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+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "OpenGLRenderer"
+
+#define SHADOW_SHRINK_SCALE 0.1f
+
+#include <math.h>
+#include <stdlib.h>
+#include <utils/Log.h>
+
+#include "ShadowTessellator.h"
+#include "SpotShadow.h"
+#include "Vertex.h"
+
+namespace android {
+namespace uirenderer {
+
+static const double EPSILON = 1e-7;
+
+/**
+ * Calculate the angle between and x and a y coordinate.
+ * The atan2 range from -PI to PI.
+ */
+static float angle(const Vector2& point, const Vector2& center) {
+ return atan2(point.y - center.y, point.x - center.x);
+}
+
+/**
+ * Calculate the intersection of a ray with the line segment defined by two points.
+ *
+ * Returns a negative value in error conditions.
+
+ * @param rayOrigin The start of the ray
+ * @param dx The x vector of the ray
+ * @param dy The y vector of the ray
+ * @param p1 The first point defining the line segment
+ * @param p2 The second point defining the line segment
+ * @return The distance along the ray if it intersects with the line segment, negative if otherwise
+ */
+static float rayIntersectPoints(const Vector2& rayOrigin, float dx, float dy,
+ const Vector2& p1, const Vector2& p2) {
+ // The math below is derived from solving this formula, basically the
+ // intersection point should stay on both the ray and the edge of (p1, p2).
+ // solve([p1x+t*(p2x-p1x)=dx*t2+px,p1y+t*(p2y-p1y)=dy*t2+py],[t,t2]);
+
+ double divisor = (dx * (p1.y - p2.y) + dy * p2.x - dy * p1.x);
+ if (divisor == 0) return -1.0f; // error, invalid divisor
+
+#if DEBUG_SHADOW
+ double interpVal = (dx * (p1.y - rayOrigin.y) + dy * rayOrigin.x - dy * p1.x) / divisor;
+ if (interpVal < 0 || interpVal > 1) {
+ ALOGW("rayIntersectPoints is hitting outside the segment %f", interpVal);
+ }
+#endif
+
+ double distance = (p1.x * (rayOrigin.y - p2.y) + p2.x * (p1.y - rayOrigin.y) +
+ rayOrigin.x * (p2.y - p1.y)) / divisor;
+
+ return distance; // may be negative in error cases
+}
+
+/**
+ * Sort points by their X coordinates
+ *
+ * @param points the points as a Vector2 array.
+ * @param pointsLength the number of vertices of the polygon.
+ */
+void SpotShadow::xsort(Vector2* points, int pointsLength) {
+ quicksortX(points, 0, pointsLength - 1);
+}
+
+/**
+ * compute the convex hull of a collection of Points
+ *
+ * @param points the points as a Vector2 array.
+ * @param pointsLength the number of vertices of the polygon.
+ * @param retPoly pre allocated array of floats to put the vertices
+ * @return the number of points in the polygon 0 if no intersection
+ */
+int SpotShadow::hull(Vector2* points, int pointsLength, Vector2* retPoly) {
+ xsort(points, pointsLength);
+ int n = pointsLength;
+ Vector2 lUpper[n];
+ lUpper[0] = points[0];
+ lUpper[1] = points[1];
+
+ int lUpperSize = 2;
+
+ for (int i = 2; i < n; i++) {
+ lUpper[lUpperSize] = points[i];
+ lUpperSize++;
+
+ while (lUpperSize > 2 && !ccw(
+ lUpper[lUpperSize - 3].x, lUpper[lUpperSize - 3].y,
+ lUpper[lUpperSize - 2].x, lUpper[lUpperSize - 2].y,
+ lUpper[lUpperSize - 1].x, lUpper[lUpperSize - 1].y)) {
+ // Remove the middle point of the three last
+ lUpper[lUpperSize - 2].x = lUpper[lUpperSize - 1].x;
+ lUpper[lUpperSize - 2].y = lUpper[lUpperSize - 1].y;
+ lUpperSize--;
+ }
+ }
+
+ Vector2 lLower[n];
+ lLower[0] = points[n - 1];
+ lLower[1] = points[n - 2];
+
+ int lLowerSize = 2;
+
+ for (int i = n - 3; i >= 0; i--) {
+ lLower[lLowerSize] = points[i];
+ lLowerSize++;
+
+ while (lLowerSize > 2 && !ccw(
+ lLower[lLowerSize - 3].x, lLower[lLowerSize - 3].y,
+ lLower[lLowerSize - 2].x, lLower[lLowerSize - 2].y,
+ lLower[lLowerSize - 1].x, lLower[lLowerSize - 1].y)) {
+ // Remove the middle point of the three last
+ lLower[lLowerSize - 2] = lLower[lLowerSize - 1];
+ lLowerSize--;
+ }
+ }
+
+ // output points in CW ordering
+ const int total = lUpperSize + lLowerSize - 2;
+ int outIndex = total - 1;
+ for (int i = 0; i < lUpperSize; i++) {
+ retPoly[outIndex] = lUpper[i];
+ outIndex--;
+ }
+
+ for (int i = 1; i < lLowerSize - 1; i++) {
+ retPoly[outIndex] = lLower[i];
+ outIndex--;
+ }
+ // TODO: Add test harness which verify that all the points are inside the hull.
+ return total;
+}
+
+/**
+ * Test whether the 3 points form a counter clockwise turn.
+ *
+ * @return true if a right hand turn
+ */
+bool SpotShadow::ccw(double ax, double ay, double bx, double by,
+ double cx, double cy) {
+ return (bx - ax) * (cy - ay) - (by - ay) * (cx - ax) > EPSILON;
+}
+
+/**
+ * Calculates the intersection of poly1 with poly2 and put in poly2.
+ * Note that both poly1 and poly2 must be in CW order already!
+ *
+ * @param poly1 The 1st polygon, as a Vector2 array.
+ * @param poly1Length The number of vertices of 1st polygon.
+ * @param poly2 The 2nd and output polygon, as a Vector2 array.
+ * @param poly2Length The number of vertices of 2nd polygon.
+ * @return number of vertices in output polygon as poly2.
+ */
+int SpotShadow::intersection(const Vector2* poly1, int poly1Length,
+ Vector2* poly2, int poly2Length) {
+#if DEBUG_SHADOW
+ if (!ShadowTessellator::isClockwise(poly1, poly1Length)) {
+ ALOGW("Poly1 is not clockwise! Intersection is wrong!");
+ }
+ if (!ShadowTessellator::isClockwise(poly2, poly2Length)) {
+ ALOGW("Poly2 is not clockwise! Intersection is wrong!");
+ }
+#endif
+ Vector2 poly[poly1Length * poly2Length + 2];
+ int count = 0;
+ int pcount = 0;
+
+ // If one vertex from one polygon sits inside another polygon, add it and
+ // count them.
+ for (int i = 0; i < poly1Length; i++) {
+ if (testPointInsidePolygon(poly1[i], poly2, poly2Length)) {
+ poly[count] = poly1[i];
+ count++;
+ pcount++;
+
+ }
+ }
+
+ int insidePoly2 = pcount;
+ for (int i = 0; i < poly2Length; i++) {
+ if (testPointInsidePolygon(poly2[i], poly1, poly1Length)) {
+ poly[count] = poly2[i];
+ count++;
+ }
+ }
+
+ int insidePoly1 = count - insidePoly2;
+ // If all vertices from poly1 are inside poly2, then just return poly1.
+ if (insidePoly2 == poly1Length) {
+ memcpy(poly2, poly1, poly1Length * sizeof(Vector2));
+ return poly1Length;
+ }
+
+ // If all vertices from poly2 are inside poly1, then just return poly2.
+ if (insidePoly1 == poly2Length) {
+ return poly2Length;
+ }
+
+ // Since neither polygon fully contain the other one, we need to add all the
+ // intersection points.
+ Vector2 intersection;
+ for (int i = 0; i < poly2Length; i++) {
+ for (int j = 0; j < poly1Length; j++) {
+ int poly2LineStart = i;
+ int poly2LineEnd = ((i + 1) % poly2Length);
+ int poly1LineStart = j;
+ int poly1LineEnd = ((j + 1) % poly1Length);
+ bool found = lineIntersection(
+ poly2[poly2LineStart].x, poly2[poly2LineStart].y,
+ poly2[poly2LineEnd].x, poly2[poly2LineEnd].y,
+ poly1[poly1LineStart].x, poly1[poly1LineStart].y,
+ poly1[poly1LineEnd].x, poly1[poly1LineEnd].y,
+ intersection);
+ if (found) {
+ poly[count].x = intersection.x;
+ poly[count].y = intersection.y;
+ count++;
+ } else {
+ Vector2 delta = poly2[i] - poly1[j];
+ if (delta.lengthSquared() < EPSILON) {
+ poly[count] = poly2[i];
+ count++;
+ }
+ }
+ }
+ }
+
+ if (count == 0) {
+ return 0;
+ }
+
+ // Sort the result polygon around the center.
+ Vector2 center(0.0f, 0.0f);
+ for (int i = 0; i < count; i++) {
+ center += poly[i];
+ }
+ center /= count;
+ sort(poly, count, center);
+
+#if DEBUG_SHADOW
+ // Since poly2 is overwritten as the result, we need to save a copy to do
+ // our verification.
+ Vector2 oldPoly2[poly2Length];
+ int oldPoly2Length = poly2Length;
+ memcpy(oldPoly2, poly2, sizeof(Vector2) * poly2Length);
+#endif
+
+ // Filter the result out from poly and put it into poly2.
+ poly2[0] = poly[0];
+ int lastOutputIndex = 0;
+ for (int i = 1; i < count; i++) {
+ Vector2 delta = poly[i] - poly2[lastOutputIndex];
+ if (delta.lengthSquared() >= EPSILON) {
+ poly2[++lastOutputIndex] = poly[i];
+ } else {
+ // If the vertices are too close, pick the inner one, because the
+ // inner one is more likely to be an intersection point.
+ Vector2 delta1 = poly[i] - center;
+ Vector2 delta2 = poly2[lastOutputIndex] - center;
+ if (delta1.lengthSquared() < delta2.lengthSquared()) {
+ poly2[lastOutputIndex] = poly[i];
+ }
+ }
+ }
+ int resultLength = lastOutputIndex + 1;
+
+#if DEBUG_SHADOW
+ testConvex(poly2, resultLength, "intersection");
+ testConvex(poly1, poly1Length, "input poly1");
+ testConvex(oldPoly2, oldPoly2Length, "input poly2");
+
+ testIntersection(poly1, poly1Length, oldPoly2, oldPoly2Length, poly2, resultLength);
+#endif
+
+ return resultLength;
+}
+
+/**
+ * Sort points about a center point
+ *
+ * @param poly The in and out polyogon as a Vector2 array.
+ * @param polyLength The number of vertices of the polygon.
+ * @param center the center ctr[0] = x , ctr[1] = y to sort around.
+ */
+void SpotShadow::sort(Vector2* poly, int polyLength, const Vector2& center) {
+ quicksortCirc(poly, 0, polyLength - 1, center);
+}
+
+/**
+ * Swap points pointed to by i and j
+ */
+void SpotShadow::swap(Vector2* points, int i, int j) {
+ Vector2 temp = points[i];
+ points[i] = points[j];
+ points[j] = temp;
+}
+
+/**
+ * quick sort implementation about the center.
+ */
+void SpotShadow::quicksortCirc(Vector2* points, int low, int high,
+ const Vector2& center) {
+ int i = low, j = high;
+ int p = low + (high - low) / 2;
+ float pivot = angle(points[p], center);
+ while (i <= j) {
+ while (angle(points[i], center) > pivot) {
+ i++;
+ }
+ while (angle(points[j], center) < pivot) {
+ j--;
+ }
+
+ if (i <= j) {
+ swap(points, i, j);
+ i++;
+ j--;
+ }
+ }
+ if (low < j) quicksortCirc(points, low, j, center);
+ if (i < high) quicksortCirc(points, i, high, center);
+}
+
+/**
+ * Sort points by x axis
+ *
+ * @param points points to sort
+ * @param low start index
+ * @param high end index
+ */
+void SpotShadow::quicksortX(Vector2* points, int low, int high) {
+ int i = low, j = high;
+ int p = low + (high - low) / 2;
+ float pivot = points[p].x;
+ while (i <= j) {
+ while (points[i].x < pivot) {
+ i++;
+ }
+ while (points[j].x > pivot) {
+ j--;
+ }
+
+ if (i <= j) {
+ swap(points, i, j);
+ i++;
+ j--;
+ }
+ }
+ if (low < j) quicksortX(points, low, j);
+ if (i < high) quicksortX(points, i, high);
+}
+
+/**
+ * Test whether a point is inside the polygon.
+ *
+ * @param testPoint the point to test
+ * @param poly the polygon
+ * @return true if the testPoint is inside the poly.
+ */
+bool SpotShadow::testPointInsidePolygon(const Vector2 testPoint,
+ const Vector2* poly, int len) {
+ bool c = false;
+ double testx = testPoint.x;
+ double testy = testPoint.y;
+ for (int i = 0, j = len - 1; i < len; j = i++) {
+ double startX = poly[j].x;
+ double startY = poly[j].y;
+ double endX = poly[i].x;
+ double endY = poly[i].y;
+
+ if (((endY > testy) != (startY > testy)) &&
+ (testx < (startX - endX) * (testy - endY)
+ / (startY - endY) + endX)) {
+ c = !c;
+ }
+ }
+ return c;
+}
+
+/**
+ * Make the polygon turn clockwise.
+ *
+ * @param polygon the polygon as a Vector2 array.
+ * @param len the number of points of the polygon
+ */
+void SpotShadow::makeClockwise(Vector2* polygon, int len) {
+ if (polygon == 0 || len == 0) {
+ return;
+ }
+ if (!ShadowTessellator::isClockwise(polygon, len)) {
+ reverse(polygon, len);
+ }
+}
+
+/**
+ * Reverse the polygon
+ *
+ * @param polygon the polygon as a Vector2 array
+ * @param len the number of points of the polygon
+ */
+void SpotShadow::reverse(Vector2* polygon, int len) {
+ int n = len / 2;
+ for (int i = 0; i < n; i++) {
+ Vector2 tmp = polygon[i];
+ int k = len - 1 - i;
+ polygon[i] = polygon[k];
+ polygon[k] = tmp;
+ }
+}
+
+/**
+ * Intersects two lines in parametric form. This function is called in a tight
+ * loop, and we need double precision to get things right.
+ *
+ * @param x1 the x coordinate point 1 of line 1
+ * @param y1 the y coordinate point 1 of line 1
+ * @param x2 the x coordinate point 2 of line 1
+ * @param y2 the y coordinate point 2 of line 1
+ * @param x3 the x coordinate point 1 of line 2
+ * @param y3 the y coordinate point 1 of line 2
+ * @param x4 the x coordinate point 2 of line 2
+ * @param y4 the y coordinate point 2 of line 2
+ * @param ret the x,y location of the intersection
+ * @return true if it found an intersection
+ */
+inline bool SpotShadow::lineIntersection(double x1, double y1, double x2, double y2,
+ double x3, double y3, double x4, double y4, Vector2& ret) {
+ double d = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4);
+ if (d == 0.0) return false;
+
+ double dx = (x1 * y2 - y1 * x2);
+ double dy = (x3 * y4 - y3 * x4);
+ double x = (dx * (x3 - x4) - (x1 - x2) * dy) / d;
+ double y = (dx * (y3 - y4) - (y1 - y2) * dy) / d;
+
+ // The intersection should be in the middle of the point 1 and point 2,
+ // likewise point 3 and point 4.
+ if (((x - x1) * (x - x2) > EPSILON)
+ || ((x - x3) * (x - x4) > EPSILON)
+ || ((y - y1) * (y - y2) > EPSILON)
+ || ((y - y3) * (y - y4) > EPSILON)) {
+ // Not interesected
+ return false;
+ }
+ ret.x = x;
+ ret.y = y;
+ return true;
+
+}
+
+/**
+ * Compute a horizontal circular polygon about point (x , y , height) of radius
+ * (size)
+ *
+ * @param points number of the points of the output polygon.
+ * @param lightCenter the center of the light.
+ * @param size the light size.
+ * @param ret result polygon.
+ */
+void SpotShadow::computeLightPolygon(int points, const Vector3& lightCenter,
+ float size, Vector3* ret) {
+ // TODO: Caching all the sin / cos values and store them in a look up table.
+ for (int i = 0; i < points; i++) {
+ double angle = 2 * i * M_PI / points;
+ ret[i].x = cosf(angle) * size + lightCenter.x;
+ ret[i].y = sinf(angle) * size + lightCenter.y;
+ ret[i].z = lightCenter.z;
+ }
+}
+
+/**
+* Generate the shadow from a spot light.
+*
+* @param poly x,y,z vertexes of a convex polygon that occludes the light source
+* @param polyLength number of vertexes of the occluding polygon
+* @param lightCenter the center of the light
+* @param lightSize the radius of the light source
+* @param lightVertexCount the vertex counter for the light polygon
+* @param shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return
+* empty strip if error.
+*
+*/
+VertexBufferMode SpotShadow::createSpotShadow(bool isCasterOpaque, const Vector3* poly,
+ int polyLength, const Vector3& lightCenter, float lightSize,
+ int lightVertexCount, VertexBuffer& retStrips) {
+ Vector3 light[lightVertexCount * 3];
+ computeLightPolygon(lightVertexCount, lightCenter, lightSize, light);
+ computeSpotShadow(isCasterOpaque, light, lightVertexCount, lightCenter, poly,
+ polyLength, retStrips);
+ return kVertexBufferMode_TwoPolyRingShadow;
+}
+
+/**
+ * Generate the shadow spot light of shape lightPoly and a object poly
+ *
+ * @param lightPoly x,y,z vertex of a convex polygon that is the light source
+ * @param lightPolyLength number of vertexes of the light source polygon
+ * @param poly x,y,z vertexes of a convex polygon that occludes the light source
+ * @param polyLength number of vertexes of the occluding polygon
+ * @param shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return
+ * empty strip if error.
+ */
+void SpotShadow::computeSpotShadow(bool isCasterOpaque, const Vector3* lightPoly,
+ int lightPolyLength, const Vector3& lightCenter, const Vector3* poly,
+ int polyLength, VertexBuffer& shadowTriangleStrip) {
+ // Point clouds for all the shadowed vertices
+ Vector2 shadowRegion[lightPolyLength * polyLength];
+ // Shadow polygon from one point light.
+ Vector2 outline[polyLength];
+ Vector2 umbraMem[polyLength * lightPolyLength];
+ Vector2* umbra = umbraMem;
+
+ int umbraLength = 0;
+
+ // Validate input, receiver is always at z = 0 plane.
+ bool inputPolyPositionValid = true;
+ for (int i = 0; i < polyLength; i++) {
+ if (poly[i].z >= lightPoly[0].z) {
+ inputPolyPositionValid = false;
+ ALOGW("polygon above the light");
+ break;
+ }
+ }
+
+ // If the caster's position is invalid, don't draw anything.
+ if (!inputPolyPositionValid) {
+ return;
+ }
+
+ // Calculate the umbra polygon based on intersections of all outlines
+ int k = 0;
+ for (int j = 0; j < lightPolyLength; j++) {
+ int m = 0;
+ for (int i = 0; i < polyLength; i++) {
+ // After validating the input, deltaZ is guaranteed to be positive.
+ float deltaZ = lightPoly[j].z - poly[i].z;
+ float ratioZ = lightPoly[j].z / deltaZ;
+ float x = lightPoly[j].x - ratioZ * (lightPoly[j].x - poly[i].x);
+ float y = lightPoly[j].y - ratioZ * (lightPoly[j].y - poly[i].y);
+
+ Vector2 newPoint = Vector2(x, y);
+ shadowRegion[k] = newPoint;
+ outline[m] = newPoint;
+
+ k++;
+ m++;
+ }
+
+ // For the first light polygon's vertex, use the outline as the umbra.
+ // Later on, use the intersection of the outline and existing umbra.
+ if (umbraLength == 0) {
+ for (int i = 0; i < polyLength; i++) {
+ umbra[i] = outline[i];
+ }
+ umbraLength = polyLength;
+ } else {
+ int col = ((j * 255) / lightPolyLength);
+ umbraLength = intersection(outline, polyLength, umbra, umbraLength);
+ if (umbraLength == 0) {
+ break;
+ }
+ }
+ }
+
+ // Generate the penumbra area using the hull of all shadow regions.
+ int shadowRegionLength = k;
+ Vector2 penumbra[k];
+ int penumbraLength = hull(shadowRegion, shadowRegionLength, penumbra);
+
+ Vector2 fakeUmbra[polyLength];
+ if (umbraLength < 3) {
+ // If there is no real umbra, make a fake one.
+ for (int i = 0; i < polyLength; i++) {
+ float deltaZ = lightCenter.z - poly[i].z;
+ float ratioZ = lightCenter.z / deltaZ;
+ float x = lightCenter.x - ratioZ * (lightCenter.x - poly[i].x);
+ float y = lightCenter.y - ratioZ * (lightCenter.y - poly[i].y);
+
+ fakeUmbra[i].x = x;
+ fakeUmbra[i].y = y;
+ }
+
+ // Shrink the centroid's shadow by 10%.
+ // TODO: Study the magic number of 10%.
+ Vector2 shadowCentroid =
+ ShadowTessellator::centroid2d(fakeUmbra, polyLength);
+ for (int i = 0; i < polyLength; i++) {
+ fakeUmbra[i] = shadowCentroid * (1.0f - SHADOW_SHRINK_SCALE) +
+ fakeUmbra[i] * SHADOW_SHRINK_SCALE;
+ }
+#if DEBUG_SHADOW
+ ALOGD("No real umbra make a fake one, centroid2d = %f , %f",
+ shadowCentroid.x, shadowCentroid.y);
+#endif
+ // Set the fake umbra, whose size is the same as the original polygon.
+ umbra = fakeUmbra;
+ umbraLength = polyLength;
+ }
+
+ generateTriangleStrip(isCasterOpaque, penumbra, penumbraLength, umbra,
+ umbraLength, poly, polyLength, shadowTriangleStrip);
+}
+
+/**
+ * Converts a polygon specified with CW vertices into an array of distance-from-centroid values.
+ *
+ * Returns false in error conditions
+ *
+ * @param poly Array of vertices. Note that these *must* be CW.
+ * @param polyLength The number of vertices in the polygon.
+ * @param polyCentroid The centroid of the polygon, from which rays will be cast
+ * @param rayDist The output array for the calculated distances, must be SHADOW_RAY_COUNT in size
+ */
+bool convertPolyToRayDist(const Vector2* poly, int polyLength, const Vector2& polyCentroid,
+ float* rayDist) {
+ const int rays = SHADOW_RAY_COUNT;
+ const float step = M_PI * 2 / rays;
+
+ const Vector2* lastVertex = &(poly[polyLength - 1]);
+ float startAngle = angle(*lastVertex, polyCentroid);
+
+ // Start with the ray that's closest to and less than startAngle
+ int rayIndex = floor((startAngle - EPSILON) / step);
+ rayIndex = (rayIndex + rays) % rays; // ensure positive
+
+ for (int polyIndex = 0; polyIndex < polyLength; polyIndex++) {
+ /*
+ * For a given pair of vertices on the polygon, poly[i-1] and poly[i], the rays that
+ * intersect these will be those that are between the two angles from the centroid that the
+ * vertices define.
+ *
+ * Because the polygon vertices are stored clockwise, the closest ray with an angle
+ * *smaller* than that defined by angle(poly[i], centroid) will be the first ray that does
+ * not intersect with poly[i-1], poly[i].
+ */
+ float currentAngle = angle(poly[polyIndex], polyCentroid);
+
+ // find first ray that will not intersect the line segment poly[i-1] & poly[i]
+ int firstRayIndexOnNextSegment = floor((currentAngle - EPSILON) / step);
+ firstRayIndexOnNextSegment = (firstRayIndexOnNextSegment + rays) % rays; // ensure positive
+
+ // Iterate through all rays that intersect with poly[i-1], poly[i] line segment.
+ // This may be 0 rays.
+ while (rayIndex != firstRayIndexOnNextSegment) {
+ float distanceToIntersect = rayIntersectPoints(polyCentroid,
+ cos(rayIndex * step),
+ sin(rayIndex * step),
+ *lastVertex, poly[polyIndex]);
+ if (distanceToIntersect < 0) {
+#if DEBUG_SHADOW
+ ALOGW("ERROR: convertPolyToRayDist failed");
+#endif
+ return false; // error case, abort
+ }
+
+ rayDist[rayIndex] = distanceToIntersect;
+
+ rayIndex = (rayIndex - 1 + rays) % rays;
+ }
+ lastVertex = &poly[polyIndex];
+ }
+
+ return true;
+}
+
+int SpotShadow::calculateOccludedUmbra(const Vector2* umbra, int umbraLength,
+ const Vector3* poly, int polyLength, Vector2* occludedUmbra) {
+ // Occluded umbra area is computed as the intersection of the projected 2D
+ // poly and umbra.
+ for (int i = 0; i < polyLength; i++) {
+ occludedUmbra[i].x = poly[i].x;
+ occludedUmbra[i].y = poly[i].y;
+ }
+
+ // Both umbra and incoming polygon are guaranteed to be CW, so we can call
+ // intersection() directly.
+ return intersection(umbra, umbraLength,
+ occludedUmbra, polyLength);
+}
+
+#define OCLLUDED_UMBRA_SHRINK_FACTOR 0.95f
+/**
+ * Generate a triangle strip given two convex polygons
+ *
+ * @param penumbra The outer polygon x,y vertexes
+ * @param penumbraLength The number of vertexes in the outer polygon
+ * @param umbra The inner outer polygon x,y vertexes
+ * @param umbraLength The number of vertexes in the inner polygon
+ * @param shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return
+ * empty strip if error.
+**/
+void SpotShadow::generateTriangleStrip(bool isCasterOpaque, const Vector2* penumbra,
+ int penumbraLength, const Vector2* umbra, int umbraLength,
+ const Vector3* poly, int polyLength, VertexBuffer& shadowTriangleStrip) {
+ const int rays = SHADOW_RAY_COUNT;
+ const int size = 2 * rays;
+ const float step = M_PI * 2 / rays;
+ // Centroid of the umbra.
+ Vector2 centroid = ShadowTessellator::centroid2d(umbra, umbraLength);
+#if DEBUG_SHADOW
+ ALOGD("centroid2d = %f , %f", centroid.x, centroid.y);
+#endif
+ // Intersection to the penumbra.
+ float penumbraDistPerRay[rays];
+ // Intersection to the umbra.
+ float umbraDistPerRay[rays];
+ // Intersection to the occluded umbra area.
+ float occludedUmbraDistPerRay[rays];
+
+ // convert CW polygons to ray distance encoding, aborting on conversion failure
+ if (!convertPolyToRayDist(umbra, umbraLength, centroid, umbraDistPerRay)) return;
+ if (!convertPolyToRayDist(penumbra, penumbraLength, centroid, penumbraDistPerRay)) return;
+
+ bool hasOccludedUmbraArea = false;
+ if (isCasterOpaque) {
+ Vector2 occludedUmbra[polyLength + umbraLength];
+ int occludedUmbraLength = calculateOccludedUmbra(umbra, umbraLength, poly, polyLength,
+ occludedUmbra);
+ // Make sure the centroid is inside the umbra, otherwise, fall back to the
+ // approach as if there is no occluded umbra area.
+ if (testPointInsidePolygon(centroid, occludedUmbra, occludedUmbraLength)) {
+ hasOccludedUmbraArea = true;
+ // Shrink the occluded umbra area to avoid pixel level artifacts.
+ for (int i = 0; i < occludedUmbraLength; i ++) {
+ occludedUmbra[i] = centroid + (occludedUmbra[i] - centroid) *
+ OCLLUDED_UMBRA_SHRINK_FACTOR;
+ }
+ if (!convertPolyToRayDist(occludedUmbra, occludedUmbraLength, centroid,
+ occludedUmbraDistPerRay)) {
+ return;
+ }
+ }
+ }
+
+ AlphaVertex* shadowVertices =
+ shadowTriangleStrip.alloc<AlphaVertex>(SHADOW_VERTEX_COUNT);
+
+ // Calculate the vertices (x, y, alpha) in the shadow area.
+ AlphaVertex centroidXYA;
+ AlphaVertex::set(&centroidXYA, centroid.x, centroid.y, 1.0f);
+ for (int rayIndex = 0; rayIndex < rays; rayIndex++) {
+ float dx = cosf(step * rayIndex);
+ float dy = sinf(step * rayIndex);
+
+ // penumbra ring
+ float penumbraDistance = penumbraDistPerRay[rayIndex];
+ AlphaVertex::set(&shadowVertices[rayIndex],
+ dx * penumbraDistance + centroid.x,
+ dy * penumbraDistance + centroid.y, 0.0f);
+
+ // umbra ring
+ float umbraDistance = umbraDistPerRay[rayIndex];
+ AlphaVertex::set(&shadowVertices[rays + rayIndex],
+ dx * umbraDistance + centroid.x, dy * umbraDistance + centroid.y, 1.0f);
+
+ // occluded umbra ring
+ if (hasOccludedUmbraArea) {
+ float occludedUmbraDistance = occludedUmbraDistPerRay[rayIndex];
+ AlphaVertex::set(&shadowVertices[2 * rays + rayIndex],
+ dx * occludedUmbraDistance + centroid.x,
+ dy * occludedUmbraDistance + centroid.y, 1.0f);
+ } else {
+ // Put all vertices of the occluded umbra ring at the centroid.
+ shadowVertices[2 * rays + rayIndex] = centroidXYA;
+ }
+ }
+}
+
+/**
+ * This is only for experimental purpose.
+ * After intersections are calculated, we could smooth the polygon if needed.
+ * So far, we don't think it is more appealing yet.
+ *
+ * @param level The level of smoothness.
+ * @param rays The total number of rays.
+ * @param rayDist (In and Out) The distance for each ray.
+ *
+ */
+void SpotShadow::smoothPolygon(int level, int rays, float* rayDist) {
+ for (int k = 0; k < level; k++) {
+ for (int i = 0; i < rays; i++) {
+ float p1 = rayDist[(rays - 1 + i) % rays];
+ float p2 = rayDist[i];
+ float p3 = rayDist[(i + 1) % rays];
+ rayDist[i] = (p1 + p2 * 2 + p3) / 4;
+ }
+ }
+}
+
+#if DEBUG_SHADOW
+
+#define TEST_POINT_NUMBER 128
+
+/**
+ * Calculate the bounds for generating random test points.
+ */
+void SpotShadow::updateBound(const Vector2 inVector, Vector2& lowerBound,
+ Vector2& upperBound ) {
+ if (inVector.x < lowerBound.x) {
+ lowerBound.x = inVector.x;
+ }
+
+ if (inVector.y < lowerBound.y) {
+ lowerBound.y = inVector.y;
+ }
+
+ if (inVector.x > upperBound.x) {
+ upperBound.x = inVector.x;
+ }
+
+ if (inVector.y > upperBound.y) {
+ upperBound.y = inVector.y;
+ }
+}
+
+/**
+ * For debug purpose, when things go wrong, dump the whole polygon data.
+ */
+static void dumpPolygon(const Vector2* poly, int polyLength, const char* polyName) {
+ for (int i = 0; i < polyLength; i++) {
+ ALOGD("polygon %s i %d x %f y %f", polyName, i, poly[i].x, poly[i].y);
+ }
+}
+
+/**
+ * Test whether the polygon is convex.
+ */
+bool SpotShadow::testConvex(const Vector2* polygon, int polygonLength,
+ const char* name) {
+ bool isConvex = true;
+ for (int i = 0; i < polygonLength; i++) {
+ Vector2 start = polygon[i];
+ Vector2 middle = polygon[(i + 1) % polygonLength];
+ Vector2 end = polygon[(i + 2) % polygonLength];
+
+ double delta = (double(middle.x) - start.x) * (double(end.y) - start.y) -
+ (double(middle.y) - start.y) * (double(end.x) - start.x);
+ bool isCCWOrCoLinear = (delta >= EPSILON);
+
+ if (isCCWOrCoLinear) {
+ ALOGW("(Error Type 2): polygon (%s) is not a convex b/c start (x %f, y %f),"
+ "middle (x %f, y %f) and end (x %f, y %f) , delta is %f !!!",
+ name, start.x, start.y, middle.x, middle.y, end.x, end.y, delta);
+ isConvex = false;
+ break;
+ }
+ }
+ return isConvex;
+}
+
+/**
+ * Test whether or not the polygon (intersection) is within the 2 input polygons.
+ * Using Marte Carlo method, we generate a random point, and if it is inside the
+ * intersection, then it must be inside both source polygons.
+ */
+void SpotShadow::testIntersection(const Vector2* poly1, int poly1Length,
+ const Vector2* poly2, int poly2Length,
+ const Vector2* intersection, int intersectionLength) {
+ // Find the min and max of x and y.
+ Vector2 lowerBound(FLT_MAX, FLT_MAX);
+ Vector2 upperBound(-FLT_MAX, -FLT_MAX);
+ for (int i = 0; i < poly1Length; i++) {
+ updateBound(poly1[i], lowerBound, upperBound);
+ }
+ for (int i = 0; i < poly2Length; i++) {
+ updateBound(poly2[i], lowerBound, upperBound);
+ }
+
+ bool dumpPoly = false;
+ for (int k = 0; k < TEST_POINT_NUMBER; k++) {
+ // Generate a random point between minX, minY and maxX, maxY.
+ double randomX = rand() / double(RAND_MAX);
+ double randomY = rand() / double(RAND_MAX);
+
+ Vector2 testPoint;
+ testPoint.x = lowerBound.x + randomX * (upperBound.x - lowerBound.x);
+ testPoint.y = lowerBound.y + randomY * (upperBound.y - lowerBound.y);
+
+ // If the random point is in both poly 1 and 2, then it must be intersection.
+ if (testPointInsidePolygon(testPoint, intersection, intersectionLength)) {
+ if (!testPointInsidePolygon(testPoint, poly1, poly1Length)) {
+ dumpPoly = true;
+ ALOGW("(Error Type 1): one point (%f, %f) in the intersection is"
+ " not in the poly1",
+ testPoint.x, testPoint.y);
+ }
+
+ if (!testPointInsidePolygon(testPoint, poly2, poly2Length)) {
+ dumpPoly = true;
+ ALOGW("(Error Type 1): one point (%f, %f) in the intersection is"
+ " not in the poly2",
+ testPoint.x, testPoint.y);
+ }
+ }
+ }
+
+ if (dumpPoly) {
+ dumpPolygon(intersection, intersectionLength, "intersection");
+ for (int i = 1; i < intersectionLength; i++) {
+ Vector2 delta = intersection[i] - intersection[i - 1];
+ ALOGD("Intersetion i, %d Vs i-1 is delta %f", i, delta.lengthSquared());
+ }
+
+ dumpPolygon(poly1, poly1Length, "poly 1");
+ dumpPolygon(poly2, poly2Length, "poly 2");
+ }
+}
+#endif
+
+}; // namespace uirenderer
+}; // namespace android
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