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