitionMask & 8) >> 3),
((transitionMask & 1) >> 0),
((transitionMask & 2) >> 1),
((transitionMask & 4) >> 2));
tessOuterLo = max(float4(tessLevel,tessLevel,tessLevel,tessLevel),
tessLevelMin);
tessOuterHi = float4(0,0,0,0);
}
void
OsdGetTessLevelsRefinedPoints(float3 cp[16], int3 patchParam,
out float4 tessOuterLo, out float4 tessOuterHi)
{
// Each edge of a transition patch is adjacent to one or two patches
// at the next refined level of subdivision. We compute the corresponding
// vertex-vertex and edge-vertex refined points along the edges of the
// patch using Catmull-Clark subdivision stencil weights.
// For simplicity, we let the optimizer discard unused computation.
float3 vv0 = (cp[0] + cp[2] + cp[8] + cp[10]) * 0.015625 +
(cp[1] + cp[4] + cp[6] + cp[9]) * 0.09375 + cp[5] * 0.5625;
float3 ev01 = (cp[1] + cp[2] + cp[9] + cp[10]) * 0.0625 +
(cp[5] + cp[6]) * 0.375;
float3 vv1 = (cp[1] + cp[3] + cp[9] + cp[11]) * 0.015625 +
(cp[2] + cp[5] + cp[7] + cp[10]) * 0.09375 + cp[6] * 0.5625;
float3 ev12 = (cp[5] + cp[7] + cp[9] + cp[11]) * 0.0625 +
(cp[6] + cp[10]) * 0.375;
float3 vv2 = (cp[5] + cp[7] + cp[13] + cp[15]) * 0.015625 +
(cp[6] + cp[9] + cp[11] + cp[14]) * 0.09375 + cp[10] * 0.5625;
float3 ev23 = (cp[5] + cp[6] + cp[13] + cp[14]) * 0.0625 +
(cp[9] + cp[10]) * 0.375;
float3 vv3 = (cp[4] + cp[6] + cp[12] + cp[14]) * 0.015625 +
(cp[5] + cp[8] + cp[10] + cp[13]) * 0.09375 + cp[9] * 0.5625;
float3 ev03 = (cp[4] + cp[6] + cp[8] + cp[10]) * 0.0625 +
(cp[5] + cp[9]) * 0.375;
tessOuterLo = float4(0,0,0,0);
tessOuterHi = float4(0,0,0,0);
int transitionMask = OsdGetPatchTransitionMask(patchParam);
if ((transitionMask & 8) != 0) {
tessOuterLo[0] = OsdComputeTessLevel(vv0, ev03);
tessOuterHi[0] = OsdComputeTessLevel(vv3, ev03);
} else {
tessOuterLo[0] = OsdComputeTessLevel(cp[5], cp[9]);
}
if ((transitionMask & 1) != 0) {
tessOuterLo[1] = OsdComputeTessLevel(vv0, ev01);
tessOuterHi[1] = OsdComputeTessLevel(vv1, ev01);
} else {
tessOuterLo[1] = OsdComputeTessLevel(cp[5], cp[6]);
}
if ((transitionMask & 2) != 0) {
tessOuterLo[2] = OsdComputeTessLevel(vv1, ev12);
tessOuterHi[2] = OsdComputeTessLevel(vv2, ev12);
} else {
tessOuterLo[2] = OsdComputeTessLevel(cp[6], cp[10]);
}
if ((transitionMask & 4) != 0) {
tessOuterLo[3] = OsdComputeTessLevel(vv3, ev23);
tessOuterHi[3] = OsdComputeTessLevel(vv2, ev23);
} else {
tessOuterLo[3] = OsdComputeTessLevel(cp[9], cp[10]);
}
}
void
OsdGetTessLevelsLimitPoints(OsdPerPatchVertexBezier cpBezier[16],
int3 patchParam, out float4 tessOuterLo, out float4 tessOuterHi)
{
// Each edge of a transition patch is adjacent to one or two patches
// at the next refined level of subdivision. When the patch control
// points have been converted to the Bezier basis, the control points
// at the four corners are on the limit surface (since a Bezier patch
// interpolates its corner control points). We can compute an adaptive
// tessellation level for transition edges on the limit surface by
// evaluating a limit position at the mid point of each transition edge.
tessOuterLo = float4(0,0,0,0);
tessOuterHi = float4(0,0,0,0);
int transitionMask = OsdGetPatchTransitionMask(patchParam);
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
// PERFOMANCE: we just need to pick the correct corner points from P, P1, P2
float3 p0 = OsdEvalBezier(cpBezier, patchParam, float2(0.0, 0.0));
float3 p3 = OsdEvalBezier(cpBezier, patchParam, float2(1.0, 0.0));
float3 p12 = OsdEvalBezier(cpBezier, patchParam, float2(0.0, 1.0));
float3 p15 = OsdEvalBezier(cpBezier, patchParam, float2(1.0, 1.0));
if ((transitionMask & 8) != 0) {
float3 ev03 = OsdEvalBezier(cpBezier, patchParam, float2(0.0, 0.5));
tessOuterLo[0] = OsdComputeTessLevel(p0, ev03);
tessOuterHi[0] = OsdComputeTessLevel(p12, ev03);
} else {
tessOuterLo[0] = OsdComputeTessLevel(p0, p12);
}
if ((transitionMask & 1) != 0) {
float3 ev01 = OsdEvalBezier(cpBezier, patchParam, float2(0.5, 0.0));
tessOuterLo[1] = OsdComputeTessLevel(p0, ev01);
tessOuterHi[1] = OsdComputeTessLevel(p3, ev01);
} else {
tessOuterLo[1] = OsdComputeTessLevel(p0, p3);
}
if ((transitionMask & 2) != 0) {
float3 ev12 = OsdEvalBezier(cpBezier, patchParam, float2(1.0, 0.5));
tessOuterLo[2] = OsdComputeTessLevel(p3, ev12);
tessOuterHi[2] = OsdComputeTessLevel(p15, ev12);
} else {
tessOuterLo[2] = OsdComputeTessLevel(p3, p15);
}
if ((transitionMask & 4) != 0) {
float3 ev23 = OsdEvalBezier(cpBezier, patchParam, float2(0.5, 1.0));
tessOuterLo[3] = OsdComputeTessLevel(p12, ev23);
tessOuterHi[3] = OsdComputeTessLevel(p15, ev23);
} else {
tessOuterLo[3] = OsdComputeTessLevel(p12, p15);
}
#else
if ((transitionMask & 8) != 0) {
float3 ev03 = OsdEvalBezier(cpBezier, patchParam, float2(0.0, 0.5));
tessOuterLo[0] = OsdComputeTessLevel(cpBezier[0].P, ev03);
tessOuterHi[0] = OsdComputeTessLevel(cpBezier[12].P, ev03);
} else {
tessOuterLo[0] = OsdComputeTessLevel(cpBezier[0].P, cpBezier[12].P);
}
if ((transitionMask & 1) != 0) {
float3 ev01 = OsdEvalBezier(cpBezier, patchParam, float2(0.5, 0.0));
tessOuterLo[1] = OsdComputeTessLevel(cpBezier[0].P, ev01);
tessOuterHi[1] = OsdComputeTessLevel(cpBezier[3].P, ev01);
} else {
tessOuterLo[1] = OsdComputeTessLevel(cpBezier[0].P, cpBezier[3].P);
}
if ((transitionMask & 2) != 0) {
float3 ev12 = OsdEvalBezier(cpBezier, patchParam, float2(1.0, 0.5));
tessOuterLo[2] = OsdComputeTessLevel(cpBezier[3].P, ev12);
tessOuterHi[2] = OsdComputeTessLevel(cpBezier[15].P, ev12);
} else {
tessOuterLo[2] = OsdComputeTessLevel(cpBezier[3].P, cpBezier[15].P);
}
if ((transitionMask & 4) != 0) {
float3 ev23 = OsdEvalBezier(cpBezier, patchParam, float2(0.5, 1.0));
tessOuterLo[3] = OsdComputeTessLevel(cpBezier[12].P, ev23);
tessOuterHi[3] = OsdComputeTessLevel(cpBezier[15].P, ev23);
} else {
tessOuterLo[3] = OsdComputeTessLevel(cpBezier[12].P, cpBezier[15].P);
}
#endif
}
// Round up to the nearest even integer
float OsdRoundUpEven(float x) {
return 2*ceil(x/2);
}
// Round up to the nearest odd integer
float OsdRoundUpOdd(float x) {
return 2*ceil((x+1)/2)-1;
}
// Compute outer and inner tessellation levels taking into account the
// current tessellation spacing mode.
void
OsdComputeTessLevels(inout float4 tessOuterLo, inout float4 tessOuterHi,
out float4 tessLevelOuter, out float2 tessLevelInner)
{
// Outer levels are the sum of the Lo and Hi segments where the Hi
// segments will have lengths of zero for non-transition edges.
#if defined OSD_FRACTIONAL_EVEN_SPACING
// Combine fractional outer transition edge levels before rounding.
float4 combinedOuter = tessOuterLo + tessOuterHi;
// Round the segments of transition edges separately. We will recover the
// fractional parameterization of transition edges after tessellation.
tessLevelOuter = combinedOuter;
if (tessOuterHi[0] > 0) {
tessLevelOuter[0] =
OsdRoundUpEven(tessOuterLo[0]) + OsdRoundUpEven(tessOuterHi[0]);
}
if (tessOuterHi[1] > 0) {
tessLevelOuter[1] =
OsdRoundUpEven(tessOuterLo[1]) + OsdRoundUpEven(tessOuterHi[1]);
}
if (tessOuterHi[2] > 0) {
tessLevelOuter[2] =
OsdRoundUpEven(tessOuterLo[2]) + OsdRoundUpEven(tessOuterHi[2]);
}
if (tessOuterHi[3] > 0) {
tessLevelOuter[3] =
OsdRoundUpEven(tessOuterLo[3]) + OsdRoundUpEven(tessOuterHi[3]);
}
#elif defined OSD_FRACTIONAL_ODD_SPACING
// Combine fractional outer transition edge levels before rounding.
float4 combinedOuter = tessOuterLo + tessOuterHi;
// Round the segments of transition edges separately. We will recover the
// fractional parameterization of transition edges after tessellation.
//
// The sum of the two outer odd segment lengths will be an even number
// which the tessellator will increase by +1 so that there will be a
// total odd number of segments. We clamp the combinedOuter tess levels
// (used to compute the inner tess levels) so that the outer transition
// edges will be sampled without degenerate triangles.
tessLevelOuter = combinedOuter;
if (tessOuterHi[0] > 0) {
tessLevelOuter[0] =
OsdRoundUpOdd(tessOuterLo[0]) + OsdRoundUpOdd(tessOuterHi[0]);
combinedOuter = max(float4(3,3,3,3), combinedOuter);
}
if (tessOuterHi[1] > 0) {
tessLevelOuter[1] =
OsdRoundUpOdd(tessOuterLo[1]) + OsdRoundUpOdd(tessOuterHi[1]);
combinedOuter = max(float4(3,3,3,3), combinedOuter);
}
if (tessOuterHi[2] > 0) {
tessLevelOuter[2] =
OsdRoundUpOdd(tessOuterLo[2]) + OsdRoundUpOdd(tessOuterHi[2]);
combinedOuter = max(float4(3,3,3,3), combinedOuter);
}
if (tessOuterHi[3] > 0) {
tessLevelOuter[3] =
OsdRoundUpOdd(tessOuterLo[3]) + OsdRoundUpOdd(tessOuterHi[3]);
combinedOuter = max(float4(3,3,3,3), combinedOuter);
}
#else
// Round equally spaced transition edge levels before combining.
tessOuterLo = round(tessOuterLo);
tessOuterHi = round(tessOuterHi);
float4 combinedOuter = tessOuterLo + tessOuterHi;
tessLevelOuter = combinedOuter;
#endif
// Inner levels are the averages the corresponding outer levels.
tessLevelInner[0] = (combinedOuter[1] + combinedOuter[3]) * 0.5;
tessLevelInner[1] = (combinedOuter[0] + combinedOuter[2]) * 0.5;
}
void
OsdGetTessLevelsUniform(int3 patchParam,
out float4 tessLevelOuter, out float2 tessLevelInner,
out float4 tessOuterLo, out float4 tessOuterHi)
{
OsdGetTessLevelsUniform(patchParam, tessOuterLo, tessOuterHi);
OsdComputeTessLevels(tessOuterLo, tessOuterHi,
tessLevelOuter, tessLevelInner);
}
void
OsdGetTessLevelsAdaptiveRefinedPoints(float3 cpRefined[16], int3 patchParam,
out float4 tessLevelOuter, out float2 tessLevelInner,
out float4 tessOuterLo, out float4 tessOuterHi)
{
OsdGetTessLevelsRefinedPoints(cpRefined, patchParam,
tessOuterLo, tessOuterHi);
OsdComputeTessLevels(tessOuterLo, tessOuterHi,
tessLevelOuter, tessLevelInner);
}
void
OsdGetTessLevelsAdaptiveLimitPoints(OsdPerPatchVertexBezier cpBezier[16],
int3 patchParam,
out float4 tessLevelOuter, out float2 tessLevelInner,
out float4 tessOuterLo, out float4 tessOuterHi)
{
OsdGetTessLevelsLimitPoints(cpBezier, patchParam,
tessOuterLo, tessOuterHi);
OsdComputeTessLevels(tessOuterLo, tessOuterHi,
tessLevelOuter, tessLevelInner);
}
void
OsdGetTessLevels(float3 cp0, float3 cp1, float3 cp2, float3 cp3,
int3 patchParam,
out float4 tessLevelOuter, out float2 tessLevelInner)
{
float4 tessOuterLo = float4(0,0,0,0);
float4 tessOuterHi = float4(0,0,0,0);
#if defined OSD_ENABLE_SCREENSPACE_TESSELLATION
tessOuterLo[0] = OsdComputeTessLevel(cp0, cp1);
tessOuterLo[1] = OsdComputeTessLevel(cp0, cp3);
tessOuterLo[2] = OsdComputeTessLevel(cp2, cp3);
tessOuterLo[3] = OsdComputeTessLevel(cp1, cp2);
tessOuterHi = float4(0,0,0,0);
#else
OsdGetTessLevelsUniform(patchParam, tessOuterLo, tessOuterHi);
#endif
OsdComputeTessLevels(tessOuterLo, tessOuterHi,
tessLevelOuter, tessLevelInner);
}
#if defined OSD_FRACTIONAL_EVEN_SPACING || defined OSD_FRACTIONAL_ODD_SPACING
float
OsdGetTessFractionalSplit(float t, float level, float levelUp)
{
// Fractional tessellation of an edge will produce n segments where n
// is the tessellation level of the edge (level) rounded up to the
// nearest even or odd integer (levelUp). There will be n-2 segments of
// equal length (dx1) and two additional segments of equal length (dx0)
// that are typically shorter than the other segments. The two additional
// segments should be placed symmetrically on opposite sides of the
// edge (offset).
#if defined OSD_FRACTIONAL_EVEN_SPACING
if (level <= 2) return t;
float base = pow(2.0,floor(log2(levelUp)));
float offset = 1.0/(int(2*base-levelUp)/2 & int(base/2-1));
#elif defined OSD_FRACTIONAL_ODD_SPACING
if (level <= 1) return t;
float base = pow(2.0,floor(log2(levelUp)));
float offset = 1.0/(((int(2*base-levelUp)/2+1) & int(base/2-1))+1);
#endif
float dx0 = (1.0 - (levelUp-level)/2) / levelUp;
float dx1 = (1.0 - 2.0*dx0) / (levelUp - 2.0*ceil(dx0));
if (t < 0.5) {
float x = levelUp/2 - round(t*levelUp);
return 0.5 - (x*dx1 + int(x*offset > 1) * (dx0 - dx1));
} else if (t > 0.5) {
float x = round(t*levelUp) - levelUp/2;
return 0.5 + (x*dx1 + int(x*offset > 1) * (dx0 - dx1));
} else {
return t;
}
}
#endif
float
OsdGetTessTransitionSplit(float t, float lo, float hi)
{
#if defined OSD_FRACTIONAL_EVEN_SPACING
float loRoundUp = OsdRoundUpEven(lo);
float hiRoundUp = OsdRoundUpEven(hi);
// Convert the parametric t into a segment index along the combined edge.
float ti = round(t * (loRoundUp + hiRoundUp));
if (ti <= loRoundUp) {
float t0 = ti / loRoundUp;
return OsdGetTessFractionalSplit(t0, lo, loRoundUp) * 0.5;
} else {
float t1 = (ti - loRoundUp) / hiRoundUp;
return OsdGetTessFractionalSplit(t1, hi, hiRoundUp) * 0.5 + 0.5;
}
#elif defined OSD_FRACTIONAL_ODD_SPACING
float loRoundUp = OsdRoundUpOdd(lo);
float hiRoundUp = OsdRoundUpOdd(hi);
// Convert the parametric t into a segment index along the combined edge.
// The +1 below is to account for the extra segment produced by the
// tessellator since the sum of two odd tess levels will be rounded
// up by one to the next odd integer tess level.
float ti = round(t * (loRoundUp + hiRoundUp + 1));
if (ti <= loRoundUp) {
float t0 = ti / loRoundUp;
return OsdGetTessFractionalSplit(t0, lo, loRoundUp) * 0.5;
} else if (ti > (loRoundUp+1)) {
float t1 = (ti - (loRoundUp+1)) / hiRoundUp;
return OsdGetTessFractionalSplit(t1, hi, hiRoundUp) * 0.5 + 0.5;
} else {
return 0.5;
}
#else
// Convert the parametric t into a segment index along the combined edge.
float ti = round(t * (lo + hi));
if (ti <= lo) {
return (ti / lo) * 0.5;
} else {
return ((ti - lo) / hi) * 0.5 + 0.5;
}
#endif
}
float2
OsdGetTessParameterization(float2 uv, float4 tessOuterLo, float4 tessOuterHi)
{
float2 UV = uv;
if (UV.x == 0 && tessOuterHi[0] > 0) {
UV.y = OsdGetTessTransitionSplit(UV.y, tessOuterLo[0], tessOuterHi[0]);
} else
if (UV.y == 0 && tessOuterHi[1] > 0) {
UV.x = OsdGetTessTransitionSplit(UV.x, tessOuterLo[1], tessOuterHi[1]);
} else
if (UV.x == 1 && tessOuterHi[2] > 0) {
UV.y = OsdGetTessTransitionSplit(UV.y, tessOuterLo[2], tessOuterHi[2]);
} else
if (UV.y == 1 && tessOuterHi[3] > 0) {
UV.x = OsdGetTessTransitionSplit(UV.x, tessOuterLo[3], tessOuterHi[3]);
}
return UV;
}
// ----------------------------------------------------------------------------
// BSpline
// ----------------------------------------------------------------------------
// compute single-crease patch matrix
float4x4
OsdComputeMs(float sharpness)
{
float s = pow(2.0f, sharpness);
float s2 = s*s;
float s3 = s2*s;
float4x4 m ={
0, s + 1 + 3*s2 - s3, 7*s - 2 - 6*s2 + 2*s3, (1-s)*(s-1)*(s-1),
0, (1+s)*(1+s), 6*s - 2 - 2*s2, (s-1)*(s-1),
0, 1+s, 6*s - 2, 1-s,
0, 1, 6*s - 2, 1 };
m /= (s*6.0);
m[0][0] = 1.0/6.0;
return m;
}
// flip matrix orientation
float4x4
OsdFlipMatrix(float4x4 m)
{
return float4x4(m[3][3], m[3][2], m[3][1], m[3][0],
m[2][3], m[2][2], m[2][1], m[2][0],
m[1][3], m[1][2], m[1][1], m[1][0],
m[0][3], m[0][2], m[0][1], m[0][0]);
}
// Regular BSpline to Bezier
static float4x4 Q = {
1.f/6.f, 4.f/6.f, 1.f/6.f, 0.f,
0.f, 4.f/6.f, 2.f/6.f, 0.f,
0.f, 2.f/6.f, 4.f/6.f, 0.f,
0.f, 1.f/6.f, 4.f/6.f, 1.f/6.f
};
// Infinitely Sharp (boundary)
static float4x4 Mi = {
1.f/6.f, 4.f/6.f, 1.f/6.f, 0.f,
0.f, 4.f/6.f, 2.f/6.f, 0.f,
0.f, 2.f/6.f, 4.f/6.f, 0.f,
0.f, 0.f, 1.f, 0.f
};
// convert BSpline cv to Bezier cv
void
OsdComputePerPatchVertexBSpline(int3 patchParam, int ID, float3 cv[16],
out OsdPerPatchVertexBezier result)
{
result.patchParam = patchParam;
int i = ID%4;
int j = ID/4;
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
float3 P = float3(0,0,0); // 0 to 1-2^(-Sf)
float3 P1 = float3(0,0,0); // 1-2^(-Sf) to 1-2^(-Sc)
float3 P2 = float3(0,0,0); // 1-2^(-Sc) to 1
float sharpness = OsdGetPatchSharpness(patchParam);
if (sharpness > 0) {
float Sf = floor(sharpness);
float Sc = ceil(sharpness);
float Sr = frac(sharpness);
float4x4 Mf = OsdComputeMs(Sf);
float4x4 Mc = OsdComputeMs(Sc);
float4x4 Mj = (1-Sr) * Mf + Sr * Mi;
float4x4 Ms = (1-Sr) * Mf + Sr * Mc;
float s0 = 1 - pow(2, -floor(sharpness));
float s1 = 1 - pow(2, -ceil(sharpness));
result.vSegments = float2(s0, s1);
float4x4 MUi = Q, MUj = Q, MUs = Q;
float4x4 MVi = Q, MVj = Q, MVs = Q;
int boundaryMask = OsdGetPatchBoundaryMask(patchParam);
if ((boundaryMask & 1) != 0) {
MVi = OsdFlipMatrix(Mi);
MVj = OsdFlipMatrix(Mj);
MVs = OsdFlipMatrix(Ms);
}
if ((boundaryMask & 2) != 0) {
MUi = Mi;
MUj = Mj;
MUs = Ms;
}
if ((boundaryMask & 4) != 0) {
MVi = Mi;
MVj = Mj;
MVs = Ms;
}
if ((boundaryMask & 8) != 0) {
MUi = OsdFlipMatrix(Mi);
MUj = OsdFlipMatrix(Mj);
MUs = OsdFlipMatrix(Ms);
}
float3 Hi[4], Hj[4], Hs[4];
for (int l=0; l<4; ++l) {
Hi[l] = Hj[l] = Hs[l] = float3(0,0,0);
for (int k=0; k<4; ++k) {
Hi[l] += MUi[i][k] * cv[l*4 + k];
Hj[l] += MUj[i][k] * cv[l*4 + k];
Hs[l] += MUs[i][k] * cv[l*4 + k];
}
}
for (int k=0; k<4; ++k) {
P += MVi[j][k]*Hi[k];
P1 += MVj[j][k]*Hj[k];
P2 += MVs[j][k]*Hs[k];
}
result.P = P;
result.P1 = P1;
result.P2 = P2;
} else {
result.vSegments = float2(0, 0);
OsdComputeBSplineBoundaryPoints(cv, patchParam);
float3 Hi[4];
for (int l=0; l<4; ++l) {
Hi[l] = float3(0,0,0);
for (int k=0; k<4; ++k) {
Hi[l] += Q[i][k] * cv[l*4 + k];
}
}
for (int k=0; k<4; ++k) {
P += Q[j][k]*Hi[k];
}
result.P = P;
result.P1 = P;
result.P2 = P;
}
#else
OsdComputeBSplineBoundaryPoints(cv, patchParam);
float3 H[4];
for (int l=0; l<4; ++l) {
H[l] = float3(0,0,0);
for(int k=0; k<4; ++k) {
H[l] += Q[i][k] * cv[l*4 + k];
}
}
{
result.P = float3(0,0,0);
for (int k=0; k<4; ++k){
result.P += Q[j][k]*H[k];
}
}
#endif
}
void
OsdEvalPatchBezier(int3 patchParam, float2 UV,
OsdPerPatchVertexBezier cv[16],
out float3 P, out float3 dPu, out float3 dPv,
out float3 N, out float3 dNu, out float3 dNv)
{
//
// Use the recursive nature of the basis functions to compute a 2x2 set
// of intermediate points (via repeated linear interpolation). These
// points define a bilinear surface tangent to the desired surface at P
// and so containing dPu and dPv. The cost of computing P, dPu and dPv
// this way is comparable to that of typical tensor product evaluation
// (if not faster).
//
// If N = dPu X dPv degenerates, it often results from an edge of the
// 2x2 bilinear hull collapsing or two adjacent edges colinear. In both
// cases, the expected non-planar quad degenerates into a triangle, and
// the tangent plane of that triangle provides the desired normal N.
//
// Reduce 4x4 points to 2x4 -- two levels of linear interpolation in U
// and so 3 original rows contributing to each of the 2 resulting rows:
float u = UV.x;
float uinv = 1.0f - u;
float u0 = uinv * uinv;
float u1 = u * uinv * 2.0f;
float u2 = u * u;
float3 LROW[4], RROW[4];
#ifndef OSD_PATCH_ENABLE_SINGLE_CREASE
LROW[0] = u0 * cv[ 0].P + u1 * cv[ 1].P + u2 * cv[ 2].P;
LROW[1] = u0 * cv[ 4].P + u1 * cv[ 5].P + u2 * cv[ 6].P;
LROW[2] = u0 * cv[ 8].P + u1 * cv[ 9].P + u2 * cv[10].P;
LROW[3] = u0 * cv[12].P + u1 * cv[13].P + u2 * cv[14].P;
RROW[0] = u0 * cv[ 1].P + u1 * cv[ 2].P + u2 * cv[ 3].P;
RROW[1] = u0 * cv[ 5].P + u1 * cv[ 6].P + u2 * cv[ 7].P;
RROW[2] = u0 * cv[ 9].P + u1 * cv[10].P + u2 * cv[11].P;
RROW[3] = u0 * cv[13].P + u1 * cv[14].P + u2 * cv[15].P;
#else
float2 vSegments = cv[0].vSegments;
float s = OsdGetPatchSingleCreaseSegmentParameter(patchParam, UV);
for (int i = 0; i < 4; ++i) {
int j = i*4;
if (s <= vSegments.x) {
LROW[i] = u0 * cv[ j ].P + u1 * cv[j+1].P + u2 * cv[j+2].P;
RROW[i] = u0 * cv[j+1].P + u1 * cv[j+2].P + u2 * cv[j+3].P;
} else if (s <= vSegments.y) {
LROW[i] = u0 * cv[ j ].P1 + u1 * cv[j+1].P1 + u2 * cv[j+2].P1;
RROW[i] = u0 * cv[j+1].P1 + u1 * cv[j+2].P1 + u2 * cv[j+3].P1;
} else {
LROW[i] = u0 * cv[ j ].P2 + u1 * cv[j+1].P2 + u2 * cv[j+2].P2;
RROW[i] = u0 * cv[j+1].P2 + u1 * cv[j+2].P2 + u2 * cv[j+3].P2;
}
}
#endif
// Reduce 2x4 points to 2x2 -- two levels of linear interpolation in V
// and so 3 original pairs contributing to each of the 2 resulting:
float v = UV.y;
float vinv = 1.0f - v;
float v0 = vinv * vinv;
float v1 = v * vinv * 2.0f;
float v2 = v * v;
float3 LPAIR[2], RPAIR[2];
LPAIR[0] = v0 * LROW[0] + v1 * LROW[1] + v2 * LROW[2];
RPAIR[0] = v0 * RROW[0] + v1 * RROW[1] + v2 * RROW[2];
LPAIR[1] = v0 * LROW[1] + v1 * LROW[2] + v2 * LROW[3];
RPAIR[1] = v0 * RROW[1] + v1 * RROW[2] + v2 * RROW[3];
// Interpolate points on the edges of the 2x2 bilinear hull from which
// both position and partials are trivially determined:
float3 DU0 = vinv * LPAIR[0] + v * LPAIR[1];
float3 DU1 = vinv * RPAIR[0] + v * RPAIR[1];
float3 DV0 = uinv * LPAIR[0] + u * RPAIR[0];
float3 DV1 = uinv * LPAIR[1] + u * RPAIR[1];
int level = OsdGetPatchFaceLevel(patchParam);
dPu = (DU1 - DU0) * 3 * level;
dPv = (DV1 - DV0) * 3 * level;
P = u * DU1 + uinv * DU0;
// Compute the normal and test for degeneracy:
//
// We need a geometric measure of the size of the patch for a suitable
// tolerance. Magnitudes of the partials are generally proportional to
// that size -- the sum of the partials is readily available, cheap to
// compute, and has proved effective in most cases (though not perfect).
// The size of the bounding box of the patch, or some approximation to
// it, would be better but more costly to compute.
//
float proportionalNormalTolerance = 0.00001f;
float nEpsilon = (length(dPu) + length(dPv)) * proportionalNormalTolerance;
N = cross(dPu, dPv);
float nLength = length(N);
if (nLength > nEpsilon) {
N = N / nLength;
} else {
float3 diagCross = cross(RPAIR[1] - LPAIR[0], LPAIR[1] - RPAIR[0]);
float diagCrossLength = length(diagCross);
if (diagCrossLength > nEpsilon) {
N = diagCross / diagCrossLength;
}
}
#ifndef OSD_COMPUTE_NORMAL_DERIVATIVES
dNu = float3(0,0,0);
dNv = float3(0,0,0);
#else
//
// Compute 2nd order partials of P(u,v) in order to compute 1st order partials
// for the un-normalized n(u,v) = dPu X dPv, then project into the tangent
// plane of normalized N. With resulting dNu and dNv we can make another
// attempt to resolve a still-degenerate normal.
//
// We don't use the Weingarten equations here as they require N != 0 and also
// are a little less numerically stable/accurate in single precision.
//
float B0u[4], B1u[4], B2u[4];
float B0v[4], B1v[4], B2v[4];
OsdUnivar4x4(UV.x, B0u, B1u, B2u);
OsdUnivar4x4(UV.y, B0v, B1v, B2v);
float3 dUU = float3(0,0,0);
float3 dVV = float3(0,0,0);
float3 dUV = float3(0,0,0);
for (int i=0; i<4; ++i) {
for (int j=0; j<4; ++j) {
#ifdef OSD_PATCH_ENABLE_SINGLE_CREASE
int k = 4*i + j;
float3 CV = (s <= vSegments.x) ? cv[k].P
: ((s <= vSegments.y) ? cv[k].P1
: cv[k].P2);
#else
float3 CV = cv[4*i + j].P;
#endif
dUU += (B0v[i] * B2u[j]) * CV;
dVV += (B2v[i] * B0u[j]) * CV;
dUV += (B1v[i] * B1u[j]) * CV;
}
}
dUU *= 6 * level;
dVV *= 6 * level;
dUV *= 9 * level;
dNu = cross(dUU, dPv) + cross(dPu, dUV);
dNv = cross(dUV, dPv) + cross(dPu, dVV);
float nLengthInv = 1.0;
if (nLength > nEpsilon) {
nLengthInv = 1.0 / nLength;
} else {
// N may have been resolved above if degenerate, but if N was resolved
// we don't have an accurate length for its un-normalized value, and that
// length is needed to project the un-normalized dNu and dNv into the
// tangent plane of N.
//
// So compute N more accurately with available second derivatives, i.e.
// with a 1st order Taylor approximation to un-normalized N(u,v).
float DU = (UV.x == 1.0f) ? -1.0f : 1.0f;
float DV = (UV.y == 1.0f) ? -1.0f : 1.0f;
N = DU * dNu + DV * dNv;
nLength = length(N);
if (nLength > nEpsilon) {
nLengthInv = 1.0f / nLength;
N = N * nLengthInv;
}
}
// Project derivatives of non-unit normals into tangent plane of N:
dNu = (dNu - dot(dNu,N) * N) * nLengthInv;
dNv = (dNv - dot(dNv,N) * N) * nLengthInv;
#endif
}
// ----------------------------------------------------------------------------
// GregoryBasis
// ----------------------------------------------------------------------------
struct OsdPerPatchVertexGregoryBasis {
int3 patchParam : PATCHPARAM;
float3 P : POSITION0;
};
void
OsdComputePerPatchVertexGregoryBasis(int3 patchParam, int ID, float3 cv,
out OsdPerPatchVertexGregoryBasis result)
{
result.patchParam = patchParam;
result.P = cv;
}
void
OsdEvalPatchGregory(int3 patchParam, float2 UV, float3 cv[20],
out float3 P, out float3 dPu, out float3 dPv,
out float3 N, out float3 dNu, out float3 dNv)
{
float u = UV.x, v = UV.y;
float U = 1-u, V = 1-v;
//(0,1) (1,1)
// P3 e3- e2+ P2
// 15------17-------11-------10
// | | | |
// | | | |
// | | f3- | f2+ |
// | 19 13 |
// e3+ 16-----18 14-----12 e2-
// | f3+ f2- |
// | |
// | |
// | f0- f1+ |
// e0- 2------4 8------6 e1+
// | 3 f0+ 9 |
// | | | f1- |
// | | | |
// | | | |
// 0--------1--------7--------5
// P0 e0+ e1- P1
//(0,0) (1,0)
float d11 = u+v;
float d12 = U+v;
float d21 = u+V;
float d22 = U+V;
OsdPerPatchVertexBezier bezcv[16];
bezcv[ 5].P = (d11 == 0.0) ? cv[3] : (u*cv[3] + v*cv[4])/d11;
bezcv[ 6].P = (d12 == 0.0) ? cv[8] : (U*cv[9] + v*cv[8])/d12;
bezcv[ 9].P = (d21 == 0.0) ? cv[18] : (u*cv[19] + V*cv[18])/d21;
bezcv[10].P = (d22 == 0.0) ? cv[13] : (U*cv[13] + V*cv[14])/d22;
bezcv[ 0].P = cv[0];
bezcv[ 1].P = cv[1];
bezcv[ 2].P = cv[7];
bezcv[ 3].P = cv[5];
bezcv[ 4].P = cv[2];
bezcv[ 7].P = cv[6];
bezcv[ 8].P = cv[16];
bezcv[11].P = cv[12];
bezcv[12].P = cv[15];
bezcv[13].P = cv[17];
bezcv[14].P = cv[11];
bezcv[15].P = cv[10];
#if defined OSD_PATCH_ENABLE_SINGLE_CREASE
for (int i=0; i < 16; ++i) {
bezcv[i].P1 = float3(0,0,0);
bezcv[i].P2 = float3(0,0,0);
bezcv[i].vSegments = float2(0,0);
}
#endif
OsdEvalPatchBezier(patchParam, UV, bezcv, P, dPu, dPv, N, dNu, dNv);
}
// ----------------------------------------------------------------------------
// Legacy Gregory
// ----------------------------------------------------------------------------
#if defined(OSD_PATCH_GREGORY) || defined(OSD_PATCH_GREGORY_BOUNDARY)
#if OSD_MAX_VALENCE<=10
static float ef[7] = {
0.813008, 0.500000, 0.363636, 0.287505,
0.238692, 0.204549, 0.179211
};
#else
static float ef[27] = {
0.812816, 0.500000, 0.363644, 0.287514,
0.238688, 0.204544, 0.179229, 0.159657,
0.144042, 0.131276, 0.120632, 0.111614,
0.103872, 0.09715, 0.0912559, 0.0860444,
0.0814022, 0.0772401, 0.0734867, 0.0700842,
0.0669851, 0.0641504, 0.0615475, 0.0591488,
0.0569311, 0.0548745, 0.0529621
};
#endif
float cosfn(int n, int j) {
return cos((2.0f * M_PI * j)/float(n));
}
float sinfn(int n, int j) {
return sin((2.0f * M_PI * j)/float(n));
}
#if !defined OSD_MAX_VALENCE || OSD_MAX_VALENCE < 1
#undef OSD_MAX_VALENCE
#define OSD_MAX_VALENCE 4
#endif
struct OsdPerVertexGregory {
float3 P : POSITION0;
int3 clipFlag : CLIPFLAG;
int valence : BLENDINDICE0;
float3 e0 : POSITION1;
float3 e1 : POSITION2;
#ifdef OSD_PATCH_GREGORY_BOUNDARY
int zerothNeighbor : BLENDINDICE1;
float3 org : POSITION3;
#endif
float3 r[OSD_MAX_VALENCE] : POSITION4;
};
struct OsdPerPatchVertexGregory {
int3 patchParam: PATCHPARAM;
float3 P : POSITION0;
float3 Ep : POSITION1;
float3 Em : POSITION2;
float3 Fp : POSITION3;
float3 Fm : POSITION4;
};
#ifndef OSD_NUM_ELEMENTS
#define OSD_NUM_ELEMENTS 3
#endif
Buffer<float> OsdVertexBuffer : register( t2 );
Buffer<int> OsdValenceBuffer : register( t3 );
float3 OsdReadVertex(int vertexIndex)
{
int index = int(OSD_NUM_ELEMENTS * (vertexIndex /*+ OsdBaseVertex()*/));
return float3(OsdVertexBuffer[index],
OsdVertexBuffer[index+1],
OsdVertexBuffer[index+2]);
}
int OsdReadVertexValence(int vertexID)
{
int index = int(vertexID * (2 * OSD_MAX_VALENCE + 1));
return OsdValenceBuffer[index];
}
int OsdReadVertexIndex(int vertexID, int valenceVertex)
{
int index = int(vertexID * (2 * OSD_MAX_VALENCE + 1) + 1 + valenceVertex);
return OsdValenceBuffer[index];
}
Buffer<int> OsdQuadOffsetBuffer : register( t4 );
int OsdReadQuadOffset(int primitiveID, int offsetVertex)
{
int index = int(4*primitiveID+OsdGregoryQuadOffsetBase() + offsetVertex);
return OsdQuadOffsetBuffer[index];
}
void
OsdComputePerVertexGregory(int vID, float3 P, out OsdPerVertexGregory v)
{
v.clipFlag = int3(0,0,0);
int ivalence = OsdReadVertexValence(vID);
v.valence = ivalence;
int valence = abs(ivalence);
float3 f[OSD_MAX_VALENCE];
float3 pos = P;
float3 opos = float3(0,0,0);
#ifdef OSD_PATCH_GREGORY_BOUNDARY
v.org = pos;
int boundaryEdgeNeighbors[2];
int currNeighbor = 0;
int ibefore = 0;
int zerothNeighbor = 0;
#endif
for (int i=0; i<valence; ++i) {
int im = (i+valence-1)%valence;
int ip = (i+1)%valence;
int idx_neighbor = OsdReadVertexIndex(vID, 2*i);
#ifdef OSD_PATCH_GREGORY_BOUNDARY
bool isBoundaryNeighbor = false;
int valenceNeighbor = OsdReadVertexValence(idx_neighbor);
if (valenceNeighbor < 0) {
isBoundaryNeighbor = true;
if (currNeighbor<2) {
boundaryEdgeNeighbors[currNeighbor] = idx_neighbor;
}
currNeighbor++;
if (currNeighbor == 1) {
ibefore = i;
zerothNeighbor = i;
} else {
if (i-ibefore == 1) {
int tmp = boundaryEdgeNeighbors[0];
boundaryEdgeNeighbors[0] = boundaryEdgeNeighbors[1];
boundaryEdgeNeighbors[1] = tmp;
zerothNeighbor = i;
}
}
}
#endif
float3 neighbor = OsdReadVertex(idx_neighbor);
int idx_diagonal = OsdReadVertexIndex(vID, 2*i + 1);
float3 diagonal = OsdReadVertex(idx_diagonal);
int idx_neighbor_p = OsdReadVertexIndex(vID, 2*ip);
float3 neighbor_p = OsdReadVertex(idx_neighbor_p);
int idx_neighbor_m = OsdReadVertexIndex(vID, 2*im);
float3 neighbor_m = OsdReadVertex(idx_neighbor_m);
int idx_diagonal_m = OsdReadVertexIndex(vID, 2*im + 1);
float3 diagonal_m = OsdReadVertex(idx_diagonal_m);
f[i] = (pos * float(valence) + (neighbor_p + neighbor)*2.0f + diagonal) / (float(valence)+5.0f);
opos += f[i];
v.r[i] = (neighbor_p-neighbor_m)/3.0f + (diagonal - diagonal_m)/6.0f;
}
opos /= valence;
v.P = float4(opos, 1.0f).xyz;
float3 e;
v.e0 = float3(0,0,0);
v.e1 = float3(0,0,0);
for(int iv=0; iv<valence; ++iv) {
int im = (iv + valence -1) % valence;
e = 0.5f * (f[iv] + f[im]);
v.e0 += cosfn(valence, iv)*e;
v.e1 += sinfn(valence, iv)*e;
}
v.e0 *= ef[valence - 3];
v.e1 *= ef[valence - 3];
#ifdef OSD_PATCH_GREGORY_BOUNDARY
v.zerothNeighbor = zerothNeighbor;
if (currNeighbor == 1) {
boundaryEdgeNeighbors[1] = boundaryEdgeNeighbors[0];
}
if (ivalence < 0) {
if (valence > 2) {
v.P = (OsdReadVertex(boundaryEdgeNeighbors[0]) +
OsdReadVertex(boundaryEdgeNeighbors[1]) +
4.0f * pos)/6.0f;
} else {
v.P = pos;
}
v.e0 = (OsdReadVertex(boundaryEdgeNeighbors[0]) -
OsdReadVertex(boundaryEdgeNeighbors[1]))/6.0;
float k = float(float(valence) - 1.0f); //k is the number of faces
float c = cos(M_PI/k);
float s = sin(M_PI/k);
float gamma = -(4.0f*s)/(3.0f*k+c);
float alpha_0k = -((1.0f+2.0f*c)*sqrt(1.0f+c))/((3.0f*k+c)*sqrt(1.0f-c));
float beta_0 = s/(3.0f*k + c);
int idx_diagonal = OsdReadVertexIndex(vID, 2*zerothNeighbor + 1);
float3 diagonal = OsdReadVertex(idx_diagonal);
v.e1 = gamma * pos +
alpha_0k * OsdReadVertex(boundaryEdgeNeighbors[0]) +
alpha_0k * OsdReadVertex(boundaryEdgeNeighbors[1]) +
beta_0 * diagonal;
for (int x=1; x<valence - 1; ++x) {
int curri = ((x + zerothNeighbor)%valence);
float alpha = (4.0f*sin((M_PI * float(x))/k))/(3.0f*k+c);
float beta = (sin((M_PI * float(x))/k) + sin((M_PI * float(x+1))/k))/(3.0f*k+c);
int idx_neighbor = OsdReadVertexIndex(vID, 2*curri);
float3 neighbor = OsdReadVertex(idx_neighbor);
idx_diagonal = OsdReadVertexIndex(vID, 2*curri + 1);
diagonal = OsdReadVertex(idx_diagonal);
v.e1 += alpha * neighbor + beta * diagonal;
}
v.e1 /= 3.0f;
}
#endif
}
void
OsdComputePerPatchVertexGregory(int3 patchParam, int ID, int primitiveID,
in OsdPerVertexGregory v[4],
out OsdPerPatchVertexGregory result)
{
result.patchParam = patchParam;
result.P = v[ID].P;
int i = ID;
int ip = (i+1)%4;
int im = (i+3)%4;
int valence = abs(v[i].valence);
int n = valence;
int start = OsdReadQuadOffset(primitiveID, i) & 0xff;
int prev = (OsdReadQuadOffset(primitiveID, i) >> 8) & 0xff;
int start_m = OsdReadQuadOffset(primitiveID, im) & 0xff;
int prev_p = (OsdReadQuadOffset(primitiveID, ip) >> 8) & 0xff;
int np = abs(v[ip].valence);
int nm = abs(v[im].valence);
// Control Vertices based on :
// "Approximating Subdivision Surfaces with Gregory Patches
// for Hardware Tessellation"
// Loop, Schaefer, Ni, Castano (ACM ToG Siggraph Asia 2009)
//
// P3 e3- e2+ P2
// O--------O--------O--------O
// | | | |
// | | | |
// | | f3- | f2+ |
// | O O |
// e3+ O------O O------O e2-
// | f3+ f2- |
// | |
// | |
// | f0- f1+ |
// e0- O------O O------O e1+
// | O O |
// | | f0+ | f1- |
// | | | |
// | | | |
// O--------O--------O--------O
// P0 e0+ e1- P1
//
#ifdef OSD_PATCH_GREGORY_BOUNDARY
float3 Em_ip;
if (v[ip].valence < -2) {
int j = (np + prev_p - v[ip].zerothNeighbor) % np;
Em_ip = v[ip].P + cos((M_PI*j)/float(np-1))*v[ip].e0 + sin((M_PI*j)/float(np-1))*v[ip].e1;
} else {
Em_ip = v[ip].P + v[ip].e0*cosfn(np, prev_p) + v[ip].e1*sinfn(np, prev_p);
}
float3 Ep_im;
if (v[im].valence < -2) {
int j = (nm + start_m - v[im].zerothNeighbor) % nm;
Ep_im = v[im].P + cos((M_PI*j)/float(nm-1))*v[im].e0 + sin((M_PI*j)/float(nm-1))*v[im].e1;
} else {
Ep_im = v[im].P + v[im].e0*cosfn(nm, start_m) + v[im].e1*sinfn(nm, start_m);
}
if (v[i].valence < 0) {
n = (n-1)*2;
}
if (v[im].valence < 0) {
nm = (nm-1)*2;
}
if (v[ip].valence < 0) {
np = (np-1)*2;
}
if (v[i].valence > 2) {
result.Ep = v[i].P + (v[i].e0*cosfn(n, start) + v[i].e1*sinfn(n, start));
result.Em = v[i].P + (v[i].e0*cosfn(n, prev) + v[i].e1*sinfn(n, prev));
float s1=3-2*cosfn(n,1)-cosfn(np,1);
float s2=2*cosfn(n,1);
result.Fp = (cosfn(np,1)*v[i].P + s1*result.Ep + s2*Em_ip + v[i].r[start])/3.0f;
s1 = 3.0f-2.0f*cos(2.0f*M_PI/float(n))-cos(2.0f*M_PI/float(nm));
result.Fm = (cosfn(nm,1)*v[i].P + s1*result.Em + s2*Ep_im - v[i].r[prev])/3.0f;
} else if (v[i].valence < -2) {
int j = (valence + start - v[i].zerothNeighbor) % valence;
result.Ep = v[i].P + cos((M_PI*j)/float(valence-1))*v[i].e0 + sin((M_PI*j)/float(valence-1))*v[i].e1;
j = (valence + prev - v[i].zerothNeighbor) % valence;
result.Em = v[i].P + cos((M_PI*j)/float(valence-1))*v[i].e0 + sin((M_PI*j)/float(valence-1))*v[i].e1;
float3 Rp = ((-2.0f * v[i].org - 1.0f * v[im].org) + (2.0f * v[ip].org + 1.0f * v[(i+2)%4].org))/3.0f;
float3 Rm = ((-2.0f * v[i].org - 1.0f * v[ip].org) + (2.0f * v[im].org + 1.0f * v[(i+2)%4].org))/3.0f;
float s1 = 3-2*cosfn(n,1)-cosfn(np,1);
float s2 = 2*cosfn(n,1);
result.Fp = (cosfn(np,1)*v[i].P + s1*result.Ep + s2*Em_ip + v[i].r[start])/3.0f;
s1 = 3.0f-2.0f*cos(2.0f*M_PI/float(n))-cos(2.0f*M_PI/float(nm));
result.Fm = (cosfn(nm,1)*v[i].P + s1*result.Em + s2*Ep_im - v[i].r[prev])/3.0f;
if (v[im].valence < 0) {
s1 = 3-2*cosfn(n,1)-cosfn(np,1);
result.Fp = result.Fm = (cosfn(np,1)*v[i].P + s1*result.Ep + s2*Em_ip + v[i].r[start])/3.0f;
} else if (v[ip].valence < 0) {
s1 = 3.0f-2.0f*cos(2.0f*M_PI/n)-cos(2.0f*M_PI/nm);
result.Fm = result.Fp = (cosfn(nm,1)*v[i].P + s1*result.Em + s2*Ep_im - v[i].r[prev])/3.0f;
}
} else if (v[i].valence == -2) {
result.Ep = (2.0f * v[i].org + v[ip].org)/3.0f;
result.Em = (2.0f * v[i].org + v[im].org)/3.0f;
result.Fp = result.Fm = (4.0f * v[i].org + v[(i+2)%n].org + 2.0f * v[ip].org + 2.0f * v[im].org)/9.0f;
}
#else // not OSD_PATCH_GREGORY_BOUNDARY
result.Ep = v[i].P + v[i].e0 * cosfn(n, start) + v[i].e1*sinfn(n, start);
result.Em = v[i].P + v[i].e0 * cosfn(n, prev ) + v[i].e1*sinfn(n, prev );
float3 Em_ip = v[ip].P + v[ip].e0*cosfn(np, prev_p) + v[ip].e1*sinfn(np, prev_p);
float3 Ep_im = v[im].P + v[im].e0*cosfn(nm, start_m) + v[im].e1*sinfn(nm, start_m);
float s1 = 3-2*cosfn(n,1)-cosfn(np,1);
float s2 = 2*cosfn(n,1);
result.Fp = (cosfn(np,1)*v[i].P + s1*result.Ep + s2*Em_ip + v[i].r[start])/3.0f;
s1 = 3.0f-2.0f*cos(2.0f*M_PI/float(n))-cos(2.0f*M_PI/float(nm));
result.Fm = (cosfn(nm,1)*v[i].P + s1*result.Em +s2*Ep_im - v[i].r[prev])/3.0f;
#endif
}
#endif // OSD_PATCH_GREGORY || OSD_PATCH_GREGORY_BOUNDARY
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