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ztenghui7b4516e2014-01-07 10:42:55 -08001/*
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>
ztenghuif5ca8b42014-01-27 15:53:28 -080022#include <stdlib.h>
ztenghui7b4516e2014-01-07 10:42:55 -080023#include <utils/Log.h>
24
ztenghui63d41ab2014-02-14 13:13:41 -080025#include "ShadowTessellator.h"
ztenghui7b4516e2014-01-07 10:42:55 -080026#include "SpotShadow.h"
27#include "Vertex.h"
28
29namespace android {
30namespace uirenderer {
31
Chris Craik726118b2014-03-07 18:27:49 -080032static const double EPSILON = 1e-7;
33
ztenghui7b4516e2014-01-07 10:42:55 -080034/**
Chris Craik726118b2014-03-07 18:27:49 -080035 * Calculate the angle between and x and a y coordinate.
36 * The atan2 range from -PI to PI.
ztenghui7b4516e2014-01-07 10:42:55 -080037 */
Chris Craikb79a3e32014-03-11 12:20:17 -070038static float angle(const Vector2& point, const Vector2& center) {
Chris Craik726118b2014-03-07 18:27:49 -080039 return atan2(point.y - center.y, point.x - center.x);
40}
41
42/**
43 * Calculate the intersection of a ray with the line segment defined by two points.
44 *
45 * Returns a negative value in error conditions.
46
47 * @param rayOrigin The start of the ray
48 * @param dx The x vector of the ray
49 * @param dy The y vector of the ray
50 * @param p1 The first point defining the line segment
51 * @param p2 The second point defining the line segment
52 * @return The distance along the ray if it intersects with the line segment, negative if otherwise
53 */
Chris Craikb79a3e32014-03-11 12:20:17 -070054static float rayIntersectPoints(const Vector2& rayOrigin, float dx, float dy,
Chris Craik726118b2014-03-07 18:27:49 -080055 const Vector2& p1, const Vector2& p2) {
56 // The math below is derived from solving this formula, basically the
57 // intersection point should stay on both the ray and the edge of (p1, p2).
58 // solve([p1x+t*(p2x-p1x)=dx*t2+px,p1y+t*(p2y-p1y)=dy*t2+py],[t,t2]);
59
60 double divisor = (dx * (p1.y - p2.y) + dy * p2.x - dy * p1.x);
61 if (divisor == 0) return -1.0f; // error, invalid divisor
62
63#if DEBUG_SHADOW
64 double interpVal = (dx * (p1.y - rayOrigin.y) + dy * rayOrigin.x - dy * p1.x) / divisor;
ztenghui99af9422014-03-14 14:35:54 -070065 if (interpVal < 0 || interpVal > 1) {
66 ALOGW("rayIntersectPoints is hitting outside the segment %f", interpVal);
67 }
Chris Craik726118b2014-03-07 18:27:49 -080068#endif
69
70 double distance = (p1.x * (rayOrigin.y - p2.y) + p2.x * (p1.y - rayOrigin.y) +
71 rayOrigin.x * (p2.y - p1.y)) / divisor;
72
73 return distance; // may be negative in error cases
ztenghui7b4516e2014-01-07 10:42:55 -080074}
75
76/**
ztenghui7b4516e2014-01-07 10:42:55 -080077 * Sort points by their X coordinates
78 *
79 * @param points the points as a Vector2 array.
80 * @param pointsLength the number of vertices of the polygon.
81 */
82void SpotShadow::xsort(Vector2* points, int pointsLength) {
83 quicksortX(points, 0, pointsLength - 1);
84}
85
86/**
87 * compute the convex hull of a collection of Points
88 *
89 * @param points the points as a Vector2 array.
90 * @param pointsLength the number of vertices of the polygon.
91 * @param retPoly pre allocated array of floats to put the vertices
92 * @return the number of points in the polygon 0 if no intersection
93 */
94int SpotShadow::hull(Vector2* points, int pointsLength, Vector2* retPoly) {
95 xsort(points, pointsLength);
96 int n = pointsLength;
97 Vector2 lUpper[n];
98 lUpper[0] = points[0];
99 lUpper[1] = points[1];
100
101 int lUpperSize = 2;
102
103 for (int i = 2; i < n; i++) {
104 lUpper[lUpperSize] = points[i];
105 lUpperSize++;
106
ztenghuif5ca8b42014-01-27 15:53:28 -0800107 while (lUpperSize > 2 && !ccw(
108 lUpper[lUpperSize - 3].x, lUpper[lUpperSize - 3].y,
109 lUpper[lUpperSize - 2].x, lUpper[lUpperSize - 2].y,
110 lUpper[lUpperSize - 1].x, lUpper[lUpperSize - 1].y)) {
ztenghui7b4516e2014-01-07 10:42:55 -0800111 // Remove the middle point of the three last
112 lUpper[lUpperSize - 2].x = lUpper[lUpperSize - 1].x;
113 lUpper[lUpperSize - 2].y = lUpper[lUpperSize - 1].y;
114 lUpperSize--;
115 }
116 }
117
118 Vector2 lLower[n];
119 lLower[0] = points[n - 1];
120 lLower[1] = points[n - 2];
121
122 int lLowerSize = 2;
123
124 for (int i = n - 3; i >= 0; i--) {
125 lLower[lLowerSize] = points[i];
126 lLowerSize++;
127
ztenghuif5ca8b42014-01-27 15:53:28 -0800128 while (lLowerSize > 2 && !ccw(
129 lLower[lLowerSize - 3].x, lLower[lLowerSize - 3].y,
130 lLower[lLowerSize - 2].x, lLower[lLowerSize - 2].y,
131 lLower[lLowerSize - 1].x, lLower[lLowerSize - 1].y)) {
ztenghui7b4516e2014-01-07 10:42:55 -0800132 // Remove the middle point of the three last
133 lLower[lLowerSize - 2] = lLower[lLowerSize - 1];
134 lLowerSize--;
135 }
136 }
ztenghui7b4516e2014-01-07 10:42:55 -0800137
Chris Craik726118b2014-03-07 18:27:49 -0800138 // output points in CW ordering
139 const int total = lUpperSize + lLowerSize - 2;
140 int outIndex = total - 1;
ztenghui7b4516e2014-01-07 10:42:55 -0800141 for (int i = 0; i < lUpperSize; i++) {
Chris Craik726118b2014-03-07 18:27:49 -0800142 retPoly[outIndex] = lUpper[i];
143 outIndex--;
ztenghui7b4516e2014-01-07 10:42:55 -0800144 }
145
146 for (int i = 1; i < lLowerSize - 1; i++) {
Chris Craik726118b2014-03-07 18:27:49 -0800147 retPoly[outIndex] = lLower[i];
148 outIndex--;
ztenghui7b4516e2014-01-07 10:42:55 -0800149 }
150 // TODO: Add test harness which verify that all the points are inside the hull.
Chris Craik726118b2014-03-07 18:27:49 -0800151 return total;
ztenghui7b4516e2014-01-07 10:42:55 -0800152}
153
154/**
ztenghuif5ca8b42014-01-27 15:53:28 -0800155 * Test whether the 3 points form a counter clockwise turn.
ztenghui7b4516e2014-01-07 10:42:55 -0800156 *
ztenghui7b4516e2014-01-07 10:42:55 -0800157 * @return true if a right hand turn
158 */
ztenghuif5ca8b42014-01-27 15:53:28 -0800159bool SpotShadow::ccw(double ax, double ay, double bx, double by,
ztenghui7b4516e2014-01-07 10:42:55 -0800160 double cx, double cy) {
161 return (bx - ax) * (cy - ay) - (by - ay) * (cx - ax) > EPSILON;
162}
163
164/**
165 * Calculates the intersection of poly1 with poly2 and put in poly2.
ztenghui50ecf842014-03-11 16:52:30 -0700166 * Note that both poly1 and poly2 must be in CW order already!
ztenghui7b4516e2014-01-07 10:42:55 -0800167 *
168 * @param poly1 The 1st polygon, as a Vector2 array.
169 * @param poly1Length The number of vertices of 1st polygon.
170 * @param poly2 The 2nd and output polygon, as a Vector2 array.
171 * @param poly2Length The number of vertices of 2nd polygon.
172 * @return number of vertices in output polygon as poly2.
173 */
ztenghui50ecf842014-03-11 16:52:30 -0700174int SpotShadow::intersection(const Vector2* poly1, int poly1Length,
ztenghui7b4516e2014-01-07 10:42:55 -0800175 Vector2* poly2, int poly2Length) {
ztenghui50ecf842014-03-11 16:52:30 -0700176#if DEBUG_SHADOW
ztenghui2e023f32014-04-28 16:43:13 -0700177 if (!ShadowTessellator::isClockwise(poly1, poly1Length)) {
ztenghui50ecf842014-03-11 16:52:30 -0700178 ALOGW("Poly1 is not clockwise! Intersection is wrong!");
179 }
ztenghui2e023f32014-04-28 16:43:13 -0700180 if (!ShadowTessellator::isClockwise(poly2, poly2Length)) {
ztenghui50ecf842014-03-11 16:52:30 -0700181 ALOGW("Poly2 is not clockwise! Intersection is wrong!");
182 }
183#endif
ztenghui7b4516e2014-01-07 10:42:55 -0800184 Vector2 poly[poly1Length * poly2Length + 2];
185 int count = 0;
186 int pcount = 0;
187
188 // If one vertex from one polygon sits inside another polygon, add it and
189 // count them.
190 for (int i = 0; i < poly1Length; i++) {
191 if (testPointInsidePolygon(poly1[i], poly2, poly2Length)) {
192 poly[count] = poly1[i];
193 count++;
194 pcount++;
195
196 }
197 }
198
199 int insidePoly2 = pcount;
200 for (int i = 0; i < poly2Length; i++) {
201 if (testPointInsidePolygon(poly2[i], poly1, poly1Length)) {
202 poly[count] = poly2[i];
203 count++;
204 }
205 }
206
207 int insidePoly1 = count - insidePoly2;
208 // If all vertices from poly1 are inside poly2, then just return poly1.
209 if (insidePoly2 == poly1Length) {
210 memcpy(poly2, poly1, poly1Length * sizeof(Vector2));
211 return poly1Length;
212 }
213
214 // If all vertices from poly2 are inside poly1, then just return poly2.
215 if (insidePoly1 == poly2Length) {
216 return poly2Length;
217 }
218
219 // Since neither polygon fully contain the other one, we need to add all the
220 // intersection points.
221 Vector2 intersection;
222 for (int i = 0; i < poly2Length; i++) {
223 for (int j = 0; j < poly1Length; j++) {
224 int poly2LineStart = i;
225 int poly2LineEnd = ((i + 1) % poly2Length);
226 int poly1LineStart = j;
227 int poly1LineEnd = ((j + 1) % poly1Length);
228 bool found = lineIntersection(
229 poly2[poly2LineStart].x, poly2[poly2LineStart].y,
230 poly2[poly2LineEnd].x, poly2[poly2LineEnd].y,
231 poly1[poly1LineStart].x, poly1[poly1LineStart].y,
232 poly1[poly1LineEnd].x, poly1[poly1LineEnd].y,
233 intersection);
234 if (found) {
235 poly[count].x = intersection.x;
236 poly[count].y = intersection.y;
237 count++;
238 } else {
239 Vector2 delta = poly2[i] - poly1[j];
ztenghuif5ca8b42014-01-27 15:53:28 -0800240 if (delta.lengthSquared() < EPSILON) {
ztenghui7b4516e2014-01-07 10:42:55 -0800241 poly[count] = poly2[i];
242 count++;
243 }
244 }
245 }
246 }
247
248 if (count == 0) {
249 return 0;
250 }
251
252 // Sort the result polygon around the center.
253 Vector2 center(0.0f, 0.0f);
254 for (int i = 0; i < count; i++) {
255 center += poly[i];
256 }
257 center /= count;
258 sort(poly, count, center);
259
ztenghuif5ca8b42014-01-27 15:53:28 -0800260#if DEBUG_SHADOW
261 // Since poly2 is overwritten as the result, we need to save a copy to do
262 // our verification.
263 Vector2 oldPoly2[poly2Length];
264 int oldPoly2Length = poly2Length;
265 memcpy(oldPoly2, poly2, sizeof(Vector2) * poly2Length);
266#endif
ztenghui7b4516e2014-01-07 10:42:55 -0800267
ztenghuif5ca8b42014-01-27 15:53:28 -0800268 // Filter the result out from poly and put it into poly2.
ztenghui7b4516e2014-01-07 10:42:55 -0800269 poly2[0] = poly[0];
ztenghuif5ca8b42014-01-27 15:53:28 -0800270 int lastOutputIndex = 0;
ztenghui7b4516e2014-01-07 10:42:55 -0800271 for (int i = 1; i < count; i++) {
ztenghuif5ca8b42014-01-27 15:53:28 -0800272 Vector2 delta = poly[i] - poly2[lastOutputIndex];
273 if (delta.lengthSquared() >= EPSILON) {
274 poly2[++lastOutputIndex] = poly[i];
275 } else {
276 // If the vertices are too close, pick the inner one, because the
277 // inner one is more likely to be an intersection point.
278 Vector2 delta1 = poly[i] - center;
279 Vector2 delta2 = poly2[lastOutputIndex] - center;
280 if (delta1.lengthSquared() < delta2.lengthSquared()) {
281 poly2[lastOutputIndex] = poly[i];
282 }
ztenghui7b4516e2014-01-07 10:42:55 -0800283 }
284 }
ztenghuif5ca8b42014-01-27 15:53:28 -0800285 int resultLength = lastOutputIndex + 1;
286
287#if DEBUG_SHADOW
288 testConvex(poly2, resultLength, "intersection");
289 testConvex(poly1, poly1Length, "input poly1");
290 testConvex(oldPoly2, oldPoly2Length, "input poly2");
291
292 testIntersection(poly1, poly1Length, oldPoly2, oldPoly2Length, poly2, resultLength);
293#endif
ztenghui7b4516e2014-01-07 10:42:55 -0800294
295 return resultLength;
296}
297
298/**
299 * Sort points about a center point
300 *
301 * @param poly The in and out polyogon as a Vector2 array.
302 * @param polyLength The number of vertices of the polygon.
303 * @param center the center ctr[0] = x , ctr[1] = y to sort around.
304 */
305void SpotShadow::sort(Vector2* poly, int polyLength, const Vector2& center) {
306 quicksortCirc(poly, 0, polyLength - 1, center);
307}
308
309/**
ztenghui7b4516e2014-01-07 10:42:55 -0800310 * Swap points pointed to by i and j
311 */
312void SpotShadow::swap(Vector2* points, int i, int j) {
313 Vector2 temp = points[i];
314 points[i] = points[j];
315 points[j] = temp;
316}
317
318/**
319 * quick sort implementation about the center.
320 */
321void SpotShadow::quicksortCirc(Vector2* points, int low, int high,
322 const Vector2& center) {
323 int i = low, j = high;
324 int p = low + (high - low) / 2;
325 float pivot = angle(points[p], center);
326 while (i <= j) {
Chris Craik726118b2014-03-07 18:27:49 -0800327 while (angle(points[i], center) > pivot) {
ztenghui7b4516e2014-01-07 10:42:55 -0800328 i++;
329 }
Chris Craik726118b2014-03-07 18:27:49 -0800330 while (angle(points[j], center) < pivot) {
ztenghui7b4516e2014-01-07 10:42:55 -0800331 j--;
332 }
333
334 if (i <= j) {
335 swap(points, i, j);
336 i++;
337 j--;
338 }
339 }
340 if (low < j) quicksortCirc(points, low, j, center);
341 if (i < high) quicksortCirc(points, i, high, center);
342}
343
344/**
345 * Sort points by x axis
346 *
347 * @param points points to sort
348 * @param low start index
349 * @param high end index
350 */
351void SpotShadow::quicksortX(Vector2* points, int low, int high) {
352 int i = low, j = high;
353 int p = low + (high - low) / 2;
354 float pivot = points[p].x;
355 while (i <= j) {
356 while (points[i].x < pivot) {
357 i++;
358 }
359 while (points[j].x > pivot) {
360 j--;
361 }
362
363 if (i <= j) {
364 swap(points, i, j);
365 i++;
366 j--;
367 }
368 }
369 if (low < j) quicksortX(points, low, j);
370 if (i < high) quicksortX(points, i, high);
371}
372
373/**
374 * Test whether a point is inside the polygon.
375 *
376 * @param testPoint the point to test
377 * @param poly the polygon
378 * @return true if the testPoint is inside the poly.
379 */
380bool SpotShadow::testPointInsidePolygon(const Vector2 testPoint,
381 const Vector2* poly, int len) {
382 bool c = false;
383 double testx = testPoint.x;
384 double testy = testPoint.y;
385 for (int i = 0, j = len - 1; i < len; j = i++) {
386 double startX = poly[j].x;
387 double startY = poly[j].y;
388 double endX = poly[i].x;
389 double endY = poly[i].y;
390
391 if (((endY > testy) != (startY > testy)) &&
392 (testx < (startX - endX) * (testy - endY)
393 / (startY - endY) + endX)) {
394 c = !c;
395 }
396 }
397 return c;
398}
399
400/**
401 * Make the polygon turn clockwise.
402 *
403 * @param polygon the polygon as a Vector2 array.
404 * @param len the number of points of the polygon
405 */
406void SpotShadow::makeClockwise(Vector2* polygon, int len) {
407 if (polygon == 0 || len == 0) {
408 return;
409 }
ztenghui2e023f32014-04-28 16:43:13 -0700410 if (!ShadowTessellator::isClockwise(polygon, len)) {
ztenghui7b4516e2014-01-07 10:42:55 -0800411 reverse(polygon, len);
412 }
413}
414
415/**
ztenghui7b4516e2014-01-07 10:42:55 -0800416 * Reverse the polygon
417 *
418 * @param polygon the polygon as a Vector2 array
419 * @param len the number of points of the polygon
420 */
421void SpotShadow::reverse(Vector2* polygon, int len) {
422 int n = len / 2;
423 for (int i = 0; i < n; i++) {
424 Vector2 tmp = polygon[i];
425 int k = len - 1 - i;
426 polygon[i] = polygon[k];
427 polygon[k] = tmp;
428 }
429}
430
431/**
432 * Intersects two lines in parametric form. This function is called in a tight
433 * loop, and we need double precision to get things right.
434 *
435 * @param x1 the x coordinate point 1 of line 1
436 * @param y1 the y coordinate point 1 of line 1
437 * @param x2 the x coordinate point 2 of line 1
438 * @param y2 the y coordinate point 2 of line 1
439 * @param x3 the x coordinate point 1 of line 2
440 * @param y3 the y coordinate point 1 of line 2
441 * @param x4 the x coordinate point 2 of line 2
442 * @param y4 the y coordinate point 2 of line 2
443 * @param ret the x,y location of the intersection
444 * @return true if it found an intersection
445 */
446inline bool SpotShadow::lineIntersection(double x1, double y1, double x2, double y2,
447 double x3, double y3, double x4, double y4, Vector2& ret) {
448 double d = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4);
449 if (d == 0.0) return false;
450
451 double dx = (x1 * y2 - y1 * x2);
452 double dy = (x3 * y4 - y3 * x4);
453 double x = (dx * (x3 - x4) - (x1 - x2) * dy) / d;
454 double y = (dx * (y3 - y4) - (y1 - y2) * dy) / d;
455
456 // The intersection should be in the middle of the point 1 and point 2,
457 // likewise point 3 and point 4.
458 if (((x - x1) * (x - x2) > EPSILON)
459 || ((x - x3) * (x - x4) > EPSILON)
460 || ((y - y1) * (y - y2) > EPSILON)
461 || ((y - y3) * (y - y4) > EPSILON)) {
462 // Not interesected
463 return false;
464 }
465 ret.x = x;
466 ret.y = y;
467 return true;
468
469}
470
471/**
472 * Compute a horizontal circular polygon about point (x , y , height) of radius
473 * (size)
474 *
475 * @param points number of the points of the output polygon.
476 * @param lightCenter the center of the light.
477 * @param size the light size.
478 * @param ret result polygon.
479 */
480void SpotShadow::computeLightPolygon(int points, const Vector3& lightCenter,
481 float size, Vector3* ret) {
482 // TODO: Caching all the sin / cos values and store them in a look up table.
483 for (int i = 0; i < points; i++) {
484 double angle = 2 * i * M_PI / points;
Chris Craik726118b2014-03-07 18:27:49 -0800485 ret[i].x = cosf(angle) * size + lightCenter.x;
486 ret[i].y = sinf(angle) * size + lightCenter.y;
ztenghui7b4516e2014-01-07 10:42:55 -0800487 ret[i].z = lightCenter.z;
488 }
489}
490
491/**
492* Generate the shadow from a spot light.
493*
494* @param poly x,y,z vertexes of a convex polygon that occludes the light source
495* @param polyLength number of vertexes of the occluding polygon
496* @param lightCenter the center of the light
497* @param lightSize the radius of the light source
498* @param lightVertexCount the vertex counter for the light polygon
ztenghui7b4516e2014-01-07 10:42:55 -0800499* @param shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return
500* empty strip if error.
501*
502*/
ztenghui50ecf842014-03-11 16:52:30 -0700503VertexBufferMode SpotShadow::createSpotShadow(bool isCasterOpaque, const Vector3* poly,
504 int polyLength, const Vector3& lightCenter, float lightSize,
505 int lightVertexCount, VertexBuffer& retStrips) {
ztenghui7b4516e2014-01-07 10:42:55 -0800506 Vector3 light[lightVertexCount * 3];
507 computeLightPolygon(lightVertexCount, lightCenter, lightSize, light);
ztenghui50ecf842014-03-11 16:52:30 -0700508 computeSpotShadow(isCasterOpaque, light, lightVertexCount, lightCenter, poly,
509 polyLength, retStrips);
510 return kVertexBufferMode_TwoPolyRingShadow;
ztenghui7b4516e2014-01-07 10:42:55 -0800511}
512
513/**
514 * Generate the shadow spot light of shape lightPoly and a object poly
515 *
516 * @param lightPoly x,y,z vertex of a convex polygon that is the light source
517 * @param lightPolyLength number of vertexes of the light source polygon
518 * @param poly x,y,z vertexes of a convex polygon that occludes the light source
519 * @param polyLength number of vertexes of the occluding polygon
ztenghui7b4516e2014-01-07 10:42:55 -0800520 * @param shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return
521 * empty strip if error.
522 */
ztenghui50ecf842014-03-11 16:52:30 -0700523void SpotShadow::computeSpotShadow(bool isCasterOpaque, const Vector3* lightPoly,
524 int lightPolyLength, const Vector3& lightCenter, const Vector3* poly,
525 int polyLength, VertexBuffer& shadowTriangleStrip) {
ztenghui7b4516e2014-01-07 10:42:55 -0800526 // Point clouds for all the shadowed vertices
527 Vector2 shadowRegion[lightPolyLength * polyLength];
528 // Shadow polygon from one point light.
529 Vector2 outline[polyLength];
530 Vector2 umbraMem[polyLength * lightPolyLength];
531 Vector2* umbra = umbraMem;
532
533 int umbraLength = 0;
534
535 // Validate input, receiver is always at z = 0 plane.
536 bool inputPolyPositionValid = true;
537 for (int i = 0; i < polyLength; i++) {
ztenghui7b4516e2014-01-07 10:42:55 -0800538 if (poly[i].z >= lightPoly[0].z) {
539 inputPolyPositionValid = false;
Chris Craikb79a3e32014-03-11 12:20:17 -0700540 ALOGW("polygon above the light");
ztenghui7b4516e2014-01-07 10:42:55 -0800541 break;
542 }
543 }
544
545 // If the caster's position is invalid, don't draw anything.
546 if (!inputPolyPositionValid) {
547 return;
548 }
549
550 // Calculate the umbra polygon based on intersections of all outlines
551 int k = 0;
552 for (int j = 0; j < lightPolyLength; j++) {
553 int m = 0;
554 for (int i = 0; i < polyLength; i++) {
ztenghui28c3ea02014-03-18 15:58:57 -0700555 // After validating the input, deltaZ is guaranteed to be positive.
ztenghui50ecf842014-03-11 16:52:30 -0700556 float deltaZ = lightPoly[j].z - poly[i].z;
ztenghui50ecf842014-03-11 16:52:30 -0700557 float ratioZ = lightPoly[j].z / deltaZ;
558 float x = lightPoly[j].x - ratioZ * (lightPoly[j].x - poly[i].x);
559 float y = lightPoly[j].y - ratioZ * (lightPoly[j].y - poly[i].y);
ztenghui7b4516e2014-01-07 10:42:55 -0800560
561 Vector2 newPoint = Vector2(x, y);
562 shadowRegion[k] = newPoint;
563 outline[m] = newPoint;
564
565 k++;
566 m++;
567 }
568
569 // For the first light polygon's vertex, use the outline as the umbra.
570 // Later on, use the intersection of the outline and existing umbra.
571 if (umbraLength == 0) {
572 for (int i = 0; i < polyLength; i++) {
573 umbra[i] = outline[i];
574 }
575 umbraLength = polyLength;
576 } else {
577 int col = ((j * 255) / lightPolyLength);
578 umbraLength = intersection(outline, polyLength, umbra, umbraLength);
579 if (umbraLength == 0) {
580 break;
581 }
582 }
583 }
584
585 // Generate the penumbra area using the hull of all shadow regions.
586 int shadowRegionLength = k;
587 Vector2 penumbra[k];
588 int penumbraLength = hull(shadowRegion, shadowRegionLength, penumbra);
589
ztenghui5176c972014-01-31 17:17:55 -0800590 Vector2 fakeUmbra[polyLength];
ztenghui7b4516e2014-01-07 10:42:55 -0800591 if (umbraLength < 3) {
ztenghui5176c972014-01-31 17:17:55 -0800592 // If there is no real umbra, make a fake one.
ztenghui7b4516e2014-01-07 10:42:55 -0800593 for (int i = 0; i < polyLength; i++) {
ztenghui50ecf842014-03-11 16:52:30 -0700594 float deltaZ = lightCenter.z - poly[i].z;
ztenghui50ecf842014-03-11 16:52:30 -0700595 float ratioZ = lightCenter.z / deltaZ;
596 float x = lightCenter.x - ratioZ * (lightCenter.x - poly[i].x);
597 float y = lightCenter.y - ratioZ * (lightCenter.y - poly[i].y);
ztenghui7b4516e2014-01-07 10:42:55 -0800598
ztenghui5176c972014-01-31 17:17:55 -0800599 fakeUmbra[i].x = x;
600 fakeUmbra[i].y = y;
ztenghui7b4516e2014-01-07 10:42:55 -0800601 }
602
603 // Shrink the centroid's shadow by 10%.
604 // TODO: Study the magic number of 10%.
ztenghui63d41ab2014-02-14 13:13:41 -0800605 Vector2 shadowCentroid =
606 ShadowTessellator::centroid2d(fakeUmbra, polyLength);
ztenghui7b4516e2014-01-07 10:42:55 -0800607 for (int i = 0; i < polyLength; i++) {
ztenghui5176c972014-01-31 17:17:55 -0800608 fakeUmbra[i] = shadowCentroid * (1.0f - SHADOW_SHRINK_SCALE) +
609 fakeUmbra[i] * SHADOW_SHRINK_SCALE;
ztenghui7b4516e2014-01-07 10:42:55 -0800610 }
611#if DEBUG_SHADOW
612 ALOGD("No real umbra make a fake one, centroid2d = %f , %f",
613 shadowCentroid.x, shadowCentroid.y);
614#endif
615 // Set the fake umbra, whose size is the same as the original polygon.
ztenghui5176c972014-01-31 17:17:55 -0800616 umbra = fakeUmbra;
ztenghui7b4516e2014-01-07 10:42:55 -0800617 umbraLength = polyLength;
618 }
619
ztenghui50ecf842014-03-11 16:52:30 -0700620 generateTriangleStrip(isCasterOpaque, penumbra, penumbraLength, umbra,
621 umbraLength, poly, polyLength, shadowTriangleStrip);
ztenghui7b4516e2014-01-07 10:42:55 -0800622}
623
624/**
Chris Craik726118b2014-03-07 18:27:49 -0800625 * Converts a polygon specified with CW vertices into an array of distance-from-centroid values.
626 *
627 * Returns false in error conditions
628 *
629 * @param poly Array of vertices. Note that these *must* be CW.
630 * @param polyLength The number of vertices in the polygon.
631 * @param polyCentroid The centroid of the polygon, from which rays will be cast
632 * @param rayDist The output array for the calculated distances, must be SHADOW_RAY_COUNT in size
633 */
634bool convertPolyToRayDist(const Vector2* poly, int polyLength, const Vector2& polyCentroid,
635 float* rayDist) {
636 const int rays = SHADOW_RAY_COUNT;
637 const float step = M_PI * 2 / rays;
638
639 const Vector2* lastVertex = &(poly[polyLength - 1]);
640 float startAngle = angle(*lastVertex, polyCentroid);
641
642 // Start with the ray that's closest to and less than startAngle
643 int rayIndex = floor((startAngle - EPSILON) / step);
644 rayIndex = (rayIndex + rays) % rays; // ensure positive
645
646 for (int polyIndex = 0; polyIndex < polyLength; polyIndex++) {
647 /*
648 * For a given pair of vertices on the polygon, poly[i-1] and poly[i], the rays that
649 * intersect these will be those that are between the two angles from the centroid that the
650 * vertices define.
651 *
652 * Because the polygon vertices are stored clockwise, the closest ray with an angle
653 * *smaller* than that defined by angle(poly[i], centroid) will be the first ray that does
654 * not intersect with poly[i-1], poly[i].
655 */
656 float currentAngle = angle(poly[polyIndex], polyCentroid);
657
658 // find first ray that will not intersect the line segment poly[i-1] & poly[i]
659 int firstRayIndexOnNextSegment = floor((currentAngle - EPSILON) / step);
660 firstRayIndexOnNextSegment = (firstRayIndexOnNextSegment + rays) % rays; // ensure positive
661
662 // Iterate through all rays that intersect with poly[i-1], poly[i] line segment.
663 // This may be 0 rays.
664 while (rayIndex != firstRayIndexOnNextSegment) {
665 float distanceToIntersect = rayIntersectPoints(polyCentroid,
666 cos(rayIndex * step),
667 sin(rayIndex * step),
668 *lastVertex, poly[polyIndex]);
ztenghui50ecf842014-03-11 16:52:30 -0700669 if (distanceToIntersect < 0) {
670#if DEBUG_SHADOW
671 ALOGW("ERROR: convertPolyToRayDist failed");
672#endif
673 return false; // error case, abort
674 }
Chris Craik726118b2014-03-07 18:27:49 -0800675
676 rayDist[rayIndex] = distanceToIntersect;
677
678 rayIndex = (rayIndex - 1 + rays) % rays;
679 }
680 lastVertex = &poly[polyIndex];
681 }
682
683 return true;
684}
685
ztenghui50ecf842014-03-11 16:52:30 -0700686int SpotShadow::calculateOccludedUmbra(const Vector2* umbra, int umbraLength,
687 const Vector3* poly, int polyLength, Vector2* occludedUmbra) {
688 // Occluded umbra area is computed as the intersection of the projected 2D
689 // poly and umbra.
690 for (int i = 0; i < polyLength; i++) {
691 occludedUmbra[i].x = poly[i].x;
692 occludedUmbra[i].y = poly[i].y;
693 }
694
695 // Both umbra and incoming polygon are guaranteed to be CW, so we can call
696 // intersection() directly.
697 return intersection(umbra, umbraLength,
698 occludedUmbra, polyLength);
699}
700
701#define OCLLUDED_UMBRA_SHRINK_FACTOR 0.95f
Chris Craik726118b2014-03-07 18:27:49 -0800702/**
ztenghui7b4516e2014-01-07 10:42:55 -0800703 * Generate a triangle strip given two convex polygons
704 *
705 * @param penumbra The outer polygon x,y vertexes
706 * @param penumbraLength The number of vertexes in the outer polygon
707 * @param umbra The inner outer polygon x,y vertexes
708 * @param umbraLength The number of vertexes in the inner polygon
ztenghui7b4516e2014-01-07 10:42:55 -0800709 * @param shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return
710 * empty strip if error.
711**/
ztenghui50ecf842014-03-11 16:52:30 -0700712void SpotShadow::generateTriangleStrip(bool isCasterOpaque, const Vector2* penumbra,
713 int penumbraLength, const Vector2* umbra, int umbraLength,
714 const Vector3* poly, int polyLength, VertexBuffer& shadowTriangleStrip) {
ztenghui63d41ab2014-02-14 13:13:41 -0800715 const int rays = SHADOW_RAY_COUNT;
Chris Craik726118b2014-03-07 18:27:49 -0800716 const int size = 2 * rays;
717 const float step = M_PI * 2 / rays;
ztenghui7b4516e2014-01-07 10:42:55 -0800718 // Centroid of the umbra.
ztenghui63d41ab2014-02-14 13:13:41 -0800719 Vector2 centroid = ShadowTessellator::centroid2d(umbra, umbraLength);
ztenghui7b4516e2014-01-07 10:42:55 -0800720#if DEBUG_SHADOW
721 ALOGD("centroid2d = %f , %f", centroid.x, centroid.y);
722#endif
723 // Intersection to the penumbra.
724 float penumbraDistPerRay[rays];
725 // Intersection to the umbra.
726 float umbraDistPerRay[rays];
ztenghui50ecf842014-03-11 16:52:30 -0700727 // Intersection to the occluded umbra area.
728 float occludedUmbraDistPerRay[rays];
ztenghui7b4516e2014-01-07 10:42:55 -0800729
Chris Craik726118b2014-03-07 18:27:49 -0800730 // convert CW polygons to ray distance encoding, aborting on conversion failure
731 if (!convertPolyToRayDist(umbra, umbraLength, centroid, umbraDistPerRay)) return;
732 if (!convertPolyToRayDist(penumbra, penumbraLength, centroid, penumbraDistPerRay)) return;
ztenghui7b4516e2014-01-07 10:42:55 -0800733
ztenghui50ecf842014-03-11 16:52:30 -0700734 bool hasOccludedUmbraArea = false;
735 if (isCasterOpaque) {
736 Vector2 occludedUmbra[polyLength + umbraLength];
737 int occludedUmbraLength = calculateOccludedUmbra(umbra, umbraLength, poly, polyLength,
738 occludedUmbra);
739 // Make sure the centroid is inside the umbra, otherwise, fall back to the
740 // approach as if there is no occluded umbra area.
741 if (testPointInsidePolygon(centroid, occludedUmbra, occludedUmbraLength)) {
742 hasOccludedUmbraArea = true;
743 // Shrink the occluded umbra area to avoid pixel level artifacts.
744 for (int i = 0; i < occludedUmbraLength; i ++) {
745 occludedUmbra[i] = centroid + (occludedUmbra[i] - centroid) *
746 OCLLUDED_UMBRA_SHRINK_FACTOR;
747 }
748 if (!convertPolyToRayDist(occludedUmbra, occludedUmbraLength, centroid,
749 occludedUmbraDistPerRay)) {
750 return;
751 }
752 }
753 }
754
755 AlphaVertex* shadowVertices =
756 shadowTriangleStrip.alloc<AlphaVertex>(SHADOW_VERTEX_COUNT);
ztenghui7b4516e2014-01-07 10:42:55 -0800757
ztenghui63d41ab2014-02-14 13:13:41 -0800758 // Calculate the vertices (x, y, alpha) in the shadow area.
ztenghui50ecf842014-03-11 16:52:30 -0700759 AlphaVertex centroidXYA;
760 AlphaVertex::set(&centroidXYA, centroid.x, centroid.y, 1.0f);
Chris Craik726118b2014-03-07 18:27:49 -0800761 for (int rayIndex = 0; rayIndex < rays; rayIndex++) {
762 float dx = cosf(step * rayIndex);
763 float dy = sinf(step * rayIndex);
764
ztenghui50ecf842014-03-11 16:52:30 -0700765 // penumbra ring
766 float penumbraDistance = penumbraDistPerRay[rayIndex];
Chris Craik726118b2014-03-07 18:27:49 -0800767 AlphaVertex::set(&shadowVertices[rayIndex],
ztenghui50ecf842014-03-11 16:52:30 -0700768 dx * penumbraDistance + centroid.x,
769 dy * penumbraDistance + centroid.y, 0.0f);
Chris Craik726118b2014-03-07 18:27:49 -0800770
ztenghui50ecf842014-03-11 16:52:30 -0700771 // umbra ring
772 float umbraDistance = umbraDistPerRay[rayIndex];
Chris Craik726118b2014-03-07 18:27:49 -0800773 AlphaVertex::set(&shadowVertices[rays + rayIndex],
ztenghui50ecf842014-03-11 16:52:30 -0700774 dx * umbraDistance + centroid.x, dy * umbraDistance + centroid.y, 1.0f);
775
776 // occluded umbra ring
777 if (hasOccludedUmbraArea) {
778 float occludedUmbraDistance = occludedUmbraDistPerRay[rayIndex];
779 AlphaVertex::set(&shadowVertices[2 * rays + rayIndex],
780 dx * occludedUmbraDistance + centroid.x,
781 dy * occludedUmbraDistance + centroid.y, 1.0f);
782 } else {
783 // Put all vertices of the occluded umbra ring at the centroid.
784 shadowVertices[2 * rays + rayIndex] = centroidXYA;
785 }
ztenghui7b4516e2014-01-07 10:42:55 -0800786 }
ztenghui7b4516e2014-01-07 10:42:55 -0800787}
788
789/**
790 * This is only for experimental purpose.
791 * After intersections are calculated, we could smooth the polygon if needed.
792 * So far, we don't think it is more appealing yet.
793 *
794 * @param level The level of smoothness.
795 * @param rays The total number of rays.
796 * @param rayDist (In and Out) The distance for each ray.
797 *
798 */
799void SpotShadow::smoothPolygon(int level, int rays, float* rayDist) {
800 for (int k = 0; k < level; k++) {
801 for (int i = 0; i < rays; i++) {
802 float p1 = rayDist[(rays - 1 + i) % rays];
803 float p2 = rayDist[i];
804 float p3 = rayDist[(i + 1) % rays];
805 rayDist[i] = (p1 + p2 * 2 + p3) / 4;
806 }
807 }
808}
809
ztenghuif5ca8b42014-01-27 15:53:28 -0800810#if DEBUG_SHADOW
811
812#define TEST_POINT_NUMBER 128
813
814/**
815 * Calculate the bounds for generating random test points.
816 */
817void SpotShadow::updateBound(const Vector2 inVector, Vector2& lowerBound,
818 Vector2& upperBound ) {
819 if (inVector.x < lowerBound.x) {
820 lowerBound.x = inVector.x;
821 }
822
823 if (inVector.y < lowerBound.y) {
824 lowerBound.y = inVector.y;
825 }
826
827 if (inVector.x > upperBound.x) {
828 upperBound.x = inVector.x;
829 }
830
831 if (inVector.y > upperBound.y) {
832 upperBound.y = inVector.y;
833 }
834}
835
836/**
837 * For debug purpose, when things go wrong, dump the whole polygon data.
838 */
839static void dumpPolygon(const Vector2* poly, int polyLength, const char* polyName) {
840 for (int i = 0; i < polyLength; i++) {
841 ALOGD("polygon %s i %d x %f y %f", polyName, i, poly[i].x, poly[i].y);
842 }
843}
844
845/**
846 * Test whether the polygon is convex.
847 */
848bool SpotShadow::testConvex(const Vector2* polygon, int polygonLength,
849 const char* name) {
850 bool isConvex = true;
851 for (int i = 0; i < polygonLength; i++) {
852 Vector2 start = polygon[i];
853 Vector2 middle = polygon[(i + 1) % polygonLength];
854 Vector2 end = polygon[(i + 2) % polygonLength];
855
856 double delta = (double(middle.x) - start.x) * (double(end.y) - start.y) -
857 (double(middle.y) - start.y) * (double(end.x) - start.x);
858 bool isCCWOrCoLinear = (delta >= EPSILON);
859
860 if (isCCWOrCoLinear) {
ztenghui50ecf842014-03-11 16:52:30 -0700861 ALOGW("(Error Type 2): polygon (%s) is not a convex b/c start (x %f, y %f),"
ztenghuif5ca8b42014-01-27 15:53:28 -0800862 "middle (x %f, y %f) and end (x %f, y %f) , delta is %f !!!",
863 name, start.x, start.y, middle.x, middle.y, end.x, end.y, delta);
864 isConvex = false;
865 break;
866 }
867 }
868 return isConvex;
869}
870
871/**
872 * Test whether or not the polygon (intersection) is within the 2 input polygons.
873 * Using Marte Carlo method, we generate a random point, and if it is inside the
874 * intersection, then it must be inside both source polygons.
875 */
876void SpotShadow::testIntersection(const Vector2* poly1, int poly1Length,
877 const Vector2* poly2, int poly2Length,
878 const Vector2* intersection, int intersectionLength) {
879 // Find the min and max of x and y.
880 Vector2 lowerBound(FLT_MAX, FLT_MAX);
881 Vector2 upperBound(-FLT_MAX, -FLT_MAX);
882 for (int i = 0; i < poly1Length; i++) {
883 updateBound(poly1[i], lowerBound, upperBound);
884 }
885 for (int i = 0; i < poly2Length; i++) {
886 updateBound(poly2[i], lowerBound, upperBound);
887 }
888
889 bool dumpPoly = false;
890 for (int k = 0; k < TEST_POINT_NUMBER; k++) {
891 // Generate a random point between minX, minY and maxX, maxY.
892 double randomX = rand() / double(RAND_MAX);
893 double randomY = rand() / double(RAND_MAX);
894
895 Vector2 testPoint;
896 testPoint.x = lowerBound.x + randomX * (upperBound.x - lowerBound.x);
897 testPoint.y = lowerBound.y + randomY * (upperBound.y - lowerBound.y);
898
899 // If the random point is in both poly 1 and 2, then it must be intersection.
900 if (testPointInsidePolygon(testPoint, intersection, intersectionLength)) {
901 if (!testPointInsidePolygon(testPoint, poly1, poly1Length)) {
902 dumpPoly = true;
ztenghui50ecf842014-03-11 16:52:30 -0700903 ALOGW("(Error Type 1): one point (%f, %f) in the intersection is"
ztenghuif5ca8b42014-01-27 15:53:28 -0800904 " not in the poly1",
905 testPoint.x, testPoint.y);
906 }
907
908 if (!testPointInsidePolygon(testPoint, poly2, poly2Length)) {
909 dumpPoly = true;
ztenghui50ecf842014-03-11 16:52:30 -0700910 ALOGW("(Error Type 1): one point (%f, %f) in the intersection is"
ztenghuif5ca8b42014-01-27 15:53:28 -0800911 " not in the poly2",
912 testPoint.x, testPoint.y);
913 }
914 }
915 }
916
917 if (dumpPoly) {
918 dumpPolygon(intersection, intersectionLength, "intersection");
919 for (int i = 1; i < intersectionLength; i++) {
920 Vector2 delta = intersection[i] - intersection[i - 1];
921 ALOGD("Intersetion i, %d Vs i-1 is delta %f", i, delta.lengthSquared());
922 }
923
924 dumpPolygon(poly1, poly1Length, "poly 1");
925 dumpPolygon(poly2, poly2Length, "poly 2");
926 }
927}
928#endif
929
ztenghui7b4516e2014-01-07 10:42:55 -0800930}; // namespace uirenderer
931}; // namespace android