| /* |
| * 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 |
| #define CASTER_Z_CAP_RATIO 0.95f |
| #define FAKE_UMBRA_SIZE_RATIO 0.01f |
| #define OCLLUDED_UMBRA_SHRINK_FACTOR 0.95f |
| |
| #include <math.h> |
| #include <stdlib.h> |
| #include <utils/Log.h> |
| |
| #include "ShadowTessellator.h" |
| #include "SpotShadow.h" |
| #include "Vertex.h" |
| #include "utils/MathUtils.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 double 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; |
| }; |
| |
| /** |
| * 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 = {0, 0}; |
| 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. |
| * |
| */ |
| |
| void SpotShadow::createSpotShadow_old(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_old(isCasterOpaque, light, lightVertexCount, lightCenter, poly, |
| polyLength, retStrips); |
| } |
| |
| /** |
| * 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_old(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 = {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, 1.0, penumbra, penumbraLength, umbra, |
| umbraLength, poly, polyLength, shadowTriangleStrip); |
| } |
| |
| 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; |
| } |
| 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; |
| int penumbraLength = polyLength * 3; |
| Vector2 penumbra[penumbraLength]; |
| |
| Vector2 umbra[polyLength]; |
| float distOutline = 0; |
| float ratioVI = 0; |
| |
| bool hasValidUmbra = true; |
| // We need the maxRatioVI to decrease the spot shadow strength accordingly. |
| float maxRaitoVI = 1.0; |
| |
| 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; |
| penumbra[penumbraIndex++] = outlineData[i].position + |
| outlineData[preNormalIndex].normal * outlineData[i].radius; |
| |
| int currentNormalIndex = i; |
| // (TODO) 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. |
| Vector2 avgNormal = |
| (outlineData[preNormalIndex].normal + outlineData[currentNormalIndex].normal) / 2; |
| |
| penumbra[penumbraIndex++] = outlineData[i].position + |
| avgNormal * outlineData[i].radius; |
| |
| penumbra[penumbraIndex++] = outlineData[i].position + |
| outlineData[currentNormalIndex].normal * 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 one of the outline circle 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). |
| 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; |
| } |
| ratioVI = outlineData[i].radius / distOutline; |
| if (ratioVI >= 1.0) { |
| maxRaitoVI = ratioVI; |
| hasValidUmbra = false; |
| } |
| // 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. |
| if (hasValidUmbra) { |
| float ratioIC = (distOutline - outlineData[i].radius) / distOutline; |
| umbra[i] = outlineData[i].position * ratioIC + outlineCentroid * ratioVI; |
| } |
| } |
| |
| float shadowStrengthScale = 1.0; |
| if (!hasValidUmbra) { |
| ALOGW("The object is too close to the light or too small, no real umbra!"); |
| 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 / maxRaitoVI; |
| } |
| |
| #if DEBUG_SHADOW |
| dumpPolygon(poly, polyLength, "input poly"); |
| dumpPolygon(outline, polyLength, "outline"); |
| dumpPolygon(penumbra, penumbraLength, "penumbra"); |
| dumpPolygon(umbra, polyLength, "umbra"); |
| ALOGD("hasValidUmbra is %d and shadowStrengthScale is %f", hasValidUmbra, shadowStrengthScale); |
| #endif |
| |
| generateTriangleStrip(isCasterOpaque, shadowStrengthScale, penumbra, |
| penumbraLength, umbra, polyLength, 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); |
| } |
| |
| /** |
| * 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, float shadowStrengthScale, |
| 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); |
| |
| // NOTE: Shadow alpha values are transformed when stored in alphavertices, |
| // so that they can be consumed directly by gFS_Main_ApplyVertexAlphaShadowInterp |
| float transformedMaxAlpha = M_PI * shadowStrengthScale; |
| |
| // Calculate the vertices (x, y, alpha) in the shadow area. |
| AlphaVertex centroidXYA; |
| AlphaVertex::set(¢roidXYA, centroid.x, centroid.y, transformedMaxAlpha); |
| 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, |
| transformedMaxAlpha); |
| |
| // occluded umbra ring |
| if (hasOccludedUmbraArea) { |
| float occludedUmbraDistance = occludedUmbraDistPerRay[rayIndex]; |
| AlphaVertex::set(&shadowVertices[2 * rays + rayIndex], |
| dx * occludedUmbraDistance + centroid.x, |
| dy * occludedUmbraDistance + centroid.y, transformedMaxAlpha); |
| } else { |
| // Put all vertices of the occluded umbra ring at the centroid. |
| shadowVertices[2 * rays + rayIndex] = centroidXYA; |
| } |
| } |
| shadowTriangleStrip.setMode(VertexBuffer::kTwoPolyRingShadow); |
| shadowTriangleStrip.computeBounds<AlphaVertex>(); |
| } |
| |
| /** |
| * 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. |
| */ |
| 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", 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 |
