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Autodesk: Skip use of geometry shader for patch tessellation when possible #3422

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Autodesk: Skip use of geometry shader for patch tessellation when possible #3422

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db40b6f
Skip use of geometry shader for patch tessellation when possible
peter-janson-autodesk Nov 11, 2024
f84cd9a
Remove debug symbol
peter-janson-autodesk Nov 25, 2024
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37 changes: 32 additions & 5 deletions pxr/imaging/hdSt/codeGen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -166,6 +166,7 @@ HdSt_CodeGen::HdSt_CodeGen(
, _hasCS(false)
, _hasPTCS(false)
, _hasPTVS(false)
, _hasTESWithNoGS(false)
, _hasClipPlanes(false)
{
TF_VERIFY(geometricShader);
Expand All @@ -187,6 +188,7 @@ HdSt_CodeGen::HdSt_CodeGen(
, _hasCS(false)
, _hasPTCS(false)
, _hasPTVS(false)
, _hasTESWithNoGS(false)
, _hasClipPlanes(false)
{
TF_VERIFY(_metaData,
Expand Down Expand Up @@ -1902,6 +1904,7 @@ HdSt_CodeGen::Compile(HdStResourceRegistry*const registry)
_hasGS = (!geometryShader.empty()) && !metalTessellationEnabled;
_hasFS = (!fragmentShader.empty());
_hasCS = (!computeShader.empty());
_hasTESWithNoGS = _hasTES && !_hasGS;

// Initialize source buckets
_genDefines.str(""); _genDecl.str(""); _genAccessors.str("");
Expand Down Expand Up @@ -2186,13 +2189,14 @@ HdSt_CodeGen::Compile(HdStResourceRegistry*const registry)
}
}

// We plumb the evaluated position in patch from PTVS to FS since this
// We plumb the evaluated position in patch from PTVS or TES to FS since this
// is more consistent than using built-in barycentric coords and can be
// used even when builtin barycentric coords are not available. We pass
// only the first two components between stages and provide an accessor
// which can reconstruct the full three component barycentric form.
if (_hasPTVS) {
_AddInterstageElement(&_resPTVS,
if (_hasPTVS || _hasTESWithNoGS) {
auto& resTess = _hasPTVS ? _resPTVS : _resTES;
_AddInterstageElement(&resTess,
HioGlslfxResourceLayout::InOut::STAGE_OUT,
/*name=*/_tokens->hd_tessCoord,
/*dataType=*/_tokens->vec2);
Expand Down Expand Up @@ -2326,8 +2330,9 @@ HdSt_CodeGen::Compile(HdStResourceRegistry*const registry)
}
}

if (_hasPTVS) {
_procPTVSOut << " hd_tessCoord = gl_TessCoord.xy;\n";
if (_hasPTVS || _hasTESWithNoGS) {
auto& procTess = _hasPTVS ? _procPTVSOut : _procTES;
procTess << " hd_tessCoord = gl_TessCoord.xy;\n";
}

if (requiresPrimitiveIdEmulation) {
Expand Down Expand Up @@ -2375,6 +2380,9 @@ HdSt_CodeGen::Compile(HdStResourceRegistry*const registry)
}
if (_hasTES) {
_genTES << shader->GetSource(HdShaderTokens->tessEvalShader);
if (_hasTESWithNoGS) {
_genTES << shader->GetSource(HdShaderTokens->displacementShader);
}
}
if (_hasPTCS) {
_genPTCS << shader->GetSource(
Expand Down Expand Up @@ -2690,6 +2698,14 @@ HdSt_CodeGen::_CompileWithGeneratedGLSLResources(
resourceGen._GenerateGLSLResources(&desc, resDecl,
HdShaderTokens->tessEvalShader, _resTES, _GetMetaData());

// material in TES
if (_hasTESWithNoGS) {
resourceGen._GenerateGLSLResources(&desc, resDecl,
HdShaderTokens->tessEvalShader, _resMaterial, _GetMetaData());
resourceGen._GenerateGLSLTextureResources(resDecl,
HdShaderTokens->tessEvalShader, _resTextures, _GetMetaData());
}

std::string const declarations =
_genDefines.str() + _osd.str();
std::string const source =
Expand Down Expand Up @@ -2901,6 +2917,14 @@ HdSt_CodeGen::_CompileWithGeneratedHgiResources(
resourceGen._GenerateHgiResources(registry->GetHgi(), &tesDesc,
HdShaderTokens->tessEvalShader, _resTES, _GetMetaData());

// material in TES
if (_hasTESWithNoGS) {
resourceGen._GenerateHgiResources(registry->GetHgi(), &tesDesc,
HdShaderTokens->tessEvalShader, _resMaterial, _GetMetaData());
resourceGen._GenerateHgiTextureResources(&tesDesc,
HdShaderTokens->tessEvalShader, _resTextures, _GetMetaData());
}

std::string const declarations =
_genDefines.str() + _genDecl.str() + _osd.str();
std::string const source = _genAccessors.str() + _genTES.str();
Expand Down Expand Up @@ -6857,6 +6881,9 @@ HdSt_CodeGen::_GenerateShaderParameters(bool bindlessTextureEnabled)

_genGS << accessors.str();
_genFS << accessors.str();
if (_hasTESWithNoGS) {
_genTES << accessors.str();
}
_genPTCS << accessors.str();
_genPTVS << accessors.str();
}
Expand Down
1 change: 1 addition & 0 deletions pxr/imaging/hdSt/codeGen.h
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Original file line number Diff line number Diff line change
Expand Up @@ -222,6 +222,7 @@ class HdSt_CodeGen
bool _hasCS;
bool _hasPTCS;
bool _hasPTVS;
bool _hasTESWithNoGS;

bool _hasClipPlanes;
};
Expand Down
88 changes: 73 additions & 15 deletions pxr/imaging/hdSt/meshShaderKey.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -93,8 +93,10 @@ TF_DEFINE_PRIVATE_TOKENS(
((mainPatchCommonTCS, "Mesh.TessControl.PatchCommon"))
((mainBSplineQuadTCS, "Mesh.TessControl.BSplineQuad"))
((mainBezierQuadTES, "Mesh.TessEval.BezierQuad"))
((mainBezierQuadNoGSTES, "Mesh.TessEval.BezierQuadNoGS"))
((mainBoxSplineTriangleTCS, "Mesh.TessControl.BoxSplineTriangle"))
((mainBezierTriangleTES, "Mesh.TessEval.BezierTriangle"))
((mainBezierTriangleNoGSTES, "Mesh.TessEval.BezierTriangleNoGS"))
((mainVaryingInterpTES, "Mesh.TessEval.VaryingInterpolation"))
((mainTrianglePTVS, "Mesh.PostTessVertex.Triangle"))
((mainQuadPTVS, "Mesh.PostTessVertex.Quad"))
Expand Down Expand Up @@ -123,6 +125,8 @@ TF_DEFINE_PRIVATE_TOKENS(
((instancing, "Instancing.Transform"))

// terminals
((customDisplacementTES, "TessEval.CustomDisplacement"))
((noCustomDisplacementTES, "TessEval.NoCustomDisplacement"))
((customDisplacementGS, "Geometry.CustomDisplacement"))
((noCustomDisplacementGS, "Geometry.NoCustomDisplacement"))
((commonFS, "Fragment.CommonTerminals"))
Expand Down Expand Up @@ -346,28 +350,82 @@ HdSt_MeshShaderKey::HdSt_MeshShaderKey(
}

bool const ptvsStageEnabled = !PTVS[0].IsEmpty();
bool finalTesStageEnabled = false;

// tessellation control shader
if (isPrimTypePatches && !ptvsStageEnabled) {
TCS[0] = _tokens->instancing;
TCS[1] = _tokens->mainPatchCommonTCS;
TCS[2] = isPrimTypePatchesBSpline

// Tessellation control shader.
uint8_t tcsIndex = 0;
TCS[tcsIndex++] = _tokens->instancing;
TCS[tcsIndex++] = _tokens->mainPatchCommonTCS;
TCS[tcsIndex++] = isPrimTypePatchesBSpline
? _tokens->mainBSplineQuadTCS
: _tokens->mainBoxSplineTriangleTCS;
TCS[3] = TfToken();

// tessellation evaluation shader
TES[0] = _tokens->instancing;
TES[1] = isPrimTypePatchesBSpline
? _tokens->mainBezierQuadTES
: _tokens->mainBezierTriangleTES;
TES[2] = _tokens->mainVaryingInterpTES;
TES[3] = TfToken();
TCS[tcsIndex++] = TfToken();

// Tessellation evaluation shader
uint8_t tesIndex = 0;
TES[tesIndex++] = _tokens->instancing;

if (geomStyle == HdMeshGeomStyleEdgeOnSurf) {
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This seems not quite right. Minimally, this should also test hasBuiltinBarycentrics, which is the only thing that edges need from GS.

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Ah, right, when the fragment shader has barycentrics, it can render edges.


// TES configuration with a geometry shader.
TES[tesIndex++] = isPrimTypePatchesBSpline ? _tokens->mainBezierQuadTES
: _tokens->mainBezierTriangleTES;
TES[tesIndex++] = _tokens->mainVaryingInterpTES;
TES[tesIndex++] = TfToken();
}
else {

// TES configuration without a geometry shader.
if (ptvsGeometricNormals) {
TES[tesIndex++] = _tokens->normalsGeometryFlat;
}
else {
TES[tesIndex++] = _tokens->normalsGeometryNoFlat;
}

// Now handle the vs style normals
if (normalsSource == NormalSourceFlat) {
TES[tesIndex++] = _tokens->normalsFlat;
}
else if (normalsSource == NormalSourceSmooth) {
TES[tesIndex++] = _tokens->normalsSmooth;
}
else if (vsSceneNormals) {
TES[tesIndex++] = _tokens->normalsScene;
}
else if (gsSceneNormals && isPrimTypePatches) {
TES[tesIndex++] = _tokens->normalsScenePatches;
}
else {
TES[tesIndex++] = _tokens->normalsPass;
}

TES[tesIndex++] = _tokens->mainVaryingInterpTES;

if (hasCustomDisplacement) {
TES[tesIndex++] = _tokens->customDisplacementTES;
}
else {
TES[tesIndex++] = _tokens->noCustomDisplacementTES;
}

TES[tesIndex++] = isPrimTypePatchesBSpline
? _tokens->mainBezierQuadNoGSTES
: _tokens->mainBezierTriangleNoGSTES;
TES[tesIndex++] = TfToken();
finalTesStageEnabled = true;
}

} else {

TCS[0] = TfToken();
TES[0] = TfToken();
}

bool const tessOnlyEnabled = finalTesStageEnabled || ptvsStageEnabled;

// geometry shader
uint8_t gsIndex = 0;
GS[gsIndex++] = _tokens->instancing;
Expand Down Expand Up @@ -398,7 +456,7 @@ HdSt_MeshShaderKey::HdSt_MeshShaderKey(

// Optimization : See if we can skip the geometry shader.
bool const canSkipGS =
ptvsStageEnabled ||
tessOnlyEnabled ||
// Whether we can skip executing the displacement shading terminal
(!hasCustomDisplacement
&& (normalsSource != NormalSourceLimit)
Expand Down Expand Up @@ -603,7 +661,7 @@ HdSt_MeshShaderKey::HdSt_MeshShaderKey(
FS[fsIndex++] = _tokens->mainPatchCoordTriQuadFS;

// Patches
} else if (isPrimTypePatches && ptvsStageEnabled) {
} else if (isPrimTypePatches && tessOnlyEnabled) {
FS[fsIndex++] = _tokens->mainPatchCoordTessFS;
// Points/No GS
} else if (isPrimTypePoints || canSkipGS) {
Expand Down
2 changes: 1 addition & 1 deletion pxr/imaging/hdSt/meshShaderKey.h
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Original file line number Diff line number Diff line change
Expand Up @@ -103,7 +103,7 @@ struct HdSt_MeshShaderKey : public HdSt_ShaderKey
TfToken glslfx;
TfToken VS[7];
TfToken TCS[4];
TfToken TES[4];
TfToken TES[12];
TfToken PTCS[4];
TfToken PTVS[12];
TfToken GS[10];
Expand Down
122 changes: 122 additions & 0 deletions pxr/imaging/hdSt/shaders/mesh.glslfx
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Original file line number Diff line number Diff line change
Expand Up @@ -425,6 +425,67 @@ void main(void)
ProcessPrimvarsOut(basis, 5, 6, 9, 10, UV);
}

--- --------------------------------------------------------------------------
-- layout Mesh.TessEval.BezierQuadNoGS

# XXX: due to NVIDIA shader compiler bug (filed as 1687344)
# we can't put patchCoord into interface block.
[
["in", "quads"],
["in", "vec4", "tessOuterLo", "patch"],
["in", "vec4", "tessOuterHi", "patch"],
["in block array", "VertexDataTess", "inpt", "gl_MaxPatchVertices",
["OsdPerPatchVertexBezier", "v"]
],
["out block", "VertexData", "outData",
["vec4", "Peye"],
["vec3", "Neye"]
],
["out", "vec4", "tesPatchCoord"],
["out", "vec2", "tesTessCoord"]
]

--- --------------------------------------------------------------------------
-- glsl Mesh.TessEval.BezierQuadNoGS

void main(void)
{
OsdPerPatchVertexBezier cv[16];
for (int i = 0; i < 16; ++i) {
cv[i] = inpt[i].v;
}
vec2 UV = OsdGetTessParameterization(gl_TessCoord.xy,
tessOuterLo,
tessOuterHi);

vec3 P = vec3(0), dPu = vec3(0), dPv = vec3(0);
vec3 N = vec3(0), dNu = vec3(0), dNv = vec3(0);

ivec3 patchParam = inpt[0].v.patchParam;
OsdEvalPatchBezier(patchParam, UV, cv, P, dPu, dPv, N, dNu, dNv);

tesPatchCoord = OsdInterpolatePatchCoord(UV, patchParam);
tesTessCoord = UV;

// Bilinear basis
vec4 basis = vec4(
(1.0-UV.x) * (1.0-UV.y), UV.x * (1.0-UV.y),
(1.0-UV.x) * UV.y, UV.x * UV.y );

bool isFlipped = IsFlipped(); // consider handedness AND negative-scale
vec3 Neye = isFlipped ? -N : N;

vec3 point = DisplacementTerminal(5, 6, 9, 10, P, Neye, basis, UV);

outData.Peye = vec4(point, 1.0);
outData.Neye = Neye; // normalized

gl_Position = vec4(GetProjectionMatrix() * outData.Peye);
ApplyClipPlanes(outData.Peye);

ProcessPrimvarsOut(basis, 5, 6, 9, 10, UV);
}

--- --------------------------------------------------------------------------
-- layout Mesh.TessControl.BoxSplineTriangle

Expand Down Expand Up @@ -537,6 +598,67 @@ void main(void)
ProcessPrimvarsOut(basis, 4, 5, 8, 0, UV);
}

--- --------------------------------------------------------------------------
-- layout Mesh.TessEval.BezierTriangleNoGS

# XXX: due to NVIDIA shader compiler bug (filed as 1687344)
# we can't put patchCoord into interface block.
[
["in", "triangles"],
["in", "vec4", "tessOuterLo", "patch"],
["in", "vec4", "tessOuterHi", "patch"],
["in block array", "VertexDataTess", "inpt", "gl_MaxPatchVertices",
["OsdPerPatchVertexBezier", "v"]
],
["out block", "VertexData", "outData",
["vec4", "Peye"],
["vec3", "Neye"]
],
["out", "vec4", "tesPatchCoord"],
["out", "vec2", "tesTessCoord"]
]

--- --------------------------------------------------------------------------
-- glsl Mesh.TessEval.BezierTriangleNoGS

void main(void)
{
OsdPerPatchVertexBezier cv[15];
for (int i = 0; i < 15; ++i) {
cv[i] = inpt[i].v;
}
vec2 UV = OsdGetTessParameterizationTriangle(gl_TessCoord.xyz,
tessOuterLo,
tessOuterHi);

vec3 P = vec3(0), dPu = vec3(0), dPv = vec3(0);
vec3 N = vec3(0), dNu = vec3(0), dNv = vec3(0);

ivec3 patchParam = inpt[0].v.patchParam;
OsdEvalPatchBezierTriangle(patchParam, UV, cv, P, dPu, dPv, N, dNu, dNv);

tesPatchCoord = OsdInterpolatePatchCoordTriangle(UV, patchParam);
tesTessCoord = UV;

// Barycentric basis
vec4 basis = vec4(
(1.0f-UV.x-UV.y), UV.x, UV.y, 0.0f);

bool isFlipped = IsFlipped(); // consider handedness AND negative-scale
vec3 Neye = isFlipped ? -N : N;

vec3 point = DisplacementTerminal(4, 5, 8, 0, P, Neye, basis, UV);

outData.Peye = vec4(P, 1);
outData.Neye = Neye; // normalized

gl_Position = vec4(GetProjectionMatrix() * outData.Peye);
ApplyClipPlanes(outData.Peye);

ProcessPrimvarsOut(basis, 4, 5, 8, 0, UV);
}


--- --------------------------------------------------------------------------
-- glsl Mesh.PostTessControl.PatchCommon

Expand Down
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