/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "SkNormalMapSource.h"
#include "SkArenaAlloc.h"
#include "SkLightingShader.h"
#include "SkMatrix.h"
#include "SkNormalSource.h"
#include "SkReadBuffer.h"
#include "SkWriteBuffer.h"
#if SK_SUPPORT_GPU
#include "GrCoordTransform.h"
#include "glsl/GrGLSLFragmentProcessor.h"
#include "glsl/GrGLSLFragmentShaderBuilder.h"
#include "SkGr.h"
class NormalMapFP : public GrFragmentProcessor {
public:
static std::unique_ptr<GrFragmentProcessor> Make(std::unique_ptr<GrFragmentProcessor> mapFP,
const SkMatrix& invCTM) {
return std::unique_ptr<GrFragmentProcessor>(new NormalMapFP(std::move(mapFP), invCTM));
}
const char* name() const override { return "NormalMapFP"; }
const SkMatrix& invCTM() const { return fInvCTM; }
std::unique_ptr<GrFragmentProcessor> clone() const override {
return Make(this->childProcessor(0).clone(), fInvCTM);
}
private:
class GLSLNormalMapFP : public GrGLSLFragmentProcessor {
public:
GLSLNormalMapFP() : fColumnMajorInvCTM22{0.0f} {}
void emitCode(EmitArgs& args) override {
GrGLSLFPFragmentBuilder* fragBuilder = args.fFragBuilder;
GrGLSLUniformHandler* uniformHandler = args.fUniformHandler;
// add uniform
const char* xformUniName = nullptr;
fXformUni = uniformHandler->addUniform(kFragment_GrShaderFlag, kFloat2x2_GrSLType,
kDefault_GrSLPrecision, "Xform", &xformUniName);
SkString dstNormalColorName("dstNormalColor");
this->emitChild(0, &dstNormalColorName, args);
fragBuilder->codeAppendf("float3 normal = normalize(%s.rgb - float3(0.5));",
dstNormalColorName.c_str());
// If there's no x & y components, return (0, 0, +/- 1) instead to avoid division by 0
fragBuilder->codeAppend( "if (abs(normal.z) > 0.999) {");
fragBuilder->codeAppendf(" %s = normalize(float4(0.0, 0.0, normal.z, 0.0));",
args.fOutputColor);
// Else, Normalizing the transformed X and Y, while keeping constant both Z and the
// vector's angle in the XY plane. This maintains the "slope" for the surface while
// appropriately rotating the normal regardless of any anisotropic scaling that occurs.
// Here, we call 'scaling factor' the number that must divide the transformed X and Y so
// that the normal's length remains equal to 1.
fragBuilder->codeAppend( "} else {");
fragBuilder->codeAppendf(" float2 transformed = %s * normal.xy;",
xformUniName);
fragBuilder->codeAppend( " float scalingFactorSquared = "
"( (transformed.x * transformed.x) "
"+ (transformed.y * transformed.y) )"
"/(1.0 - (normal.z * normal.z));");
fragBuilder->codeAppendf(" %s = float4(transformed*inversesqrt(scalingFactorSquared),"
"normal.z, 0.0);",
args.fOutputColor);
fragBuilder->codeAppend( "}");
}
static void GenKey(const GrProcessor&, const GrShaderCaps&, GrProcessorKeyBuilder* b) {
b->add32(0x0);
}
private:
void onSetData(const GrGLSLProgramDataManager& pdman,
const GrFragmentProcessor& proc) override {
const NormalMapFP& normalMapFP = proc.cast<NormalMapFP>();
const SkMatrix& invCTM = normalMapFP.invCTM();
fColumnMajorInvCTM22[0] = invCTM.get(SkMatrix::kMScaleX);
fColumnMajorInvCTM22[1] = invCTM.get(SkMatrix::kMSkewY);
fColumnMajorInvCTM22[2] = invCTM.get(SkMatrix::kMSkewX);
fColumnMajorInvCTM22[3] = invCTM.get(SkMatrix::kMScaleY);
pdman.setMatrix2f(fXformUni, fColumnMajorInvCTM22);
}
private:
// Upper-right 2x2 corner of the inverse of the CTM in column-major form
float fColumnMajorInvCTM22[4];
GrGLSLProgramDataManager::UniformHandle fXformUni;
};
void onGetGLSLProcessorKey(const GrShaderCaps& caps, GrProcessorKeyBuilder* b) const override {
GLSLNormalMapFP::GenKey(*this, caps, b);
}
NormalMapFP(std::unique_ptr<GrFragmentProcessor> mapFP, const SkMatrix& invCTM)
: INHERITED(kMappedNormalsFP_ClassID, kNone_OptimizationFlags)
, fInvCTM(invCTM) {
this->registerChildProcessor(std::move(mapFP));
}
GrGLSLFragmentProcessor* onCreateGLSLInstance() const override { return new GLSLNormalMapFP; }
bool onIsEqual(const GrFragmentProcessor& proc) const override {
const NormalMapFP& normalMapFP = proc.cast<NormalMapFP>();
return fInvCTM == normalMapFP.fInvCTM;
}
SkMatrix fInvCTM;
typedef GrFragmentProcessor INHERITED;
};
std::unique_ptr<GrFragmentProcessor> SkNormalMapSourceImpl::asFragmentProcessor(
const GrFPArgs& args) const {
std::unique_ptr<GrFragmentProcessor> mapFP = as_SB(fMapShader)->asFragmentProcessor(args);
if (!mapFP) {
return nullptr;
}
return NormalMapFP::Make(std::move(mapFP), fInvCTM);
}
#endif // SK_SUPPORT_GPU
////////////////////////////////////////////////////////////////////////////
SkNormalMapSourceImpl::Provider::Provider(const SkNormalMapSourceImpl& source,
SkShaderBase::Context* mapContext)
: fSource(source)
, fMapContext(mapContext) {}
SkNormalSource::Provider* SkNormalMapSourceImpl::asProvider(const SkShaderBase::ContextRec &rec,
SkArenaAlloc* alloc) const {
SkMatrix normTotalInv;
if (!this->computeNormTotalInverse(rec, &normTotalInv)) {
return nullptr;
}
// Overriding paint's alpha because we need the normal map's RGB channels to be unpremul'd
SkPaint overridePaint {*(rec.fPaint)};
overridePaint.setAlpha(0xFF);
SkShaderBase::ContextRec overrideRec(overridePaint, *(rec.fMatrix), rec.fLocalMatrix,
rec.fDstColorType, rec.fDstColorSpace);
auto* context = as_SB(fMapShader)->makeContext(overrideRec, alloc);
if (!context) {
return nullptr;
}
return alloc->make<Provider>(*this, context);
}
bool SkNormalMapSourceImpl::computeNormTotalInverse(const SkShaderBase::ContextRec& rec,
SkMatrix* normTotalInverse) const {
SkMatrix total = SkMatrix::Concat(*rec.fMatrix, fMapShader->getLocalMatrix());
if (rec.fLocalMatrix) {
total.preConcat(*rec.fLocalMatrix);
}
return total.invert(normTotalInverse);
}
#define BUFFER_MAX 16
void SkNormalMapSourceImpl::Provider::fillScanLine(int x, int y, SkPoint3 output[],
int count) const {
SkPMColor tmpNormalColors[BUFFER_MAX];
do {
int n = SkTMin(count, BUFFER_MAX);
fMapContext->shadeSpan(x, y, tmpNormalColors, n);
for (int i = 0; i < n; i++) {
SkPoint3 tempNorm;
tempNorm.set(SkIntToScalar(SkGetPackedR32(tmpNormalColors[i])) - 127.0f,
SkIntToScalar(SkGetPackedG32(tmpNormalColors[i])) - 127.0f,
SkIntToScalar(SkGetPackedB32(tmpNormalColors[i])) - 127.0f);
tempNorm.normalize();
if (!SkScalarNearlyEqual(SkScalarAbs(tempNorm.fZ), 1.0f)) {
SkVector transformed = fSource.fInvCTM.mapVector(tempNorm.fX, tempNorm.fY);
// Normalizing the transformed X and Y, while keeping constant both Z and the
// vector's angle in the XY plane. This maintains the "slope" for the surface while
// appropriately rotating the normal for any anisotropic scaling that occurs.
// Here, we call scaling factor the number that must divide the transformed X and Y
// so that the normal's length remains equal to 1.
SkScalar scalingFactorSquared =
(SkScalarSquare(transformed.fX) + SkScalarSquare(transformed.fY))
/ (1.0f - SkScalarSquare(tempNorm.fZ));
SkScalar invScalingFactor = SkScalarInvert(SkScalarSqrt(scalingFactorSquared));
output[i].fX = transformed.fX * invScalingFactor;
output[i].fY = transformed.fY * invScalingFactor;
output[i].fZ = tempNorm.fZ;
} else {
output[i] = {0.0f, 0.0f, tempNorm.fZ};
output[i].normalize();
}
SkASSERT(SkScalarNearlyEqual(output[i].length(), 1.0f));
}
output += n;
x += n;
count -= n;
} while (count > 0);
}
////////////////////////////////////////////////////////////////////////////////
sk_sp<SkFlattenable> SkNormalMapSourceImpl::CreateProc(SkReadBuffer& buf) {
sk_sp<SkShader> mapShader = buf.readFlattenable<SkShaderBase>();
SkMatrix invCTM;
buf.readMatrix(&invCTM);
return sk_make_sp<SkNormalMapSourceImpl>(std::move(mapShader), invCTM);
}
void SkNormalMapSourceImpl::flatten(SkWriteBuffer& buf) const {
this->INHERITED::flatten(buf);
buf.writeFlattenable(fMapShader.get());
buf.writeMatrix(fInvCTM);
}
////////////////////////////////////////////////////////////////////////////
sk_sp<SkNormalSource> SkNormalSource::MakeFromNormalMap(sk_sp<SkShader> map, const SkMatrix& ctm) {
SkMatrix invCTM;
if (!ctm.invert(&invCTM) || !map) {
return nullptr;
}
return sk_make_sp<SkNormalMapSourceImpl>(std::move(map), invCTM);
}