/*
* Copyright 2011 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "GrAAHairLinePathRenderer.h"
#include "GrContext.h"
#include "GrDrawState.h"
#include "GrGpu.h"
#include "GrIndexBuffer.h"
#include "GrPathUtils.h"
#include "SkGeometry.h"
#include "SkTemplates.h"
namespace {
// quadratics are rendered as 5-sided polys in order to bound the
// AA stroke around the center-curve. See comments in push_quad_index_buffer and
// bloat_quad.
static const int kVertsPerQuad = 5;
static const int kIdxsPerQuad = 9;
static const int kVertsPerLineSeg = 4;
static const int kIdxsPerLineSeg = 6;
static const int kNumQuadsInIdxBuffer = 256;
static const size_t kQuadIdxSBufize = kIdxsPerQuad *
sizeof(uint16_t) *
kNumQuadsInIdxBuffer;
bool push_quad_index_data(GrIndexBuffer* qIdxBuffer) {
uint16_t* data = (uint16_t*) qIdxBuffer->lock();
bool tempData = NULL == data;
if (tempData) {
data = new uint16_t[kNumQuadsInIdxBuffer * kIdxsPerQuad];
}
for (int i = 0; i < kNumQuadsInIdxBuffer; ++i) {
// Each quadratic is rendered as a five sided polygon. This poly bounds
// the quadratic's bounding triangle but has been expanded so that the
// 1-pixel wide area around the curve is inside the poly.
// If a,b,c are the original control points then the poly a0,b0,c0,c1,a1
// that is rendered would look like this:
// b0
// b
//
// a0 c0
// a c
// a1 c1
// Each is drawn as three triagnles specified by these 9 indices:
int baseIdx = i * kIdxsPerQuad;
uint16_t baseVert = (uint16_t)(i * kVertsPerQuad);
data[0 + baseIdx] = baseVert + 0; // a0
data[1 + baseIdx] = baseVert + 1; // a1
data[2 + baseIdx] = baseVert + 2; // b0
data[3 + baseIdx] = baseVert + 2; // b0
data[4 + baseIdx] = baseVert + 4; // c1
data[5 + baseIdx] = baseVert + 3; // c0
data[6 + baseIdx] = baseVert + 1; // a1
data[7 + baseIdx] = baseVert + 4; // c1
data[8 + baseIdx] = baseVert + 2; // b0
}
if (tempData) {
bool ret = qIdxBuffer->updateData(data, kQuadIdxSBufize);
delete[] data;
return ret;
} else {
qIdxBuffer->unlock();
return true;
}
}
}
GrPathRenderer* GrAAHairLinePathRenderer::Create(GrContext* context) {
const GrIndexBuffer* lIdxBuffer = context->getQuadIndexBuffer();
if (NULL == lIdxBuffer) {
return NULL;
}
GrGpu* gpu = context->getGpu();
GrIndexBuffer* qIdxBuf = gpu->createIndexBuffer(kQuadIdxSBufize, false);
SkAutoTUnref<GrIndexBuffer> qIdxBuffer(qIdxBuf);
if (NULL == qIdxBuf ||
!push_quad_index_data(qIdxBuf)) {
return NULL;
}
return new GrAAHairLinePathRenderer(context,
lIdxBuffer,
qIdxBuf);
}
GrAAHairLinePathRenderer::GrAAHairLinePathRenderer(
const GrContext* context,
const GrIndexBuffer* linesIndexBuffer,
const GrIndexBuffer* quadsIndexBuffer) {
fLinesIndexBuffer = linesIndexBuffer;
linesIndexBuffer->ref();
fQuadsIndexBuffer = quadsIndexBuffer;
quadsIndexBuffer->ref();
}
GrAAHairLinePathRenderer::~GrAAHairLinePathRenderer() {
fLinesIndexBuffer->unref();
fQuadsIndexBuffer->unref();
}
namespace {
typedef SkTArray<SkPoint, true> PtArray;
#define PREALLOC_PTARRAY(N) SkSTArray<(N),SkPoint, true>
typedef SkTArray<int, true> IntArray;
// Takes 178th time of logf on Z600 / VC2010
int get_float_exp(float x) {
GR_STATIC_ASSERT(sizeof(int) == sizeof(float));
#if GR_DEBUG
static bool tested;
if (!tested) {
tested = true;
GrAssert(get_float_exp(0.25f) == -2);
GrAssert(get_float_exp(0.3f) == -2);
GrAssert(get_float_exp(0.5f) == -1);
GrAssert(get_float_exp(1.f) == 0);
GrAssert(get_float_exp(2.f) == 1);
GrAssert(get_float_exp(2.5f) == 1);
GrAssert(get_float_exp(8.f) == 3);
GrAssert(get_float_exp(100.f) == 6);
GrAssert(get_float_exp(1000.f) == 9);
GrAssert(get_float_exp(1024.f) == 10);
GrAssert(get_float_exp(3000000.f) == 21);
}
#endif
const int* iptr = (const int*)&x;
return (((*iptr) & 0x7f800000) >> 23) - 127;
}
// we subdivide the quads to avoid huge overfill
// if it returns -1 then should be drawn as lines
int num_quad_subdivs(const SkPoint p[3]) {
static const SkScalar gDegenerateToLineTol = SK_Scalar1;
static const SkScalar gDegenerateToLineTolSqd =
SkScalarMul(gDegenerateToLineTol, gDegenerateToLineTol);
if (p[0].distanceToSqd(p[1]) < gDegenerateToLineTolSqd ||
p[1].distanceToSqd(p[2]) < gDegenerateToLineTolSqd) {
return -1;
}
GrScalar dsqd = p[1].distanceToLineBetweenSqd(p[0], p[2]);
if (dsqd < gDegenerateToLineTolSqd) {
return -1;
}
if (p[2].distanceToLineBetweenSqd(p[1], p[0]) < gDegenerateToLineTolSqd) {
return -1;
}
static const int kMaxSub = 4;
// tolerance of triangle height in pixels
// tuned on windows Quadro FX 380 / Z600
// trade off of fill vs cpu time on verts
// maybe different when do this using gpu (geo or tess shaders)
static const SkScalar gSubdivTol = 175 * SK_Scalar1;
if (dsqd <= gSubdivTol*gSubdivTol) {
return 0;
} else {
// subdividing the quad reduces d by 4. so we want x = log4(d/tol)
// = log4(d*d/tol*tol)/2
// = log2(d*d/tol*tol)
#ifdef SK_SCALAR_IS_FLOAT
// +1 since we're ignoring the mantissa contribution.
int log = get_float_exp(dsqd/(gSubdivTol*gSubdivTol)) + 1;
log = GrMin(GrMax(0, log), kMaxSub);
return log;
#else
SkScalar log = SkScalarLog(SkScalarDiv(dsqd,gSubdivTol*gSubdivTol));
static const SkScalar conv = SkScalarInvert(SkScalarLog(2));
log = SkScalarMul(log, conv);
return GrMin(GrMax(0, SkScalarCeilToInt(log)),kMaxSub);
#endif
}
}
/**
* Generates the lines and quads to be rendered. Lines are always recorded in
* device space. We will do a device space bloat to account for the 1pixel
* thickness.
* Quads are recorded in device space unless m contains
* perspective, then in they are in src space. We do this because we will
* subdivide large quads to reduce over-fill. This subdivision has to be
* performed before applying the perspective matrix.
*/
int generate_lines_and_quads(const SkPath& path,
const SkMatrix& m,
const SkVector& translate,
GrIRect clip,
PtArray* lines,
PtArray* quads,
IntArray* quadSubdivCnts) {
SkPath::Iter iter(path, false);
int totalQuadCount = 0;
GrRect bounds;
GrIRect ibounds;
bool persp = m.hasPerspective();
for (;;) {
GrPoint pts[4];
GrPoint devPts[4];
GrPathCmd cmd = (GrPathCmd)iter.next(pts);
switch (cmd) {
case kMove_PathCmd:
break;
case kLine_PathCmd:
SkPoint::Offset(pts, 2, translate);
m.mapPoints(devPts, pts, 2);
bounds.setBounds(devPts, 2);
bounds.outset(SK_Scalar1, SK_Scalar1);
bounds.roundOut(&ibounds);
if (SkIRect::Intersects(clip, ibounds)) {
SkPoint* pts = lines->push_back_n(2);
pts[0] = devPts[0];
pts[1] = devPts[1];
}
break;
case kQuadratic_PathCmd:
SkPoint::Offset(pts, 3, translate);
m.mapPoints(devPts, pts, 3);
bounds.setBounds(devPts, 3);
bounds.outset(SK_Scalar1, SK_Scalar1);
bounds.roundOut(&ibounds);
if (SkIRect::Intersects(clip, ibounds)) {
int subdiv = num_quad_subdivs(devPts);
GrAssert(subdiv >= -1);
if (-1 == subdiv) {
SkPoint* pts = lines->push_back_n(4);
pts[0] = devPts[0];
pts[1] = devPts[1];
pts[2] = devPts[1];
pts[3] = devPts[2];
} else {
// when in perspective keep quads in src space
SkPoint* qPts = persp ? pts : devPts;
SkPoint* pts = quads->push_back_n(3);
pts[0] = qPts[0];
pts[1] = qPts[1];
pts[2] = qPts[2];
quadSubdivCnts->push_back() = subdiv;
totalQuadCount += 1 << subdiv;
}
}
break;
case kCubic_PathCmd:
SkPoint::Offset(pts, 4, translate);
m.mapPoints(devPts, pts, 4);
bounds.setBounds(devPts, 4);
bounds.outset(SK_Scalar1, SK_Scalar1);
bounds.roundOut(&ibounds);
if (SkIRect::Intersects(clip, ibounds)) {
PREALLOC_PTARRAY(32) q;
// We convert cubics to quadratics (for now).
// In perspective have to do conversion in src space.
if (persp) {
SkScalar tolScale =
GrPathUtils::scaleToleranceToSrc(SK_Scalar1, m,
path.getBounds());
GrPathUtils::convertCubicToQuads(pts, tolScale, &q);
} else {
GrPathUtils::convertCubicToQuads(devPts, SK_Scalar1, &q);
}
for (int i = 0; i < q.count(); i += 3) {
SkPoint* qInDevSpace;
// bounds has to be calculated in device space, but q is
// in src space when there is perspective.
if (persp) {
m.mapPoints(devPts, &q[i], 3);
bounds.setBounds(devPts, 3);
qInDevSpace = devPts;
} else {
bounds.setBounds(&q[i], 3);
qInDevSpace = &q[i];
}
bounds.outset(SK_Scalar1, SK_Scalar1);
bounds.roundOut(&ibounds);
if (SkIRect::Intersects(clip, ibounds)) {
int subdiv = num_quad_subdivs(qInDevSpace);
GrAssert(subdiv >= -1);
if (-1 == subdiv) {
SkPoint* pts = lines->push_back_n(4);
// lines should always be in device coords
pts[0] = qInDevSpace[0];
pts[1] = qInDevSpace[1];
pts[2] = qInDevSpace[1];
pts[3] = qInDevSpace[2];
} else {
SkPoint* pts = quads->push_back_n(3);
// q is already in src space when there is no
// perspective and dev coords otherwise.
pts[0] = q[0 + i];
pts[1] = q[1 + i];
pts[2] = q[2 + i];
quadSubdivCnts->push_back() = subdiv;
totalQuadCount += 1 << subdiv;
}
}
}
}
break;
case kClose_PathCmd:
break;
case kEnd_PathCmd:
return totalQuadCount;
}
}
}
struct Vertex {
GrPoint fPos;
union {
struct {
GrScalar fA;
GrScalar fB;
GrScalar fC;
} fLine;
GrVec fQuadCoord;
struct {
GrScalar fBogus[4];
};
};
};
GR_STATIC_ASSERT(sizeof(Vertex) == 3 * sizeof(GrPoint));
void intersect_lines(const SkPoint& ptA, const SkVector& normA,
const SkPoint& ptB, const SkVector& normB,
SkPoint* result) {
SkScalar lineAW = -normA.dot(ptA);
SkScalar lineBW = -normB.dot(ptB);
SkScalar wInv = SkScalarMul(normA.fX, normB.fY) -
SkScalarMul(normA.fY, normB.fX);
wInv = SkScalarInvert(wInv);
result->fX = SkScalarMul(normA.fY, lineBW) - SkScalarMul(lineAW, normB.fY);
result->fX = SkScalarMul(result->fX, wInv);
result->fY = SkScalarMul(lineAW, normB.fX) - SkScalarMul(normA.fX, lineBW);
result->fY = SkScalarMul(result->fY, wInv);
}
void bloat_quad(const SkPoint qpts[3], const GrMatrix* toDevice,
const GrMatrix* toSrc, Vertex verts[kVertsPerQuad]) {
GrAssert(!toDevice == !toSrc);
// original quad is specified by tri a,b,c
SkPoint a = qpts[0];
SkPoint b = qpts[1];
SkPoint c = qpts[2];
// this should be in the src space, not dev coords, when we have perspective
SkMatrix DevToUV;
GrPathUtils::quadDesignSpaceToUVCoordsMatrix(qpts, &DevToUV);
if (toDevice) {
toDevice->mapPoints(&a, 1);
toDevice->mapPoints(&b, 1);
toDevice->mapPoints(&c, 1);
}
// make a new poly where we replace a and c by a 1-pixel wide edges orthog
// to edges ab and bc:
//
// before | after
// | b0
// b |
// |
// | a0 c0
// a c | a1 c1
//
// edges a0->b0 and b0->c0 are parallel to original edges a->b and b->c,
// respectively.
Vertex& a0 = verts[0];
Vertex& a1 = verts[1];
Vertex& b0 = verts[2];
Vertex& c0 = verts[3];
Vertex& c1 = verts[4];
SkVector ab = b;
ab -= a;
SkVector ac = c;
ac -= a;
SkVector cb = b;
cb -= c;
// We should have already handled degenerates
GrAssert(ab.length() > 0 && cb.length() > 0);
ab.normalize();
SkVector abN;
abN.setOrthog(ab, SkVector::kLeft_Side);
if (abN.dot(ac) > 0) {
abN.negate();
}
cb.normalize();
SkVector cbN;
cbN.setOrthog(cb, SkVector::kLeft_Side);
if (cbN.dot(ac) < 0) {
cbN.negate();
}
a0.fPos = a;
a0.fPos += abN;
a1.fPos = a;
a1.fPos -= abN;
c0.fPos = c;
c0.fPos += cbN;
c1.fPos = c;
c1.fPos -= cbN;
intersect_lines(a0.fPos, abN, c0.fPos, cbN, &b0.fPos);
if (toSrc) {
toSrc->mapPointsWithStride(&verts[0].fPos, sizeof(Vertex), kVertsPerQuad);
}
DevToUV.mapPointsWithStride(&verts[0].fQuadCoord,
&verts[0].fPos, sizeof(Vertex), kVertsPerQuad);
}
void add_quads(const SkPoint p[3],
int subdiv,
const GrMatrix* toDevice,
const GrMatrix* toSrc,
Vertex** vert) {
GrAssert(subdiv >= 0);
if (subdiv) {
SkPoint newP[5];
SkChopQuadAtHalf(p, newP);
add_quads(newP + 0, subdiv-1, toDevice, toSrc, vert);
add_quads(newP + 2, subdiv-1, toDevice, toSrc, vert);
} else {
bloat_quad(p, toDevice, toSrc, *vert);
*vert += kVertsPerQuad;
}
}
void add_line(const SkPoint p[2],
int rtHeight,
const SkMatrix* toSrc,
Vertex** vert) {
const SkPoint& a = p[0];
const SkPoint& b = p[1];
SkVector orthVec = b;
orthVec -= a;
if (orthVec.setLength(SK_Scalar1)) {
orthVec.setOrthog(orthVec);
// the values we pass down to the frag shader
// have to be in y-points-up space;
SkVector normal;
normal.fX = orthVec.fX;
normal.fY = -orthVec.fY;
SkPoint aYDown;
aYDown.fX = a.fX;
aYDown.fY = rtHeight - a.fY;
SkScalar lineC = -(aYDown.dot(normal));
for (int i = 0; i < kVertsPerLineSeg; ++i) {
(*vert)[i].fPos = (i < 2) ? a : b;
if (0 == i || 3 == i) {
(*vert)[i].fPos -= orthVec;
} else {
(*vert)[i].fPos += orthVec;
}
(*vert)[i].fLine.fA = normal.fX;
(*vert)[i].fLine.fB = normal.fY;
(*vert)[i].fLine.fC = lineC;
}
if (NULL != toSrc) {
toSrc->mapPointsWithStride(&(*vert)->fPos,
sizeof(Vertex),
kVertsPerLineSeg);
}
} else {
// just make it degenerate and likely offscreen
(*vert)[0].fPos.set(SK_ScalarMax, SK_ScalarMax);
(*vert)[1].fPos.set(SK_ScalarMax, SK_ScalarMax);
(*vert)[2].fPos.set(SK_ScalarMax, SK_ScalarMax);
(*vert)[3].fPos.set(SK_ScalarMax, SK_ScalarMax);
}
*vert += kVertsPerLineSeg;
}
}
bool GrAAHairLinePathRenderer::createGeom(const SkPath& path,
const GrVec* translate,
GrDrawTarget* target,
GrDrawState::StageMask stageMask,
int* lineCnt,
int* quadCnt) {
const GrDrawState& drawState = target->getDrawState();
int rtHeight = drawState.getRenderTarget()->height();
GrIRect clip;
if (target->getClip().hasConservativeBounds()) {
GrRect clipRect = target->getClip().getConservativeBounds();
clipRect.roundOut(&clip);
} else {
clip.setLargest();
}
GrVertexLayout layout = GrDrawTarget::kEdge_VertexLayoutBit;
for (int s = 0; s < GrDrawState::kNumStages; ++s) {
if ((1 << s) & stageMask) {
layout |= GrDrawTarget::StagePosAsTexCoordVertexLayoutBit(s);
}
}
GrMatrix viewM = drawState.getViewMatrix();
PREALLOC_PTARRAY(128) lines;
PREALLOC_PTARRAY(128) quads;
IntArray qSubdivs;
static const GrVec gZeroVec = {0, 0};
if (NULL == translate) {
translate = &gZeroVec;
}
*quadCnt = generate_lines_and_quads(path, viewM, *translate, clip,
&lines, &quads, &qSubdivs);
*lineCnt = lines.count() / 2;
int vertCnt = kVertsPerLineSeg * *lineCnt + kVertsPerQuad * *quadCnt;
GrAssert(sizeof(Vertex) == GrDrawTarget::VertexSize(layout));
Vertex* verts;
if (!target->reserveVertexSpace(layout, vertCnt, (void**)&verts)) {
return false;
}
const GrMatrix* toDevice = NULL;
const GrMatrix* toSrc = NULL;
GrMatrix ivm;
if (viewM.hasPerspective()) {
if (viewM.invert(&ivm)) {
toDevice = &viewM;
toSrc = &ivm;
}
}
for (int i = 0; i < *lineCnt; ++i) {
add_line(&lines[2*i], rtHeight, toSrc, &verts);
}
int unsubdivQuadCnt = quads.count() / 3;
for (int i = 0; i < unsubdivQuadCnt; ++i) {
GrAssert(qSubdivs[i] >= 0);
add_quads(&quads[3*i], qSubdivs[i], toDevice, toSrc, &verts);
}
return true;
}
bool GrAAHairLinePathRenderer::canDrawPath(const SkPath& path,
GrPathFill fill,
const GrDrawTarget* target,
bool antiAlias) const {
if (fill != kHairLine_PathFill || !antiAlias) {
return false;
}
static const uint32_t gReqDerivMask = SkPath::kCubic_SegmentMask |
SkPath::kQuad_SegmentMask;
if (!target->getCaps().fShaderDerivativeSupport &&
(gReqDerivMask & path.getSegmentMasks())) {
return false;
}
return true;
}
bool GrAAHairLinePathRenderer::onDrawPath(const SkPath& path,
GrPathFill fill,
const GrVec* translate,
GrDrawTarget* target,
GrDrawState::StageMask stageMask,
bool antiAlias) {
int lineCnt;
int quadCnt;
if (!this->createGeom(path,
translate,
target,
stageMask,
&lineCnt,
&quadCnt)) {
return false;
}
GrDrawState* drawState = target->drawState();
GrDrawTarget::AutoStateRestore asr;
if (!drawState->getViewMatrix().hasPerspective()) {
asr.set(target);
GrMatrix ivm;
if (drawState->getViewInverse(&ivm)) {
drawState->preConcatSamplerMatrices(stageMask, ivm);
}
drawState->setViewMatrix(GrMatrix::I());
}
// TODO: See whether rendering lines as degenerate quads improves perf
// when we have a mix
target->setIndexSourceToBuffer(fLinesIndexBuffer);
int lines = 0;
int nBufLines = fLinesIndexBuffer->maxQuads();
while (lines < lineCnt) {
int n = GrMin(lineCnt - lines, nBufLines);
drawState->setVertexEdgeType(GrDrawState::kHairLine_EdgeType);
target->drawIndexed(kTriangles_PrimitiveType,
kVertsPerLineSeg*lines, // startV
0, // startI
kVertsPerLineSeg*n, // vCount
kIdxsPerLineSeg*n); // iCount
lines += n;
}
target->setIndexSourceToBuffer(fQuadsIndexBuffer);
int quads = 0;
while (quads < quadCnt) {
int n = GrMin(quadCnt - quads, kNumQuadsInIdxBuffer);
drawState->setVertexEdgeType(GrDrawState::kHairQuad_EdgeType);
target->drawIndexed(kTriangles_PrimitiveType,
4 * lineCnt + kVertsPerQuad*quads, // startV
0, // startI
kVertsPerQuad*n, // vCount
kIdxsPerQuad*n); // iCount
quads += n;
}
return true;
}