1 /* 2 * Copyright 2011 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "GrAAHairLinePathRenderer.h" 9 10 #include "GrContext.h" 11 #include "GrDrawState.h" 12 #include "GrDrawTargetCaps.h" 13 #include "GrEffect.h" 14 #include "GrGpu.h" 15 #include "GrIndexBuffer.h" 16 #include "GrPathUtils.h" 17 #include "GrTBackendEffectFactory.h" 18 #include "SkGeometry.h" 19 #include "SkStroke.h" 20 #include "SkTemplates.h" 21 22 #include "effects/GrBezierEffect.h" 23 24 namespace { 25 // quadratics are rendered as 5-sided polys in order to bound the 26 // AA stroke around the center-curve. See comments in push_quad_index_buffer and 27 // bloat_quad. Quadratics and conics share an index buffer 28 static const int kVertsPerQuad = 5; 29 static const int kIdxsPerQuad = 9; 30 31 // lines are rendered as: 32 // *______________* 33 // |\ -_______ /| 34 // | \ \ / | 35 // | *--------* | 36 // | / ______/ \ | 37 // */_-__________\* 38 // For: 6 vertices and 18 indices (for 6 triangles) 39 static const int kVertsPerLineSeg = 6; 40 static const int kIdxsPerLineSeg = 18; 41 42 static const int kNumQuadsInIdxBuffer = 256; 43 static const size_t kQuadIdxSBufize = kIdxsPerQuad * 44 sizeof(uint16_t) * 45 kNumQuadsInIdxBuffer; 46 47 static const int kNumLineSegsInIdxBuffer = 256; 48 static const size_t kLineSegIdxSBufize = kIdxsPerLineSeg * 49 sizeof(uint16_t) * 50 kNumLineSegsInIdxBuffer; 51 52 static bool push_quad_index_data(GrIndexBuffer* qIdxBuffer) { 53 uint16_t* data = (uint16_t*) qIdxBuffer->map(); 54 bool tempData = NULL == data; 55 if (tempData) { 56 data = SkNEW_ARRAY(uint16_t, kNumQuadsInIdxBuffer * kIdxsPerQuad); 57 } 58 for (int i = 0; i < kNumQuadsInIdxBuffer; ++i) { 59 60 // Each quadratic is rendered as a five sided polygon. This poly bounds 61 // the quadratic's bounding triangle but has been expanded so that the 62 // 1-pixel wide area around the curve is inside the poly. 63 // If a,b,c are the original control points then the poly a0,b0,c0,c1,a1 64 // that is rendered would look like this: 65 // b0 66 // b 67 // 68 // a0 c0 69 // a c 70 // a1 c1 71 // Each is drawn as three triangles specified by these 9 indices: 72 int baseIdx = i * kIdxsPerQuad; 73 uint16_t baseVert = (uint16_t)(i * kVertsPerQuad); 74 data[0 + baseIdx] = baseVert + 0; // a0 75 data[1 + baseIdx] = baseVert + 1; // a1 76 data[2 + baseIdx] = baseVert + 2; // b0 77 data[3 + baseIdx] = baseVert + 2; // b0 78 data[4 + baseIdx] = baseVert + 4; // c1 79 data[5 + baseIdx] = baseVert + 3; // c0 80 data[6 + baseIdx] = baseVert + 1; // a1 81 data[7 + baseIdx] = baseVert + 4; // c1 82 data[8 + baseIdx] = baseVert + 2; // b0 83 } 84 if (tempData) { 85 bool ret = qIdxBuffer->updateData(data, kQuadIdxSBufize); 86 delete[] data; 87 return ret; 88 } else { 89 qIdxBuffer->unmap(); 90 return true; 91 } 92 } 93 94 static bool push_line_index_data(GrIndexBuffer* lIdxBuffer) { 95 uint16_t* data = (uint16_t*) lIdxBuffer->map(); 96 bool tempData = NULL == data; 97 if (tempData) { 98 data = SkNEW_ARRAY(uint16_t, kNumLineSegsInIdxBuffer * kIdxsPerLineSeg); 99 } 100 for (int i = 0; i < kNumLineSegsInIdxBuffer; ++i) { 101 // Each line segment is rendered as two quads and two triangles. 102 // p0 and p1 have alpha = 1 while all other points have alpha = 0. 103 // The four external points are offset 1 pixel perpendicular to the 104 // line and half a pixel parallel to the line. 105 // 106 // p4 p5 107 // p0 p1 108 // p2 p3 109 // 110 // Each is drawn as six triangles specified by these 18 indices: 111 int baseIdx = i * kIdxsPerLineSeg; 112 uint16_t baseVert = (uint16_t)(i * kVertsPerLineSeg); 113 data[0 + baseIdx] = baseVert + 0; 114 data[1 + baseIdx] = baseVert + 1; 115 data[2 + baseIdx] = baseVert + 3; 116 117 data[3 + baseIdx] = baseVert + 0; 118 data[4 + baseIdx] = baseVert + 3; 119 data[5 + baseIdx] = baseVert + 2; 120 121 data[6 + baseIdx] = baseVert + 0; 122 data[7 + baseIdx] = baseVert + 4; 123 data[8 + baseIdx] = baseVert + 5; 124 125 data[9 + baseIdx] = baseVert + 0; 126 data[10+ baseIdx] = baseVert + 5; 127 data[11+ baseIdx] = baseVert + 1; 128 129 data[12 + baseIdx] = baseVert + 0; 130 data[13 + baseIdx] = baseVert + 2; 131 data[14 + baseIdx] = baseVert + 4; 132 133 data[15 + baseIdx] = baseVert + 1; 134 data[16 + baseIdx] = baseVert + 5; 135 data[17 + baseIdx] = baseVert + 3; 136 } 137 if (tempData) { 138 bool ret = lIdxBuffer->updateData(data, kLineSegIdxSBufize); 139 delete[] data; 140 return ret; 141 } else { 142 lIdxBuffer->unmap(); 143 return true; 144 } 145 } 146 } 147 148 GrPathRenderer* GrAAHairLinePathRenderer::Create(GrContext* context) { 149 GrGpu* gpu = context->getGpu(); 150 GrIndexBuffer* qIdxBuf = gpu->createIndexBuffer(kQuadIdxSBufize, false); 151 SkAutoTUnref<GrIndexBuffer> qIdxBuffer(qIdxBuf); 152 if (NULL == qIdxBuf || !push_quad_index_data(qIdxBuf)) { 153 return NULL; 154 } 155 GrIndexBuffer* lIdxBuf = gpu->createIndexBuffer(kLineSegIdxSBufize, false); 156 SkAutoTUnref<GrIndexBuffer> lIdxBuffer(lIdxBuf); 157 if (NULL == lIdxBuf || !push_line_index_data(lIdxBuf)) { 158 return NULL; 159 } 160 return SkNEW_ARGS(GrAAHairLinePathRenderer, 161 (context, lIdxBuf, qIdxBuf)); 162 } 163 164 GrAAHairLinePathRenderer::GrAAHairLinePathRenderer( 165 const GrContext* context, 166 const GrIndexBuffer* linesIndexBuffer, 167 const GrIndexBuffer* quadsIndexBuffer) { 168 fLinesIndexBuffer = linesIndexBuffer; 169 linesIndexBuffer->ref(); 170 fQuadsIndexBuffer = quadsIndexBuffer; 171 quadsIndexBuffer->ref(); 172 } 173 174 GrAAHairLinePathRenderer::~GrAAHairLinePathRenderer() { 175 fLinesIndexBuffer->unref(); 176 fQuadsIndexBuffer->unref(); 177 } 178 179 namespace { 180 181 #define PREALLOC_PTARRAY(N) SkSTArray<(N),SkPoint, true> 182 183 // Takes 178th time of logf on Z600 / VC2010 184 int get_float_exp(float x) { 185 GR_STATIC_ASSERT(sizeof(int) == sizeof(float)); 186 #ifdef SK_DEBUG 187 static bool tested; 188 if (!tested) { 189 tested = true; 190 SkASSERT(get_float_exp(0.25f) == -2); 191 SkASSERT(get_float_exp(0.3f) == -2); 192 SkASSERT(get_float_exp(0.5f) == -1); 193 SkASSERT(get_float_exp(1.f) == 0); 194 SkASSERT(get_float_exp(2.f) == 1); 195 SkASSERT(get_float_exp(2.5f) == 1); 196 SkASSERT(get_float_exp(8.f) == 3); 197 SkASSERT(get_float_exp(100.f) == 6); 198 SkASSERT(get_float_exp(1000.f) == 9); 199 SkASSERT(get_float_exp(1024.f) == 10); 200 SkASSERT(get_float_exp(3000000.f) == 21); 201 } 202 #endif 203 const int* iptr = (const int*)&x; 204 return (((*iptr) & 0x7f800000) >> 23) - 127; 205 } 206 207 // Uses the max curvature function for quads to estimate 208 // where to chop the conic. If the max curvature is not 209 // found along the curve segment it will return 1 and 210 // dst[0] is the original conic. If it returns 2 the dst[0] 211 // and dst[1] are the two new conics. 212 int split_conic(const SkPoint src[3], SkConic dst[2], const SkScalar weight) { 213 SkScalar t = SkFindQuadMaxCurvature(src); 214 if (t == 0) { 215 if (dst) { 216 dst[0].set(src, weight); 217 } 218 return 1; 219 } else { 220 if (dst) { 221 SkConic conic; 222 conic.set(src, weight); 223 conic.chopAt(t, dst); 224 } 225 return 2; 226 } 227 } 228 229 // Calls split_conic on the entire conic and then once more on each subsection. 230 // Most cases will result in either 1 conic (chop point is not within t range) 231 // or 3 points (split once and then one subsection is split again). 232 int chop_conic(const SkPoint src[3], SkConic dst[4], const SkScalar weight) { 233 SkConic dstTemp[2]; 234 int conicCnt = split_conic(src, dstTemp, weight); 235 if (2 == conicCnt) { 236 int conicCnt2 = split_conic(dstTemp[0].fPts, dst, dstTemp[0].fW); 237 conicCnt = conicCnt2 + split_conic(dstTemp[1].fPts, &dst[conicCnt2], dstTemp[1].fW); 238 } else { 239 dst[0] = dstTemp[0]; 240 } 241 return conicCnt; 242 } 243 244 // returns 0 if quad/conic is degen or close to it 245 // in this case approx the path with lines 246 // otherwise returns 1 247 int is_degen_quad_or_conic(const SkPoint p[3]) { 248 static const SkScalar gDegenerateToLineTol = SK_Scalar1; 249 static const SkScalar gDegenerateToLineTolSqd = 250 SkScalarMul(gDegenerateToLineTol, gDegenerateToLineTol); 251 252 if (p[0].distanceToSqd(p[1]) < gDegenerateToLineTolSqd || 253 p[1].distanceToSqd(p[2]) < gDegenerateToLineTolSqd) { 254 return 1; 255 } 256 257 SkScalar dsqd = p[1].distanceToLineBetweenSqd(p[0], p[2]); 258 if (dsqd < gDegenerateToLineTolSqd) { 259 return 1; 260 } 261 262 if (p[2].distanceToLineBetweenSqd(p[1], p[0]) < gDegenerateToLineTolSqd) { 263 return 1; 264 } 265 return 0; 266 } 267 268 // we subdivide the quads to avoid huge overfill 269 // if it returns -1 then should be drawn as lines 270 int num_quad_subdivs(const SkPoint p[3]) { 271 static const SkScalar gDegenerateToLineTol = SK_Scalar1; 272 static const SkScalar gDegenerateToLineTolSqd = 273 SkScalarMul(gDegenerateToLineTol, gDegenerateToLineTol); 274 275 if (p[0].distanceToSqd(p[1]) < gDegenerateToLineTolSqd || 276 p[1].distanceToSqd(p[2]) < gDegenerateToLineTolSqd) { 277 return -1; 278 } 279 280 SkScalar dsqd = p[1].distanceToLineBetweenSqd(p[0], p[2]); 281 if (dsqd < gDegenerateToLineTolSqd) { 282 return -1; 283 } 284 285 if (p[2].distanceToLineBetweenSqd(p[1], p[0]) < gDegenerateToLineTolSqd) { 286 return -1; 287 } 288 289 // tolerance of triangle height in pixels 290 // tuned on windows Quadro FX 380 / Z600 291 // trade off of fill vs cpu time on verts 292 // maybe different when do this using gpu (geo or tess shaders) 293 static const SkScalar gSubdivTol = 175 * SK_Scalar1; 294 295 if (dsqd <= SkScalarMul(gSubdivTol, gSubdivTol)) { 296 return 0; 297 } else { 298 static const int kMaxSub = 4; 299 // subdividing the quad reduces d by 4. so we want x = log4(d/tol) 300 // = log4(d*d/tol*tol)/2 301 // = log2(d*d/tol*tol) 302 303 // +1 since we're ignoring the mantissa contribution. 304 int log = get_float_exp(dsqd/(gSubdivTol*gSubdivTol)) + 1; 305 log = SkTMin(SkTMax(0, log), kMaxSub); 306 return log; 307 } 308 } 309 310 /** 311 * Generates the lines and quads to be rendered. Lines are always recorded in 312 * device space. We will do a device space bloat to account for the 1pixel 313 * thickness. 314 * Quads are recorded in device space unless m contains 315 * perspective, then in they are in src space. We do this because we will 316 * subdivide large quads to reduce over-fill. This subdivision has to be 317 * performed before applying the perspective matrix. 318 */ 319 int generate_lines_and_quads(const SkPath& path, 320 const SkMatrix& m, 321 const SkIRect& devClipBounds, 322 GrAAHairLinePathRenderer::PtArray* lines, 323 GrAAHairLinePathRenderer::PtArray* quads, 324 GrAAHairLinePathRenderer::PtArray* conics, 325 GrAAHairLinePathRenderer::IntArray* quadSubdivCnts, 326 GrAAHairLinePathRenderer::FloatArray* conicWeights) { 327 SkPath::Iter iter(path, false); 328 329 int totalQuadCount = 0; 330 SkRect bounds; 331 SkIRect ibounds; 332 333 bool persp = m.hasPerspective(); 334 335 for (;;) { 336 SkPoint pathPts[4]; 337 SkPoint devPts[4]; 338 SkPath::Verb verb = iter.next(pathPts); 339 switch (verb) { 340 case SkPath::kConic_Verb: { 341 SkConic dst[4]; 342 // We chop the conics to create tighter clipping to hide error 343 // that appears near max curvature of very thin conics. Thin 344 // hyperbolas with high weight still show error. 345 int conicCnt = chop_conic(pathPts, dst, iter.conicWeight()); 346 for (int i = 0; i < conicCnt; ++i) { 347 SkPoint* chopPnts = dst[i].fPts; 348 m.mapPoints(devPts, chopPnts, 3); 349 bounds.setBounds(devPts, 3); 350 bounds.outset(SK_Scalar1, SK_Scalar1); 351 bounds.roundOut(&ibounds); 352 if (SkIRect::Intersects(devClipBounds, ibounds)) { 353 if (is_degen_quad_or_conic(devPts)) { 354 SkPoint* pts = lines->push_back_n(4); 355 pts[0] = devPts[0]; 356 pts[1] = devPts[1]; 357 pts[2] = devPts[1]; 358 pts[3] = devPts[2]; 359 } else { 360 // when in perspective keep conics in src space 361 SkPoint* cPts = persp ? chopPnts : devPts; 362 SkPoint* pts = conics->push_back_n(3); 363 pts[0] = cPts[0]; 364 pts[1] = cPts[1]; 365 pts[2] = cPts[2]; 366 conicWeights->push_back() = dst[i].fW; 367 } 368 } 369 } 370 break; 371 } 372 case SkPath::kMove_Verb: 373 break; 374 case SkPath::kLine_Verb: 375 m.mapPoints(devPts, pathPts, 2); 376 bounds.setBounds(devPts, 2); 377 bounds.outset(SK_Scalar1, SK_Scalar1); 378 bounds.roundOut(&ibounds); 379 if (SkIRect::Intersects(devClipBounds, ibounds)) { 380 SkPoint* pts = lines->push_back_n(2); 381 pts[0] = devPts[0]; 382 pts[1] = devPts[1]; 383 } 384 break; 385 case SkPath::kQuad_Verb: { 386 SkPoint choppedPts[5]; 387 // Chopping the quad helps when the quad is either degenerate or nearly degenerate. 388 // When it is degenerate it allows the approximation with lines to work since the 389 // chop point (if there is one) will be at the parabola's vertex. In the nearly 390 // degenerate the QuadUVMatrix computed for the points is almost singular which 391 // can cause rendering artifacts. 392 int n = SkChopQuadAtMaxCurvature(pathPts, choppedPts); 393 for (int i = 0; i < n; ++i) { 394 SkPoint* quadPts = choppedPts + i * 2; 395 m.mapPoints(devPts, quadPts, 3); 396 bounds.setBounds(devPts, 3); 397 bounds.outset(SK_Scalar1, SK_Scalar1); 398 bounds.roundOut(&ibounds); 399 400 if (SkIRect::Intersects(devClipBounds, ibounds)) { 401 int subdiv = num_quad_subdivs(devPts); 402 SkASSERT(subdiv >= -1); 403 if (-1 == subdiv) { 404 SkPoint* pts = lines->push_back_n(4); 405 pts[0] = devPts[0]; 406 pts[1] = devPts[1]; 407 pts[2] = devPts[1]; 408 pts[3] = devPts[2]; 409 } else { 410 // when in perspective keep quads in src space 411 SkPoint* qPts = persp ? quadPts : devPts; 412 SkPoint* pts = quads->push_back_n(3); 413 pts[0] = qPts[0]; 414 pts[1] = qPts[1]; 415 pts[2] = qPts[2]; 416 quadSubdivCnts->push_back() = subdiv; 417 totalQuadCount += 1 << subdiv; 418 } 419 } 420 } 421 break; 422 } 423 case SkPath::kCubic_Verb: 424 m.mapPoints(devPts, pathPts, 4); 425 bounds.setBounds(devPts, 4); 426 bounds.outset(SK_Scalar1, SK_Scalar1); 427 bounds.roundOut(&ibounds); 428 if (SkIRect::Intersects(devClipBounds, ibounds)) { 429 PREALLOC_PTARRAY(32) q; 430 // we don't need a direction if we aren't constraining the subdivision 431 static const SkPath::Direction kDummyDir = SkPath::kCCW_Direction; 432 // We convert cubics to quadratics (for now). 433 // In perspective have to do conversion in src space. 434 if (persp) { 435 SkScalar tolScale = 436 GrPathUtils::scaleToleranceToSrc(SK_Scalar1, m, 437 path.getBounds()); 438 GrPathUtils::convertCubicToQuads(pathPts, tolScale, false, kDummyDir, &q); 439 } else { 440 GrPathUtils::convertCubicToQuads(devPts, SK_Scalar1, false, kDummyDir, &q); 441 } 442 for (int i = 0; i < q.count(); i += 3) { 443 SkPoint* qInDevSpace; 444 // bounds has to be calculated in device space, but q is 445 // in src space when there is perspective. 446 if (persp) { 447 m.mapPoints(devPts, &q[i], 3); 448 bounds.setBounds(devPts, 3); 449 qInDevSpace = devPts; 450 } else { 451 bounds.setBounds(&q[i], 3); 452 qInDevSpace = &q[i]; 453 } 454 bounds.outset(SK_Scalar1, SK_Scalar1); 455 bounds.roundOut(&ibounds); 456 if (SkIRect::Intersects(devClipBounds, ibounds)) { 457 int subdiv = num_quad_subdivs(qInDevSpace); 458 SkASSERT(subdiv >= -1); 459 if (-1 == subdiv) { 460 SkPoint* pts = lines->push_back_n(4); 461 // lines should always be in device coords 462 pts[0] = qInDevSpace[0]; 463 pts[1] = qInDevSpace[1]; 464 pts[2] = qInDevSpace[1]; 465 pts[3] = qInDevSpace[2]; 466 } else { 467 SkPoint* pts = quads->push_back_n(3); 468 // q is already in src space when there is no 469 // perspective and dev coords otherwise. 470 pts[0] = q[0 + i]; 471 pts[1] = q[1 + i]; 472 pts[2] = q[2 + i]; 473 quadSubdivCnts->push_back() = subdiv; 474 totalQuadCount += 1 << subdiv; 475 } 476 } 477 } 478 } 479 break; 480 case SkPath::kClose_Verb: 481 break; 482 case SkPath::kDone_Verb: 483 return totalQuadCount; 484 } 485 } 486 } 487 488 struct LineVertex { 489 SkPoint fPos; 490 GrColor fCoverage; 491 }; 492 493 struct BezierVertex { 494 SkPoint fPos; 495 union { 496 struct { 497 SkScalar fK; 498 SkScalar fL; 499 SkScalar fM; 500 } fConic; 501 SkVector fQuadCoord; 502 struct { 503 SkScalar fBogus[4]; 504 }; 505 }; 506 }; 507 508 GR_STATIC_ASSERT(sizeof(BezierVertex) == 3 * sizeof(SkPoint)); 509 510 void intersect_lines(const SkPoint& ptA, const SkVector& normA, 511 const SkPoint& ptB, const SkVector& normB, 512 SkPoint* result) { 513 514 SkScalar lineAW = -normA.dot(ptA); 515 SkScalar lineBW = -normB.dot(ptB); 516 517 SkScalar wInv = SkScalarMul(normA.fX, normB.fY) - 518 SkScalarMul(normA.fY, normB.fX); 519 wInv = SkScalarInvert(wInv); 520 521 result->fX = SkScalarMul(normA.fY, lineBW) - SkScalarMul(lineAW, normB.fY); 522 result->fX = SkScalarMul(result->fX, wInv); 523 524 result->fY = SkScalarMul(lineAW, normB.fX) - SkScalarMul(normA.fX, lineBW); 525 result->fY = SkScalarMul(result->fY, wInv); 526 } 527 528 void set_uv_quad(const SkPoint qpts[3], BezierVertex verts[kVertsPerQuad]) { 529 // this should be in the src space, not dev coords, when we have perspective 530 GrPathUtils::QuadUVMatrix DevToUV(qpts); 531 DevToUV.apply<kVertsPerQuad, sizeof(BezierVertex), sizeof(SkPoint)>(verts); 532 } 533 534 void bloat_quad(const SkPoint qpts[3], const SkMatrix* toDevice, 535 const SkMatrix* toSrc, BezierVertex verts[kVertsPerQuad], 536 SkRect* devBounds) { 537 SkASSERT(!toDevice == !toSrc); 538 // original quad is specified by tri a,b,c 539 SkPoint a = qpts[0]; 540 SkPoint b = qpts[1]; 541 SkPoint c = qpts[2]; 542 543 if (toDevice) { 544 toDevice->mapPoints(&a, 1); 545 toDevice->mapPoints(&b, 1); 546 toDevice->mapPoints(&c, 1); 547 } 548 // make a new poly where we replace a and c by a 1-pixel wide edges orthog 549 // to edges ab and bc: 550 // 551 // before | after 552 // | b0 553 // b | 554 // | 555 // | a0 c0 556 // a c | a1 c1 557 // 558 // edges a0->b0 and b0->c0 are parallel to original edges a->b and b->c, 559 // respectively. 560 BezierVertex& a0 = verts[0]; 561 BezierVertex& a1 = verts[1]; 562 BezierVertex& b0 = verts[2]; 563 BezierVertex& c0 = verts[3]; 564 BezierVertex& c1 = verts[4]; 565 566 SkVector ab = b; 567 ab -= a; 568 SkVector ac = c; 569 ac -= a; 570 SkVector cb = b; 571 cb -= c; 572 573 // We should have already handled degenerates 574 SkASSERT(ab.length() > 0 && cb.length() > 0); 575 576 ab.normalize(); 577 SkVector abN; 578 abN.setOrthog(ab, SkVector::kLeft_Side); 579 if (abN.dot(ac) > 0) { 580 abN.negate(); 581 } 582 583 cb.normalize(); 584 SkVector cbN; 585 cbN.setOrthog(cb, SkVector::kLeft_Side); 586 if (cbN.dot(ac) < 0) { 587 cbN.negate(); 588 } 589 590 a0.fPos = a; 591 a0.fPos += abN; 592 a1.fPos = a; 593 a1.fPos -= abN; 594 595 c0.fPos = c; 596 c0.fPos += cbN; 597 c1.fPos = c; 598 c1.fPos -= cbN; 599 600 intersect_lines(a0.fPos, abN, c0.fPos, cbN, &b0.fPos); 601 devBounds->growToInclude(&verts[0].fPos, sizeof(BezierVertex), kVertsPerQuad); 602 603 if (toSrc) { 604 toSrc->mapPointsWithStride(&verts[0].fPos, sizeof(BezierVertex), kVertsPerQuad); 605 } 606 } 607 608 // Equations based off of Loop-Blinn Quadratic GPU Rendering 609 // Input Parametric: 610 // P(t) = (P0*(1-t)^2 + 2*w*P1*t*(1-t) + P2*t^2) / (1-t)^2 + 2*w*t*(1-t) + t^2) 611 // Output Implicit: 612 // f(x, y, w) = f(P) = K^2 - LM 613 // K = dot(k, P), L = dot(l, P), M = dot(m, P) 614 // k, l, m are calculated in function GrPathUtils::getConicKLM 615 void set_conic_coeffs(const SkPoint p[3], BezierVertex verts[kVertsPerQuad], 616 const SkScalar weight) { 617 SkScalar klm[9]; 618 619 GrPathUtils::getConicKLM(p, weight, klm); 620 621 for (int i = 0; i < kVertsPerQuad; ++i) { 622 const SkPoint pnt = verts[i].fPos; 623 verts[i].fConic.fK = pnt.fX * klm[0] + pnt.fY * klm[1] + klm[2]; 624 verts[i].fConic.fL = pnt.fX * klm[3] + pnt.fY * klm[4] + klm[5]; 625 verts[i].fConic.fM = pnt.fX * klm[6] + pnt.fY * klm[7] + klm[8]; 626 } 627 } 628 629 void add_conics(const SkPoint p[3], 630 const SkScalar weight, 631 const SkMatrix* toDevice, 632 const SkMatrix* toSrc, 633 BezierVertex** vert, 634 SkRect* devBounds) { 635 bloat_quad(p, toDevice, toSrc, *vert, devBounds); 636 set_conic_coeffs(p, *vert, weight); 637 *vert += kVertsPerQuad; 638 } 639 640 void add_quads(const SkPoint p[3], 641 int subdiv, 642 const SkMatrix* toDevice, 643 const SkMatrix* toSrc, 644 BezierVertex** vert, 645 SkRect* devBounds) { 646 SkASSERT(subdiv >= 0); 647 if (subdiv) { 648 SkPoint newP[5]; 649 SkChopQuadAtHalf(p, newP); 650 add_quads(newP + 0, subdiv-1, toDevice, toSrc, vert, devBounds); 651 add_quads(newP + 2, subdiv-1, toDevice, toSrc, vert, devBounds); 652 } else { 653 bloat_quad(p, toDevice, toSrc, *vert, devBounds); 654 set_uv_quad(p, *vert); 655 *vert += kVertsPerQuad; 656 } 657 } 658 659 void add_line(const SkPoint p[2], 660 const SkMatrix* toSrc, 661 GrColor coverage, 662 LineVertex** vert) { 663 const SkPoint& a = p[0]; 664 const SkPoint& b = p[1]; 665 666 SkVector ortho, vec = b; 667 vec -= a; 668 669 if (vec.setLength(SK_ScalarHalf)) { 670 // Create a vector orthogonal to 'vec' and of unit length 671 ortho.fX = 2.0f * vec.fY; 672 ortho.fY = -2.0f * vec.fX; 673 674 (*vert)[0].fPos = a; 675 (*vert)[0].fCoverage = coverage; 676 (*vert)[1].fPos = b; 677 (*vert)[1].fCoverage = coverage; 678 (*vert)[2].fPos = a - vec + ortho; 679 (*vert)[2].fCoverage = 0; 680 (*vert)[3].fPos = b + vec + ortho; 681 (*vert)[3].fCoverage = 0; 682 (*vert)[4].fPos = a - vec - ortho; 683 (*vert)[4].fCoverage = 0; 684 (*vert)[5].fPos = b + vec - ortho; 685 (*vert)[5].fCoverage = 0; 686 687 if (NULL != toSrc) { 688 toSrc->mapPointsWithStride(&(*vert)->fPos, 689 sizeof(LineVertex), 690 kVertsPerLineSeg); 691 } 692 } else { 693 // just make it degenerate and likely offscreen 694 for (int i = 0; i < kVertsPerLineSeg; ++i) { 695 (*vert)[i].fPos.set(SK_ScalarMax, SK_ScalarMax); 696 } 697 } 698 699 *vert += kVertsPerLineSeg; 700 } 701 702 } 703 704 /////////////////////////////////////////////////////////////////////////////// 705 706 namespace { 707 708 // position + edge 709 extern const GrVertexAttrib gHairlineBezierAttribs[] = { 710 {kVec2f_GrVertexAttribType, 0, kPosition_GrVertexAttribBinding}, 711 {kVec4f_GrVertexAttribType, sizeof(SkPoint), kEffect_GrVertexAttribBinding} 712 }; 713 714 // position + coverage 715 extern const GrVertexAttrib gHairlineLineAttribs[] = { 716 {kVec2f_GrVertexAttribType, 0, kPosition_GrVertexAttribBinding}, 717 {kVec4ub_GrVertexAttribType, sizeof(SkPoint), kCoverage_GrVertexAttribBinding}, 718 }; 719 720 }; 721 722 bool GrAAHairLinePathRenderer::createLineGeom(const SkPath& path, 723 GrDrawTarget* target, 724 const PtArray& lines, 725 int lineCnt, 726 GrDrawTarget::AutoReleaseGeometry* arg, 727 SkRect* devBounds) { 728 GrDrawState* drawState = target->drawState(); 729 730 const SkMatrix& viewM = drawState->getViewMatrix(); 731 732 int vertCnt = kVertsPerLineSeg * lineCnt; 733 734 drawState->setVertexAttribs<gHairlineLineAttribs>(SK_ARRAY_COUNT(gHairlineLineAttribs)); 735 SkASSERT(sizeof(LineVertex) == drawState->getVertexSize()); 736 737 if (!arg->set(target, vertCnt, 0)) { 738 return false; 739 } 740 741 LineVertex* verts = reinterpret_cast<LineVertex*>(arg->vertices()); 742 743 const SkMatrix* toSrc = NULL; 744 SkMatrix ivm; 745 746 if (viewM.hasPerspective()) { 747 if (viewM.invert(&ivm)) { 748 toSrc = &ivm; 749 } 750 } 751 devBounds->set(lines.begin(), lines.count()); 752 for (int i = 0; i < lineCnt; ++i) { 753 add_line(&lines[2*i], toSrc, drawState->getCoverageColor(), &verts); 754 } 755 // All the verts computed by add_line are within sqrt(1^2 + 0.5^2) of the end points. 756 static const SkScalar kSqrtOfOneAndAQuarter = 1.118f; 757 // Add a little extra to account for vector normalization precision. 758 static const SkScalar kOutset = kSqrtOfOneAndAQuarter + SK_Scalar1 / 20; 759 devBounds->outset(kOutset, kOutset); 760 761 return true; 762 } 763 764 bool GrAAHairLinePathRenderer::createBezierGeom( 765 const SkPath& path, 766 GrDrawTarget* target, 767 const PtArray& quads, 768 int quadCnt, 769 const PtArray& conics, 770 int conicCnt, 771 const IntArray& qSubdivs, 772 const FloatArray& cWeights, 773 GrDrawTarget::AutoReleaseGeometry* arg, 774 SkRect* devBounds) { 775 GrDrawState* drawState = target->drawState(); 776 777 const SkMatrix& viewM = drawState->getViewMatrix(); 778 779 int vertCnt = kVertsPerQuad * quadCnt + kVertsPerQuad * conicCnt; 780 781 target->drawState()->setVertexAttribs<gHairlineBezierAttribs>(SK_ARRAY_COUNT(gHairlineBezierAttribs)); 782 SkASSERT(sizeof(BezierVertex) == target->getDrawState().getVertexSize()); 783 784 if (!arg->set(target, vertCnt, 0)) { 785 return false; 786 } 787 788 BezierVertex* verts = reinterpret_cast<BezierVertex*>(arg->vertices()); 789 790 const SkMatrix* toDevice = NULL; 791 const SkMatrix* toSrc = NULL; 792 SkMatrix ivm; 793 794 if (viewM.hasPerspective()) { 795 if (viewM.invert(&ivm)) { 796 toDevice = &viewM; 797 toSrc = &ivm; 798 } 799 } 800 801 // Seed the dev bounds with some pts known to be inside. Each quad and conic grows the bounding 802 // box to include its vertices. 803 SkPoint seedPts[2]; 804 if (quadCnt) { 805 seedPts[0] = quads[0]; 806 seedPts[1] = quads[2]; 807 } else if (conicCnt) { 808 seedPts[0] = conics[0]; 809 seedPts[1] = conics[2]; 810 } 811 if (NULL != toDevice) { 812 toDevice->mapPoints(seedPts, 2); 813 } 814 devBounds->set(seedPts[0], seedPts[1]); 815 816 int unsubdivQuadCnt = quads.count() / 3; 817 for (int i = 0; i < unsubdivQuadCnt; ++i) { 818 SkASSERT(qSubdivs[i] >= 0); 819 add_quads(&quads[3*i], qSubdivs[i], toDevice, toSrc, &verts, devBounds); 820 } 821 822 // Start Conics 823 for (int i = 0; i < conicCnt; ++i) { 824 add_conics(&conics[3*i], cWeights[i], toDevice, toSrc, &verts, devBounds); 825 } 826 return true; 827 } 828 829 bool GrAAHairLinePathRenderer::canDrawPath(const SkPath& path, 830 const SkStrokeRec& stroke, 831 const GrDrawTarget* target, 832 bool antiAlias) const { 833 if (!antiAlias) { 834 return false; 835 } 836 837 if (!IsStrokeHairlineOrEquivalent(stroke, 838 target->getDrawState().getViewMatrix(), 839 NULL)) { 840 return false; 841 } 842 843 if (SkPath::kLine_SegmentMask == path.getSegmentMasks() || 844 target->caps()->shaderDerivativeSupport()) { 845 return true; 846 } 847 return false; 848 } 849 850 template <class VertexType> 851 bool check_bounds(GrDrawState* drawState, const SkRect& devBounds, void* vertices, int vCount) 852 { 853 SkRect tolDevBounds = devBounds; 854 // The bounds ought to be tight, but in perspective the below code runs the verts 855 // through the view matrix to get back to dev coords, which can introduce imprecision. 856 if (drawState->getViewMatrix().hasPerspective()) { 857 tolDevBounds.outset(SK_Scalar1 / 1000, SK_Scalar1 / 1000); 858 } else { 859 // Non-persp matrices cause this path renderer to draw in device space. 860 SkASSERT(drawState->getViewMatrix().isIdentity()); 861 } 862 SkRect actualBounds; 863 864 VertexType* verts = reinterpret_cast<VertexType*>(vertices); 865 bool first = true; 866 for (int i = 0; i < vCount; ++i) { 867 SkPoint pos = verts[i].fPos; 868 // This is a hack to workaround the fact that we move some degenerate segments offscreen. 869 if (SK_ScalarMax == pos.fX) { 870 continue; 871 } 872 drawState->getViewMatrix().mapPoints(&pos, 1); 873 if (first) { 874 actualBounds.set(pos.fX, pos.fY, pos.fX, pos.fY); 875 first = false; 876 } else { 877 actualBounds.growToInclude(pos.fX, pos.fY); 878 } 879 } 880 if (!first) { 881 return tolDevBounds.contains(actualBounds); 882 } 883 884 return true; 885 } 886 887 bool GrAAHairLinePathRenderer::onDrawPath(const SkPath& path, 888 const SkStrokeRec& stroke, 889 GrDrawTarget* target, 890 bool antiAlias) { 891 GrDrawState* drawState = target->drawState(); 892 893 SkScalar hairlineCoverage; 894 if (IsStrokeHairlineOrEquivalent(stroke, 895 target->getDrawState().getViewMatrix(), 896 &hairlineCoverage)) { 897 uint8_t newCoverage = SkScalarRoundToInt(hairlineCoverage * 898 target->getDrawState().getCoverage()); 899 target->drawState()->setCoverage(newCoverage); 900 } 901 902 SkIRect devClipBounds; 903 target->getClip()->getConservativeBounds(drawState->getRenderTarget(), &devClipBounds); 904 905 int lineCnt; 906 int quadCnt; 907 int conicCnt; 908 PREALLOC_PTARRAY(128) lines; 909 PREALLOC_PTARRAY(128) quads; 910 PREALLOC_PTARRAY(128) conics; 911 IntArray qSubdivs; 912 FloatArray cWeights; 913 quadCnt = generate_lines_and_quads(path, drawState->getViewMatrix(), devClipBounds, 914 &lines, &quads, &conics, &qSubdivs, &cWeights); 915 lineCnt = lines.count() / 2; 916 conicCnt = conics.count() / 3; 917 918 // do lines first 919 if (lineCnt) { 920 GrDrawTarget::AutoReleaseGeometry arg; 921 SkRect devBounds; 922 923 if (!this->createLineGeom(path, 924 target, 925 lines, 926 lineCnt, 927 &arg, 928 &devBounds)) { 929 return false; 930 } 931 932 GrDrawTarget::AutoStateRestore asr; 933 934 // createLineGeom transforms the geometry to device space when the matrix does not have 935 // perspective. 936 if (target->getDrawState().getViewMatrix().hasPerspective()) { 937 asr.set(target, GrDrawTarget::kPreserve_ASRInit); 938 } else if (!asr.setIdentity(target, GrDrawTarget::kPreserve_ASRInit)) { 939 return false; 940 } 941 GrDrawState* drawState = target->drawState(); 942 943 // Check devBounds 944 SkASSERT(check_bounds<LineVertex>(drawState, devBounds, arg.vertices(), 945 kVertsPerLineSeg * lineCnt)); 946 947 { 948 GrDrawState::AutoRestoreEffects are(drawState); 949 target->setIndexSourceToBuffer(fLinesIndexBuffer); 950 int lines = 0; 951 while (lines < lineCnt) { 952 int n = SkTMin(lineCnt - lines, kNumLineSegsInIdxBuffer); 953 target->drawIndexed(kTriangles_GrPrimitiveType, 954 kVertsPerLineSeg*lines, // startV 955 0, // startI 956 kVertsPerLineSeg*n, // vCount 957 kIdxsPerLineSeg*n, // iCount 958 &devBounds); 959 lines += n; 960 } 961 } 962 } 963 964 // then quadratics/conics 965 if (quadCnt || conicCnt) { 966 GrDrawTarget::AutoReleaseGeometry arg; 967 SkRect devBounds; 968 969 if (!this->createBezierGeom(path, 970 target, 971 quads, 972 quadCnt, 973 conics, 974 conicCnt, 975 qSubdivs, 976 cWeights, 977 &arg, 978 &devBounds)) { 979 return false; 980 } 981 982 GrDrawTarget::AutoStateRestore asr; 983 984 // createGeom transforms the geometry to device space when the matrix does not have 985 // perspective. 986 if (target->getDrawState().getViewMatrix().hasPerspective()) { 987 asr.set(target, GrDrawTarget::kPreserve_ASRInit); 988 } else if (!asr.setIdentity(target, GrDrawTarget::kPreserve_ASRInit)) { 989 return false; 990 } 991 GrDrawState* drawState = target->drawState(); 992 993 static const int kEdgeAttrIndex = 1; 994 995 // Check devBounds 996 SkASSERT(check_bounds<BezierVertex>(drawState, devBounds, arg.vertices(), 997 kVertsPerQuad * quadCnt + kVertsPerQuad * conicCnt)); 998 999 if (quadCnt > 0) { 1000 GrEffectRef* hairQuadEffect = GrQuadEffect::Create(kHairlineAA_GrEffectEdgeType, 1001 *target->caps()); 1002 SkASSERT(NULL != hairQuadEffect); 1003 GrDrawState::AutoRestoreEffects are(drawState); 1004 target->setIndexSourceToBuffer(fQuadsIndexBuffer); 1005 drawState->addCoverageEffect(hairQuadEffect, kEdgeAttrIndex)->unref(); 1006 int quads = 0; 1007 while (quads < quadCnt) { 1008 int n = SkTMin(quadCnt - quads, kNumQuadsInIdxBuffer); 1009 target->drawIndexed(kTriangles_GrPrimitiveType, 1010 kVertsPerQuad*quads, // startV 1011 0, // startI 1012 kVertsPerQuad*n, // vCount 1013 kIdxsPerQuad*n, // iCount 1014 &devBounds); 1015 quads += n; 1016 } 1017 } 1018 1019 if (conicCnt > 0) { 1020 GrDrawState::AutoRestoreEffects are(drawState); 1021 GrEffectRef* hairConicEffect = GrConicEffect::Create(kHairlineAA_GrEffectEdgeType, 1022 *target->caps()); 1023 SkASSERT(NULL != hairConicEffect); 1024 drawState->addCoverageEffect(hairConicEffect, 1, 2)->unref(); 1025 int conics = 0; 1026 while (conics < conicCnt) { 1027 int n = SkTMin(conicCnt - conics, kNumQuadsInIdxBuffer); 1028 target->drawIndexed(kTriangles_GrPrimitiveType, 1029 kVertsPerQuad*(quadCnt + conics), // startV 1030 0, // startI 1031 kVertsPerQuad*n, // vCount 1032 kIdxsPerQuad*n, // iCount 1033 &devBounds); 1034 conics += n; 1035 } 1036 } 1037 } 1038 1039 target->resetIndexSource(); 1040 1041 return true; 1042 } 1043
