SpotShadow.cpp revision 63d41abb40b3ce40d8b9bccb1cf186e8158a3687
1/* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#define LOG_TAG "OpenGLRenderer" 18 19#define SHADOW_SHRINK_SCALE 0.1f 20 21#include <math.h> 22#include <stdlib.h> 23#include <utils/Log.h> 24 25#include "ShadowTessellator.h" 26#include "SpotShadow.h" 27#include "Vertex.h" 28 29namespace android { 30namespace uirenderer { 31 32/** 33 * Calculate the intersection of a ray with a polygon. 34 * It assumes the ray originates inside the polygon. 35 * 36 * @param poly The polygon, which is represented in a Vector2 array. 37 * @param polyLength The length of caster's polygon in terms of number of 38 * vertices. 39 * @param point the start of the ray 40 * @param dx the x vector of the ray 41 * @param dy the y vector of the ray 42 * @return the distance along the ray if it intersects with the polygon FP_NAN if otherwise 43 */ 44float SpotShadow::rayIntersectPoly(const Vector2* poly, int polyLength, 45 const Vector2& point, float dx, float dy) { 46 double px = point.x; 47 double py = point.y; 48 int p1 = polyLength - 1; 49 for (int p2 = 0; p2 < polyLength; p2++) { 50 double p1x = poly[p1].x; 51 double p1y = poly[p1].y; 52 double p2x = poly[p2].x; 53 double p2y = poly[p2].y; 54 // The math below is derived from solving this formula, basically the 55 // intersection point should stay on both the ray and the edge of (p1, p2). 56 // solve([p1x+t*(p2x-p1x)=dx*t2+px,p1y+t*(p2y-p1y)=dy*t2+py],[t,t2]); 57 double div = (dx * (p1y - p2y) + dy * p2x - dy * p1x); 58 if (div != 0) { 59 double t = (dx * (p1y - py) + dy * px - dy * p1x) / (div); 60 if (t >= 0 && t <= 1) { 61 double t2 = (p1x * (py - p2y) + p2x * (p1y - py) + 62 px * (p2y - p1y)) / div; 63 if (t2 > 0) { 64 return (float)t2; 65 } 66 } 67 } 68 p1 = p2; 69 } 70 return FP_NAN; 71} 72 73/** 74 * Sort points by their X coordinates 75 * 76 * @param points the points as a Vector2 array. 77 * @param pointsLength the number of vertices of the polygon. 78 */ 79void SpotShadow::xsort(Vector2* points, int pointsLength) { 80 quicksortX(points, 0, pointsLength - 1); 81} 82 83/** 84 * compute the convex hull of a collection of Points 85 * 86 * @param points the points as a Vector2 array. 87 * @param pointsLength the number of vertices of the polygon. 88 * @param retPoly pre allocated array of floats to put the vertices 89 * @return the number of points in the polygon 0 if no intersection 90 */ 91int SpotShadow::hull(Vector2* points, int pointsLength, Vector2* retPoly) { 92 xsort(points, pointsLength); 93 int n = pointsLength; 94 Vector2 lUpper[n]; 95 lUpper[0] = points[0]; 96 lUpper[1] = points[1]; 97 98 int lUpperSize = 2; 99 100 for (int i = 2; i < n; i++) { 101 lUpper[lUpperSize] = points[i]; 102 lUpperSize++; 103 104 while (lUpperSize > 2 && !ccw( 105 lUpper[lUpperSize - 3].x, lUpper[lUpperSize - 3].y, 106 lUpper[lUpperSize - 2].x, lUpper[lUpperSize - 2].y, 107 lUpper[lUpperSize - 1].x, lUpper[lUpperSize - 1].y)) { 108 // Remove the middle point of the three last 109 lUpper[lUpperSize - 2].x = lUpper[lUpperSize - 1].x; 110 lUpper[lUpperSize - 2].y = lUpper[lUpperSize - 1].y; 111 lUpperSize--; 112 } 113 } 114 115 Vector2 lLower[n]; 116 lLower[0] = points[n - 1]; 117 lLower[1] = points[n - 2]; 118 119 int lLowerSize = 2; 120 121 for (int i = n - 3; i >= 0; i--) { 122 lLower[lLowerSize] = points[i]; 123 lLowerSize++; 124 125 while (lLowerSize > 2 && !ccw( 126 lLower[lLowerSize - 3].x, lLower[lLowerSize - 3].y, 127 lLower[lLowerSize - 2].x, lLower[lLowerSize - 2].y, 128 lLower[lLowerSize - 1].x, lLower[lLowerSize - 1].y)) { 129 // Remove the middle point of the three last 130 lLower[lLowerSize - 2] = lLower[lLowerSize - 1]; 131 lLowerSize--; 132 } 133 } 134 int count = 0; 135 136 for (int i = 0; i < lUpperSize; i++) { 137 retPoly[count] = lUpper[i]; 138 count++; 139 } 140 141 for (int i = 1; i < lLowerSize - 1; i++) { 142 retPoly[count] = lLower[i]; 143 count++; 144 } 145 // TODO: Add test harness which verify that all the points are inside the hull. 146 return count; 147} 148 149/** 150 * Test whether the 3 points form a counter clockwise turn. 151 * 152 * @param ax the x coordinate of point a 153 * @param ay the y coordinate of point a 154 * @param bx the x coordinate of point b 155 * @param by the y coordinate of point b 156 * @param cx the x coordinate of point c 157 * @param cy the y coordinate of point c 158 * @return true if a right hand turn 159 */ 160bool SpotShadow::ccw(double ax, double ay, double bx, double by, 161 double cx, double cy) { 162 return (bx - ax) * (cy - ay) - (by - ay) * (cx - ax) > EPSILON; 163} 164 165/** 166 * Calculates the intersection of poly1 with poly2 and put in poly2. 167 * 168 * 169 * @param poly1 The 1st polygon, as a Vector2 array. 170 * @param poly1Length The number of vertices of 1st polygon. 171 * @param poly2 The 2nd and output polygon, as a Vector2 array. 172 * @param poly2Length The number of vertices of 2nd polygon. 173 * @return number of vertices in output polygon as poly2. 174 */ 175int SpotShadow::intersection(Vector2* poly1, int poly1Length, 176 Vector2* poly2, int poly2Length) { 177 makeClockwise(poly1, poly1Length); 178 makeClockwise(poly2, poly2Length); 179 180 Vector2 poly[poly1Length * poly2Length + 2]; 181 int count = 0; 182 int pcount = 0; 183 184 // If one vertex from one polygon sits inside another polygon, add it and 185 // count them. 186 for (int i = 0; i < poly1Length; i++) { 187 if (testPointInsidePolygon(poly1[i], poly2, poly2Length)) { 188 poly[count] = poly1[i]; 189 count++; 190 pcount++; 191 192 } 193 } 194 195 int insidePoly2 = pcount; 196 for (int i = 0; i < poly2Length; i++) { 197 if (testPointInsidePolygon(poly2[i], poly1, poly1Length)) { 198 poly[count] = poly2[i]; 199 count++; 200 } 201 } 202 203 int insidePoly1 = count - insidePoly2; 204 // If all vertices from poly1 are inside poly2, then just return poly1. 205 if (insidePoly2 == poly1Length) { 206 memcpy(poly2, poly1, poly1Length * sizeof(Vector2)); 207 return poly1Length; 208 } 209 210 // If all vertices from poly2 are inside poly1, then just return poly2. 211 if (insidePoly1 == poly2Length) { 212 return poly2Length; 213 } 214 215 // Since neither polygon fully contain the other one, we need to add all the 216 // intersection points. 217 Vector2 intersection; 218 for (int i = 0; i < poly2Length; i++) { 219 for (int j = 0; j < poly1Length; j++) { 220 int poly2LineStart = i; 221 int poly2LineEnd = ((i + 1) % poly2Length); 222 int poly1LineStart = j; 223 int poly1LineEnd = ((j + 1) % poly1Length); 224 bool found = lineIntersection( 225 poly2[poly2LineStart].x, poly2[poly2LineStart].y, 226 poly2[poly2LineEnd].x, poly2[poly2LineEnd].y, 227 poly1[poly1LineStart].x, poly1[poly1LineStart].y, 228 poly1[poly1LineEnd].x, poly1[poly1LineEnd].y, 229 intersection); 230 if (found) { 231 poly[count].x = intersection.x; 232 poly[count].y = intersection.y; 233 count++; 234 } else { 235 Vector2 delta = poly2[i] - poly1[j]; 236 if (delta.lengthSquared() < EPSILON) { 237 poly[count] = poly2[i]; 238 count++; 239 } 240 } 241 } 242 } 243 244 if (count == 0) { 245 return 0; 246 } 247 248 // Sort the result polygon around the center. 249 Vector2 center(0.0f, 0.0f); 250 for (int i = 0; i < count; i++) { 251 center += poly[i]; 252 } 253 center /= count; 254 sort(poly, count, center); 255 256#if DEBUG_SHADOW 257 // Since poly2 is overwritten as the result, we need to save a copy to do 258 // our verification. 259 Vector2 oldPoly2[poly2Length]; 260 int oldPoly2Length = poly2Length; 261 memcpy(oldPoly2, poly2, sizeof(Vector2) * poly2Length); 262#endif 263 264 // Filter the result out from poly and put it into poly2. 265 poly2[0] = poly[0]; 266 int lastOutputIndex = 0; 267 for (int i = 1; i < count; i++) { 268 Vector2 delta = poly[i] - poly2[lastOutputIndex]; 269 if (delta.lengthSquared() >= EPSILON) { 270 poly2[++lastOutputIndex] = poly[i]; 271 } else { 272 // If the vertices are too close, pick the inner one, because the 273 // inner one is more likely to be an intersection point. 274 Vector2 delta1 = poly[i] - center; 275 Vector2 delta2 = poly2[lastOutputIndex] - center; 276 if (delta1.lengthSquared() < delta2.lengthSquared()) { 277 poly2[lastOutputIndex] = poly[i]; 278 } 279 } 280 } 281 int resultLength = lastOutputIndex + 1; 282 283#if DEBUG_SHADOW 284 testConvex(poly2, resultLength, "intersection"); 285 testConvex(poly1, poly1Length, "input poly1"); 286 testConvex(oldPoly2, oldPoly2Length, "input poly2"); 287 288 testIntersection(poly1, poly1Length, oldPoly2, oldPoly2Length, poly2, resultLength); 289#endif 290 291 return resultLength; 292} 293 294/** 295 * Sort points about a center point 296 * 297 * @param poly The in and out polyogon as a Vector2 array. 298 * @param polyLength The number of vertices of the polygon. 299 * @param center the center ctr[0] = x , ctr[1] = y to sort around. 300 */ 301void SpotShadow::sort(Vector2* poly, int polyLength, const Vector2& center) { 302 quicksortCirc(poly, 0, polyLength - 1, center); 303} 304 305/** 306 * Calculate the angle between and x and a y coordinate. 307 * The atan2 range from -PI to PI, if we want to sort the vertices as clockwise, 308 * we just negate the return angle. 309 */ 310float SpotShadow::angle(const Vector2& point, const Vector2& center) { 311 return -(float)atan2(point.y - center.y, point.x - center.x); 312} 313 314/** 315 * Swap points pointed to by i and j 316 */ 317void SpotShadow::swap(Vector2* points, int i, int j) { 318 Vector2 temp = points[i]; 319 points[i] = points[j]; 320 points[j] = temp; 321} 322 323/** 324 * quick sort implementation about the center. 325 */ 326void SpotShadow::quicksortCirc(Vector2* points, int low, int high, 327 const Vector2& center) { 328 int i = low, j = high; 329 int p = low + (high - low) / 2; 330 float pivot = angle(points[p], center); 331 while (i <= j) { 332 while (angle(points[i], center) < pivot) { 333 i++; 334 } 335 while (angle(points[j], center) > pivot) { 336 j--; 337 } 338 339 if (i <= j) { 340 swap(points, i, j); 341 i++; 342 j--; 343 } 344 } 345 if (low < j) quicksortCirc(points, low, j, center); 346 if (i < high) quicksortCirc(points, i, high, center); 347} 348 349/** 350 * Sort points by x axis 351 * 352 * @param points points to sort 353 * @param low start index 354 * @param high end index 355 */ 356void SpotShadow::quicksortX(Vector2* points, int low, int high) { 357 int i = low, j = high; 358 int p = low + (high - low) / 2; 359 float pivot = points[p].x; 360 while (i <= j) { 361 while (points[i].x < pivot) { 362 i++; 363 } 364 while (points[j].x > pivot) { 365 j--; 366 } 367 368 if (i <= j) { 369 swap(points, i, j); 370 i++; 371 j--; 372 } 373 } 374 if (low < j) quicksortX(points, low, j); 375 if (i < high) quicksortX(points, i, high); 376} 377 378/** 379 * Test whether a point is inside the polygon. 380 * 381 * @param testPoint the point to test 382 * @param poly the polygon 383 * @return true if the testPoint is inside the poly. 384 */ 385bool SpotShadow::testPointInsidePolygon(const Vector2 testPoint, 386 const Vector2* poly, int len) { 387 bool c = false; 388 double testx = testPoint.x; 389 double testy = testPoint.y; 390 for (int i = 0, j = len - 1; i < len; j = i++) { 391 double startX = poly[j].x; 392 double startY = poly[j].y; 393 double endX = poly[i].x; 394 double endY = poly[i].y; 395 396 if (((endY > testy) != (startY > testy)) && 397 (testx < (startX - endX) * (testy - endY) 398 / (startY - endY) + endX)) { 399 c = !c; 400 } 401 } 402 return c; 403} 404 405/** 406 * Make the polygon turn clockwise. 407 * 408 * @param polygon the polygon as a Vector2 array. 409 * @param len the number of points of the polygon 410 */ 411void SpotShadow::makeClockwise(Vector2* polygon, int len) { 412 if (polygon == 0 || len == 0) { 413 return; 414 } 415 if (!isClockwise(polygon, len)) { 416 reverse(polygon, len); 417 } 418} 419 420/** 421 * Test whether the polygon is order in clockwise. 422 * 423 * @param polygon the polygon as a Vector2 array 424 * @param len the number of points of the polygon 425 */ 426bool SpotShadow::isClockwise(Vector2* polygon, int len) { 427 double sum = 0; 428 double p1x = polygon[len - 1].x; 429 double p1y = polygon[len - 1].y; 430 for (int i = 0; i < len; i++) { 431 432 double p2x = polygon[i].x; 433 double p2y = polygon[i].y; 434 sum += p1x * p2y - p2x * p1y; 435 p1x = p2x; 436 p1y = p2y; 437 } 438 return sum < 0; 439} 440 441/** 442 * Reverse the polygon 443 * 444 * @param polygon the polygon as a Vector2 array 445 * @param len the number of points of the polygon 446 */ 447void SpotShadow::reverse(Vector2* polygon, int len) { 448 int n = len / 2; 449 for (int i = 0; i < n; i++) { 450 Vector2 tmp = polygon[i]; 451 int k = len - 1 - i; 452 polygon[i] = polygon[k]; 453 polygon[k] = tmp; 454 } 455} 456 457/** 458 * Intersects two lines in parametric form. This function is called in a tight 459 * loop, and we need double precision to get things right. 460 * 461 * @param x1 the x coordinate point 1 of line 1 462 * @param y1 the y coordinate point 1 of line 1 463 * @param x2 the x coordinate point 2 of line 1 464 * @param y2 the y coordinate point 2 of line 1 465 * @param x3 the x coordinate point 1 of line 2 466 * @param y3 the y coordinate point 1 of line 2 467 * @param x4 the x coordinate point 2 of line 2 468 * @param y4 the y coordinate point 2 of line 2 469 * @param ret the x,y location of the intersection 470 * @return true if it found an intersection 471 */ 472inline bool SpotShadow::lineIntersection(double x1, double y1, double x2, double y2, 473 double x3, double y3, double x4, double y4, Vector2& ret) { 474 double d = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4); 475 if (d == 0.0) return false; 476 477 double dx = (x1 * y2 - y1 * x2); 478 double dy = (x3 * y4 - y3 * x4); 479 double x = (dx * (x3 - x4) - (x1 - x2) * dy) / d; 480 double y = (dx * (y3 - y4) - (y1 - y2) * dy) / d; 481 482 // The intersection should be in the middle of the point 1 and point 2, 483 // likewise point 3 and point 4. 484 if (((x - x1) * (x - x2) > EPSILON) 485 || ((x - x3) * (x - x4) > EPSILON) 486 || ((y - y1) * (y - y2) > EPSILON) 487 || ((y - y3) * (y - y4) > EPSILON)) { 488 // Not interesected 489 return false; 490 } 491 ret.x = x; 492 ret.y = y; 493 return true; 494 495} 496 497/** 498 * Compute a horizontal circular polygon about point (x , y , height) of radius 499 * (size) 500 * 501 * @param points number of the points of the output polygon. 502 * @param lightCenter the center of the light. 503 * @param size the light size. 504 * @param ret result polygon. 505 */ 506void SpotShadow::computeLightPolygon(int points, const Vector3& lightCenter, 507 float size, Vector3* ret) { 508 // TODO: Caching all the sin / cos values and store them in a look up table. 509 for (int i = 0; i < points; i++) { 510 double angle = 2 * i * M_PI / points; 511 ret[i].x = sinf(angle) * size + lightCenter.x; 512 ret[i].y = cosf(angle) * size + lightCenter.y; 513 ret[i].z = lightCenter.z; 514 } 515} 516 517/** 518* Generate the shadow from a spot light. 519* 520* @param poly x,y,z vertexes of a convex polygon that occludes the light source 521* @param polyLength number of vertexes of the occluding polygon 522* @param lightCenter the center of the light 523* @param lightSize the radius of the light source 524* @param lightVertexCount the vertex counter for the light polygon 525* @param shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return 526* empty strip if error. 527* 528*/ 529void SpotShadow::createSpotShadow(const Vector3* poly, int polyLength, 530 const Vector3& lightCenter, float lightSize, int lightVertexCount, 531 VertexBuffer& retStrips) { 532 Vector3 light[lightVertexCount * 3]; 533 computeLightPolygon(lightVertexCount, lightCenter, lightSize, light); 534 computeSpotShadow(light, lightVertexCount, lightCenter, poly, polyLength, 535 retStrips); 536} 537 538/** 539 * Generate the shadow spot light of shape lightPoly and a object poly 540 * 541 * @param lightPoly x,y,z vertex of a convex polygon that is the light source 542 * @param lightPolyLength number of vertexes of the light source polygon 543 * @param poly x,y,z vertexes of a convex polygon that occludes the light source 544 * @param polyLength number of vertexes of the occluding polygon 545 * @param shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return 546 * empty strip if error. 547 */ 548void SpotShadow::computeSpotShadow(const Vector3* lightPoly, int lightPolyLength, 549 const Vector3& lightCenter, const Vector3* poly, int polyLength, 550 VertexBuffer& shadowTriangleStrip) { 551 // Point clouds for all the shadowed vertices 552 Vector2 shadowRegion[lightPolyLength * polyLength]; 553 // Shadow polygon from one point light. 554 Vector2 outline[polyLength]; 555 Vector2 umbraMem[polyLength * lightPolyLength]; 556 Vector2* umbra = umbraMem; 557 558 int umbraLength = 0; 559 560 // Validate input, receiver is always at z = 0 plane. 561 bool inputPolyPositionValid = true; 562 for (int i = 0; i < polyLength; i++) { 563 if (poly[i].z <= 0.00001) { 564 inputPolyPositionValid = false; 565 ALOGE("polygon below the surface"); 566 break; 567 } 568 if (poly[i].z >= lightPoly[0].z) { 569 inputPolyPositionValid = false; 570 ALOGE("polygon above the light"); 571 break; 572 } 573 } 574 575 // If the caster's position is invalid, don't draw anything. 576 if (!inputPolyPositionValid) { 577 return; 578 } 579 580 // Calculate the umbra polygon based on intersections of all outlines 581 int k = 0; 582 for (int j = 0; j < lightPolyLength; j++) { 583 int m = 0; 584 for (int i = 0; i < polyLength; i++) { 585 float t = lightPoly[j].z - poly[i].z; 586 if (t == 0) { 587 return; 588 } 589 t = lightPoly[j].z / t; 590 float x = lightPoly[j].x - t * (lightPoly[j].x - poly[i].x); 591 float y = lightPoly[j].y - t * (lightPoly[j].y - poly[i].y); 592 593 Vector2 newPoint = Vector2(x, y); 594 shadowRegion[k] = newPoint; 595 outline[m] = newPoint; 596 597 k++; 598 m++; 599 } 600 601 // For the first light polygon's vertex, use the outline as the umbra. 602 // Later on, use the intersection of the outline and existing umbra. 603 if (umbraLength == 0) { 604 for (int i = 0; i < polyLength; i++) { 605 umbra[i] = outline[i]; 606 } 607 umbraLength = polyLength; 608 } else { 609 int col = ((j * 255) / lightPolyLength); 610 umbraLength = intersection(outline, polyLength, umbra, umbraLength); 611 if (umbraLength == 0) { 612 break; 613 } 614 } 615 } 616 617 // Generate the penumbra area using the hull of all shadow regions. 618 int shadowRegionLength = k; 619 Vector2 penumbra[k]; 620 int penumbraLength = hull(shadowRegion, shadowRegionLength, penumbra); 621 622 Vector2 fakeUmbra[polyLength]; 623 if (umbraLength < 3) { 624 // If there is no real umbra, make a fake one. 625 for (int i = 0; i < polyLength; i++) { 626 float t = lightCenter.z - poly[i].z; 627 if (t == 0) { 628 return; 629 } 630 t = lightCenter.z / t; 631 float x = lightCenter.x - t * (lightCenter.x - poly[i].x); 632 float y = lightCenter.y - t * (lightCenter.y - poly[i].y); 633 634 fakeUmbra[i].x = x; 635 fakeUmbra[i].y = y; 636 } 637 638 // Shrink the centroid's shadow by 10%. 639 // TODO: Study the magic number of 10%. 640 Vector2 shadowCentroid = 641 ShadowTessellator::centroid2d(fakeUmbra, polyLength); 642 for (int i = 0; i < polyLength; i++) { 643 fakeUmbra[i] = shadowCentroid * (1.0f - SHADOW_SHRINK_SCALE) + 644 fakeUmbra[i] * SHADOW_SHRINK_SCALE; 645 } 646#if DEBUG_SHADOW 647 ALOGD("No real umbra make a fake one, centroid2d = %f , %f", 648 shadowCentroid.x, shadowCentroid.y); 649#endif 650 // Set the fake umbra, whose size is the same as the original polygon. 651 umbra = fakeUmbra; 652 umbraLength = polyLength; 653 } 654 655 generateTriangleStrip(penumbra, penumbraLength, umbra, umbraLength, 656 shadowTriangleStrip); 657} 658 659/** 660 * Generate a triangle strip given two convex polygons 661 * 662 * @param penumbra The outer polygon x,y vertexes 663 * @param penumbraLength The number of vertexes in the outer polygon 664 * @param umbra The inner outer polygon x,y vertexes 665 * @param umbraLength The number of vertexes in the inner polygon 666 * @param shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return 667 * empty strip if error. 668**/ 669void SpotShadow::generateTriangleStrip(const Vector2* penumbra, int penumbraLength, 670 const Vector2* umbra, int umbraLength, VertexBuffer& shadowTriangleStrip) { 671 const int rays = SHADOW_RAY_COUNT; 672 const int layers = SHADOW_LAYER_COUNT; 673 674 int size = rays * (layers + 1); 675 float step = M_PI * 2 / rays; 676 // Centroid of the umbra. 677 Vector2 centroid = ShadowTessellator::centroid2d(umbra, umbraLength); 678#if DEBUG_SHADOW 679 ALOGD("centroid2d = %f , %f", centroid.x, centroid.y); 680#endif 681 // Intersection to the penumbra. 682 float penumbraDistPerRay[rays]; 683 // Intersection to the umbra. 684 float umbraDistPerRay[rays]; 685 686 for (int i = 0; i < rays; i++) { 687 // TODO: Setup a lookup table for all the sin/cos. 688 float dx = sinf(step * i); 689 float dy = cosf(step * i); 690 umbraDistPerRay[i] = rayIntersectPoly(umbra, umbraLength, centroid, 691 dx, dy); 692 if (isnan(umbraDistPerRay[i])) { 693 ALOGE("rayIntersectPoly returns NAN"); 694 return; 695 } 696 penumbraDistPerRay[i] = rayIntersectPoly(penumbra, penumbraLength, 697 centroid, dx, dy); 698 if (isnan(umbraDistPerRay[i])) { 699 ALOGE("rayIntersectPoly returns NAN"); 700 return; 701 } 702 } 703 704 int stripSize = getStripSize(rays, layers); 705 AlphaVertex* shadowVertices = shadowTriangleStrip.alloc<AlphaVertex>(stripSize); 706 int currentIndex = 0; 707 708 // Calculate the vertices (x, y, alpha) in the shadow area. 709 for (int layerIndex = 0; layerIndex <= layers; layerIndex++) { 710 for (int rayIndex = 0; rayIndex < rays; rayIndex++) { 711 float dx = sinf(step * rayIndex); 712 float dy = cosf(step * rayIndex); 713 float layerRatio = layerIndex / (float) layers; 714 float deltaDist = layerRatio * 715 (umbraDistPerRay[rayIndex] - penumbraDistPerRay[rayIndex]); 716 float currentDist = penumbraDistPerRay[rayIndex] + deltaDist; 717 float op = calculateOpacity(layerRatio); 718 AlphaVertex::set(&shadowVertices[currentIndex++], 719 dx * currentDist + centroid.x, dy * currentDist + centroid.y, op); 720 } 721 } 722 // The centroid is in the umbra area, so the opacity is considered as 1.0. 723 AlphaVertex::set(&shadowVertices[currentIndex++], centroid.x, centroid.y, 1.0); 724#if DEBUG_SHADOW 725 if (currentIndex != SHADOW_VERTEX_COUNT) { 726 ALOGE("number of vertex generated for spot shadow is wrong!"); 727 } 728 for (int i = 0; i < currentIndex; i++) { 729 ALOGD("spot shadow value: i %d, (x:%f, y:%f, a:%f)", i, shadowVertices[i].x, 730 shadowVertices[i].y, shadowVertices[i].alpha); 731 } 732#endif 733} 734 735/** 736 * This is only for experimental purpose. 737 * After intersections are calculated, we could smooth the polygon if needed. 738 * So far, we don't think it is more appealing yet. 739 * 740 * @param level The level of smoothness. 741 * @param rays The total number of rays. 742 * @param rayDist (In and Out) The distance for each ray. 743 * 744 */ 745void SpotShadow::smoothPolygon(int level, int rays, float* rayDist) { 746 for (int k = 0; k < level; k++) { 747 for (int i = 0; i < rays; i++) { 748 float p1 = rayDist[(rays - 1 + i) % rays]; 749 float p2 = rayDist[i]; 750 float p3 = rayDist[(i + 1) % rays]; 751 rayDist[i] = (p1 + p2 * 2 + p3) / 4; 752 } 753 } 754} 755 756/** 757 * Calculate the opacity according to the distance. Ideally, the opacity is 1.0 758 * in the umbra area, and fall off to 0.0 till the edge of penumbra area. 759 * 760 * @param layerRatio The distance ratio of current sample between umbra and penumbra area. 761 * Penumbra edge is 0 and umbra edge is 1. 762 * @return The opacity according to the distance between umbra and penumbra. 763 */ 764float SpotShadow::calculateOpacity(float layerRatio) { 765 return (layerRatio * layerRatio + layerRatio) / 2.0; 766} 767 768/** 769 * Calculate the number of vertex we will create given a number of rays and layers 770 * 771 * @param rays number of points around the polygons you want 772 * @param layers number of layers of triangle strips you need 773 * @return number of vertex (multiply by 3 for number of floats) 774 */ 775int SpotShadow::getStripSize(int rays, int layers) { 776 return (2 + rays + ((layers) * 2 * (rays + 1))); 777} 778 779#if DEBUG_SHADOW 780 781#define TEST_POINT_NUMBER 128 782 783/** 784 * Calculate the bounds for generating random test points. 785 */ 786void SpotShadow::updateBound(const Vector2 inVector, Vector2& lowerBound, 787 Vector2& upperBound ) { 788 if (inVector.x < lowerBound.x) { 789 lowerBound.x = inVector.x; 790 } 791 792 if (inVector.y < lowerBound.y) { 793 lowerBound.y = inVector.y; 794 } 795 796 if (inVector.x > upperBound.x) { 797 upperBound.x = inVector.x; 798 } 799 800 if (inVector.y > upperBound.y) { 801 upperBound.y = inVector.y; 802 } 803} 804 805/** 806 * For debug purpose, when things go wrong, dump the whole polygon data. 807 */ 808static void dumpPolygon(const Vector2* poly, int polyLength, const char* polyName) { 809 for (int i = 0; i < polyLength; i++) { 810 ALOGD("polygon %s i %d x %f y %f", polyName, i, poly[i].x, poly[i].y); 811 } 812} 813 814/** 815 * Test whether the polygon is convex. 816 */ 817bool SpotShadow::testConvex(const Vector2* polygon, int polygonLength, 818 const char* name) { 819 bool isConvex = true; 820 for (int i = 0; i < polygonLength; i++) { 821 Vector2 start = polygon[i]; 822 Vector2 middle = polygon[(i + 1) % polygonLength]; 823 Vector2 end = polygon[(i + 2) % polygonLength]; 824 825 double delta = (double(middle.x) - start.x) * (double(end.y) - start.y) - 826 (double(middle.y) - start.y) * (double(end.x) - start.x); 827 bool isCCWOrCoLinear = (delta >= EPSILON); 828 829 if (isCCWOrCoLinear) { 830 ALOGE("(Error Type 2): polygon (%s) is not a convex b/c start (x %f, y %f)," 831 "middle (x %f, y %f) and end (x %f, y %f) , delta is %f !!!", 832 name, start.x, start.y, middle.x, middle.y, end.x, end.y, delta); 833 isConvex = false; 834 break; 835 } 836 } 837 return isConvex; 838} 839 840/** 841 * Test whether or not the polygon (intersection) is within the 2 input polygons. 842 * Using Marte Carlo method, we generate a random point, and if it is inside the 843 * intersection, then it must be inside both source polygons. 844 */ 845void SpotShadow::testIntersection(const Vector2* poly1, int poly1Length, 846 const Vector2* poly2, int poly2Length, 847 const Vector2* intersection, int intersectionLength) { 848 // Find the min and max of x and y. 849 Vector2 lowerBound(FLT_MAX, FLT_MAX); 850 Vector2 upperBound(-FLT_MAX, -FLT_MAX); 851 for (int i = 0; i < poly1Length; i++) { 852 updateBound(poly1[i], lowerBound, upperBound); 853 } 854 for (int i = 0; i < poly2Length; i++) { 855 updateBound(poly2[i], lowerBound, upperBound); 856 } 857 858 bool dumpPoly = false; 859 for (int k = 0; k < TEST_POINT_NUMBER; k++) { 860 // Generate a random point between minX, minY and maxX, maxY. 861 double randomX = rand() / double(RAND_MAX); 862 double randomY = rand() / double(RAND_MAX); 863 864 Vector2 testPoint; 865 testPoint.x = lowerBound.x + randomX * (upperBound.x - lowerBound.x); 866 testPoint.y = lowerBound.y + randomY * (upperBound.y - lowerBound.y); 867 868 // If the random point is in both poly 1 and 2, then it must be intersection. 869 if (testPointInsidePolygon(testPoint, intersection, intersectionLength)) { 870 if (!testPointInsidePolygon(testPoint, poly1, poly1Length)) { 871 dumpPoly = true; 872 ALOGE("(Error Type 1): one point (%f, %f) in the intersection is" 873 " not in the poly1", 874 testPoint.x, testPoint.y); 875 } 876 877 if (!testPointInsidePolygon(testPoint, poly2, poly2Length)) { 878 dumpPoly = true; 879 ALOGE("(Error Type 1): one point (%f, %f) in the intersection is" 880 " not in the poly2", 881 testPoint.x, testPoint.y); 882 } 883 } 884 } 885 886 if (dumpPoly) { 887 dumpPolygon(intersection, intersectionLength, "intersection"); 888 for (int i = 1; i < intersectionLength; i++) { 889 Vector2 delta = intersection[i] - intersection[i - 1]; 890 ALOGD("Intersetion i, %d Vs i-1 is delta %f", i, delta.lengthSquared()); 891 } 892 893 dumpPolygon(poly1, poly1Length, "poly 1"); 894 dumpPolygon(poly2, poly2Length, "poly 2"); 895 } 896} 897#endif 898 899}; // namespace uirenderer 900}; // namespace android 901 902 903 904 905