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Diffstat (limited to 'libs/hwui/SpotShadow.cpp')
| -rw-r--r-- | libs/hwui/SpotShadow.cpp | 1120 |
1 files changed, 0 insertions, 1120 deletions
diff --git a/libs/hwui/SpotShadow.cpp b/libs/hwui/SpotShadow.cpp deleted file mode 100644 index e371ac8da1e5..000000000000 --- a/libs/hwui/SpotShadow.cpp +++ /dev/null @@ -1,1120 +0,0 @@ -/* - * 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. - */ - -// The highest z value can't be higher than (CASTER_Z_CAP_RATIO * light.z) -#define CASTER_Z_CAP_RATIO 0.95f - -// When there is no umbra, then just fake the umbra using -// centroid * (1 - FAKE_UMBRA_SIZE_RATIO) + outline * FAKE_UMBRA_SIZE_RATIO -#define FAKE_UMBRA_SIZE_RATIO 0.05f - -// When the polygon is about 90 vertices, the penumbra + umbra can reach 270 rays. -// That is consider pretty fine tessllated polygon so far. -// This is just to prevent using too much some memory when edge slicing is not -// needed any more. -#define FINE_TESSELLATED_POLYGON_RAY_NUMBER 270 -/** - * Extra vertices for the corner for smoother corner. - * Only for outer loop. - * Note that we use such extra memory to avoid an extra loop. - */ -// For half circle, we could add EXTRA_VERTEX_PER_PI vertices. -// Set to 1 if we don't want to have any. -#define SPOT_EXTRA_CORNER_VERTEX_PER_PI 18 - -// For the whole polygon, the sum of all the deltas b/t normals is 2 * M_PI, -// therefore, the maximum number of extra vertices will be twice bigger. -#define SPOT_MAX_EXTRA_CORNER_VERTEX_NUMBER (2 * SPOT_EXTRA_CORNER_VERTEX_PER_PI) - -// For each RADIANS_DIVISOR, we would allocate one more vertex b/t the normals. -#define SPOT_CORNER_RADIANS_DIVISOR (M_PI / SPOT_EXTRA_CORNER_VERTEX_PER_PI) - -#define PENUMBRA_ALPHA 0.0f -#define UMBRA_ALPHA 1.0f - -#include "SpotShadow.h" - -#include "ShadowTessellator.h" -#include "Vertex.h" -#include "VertexBuffer.h" -#include "utils/MathUtils.h" - -#include <math.h> -#include <stdlib.h> -#include <utils/Log.h> -#include <algorithm> - -// TODO: After we settle down the new algorithm, we can remove the old one and -// its utility functions. -// Right now, we still need to keep it for comparison purpose and future expansion. -namespace android { -namespace uirenderer { - -static const float EPSILON = 1e-7; - -/** - * For each polygon's vertex, the light center will project it to the receiver - * as one of the outline vertex. - * For each outline vertex, we need to store the position and normal. - * Normal here is defined against the edge by the current vertex and the next vertex. - */ -struct OutlineData { - Vector2 position; - Vector2 normal; - float radius; -}; - -/** - * For each vertex, we need to keep track of its angle, whether it is penumbra or - * umbra, and its corresponding vertex index. - */ -struct SpotShadow::VertexAngleData { - // The angle to the vertex from the centroid. - float mAngle; - // True is the vertex comes from penumbra, otherwise it comes from umbra. - bool mIsPenumbra; - // The index of the vertex described by this data. - int mVertexIndex; - void set(float angle, bool isPenumbra, int index) { - mAngle = angle; - mIsPenumbra = isPenumbra; - mVertexIndex = index; - } -}; - -/** - * 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]); - - float divisor = (dx * (p1.y - p2.y) + dy * p2.x - dy * p1.x); - if (divisor == 0) return -1.0f; // error, invalid divisor - -#if DEBUG_SHADOW - float 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 - - float 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) { - auto cmp = [](const Vector2& a, const Vector2& b) -> bool { return a.x < b.x; }; - std::sort(points, points + pointsLength, cmp); -} - -/** - * 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(float ax, float ay, float bx, float by, float cx, float cy) { - return (bx - ax) * (cy - ay) - (by - ay) * (cx - ax) > EPSILON; -} - -/** - * 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); -} - -/** - * 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; - float testx = testPoint.x; - float testy = testPoint.y; - for (int i = 0, j = len - 1; i < len; j = i++) { - float startX = poly[j].x; - float startY = poly[j].y; - float endX = poly[i].x; - float endY = poly[i].y; - - if (((endY > testy) != (startY > testy)) && - (testx < (startX - endX) * (testy - endY) / (startY - endY) + endX)) { - c = !c; - } - } - return c; -} - -/** - * 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; - } -} - -/** - * 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++) { - float 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; - } -} - -/** - * From light center, project one vertex to the z=0 surface and get the outline. - * - * @param outline The result which is the outline position. - * @param lightCenter The center of light. - * @param polyVertex The input polygon's vertex. - * - * @return float The ratio of (polygon.z / light.z - polygon.z) - */ -float SpotShadow::projectCasterToOutline(Vector2& outline, const Vector3& lightCenter, - const Vector3& polyVertex) { - float lightToPolyZ = lightCenter.z - polyVertex.z; - float ratioZ = CASTER_Z_CAP_RATIO; - if (lightToPolyZ != 0) { - // If any caster's vertex is almost above the light, we just keep it as 95% - // of the height of the light. - ratioZ = MathUtils::clamp(polyVertex.z / lightToPolyZ, 0.0f, CASTER_Z_CAP_RATIO); - } - - outline.x = polyVertex.x - ratioZ * (lightCenter.x - polyVertex.x); - outline.y = polyVertex.y - ratioZ * (lightCenter.y - polyVertex.y); - return ratioZ; -} - -/** - * Generate the shadow spot light of shape lightPoly and a object poly - * - * @param isCasterOpaque whether the caster is opaque - * @param lightCenter the center of the light - * @param lightSize the radius of the 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 shadowTriangleStrip return an (x,y,alpha) triangle strip representing the shadow. Return - * empty strip if error. - */ -void SpotShadow::createSpotShadow(bool isCasterOpaque, const Vector3& lightCenter, float lightSize, - const Vector3* poly, int polyLength, const Vector3& polyCentroid, - VertexBuffer& shadowTriangleStrip) { - if (CC_UNLIKELY(lightCenter.z <= 0)) { - ALOGW("Relative Light Z is not positive. No spot shadow!"); - return; - } - if (CC_UNLIKELY(polyLength < 3)) { -#if DEBUG_SHADOW - ALOGW("Invalid polygon length. No spot shadow!"); -#endif - return; - } - OutlineData outlineData[polyLength]; - Vector2 outlineCentroid; - // Calculate the projected outline for each polygon's vertices from the light center. - // - // O Light - // / - // / - // . Polygon vertex - // / - // / - // O Outline vertices - // - // Ratio = (Poly - Outline) / (Light - Poly) - // Outline.x = Poly.x - Ratio * (Light.x - Poly.x) - // Outline's radius / Light's radius = Ratio - - // Compute the last outline vertex to make sure we can get the normal and outline - // in one single loop. - projectCasterToOutline(outlineData[polyLength - 1].position, lightCenter, poly[polyLength - 1]); - - // Take the outline's polygon, calculate the normal for each outline edge. - int currentNormalIndex = polyLength - 1; - int nextNormalIndex = 0; - - for (int i = 0; i < polyLength; i++) { - float ratioZ = projectCasterToOutline(outlineData[i].position, lightCenter, poly[i]); - outlineData[i].radius = ratioZ * lightSize; - - outlineData[currentNormalIndex].normal = ShadowTessellator::calculateNormal( - outlineData[currentNormalIndex].position, outlineData[nextNormalIndex].position); - currentNormalIndex = (currentNormalIndex + 1) % polyLength; - nextNormalIndex++; - } - - projectCasterToOutline(outlineCentroid, lightCenter, polyCentroid); - - int penumbraIndex = 0; - // Then each polygon's vertex produce at minmal 2 penumbra vertices. - // Since the size can be dynamic here, we keep track of the size and update - // the real size at the end. - int allocatedPenumbraLength = 2 * polyLength + SPOT_MAX_EXTRA_CORNER_VERTEX_NUMBER; - Vector2 penumbra[allocatedPenumbraLength]; - int totalExtraCornerSliceNumber = 0; - - Vector2 umbra[polyLength]; - - // When centroid is covered by all circles from outline, then we consider - // the umbra is invalid, and we will tune down the shadow strength. - bool hasValidUmbra = true; - // We need the minimal of RaitoVI to decrease the spot shadow strength accordingly. - float minRaitoVI = FLT_MAX; - - for (int i = 0; i < polyLength; i++) { - // Generate all the penumbra's vertices only using the (outline vertex + normal * radius) - // There is no guarantee that the penumbra is still convex, but for - // each outline vertex, it will connect to all its corresponding penumbra vertices as - // triangle fans. And for neighber penumbra vertex, it will be a trapezoid. - // - // Penumbra Vertices marked as Pi - // Outline Vertices marked as Vi - // (P3) - // (P2) | ' (P4) - // (P1)' | | ' - // ' | | ' - // (P0) ------------------------------------------------(P5) - // | (V0) |(V1) - // | | - // | | - // | | - // | | - // | | - // | | - // | | - // | | - // (V3)-----------------------------------(V2) - int preNormalIndex = (i + polyLength - 1) % polyLength; - - const Vector2& previousNormal = outlineData[preNormalIndex].normal; - const Vector2& currentNormal = outlineData[i].normal; - - // Depending on how roundness we want for each corner, we can subdivide - // further here and/or introduce some heuristic to decide how much the - // subdivision should be. - int currentExtraSliceNumber = ShadowTessellator::getExtraVertexNumber( - previousNormal, currentNormal, SPOT_CORNER_RADIANS_DIVISOR); - - int currentCornerSliceNumber = 1 + currentExtraSliceNumber; - totalExtraCornerSliceNumber += currentExtraSliceNumber; -#if DEBUG_SHADOW - ALOGD("currentExtraSliceNumber should be %d", currentExtraSliceNumber); - ALOGD("currentCornerSliceNumber should be %d", currentCornerSliceNumber); - ALOGD("totalCornerSliceNumber is %d", totalExtraCornerSliceNumber); -#endif - if (CC_UNLIKELY(totalExtraCornerSliceNumber > SPOT_MAX_EXTRA_CORNER_VERTEX_NUMBER)) { - currentCornerSliceNumber = 1; - } - for (int k = 0; k <= currentCornerSliceNumber; k++) { - Vector2 avgNormal = - (previousNormal * (currentCornerSliceNumber - k) + currentNormal * k) / - currentCornerSliceNumber; - avgNormal.normalize(); - penumbra[penumbraIndex++] = outlineData[i].position + avgNormal * outlineData[i].radius; - } - - // Compute the umbra by the intersection from the outline's centroid! - // - // (V) ------------------------------------ - // | ' | - // | ' | - // | ' (I) | - // | ' | - // | ' (C) | - // | | - // | | - // | | - // | | - // ------------------------------------ - // - // Connect a line b/t the outline vertex (V) and the centroid (C), it will - // intersect with the outline vertex's circle at point (I). - // Now, ratioVI = VI / VC, ratioIC = IC / VC - // Then the intersetion point can be computed as Ixy = Vxy * ratioIC + Cxy * ratioVI; - // - // When all of the outline circles cover the the outline centroid, (like I is - // on the other side of C), there is no real umbra any more, so we just fake - // a small area around the centroid as the umbra, and tune down the spot - // shadow's umbra strength to simulate the effect the whole shadow will - // become lighter in this case. - // The ratio can be simulated by using the inverse of maximum of ratioVI for - // all (V). - float distOutline = (outlineData[i].position - outlineCentroid).length(); - if (CC_UNLIKELY(distOutline == 0)) { - // If the outline has 0 area, then there is no spot shadow anyway. - ALOGW("Outline has 0 area, no spot shadow!"); - return; - } - - float ratioVI = outlineData[i].radius / distOutline; - minRaitoVI = std::min(minRaitoVI, ratioVI); - if (ratioVI >= (1 - FAKE_UMBRA_SIZE_RATIO)) { - ratioVI = (1 - FAKE_UMBRA_SIZE_RATIO); - } - // When we know we don't have valid umbra, don't bother to compute the - // values below. But we can't skip the loop yet since we want to know the - // maximum ratio. - float ratioIC = 1 - ratioVI; - umbra[i] = outlineData[i].position * ratioIC + outlineCentroid * ratioVI; - } - - hasValidUmbra = (minRaitoVI <= 1.0); - float shadowStrengthScale = 1.0; - if (!hasValidUmbra) { -#if DEBUG_SHADOW - ALOGW("The object is too close to the light or too small, no real umbra!"); -#endif - for (int i = 0; i < polyLength; i++) { - umbra[i] = outlineData[i].position * FAKE_UMBRA_SIZE_RATIO + - outlineCentroid * (1 - FAKE_UMBRA_SIZE_RATIO); - } - shadowStrengthScale = 1.0 / minRaitoVI; - } - - int penumbraLength = penumbraIndex; - int umbraLength = polyLength; - -#if DEBUG_SHADOW - ALOGD("penumbraLength is %d , allocatedPenumbraLength %d", penumbraLength, - allocatedPenumbraLength); - dumpPolygon(poly, polyLength, "input poly"); - dumpPolygon(penumbra, penumbraLength, "penumbra"); - dumpPolygon(umbra, umbraLength, "umbra"); - ALOGD("hasValidUmbra is %d and shadowStrengthScale is %f", hasValidUmbra, shadowStrengthScale); -#endif - - // The penumbra and umbra needs to be in convex shape to keep consistency - // and quality. - // Since we are still shooting rays to penumbra, it needs to be convex. - // Umbra can be represented as a fan from the centroid, but visually umbra - // looks nicer when it is convex. - Vector2 finalUmbra[umbraLength]; - Vector2 finalPenumbra[penumbraLength]; - int finalUmbraLength = hull(umbra, umbraLength, finalUmbra); - int finalPenumbraLength = hull(penumbra, penumbraLength, finalPenumbra); - - generateTriangleStrip(isCasterOpaque, shadowStrengthScale, finalPenumbra, finalPenumbraLength, - finalUmbra, finalUmbraLength, poly, polyLength, shadowTriangleStrip, - outlineCentroid); -} - -/** - * 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; - } - } -} - -// Index pair is meant for storing the tessellation information for the penumbra -// area. One index must come from exterior tangent of the circles, the other one -// must come from the interior tangent of the circles. -struct IndexPair { - int outerIndex; - int innerIndex; -}; - -// For one penumbra vertex, find the cloest umbra vertex and return its index. -inline int getClosestUmbraIndex(const Vector2& pivot, const Vector2* polygon, int polygonLength) { - float minLengthSquared = FLT_MAX; - int resultIndex = -1; - bool hasDecreased = false; - // Starting with some negative offset, assuming both umbra and penumbra are starting - // at the same angle, this can help to find the result faster. - // Normally, loop 3 times, we can find the closest point. - int offset = polygonLength - 2; - for (int i = 0; i < polygonLength; i++) { - int currentIndex = (i + offset) % polygonLength; - float currentLengthSquared = (pivot - polygon[currentIndex]).lengthSquared(); - if (currentLengthSquared < minLengthSquared) { - if (minLengthSquared != FLT_MAX) { - hasDecreased = true; - } - minLengthSquared = currentLengthSquared; - resultIndex = currentIndex; - } else if (currentLengthSquared > minLengthSquared && hasDecreased) { - // Early break b/c we have found the closet one and now the length - // is increasing again. - break; - } - } - if (resultIndex == -1) { - ALOGE("resultIndex is -1, the polygon must be invalid!"); - resultIndex = 0; - } - return resultIndex; -} - -// Allow some epsilon here since the later ray intersection did allow for some small -// floating point error, when the intersection point is slightly outside the segment. -inline bool sameDirections(bool isPositiveCross, float a, float b) { - if (isPositiveCross) { - return a >= -EPSILON && b >= -EPSILON; - } else { - return a <= EPSILON && b <= EPSILON; - } -} - -// Find the right polygon edge to shoot the ray at. -inline int findPolyIndex(bool isPositiveCross, int startPolyIndex, const Vector2& umbraDir, - const Vector2* polyToCentroid, int polyLength) { - // Make sure we loop with a bound. - for (int i = 0; i < polyLength; i++) { - int currentIndex = (i + startPolyIndex) % polyLength; - const Vector2& currentToCentroid = polyToCentroid[currentIndex]; - const Vector2& nextToCentroid = polyToCentroid[(currentIndex + 1) % polyLength]; - - float currentCrossUmbra = currentToCentroid.cross(umbraDir); - float umbraCrossNext = umbraDir.cross(nextToCentroid); - if (sameDirections(isPositiveCross, currentCrossUmbra, umbraCrossNext)) { -#if DEBUG_SHADOW - ALOGD("findPolyIndex loop %d times , index %d", i, currentIndex); -#endif - return currentIndex; - } - } - LOG_ALWAYS_FATAL("Can't find the right polygon's edge from startPolyIndex %d", startPolyIndex); - return -1; -} - -// Generate the index pair for penumbra / umbra vertices, and more penumbra vertices -// if needed. -inline void genNewPenumbraAndPairWithUmbra(const Vector2* penumbra, int penumbraLength, - const Vector2* umbra, int umbraLength, - Vector2* newPenumbra, int& newPenumbraIndex, - IndexPair* verticesPair, int& verticesPairIndex) { - // In order to keep everything in just one loop, we need to pre-compute the - // closest umbra vertex for the last penumbra vertex. - int previousClosestUmbraIndex = - getClosestUmbraIndex(penumbra[penumbraLength - 1], umbra, umbraLength); - for (int i = 0; i < penumbraLength; i++) { - const Vector2& currentPenumbraVertex = penumbra[i]; - // For current penumbra vertex, starting from previousClosestUmbraIndex, - // then check the next one until the distance increase. - // The last one before the increase is the umbra vertex we need to pair with. - float currentLengthSquared = - (currentPenumbraVertex - umbra[previousClosestUmbraIndex]).lengthSquared(); - int currentClosestUmbraIndex = previousClosestUmbraIndex; - int indexDelta = 0; - for (int j = 1; j < umbraLength; j++) { - int newUmbraIndex = (previousClosestUmbraIndex + j) % umbraLength; - float newLengthSquared = (currentPenumbraVertex - umbra[newUmbraIndex]).lengthSquared(); - if (newLengthSquared > currentLengthSquared) { - // currentClosestUmbraIndex is the umbra vertex's index which has - // currently found smallest distance, so we can simply break here. - break; - } else { - currentLengthSquared = newLengthSquared; - indexDelta++; - currentClosestUmbraIndex = newUmbraIndex; - } - } - - if (indexDelta > 1) { - // For those umbra don't have penumbra, generate new penumbra vertices by - // interpolation. - // - // Assuming Pi for penumbra vertices, and Ui for umbra vertices. - // In the case like below P1 paired with U1 and P2 paired with U5. - // U2 to U4 are unpaired umbra vertices. - // - // P1 P2 - // | | - // U1 U2 U3 U4 U5 - // - // We will need to generate 3 more penumbra vertices P1.1, P1.2, P1.3 - // to pair with U2 to U4. - // - // P1 P1.1 P1.2 P1.3 P2 - // | | | | | - // U1 U2 U3 U4 U5 - // - // That distance ratio b/t Ui to U1 and Ui to U5 decides its paired penumbra - // vertex's location. - int newPenumbraNumber = indexDelta - 1; - - float accumulatedDeltaLength[indexDelta]; - float totalDeltaLength = 0; - - // To save time, cache the previous umbra vertex info outside the loop - // and update each loop. - Vector2 previousClosestUmbra = umbra[previousClosestUmbraIndex]; - Vector2 skippedUmbra; - // Use umbra data to precompute the length b/t unpaired umbra vertices, - // and its ratio against the total length. - for (int k = 0; k < indexDelta; k++) { - int skippedUmbraIndex = (previousClosestUmbraIndex + k + 1) % umbraLength; - skippedUmbra = umbra[skippedUmbraIndex]; - float currentDeltaLength = (skippedUmbra - previousClosestUmbra).length(); - - totalDeltaLength += currentDeltaLength; - accumulatedDeltaLength[k] = totalDeltaLength; - - previousClosestUmbra = skippedUmbra; - } - - const Vector2& previousPenumbra = penumbra[(i + penumbraLength - 1) % penumbraLength]; - // Then for each unpaired umbra vertex, create a new penumbra by the ratio, - // and pair them togehter. - for (int k = 0; k < newPenumbraNumber; k++) { - float weightForCurrentPenumbra = 1.0f; - if (totalDeltaLength != 0.0f) { - weightForCurrentPenumbra = accumulatedDeltaLength[k] / totalDeltaLength; - } - float weightForPreviousPenumbra = 1.0f - weightForCurrentPenumbra; - - Vector2 interpolatedPenumbra = currentPenumbraVertex * weightForCurrentPenumbra + - previousPenumbra * weightForPreviousPenumbra; - - int skippedUmbraIndex = (previousClosestUmbraIndex + k + 1) % umbraLength; - verticesPair[verticesPairIndex].outerIndex = newPenumbraIndex; - verticesPair[verticesPairIndex].innerIndex = skippedUmbraIndex; - verticesPairIndex++; - newPenumbra[newPenumbraIndex++] = interpolatedPenumbra; - } - } - verticesPair[verticesPairIndex].outerIndex = newPenumbraIndex; - verticesPair[verticesPairIndex].innerIndex = currentClosestUmbraIndex; - verticesPairIndex++; - newPenumbra[newPenumbraIndex++] = currentPenumbraVertex; - - previousClosestUmbraIndex = currentClosestUmbraIndex; - } -} - -// Precompute all the polygon's vector, return true if the reference cross product is positive. -inline bool genPolyToCentroid(const Vector2* poly2d, int polyLength, const Vector2& centroid, - Vector2* polyToCentroid) { - for (int j = 0; j < polyLength; j++) { - polyToCentroid[j] = poly2d[j] - centroid; - // Normalize these vectors such that we can use epsilon comparison after - // computing their cross products with another normalized vector. - polyToCentroid[j].normalize(); - } - float refCrossProduct = 0; - for (int j = 0; j < polyLength; j++) { - refCrossProduct = polyToCentroid[j].cross(polyToCentroid[(j + 1) % polyLength]); - if (refCrossProduct != 0) { - break; - } - } - - return refCrossProduct > 0; -} - -// For one umbra vertex, shoot an ray from centroid to it. -// If the ray hit the polygon first, then return the intersection point as the -// closer vertex. -inline Vector2 getCloserVertex(const Vector2& umbraVertex, const Vector2& centroid, - const Vector2* poly2d, int polyLength, const Vector2* polyToCentroid, - bool isPositiveCross, int& previousPolyIndex) { - Vector2 umbraToCentroid = umbraVertex - centroid; - float distanceToUmbra = umbraToCentroid.length(); - umbraToCentroid = umbraToCentroid / distanceToUmbra; - - // previousPolyIndex is updated for each item such that we can minimize the - // looping inside findPolyIndex(); - previousPolyIndex = findPolyIndex(isPositiveCross, previousPolyIndex, umbraToCentroid, - polyToCentroid, polyLength); - - float dx = umbraToCentroid.x; - float dy = umbraToCentroid.y; - float distanceToIntersectPoly = - rayIntersectPoints(centroid, dx, dy, poly2d[previousPolyIndex], - poly2d[(previousPolyIndex + 1) % polyLength]); - if (distanceToIntersectPoly < 0) { - distanceToIntersectPoly = 0; - } - - // Pick the closer one as the occluded area vertex. - Vector2 closerVertex; - if (distanceToIntersectPoly < distanceToUmbra) { - closerVertex.x = centroid.x + dx * distanceToIntersectPoly; - closerVertex.y = centroid.y + dy * distanceToIntersectPoly; - } else { - closerVertex = umbraVertex; - } - - return closerVertex; -} - -/** - * Generate a triangle strip given two convex polygon -**/ -void SpotShadow::generateTriangleStrip(bool isCasterOpaque, float shadowStrengthScale, - Vector2* penumbra, int penumbraLength, Vector2* umbra, - int umbraLength, const Vector3* poly, int polyLength, - VertexBuffer& shadowTriangleStrip, const Vector2& centroid) { - bool hasOccludedUmbraArea = false; - Vector2 poly2d[polyLength]; - - if (isCasterOpaque) { - for (int i = 0; i < polyLength; i++) { - poly2d[i].x = poly[i].x; - poly2d[i].y = poly[i].y; - } - // 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, poly2d, polyLength)) { - hasOccludedUmbraArea = true; - } - } - - // For each penumbra vertex, find its corresponding closest umbra vertex index. - // - // Penumbra Vertices marked as Pi - // Umbra Vertices marked as Ui - // (P3) - // (P2) | ' (P4) - // (P1)' | | ' - // ' | | ' - // (P0) ------------------------------------------------(P5) - // | (U0) |(U1) - // | | - // | |(U2) (P5.1) - // | | - // | | - // | | - // | | - // | | - // | | - // (U4)-----------------------------------(U3) (P6) - // - // At least, like P0, P1, P2, they will find the matching umbra as U0. - // If we jump over some umbra vertex without matching penumbra vertex, then - // we will generate some new penumbra vertex by interpolation. Like P6 is - // matching U3, but U2 is not matched with any penumbra vertex. - // So interpolate P5.1 out and match U2. - // In this way, every umbra vertex will have a matching penumbra vertex. - // - // The total pair number can be as high as umbraLength + penumbraLength. - const int maxNewPenumbraLength = umbraLength + penumbraLength; - IndexPair verticesPair[maxNewPenumbraLength]; - int verticesPairIndex = 0; - - // Cache all the existing penumbra vertices and newly interpolated vertices into a - // a new array. - Vector2 newPenumbra[maxNewPenumbraLength]; - int newPenumbraIndex = 0; - - // For each penumbra vertex, find its closet umbra vertex by comparing the - // neighbor umbra vertices. - genNewPenumbraAndPairWithUmbra(penumbra, penumbraLength, umbra, umbraLength, newPenumbra, - newPenumbraIndex, verticesPair, verticesPairIndex); - ShadowTessellator::checkOverflow(verticesPairIndex, maxNewPenumbraLength, "Spot pair"); - ShadowTessellator::checkOverflow(newPenumbraIndex, maxNewPenumbraLength, "Spot new penumbra"); -#if DEBUG_SHADOW - for (int i = 0; i < umbraLength; i++) { - ALOGD("umbra i %d, [%f, %f]", i, umbra[i].x, umbra[i].y); - } - for (int i = 0; i < newPenumbraIndex; i++) { - ALOGD("new penumbra i %d, [%f, %f]", i, newPenumbra[i].x, newPenumbra[i].y); - } - for (int i = 0; i < verticesPairIndex; i++) { - ALOGD("index i %d, [%d, %d]", i, verticesPair[i].outerIndex, verticesPair[i].innerIndex); - } -#endif - - // For the size of vertex buffer, we need 3 rings, one has newPenumbraSize, - // one has umbraLength, the last one has at most umbraLength. - // - // For the size of index buffer, the umbra area needs (2 * umbraLength + 2). - // The penumbra one can vary a bit, but it is bounded by (2 * verticesPairIndex + 2). - // And 2 more for jumping between penumbra to umbra. - const int newPenumbraLength = newPenumbraIndex; - const int totalVertexCount = newPenumbraLength + umbraLength * 2; - const int totalIndexCount = 2 * umbraLength + 2 * verticesPairIndex + 6; - AlphaVertex* shadowVertices = shadowTriangleStrip.alloc<AlphaVertex>(totalVertexCount); - uint16_t* indexBuffer = shadowTriangleStrip.allocIndices<uint16_t>(totalIndexCount); - int vertexBufferIndex = 0; - int indexBufferIndex = 0; - - // Fill the IB and VB for the penumbra area. - for (int i = 0; i < newPenumbraLength; i++) { - AlphaVertex::set(&shadowVertices[vertexBufferIndex++], newPenumbra[i].x, newPenumbra[i].y, - PENUMBRA_ALPHA); - } - // Since the umbra can be a faked one when the occluder is too high, the umbra should be lighter - // in this case. - float scaledUmbraAlpha = UMBRA_ALPHA * shadowStrengthScale; - - for (int i = 0; i < umbraLength; i++) { - AlphaVertex::set(&shadowVertices[vertexBufferIndex++], umbra[i].x, umbra[i].y, - scaledUmbraAlpha); - } - - for (int i = 0; i < verticesPairIndex; i++) { - indexBuffer[indexBufferIndex++] = verticesPair[i].outerIndex; - // All umbra index need to be offseted by newPenumbraSize. - indexBuffer[indexBufferIndex++] = verticesPair[i].innerIndex + newPenumbraLength; - } - indexBuffer[indexBufferIndex++] = verticesPair[0].outerIndex; - indexBuffer[indexBufferIndex++] = verticesPair[0].innerIndex + newPenumbraLength; - - // Now fill the IB and VB for the umbra area. - // First duplicated the index from previous strip and the first one for the - // degenerated triangles. - indexBuffer[indexBufferIndex] = indexBuffer[indexBufferIndex - 1]; - indexBufferIndex++; - indexBuffer[indexBufferIndex++] = newPenumbraLength + 0; - // Save the first VB index for umbra area in order to close the loop. - int savedStartIndex = vertexBufferIndex; - - if (hasOccludedUmbraArea) { - // Precompute all the polygon's vector, and the reference cross product, - // in order to find the right polygon edge for the ray to intersect. - Vector2 polyToCentroid[polyLength]; - bool isPositiveCross = genPolyToCentroid(poly2d, polyLength, centroid, polyToCentroid); - - // Because both the umbra and polygon are going in the same direction, - // we can save the previous polygon index to make sure we have less polygon - // vertex to compute for each ray. - int previousPolyIndex = 0; - for (int i = 0; i < umbraLength; i++) { - // Shoot a ray from centroid to each umbra vertices and pick the one with - // shorter distance to the centroid, b/t the umbra vertex or the intersection point. - Vector2 closerVertex = - getCloserVertex(umbra[i], centroid, poly2d, polyLength, polyToCentroid, - isPositiveCross, previousPolyIndex); - - // We already stored the umbra vertices, just need to add the occlued umbra's ones. - indexBuffer[indexBufferIndex++] = newPenumbraLength + i; - indexBuffer[indexBufferIndex++] = vertexBufferIndex; - AlphaVertex::set(&shadowVertices[vertexBufferIndex++], closerVertex.x, closerVertex.y, - scaledUmbraAlpha); - } - } else { - // If there is no occluded umbra at all, then draw the triangle fan - // starting from the centroid to all umbra vertices. - int lastCentroidIndex = vertexBufferIndex; - AlphaVertex::set(&shadowVertices[vertexBufferIndex++], centroid.x, centroid.y, - scaledUmbraAlpha); - for (int i = 0; i < umbraLength; i++) { - indexBuffer[indexBufferIndex++] = newPenumbraLength + i; - indexBuffer[indexBufferIndex++] = lastCentroidIndex; - } - } - // Closing the umbra area triangle's loop here. - indexBuffer[indexBufferIndex++] = newPenumbraLength; - indexBuffer[indexBufferIndex++] = savedStartIndex; - - // At the end, update the real index and vertex buffer size. - shadowTriangleStrip.updateVertexCount(vertexBufferIndex); - shadowTriangleStrip.updateIndexCount(indexBufferIndex); - ShadowTessellator::checkOverflow(vertexBufferIndex, totalVertexCount, "Spot Vertex Buffer"); - ShadowTessellator::checkOverflow(indexBufferIndex, totalIndexCount, "Spot Index Buffer"); - - shadowTriangleStrip.setMeshFeatureFlags(VertexBuffer::kAlpha | VertexBuffer::kIndices); - shadowTriangleStrip.computeBounds<AlphaVertex>(); -} - -#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. - */ -void SpotShadow::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); - } -} - -/** - * For debug purpose, when things go wrong, dump the whole polygon data. - */ -void SpotShadow::dumpPolygon(const Vector3* poly, int polyLength, const char* polyName) { - for (int i = 0; i < polyLength; i++) { - ALOGD("polygon %s i %d x %f y %f z %f", polyName, i, poly[i].x, poly[i].y, poly[i].z); - } -} - -/** - * 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]; - - float delta = (float(middle.x) - start.x) * (float(end.y) - start.y) - - (float(middle.y) - start.y) * (float(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. - float randomX = rand() / float(RAND_MAX); - float randomY = rand() / float(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 |