| /* |
| * 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 <algorithm> |
| #include <math.h> |
| #include <stdlib.h> |
| #include <utils/Log.h> |
| |
| // 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 |