1/*
2 * Copyright (C) 2013 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define LOG_TAG "OpenGLRenderer"
18#define ATRACE_TAG ATRACE_TAG_VIEW
19
20#include <math.h>
21#include <utils/Log.h>
22#include <utils/Trace.h>
23
24#include "AmbientShadow.h"
25#include "Caches.h"
26#include "ShadowTessellator.h"
27#include "SpotShadow.h"
28
29namespace android {
30namespace uirenderer {
31
32void ShadowTessellator::tessellateAmbientShadow(bool isCasterOpaque,
33        const Vector3* casterPolygon, int casterVertexCount,
34        const Vector3& centroid3d, const Rect& casterBounds,
35        const Rect& localClip, float maxZ, VertexBuffer& shadowVertexBuffer) {
36    ATRACE_CALL();
37
38    // A bunch of parameters to tweak the shadow.
39    // TODO: Allow some of these changable by debug settings or APIs.
40    float heightFactor = 1.0f / 128;
41    const float geomFactor = 64;
42
43    Caches& caches = Caches::getInstance();
44    if (CC_UNLIKELY(caches.propertyAmbientRatio > 0.0f)) {
45        heightFactor *= caches.propertyAmbientRatio;
46    }
47
48    Rect ambientShadowBounds(casterBounds);
49    ambientShadowBounds.outset(maxZ * geomFactor * heightFactor);
50
51    if (!localClip.intersects(ambientShadowBounds)) {
52#if DEBUG_SHADOW
53        ALOGD("Ambient shadow is out of clip rect!");
54#endif
55        return;
56    }
57
58    AmbientShadow::createAmbientShadow(isCasterOpaque, casterPolygon,
59            casterVertexCount, centroid3d, heightFactor, geomFactor,
60            shadowVertexBuffer);
61}
62
63void ShadowTessellator::tessellateSpotShadow(bool isCasterOpaque,
64        const Vector3* casterPolygon, int casterVertexCount, const Vector3& casterCentroid,
65        const mat4& receiverTransform, const Vector3& lightCenter, int lightRadius,
66        const Rect& casterBounds, const Rect& localClip, VertexBuffer& shadowVertexBuffer) {
67    ATRACE_CALL();
68
69    Caches& caches = Caches::getInstance();
70
71    Vector3 adjustedLightCenter(lightCenter);
72    if (CC_UNLIKELY(caches.propertyLightPosY > 0)) {
73        adjustedLightCenter.y = - caches.propertyLightPosY; // negated since this shifts up
74    }
75    if (CC_UNLIKELY(caches.propertyLightPosZ > 0)) {
76        adjustedLightCenter.z = caches.propertyLightPosZ;
77    }
78
79#if DEBUG_SHADOW
80    ALOGD("light center %f %f %f",
81            adjustedLightCenter.x, adjustedLightCenter.y, adjustedLightCenter.z);
82#endif
83
84    // light position (because it's in local space) needs to compensate for receiver transform
85    // TODO: should apply to light orientation, not just position
86    Matrix4 reverseReceiverTransform;
87    reverseReceiverTransform.loadInverse(receiverTransform);
88    reverseReceiverTransform.mapPoint3d(adjustedLightCenter);
89
90    const int lightVertexCount = 8;
91    if (CC_UNLIKELY(caches.propertyLightDiameter > 0)) {
92        lightRadius = caches.propertyLightDiameter;
93    }
94
95    // Now light and caster are both in local space, we will check whether
96    // the shadow is within the clip area.
97    Rect lightRect = Rect(adjustedLightCenter.x - lightRadius, adjustedLightCenter.y - lightRadius,
98            adjustedLightCenter.x + lightRadius, adjustedLightCenter.y + lightRadius);
99    lightRect.unionWith(localClip);
100    if (!lightRect.intersects(casterBounds)) {
101#if DEBUG_SHADOW
102        ALOGD("Spot shadow is out of clip rect!");
103#endif
104        return;
105    }
106
107    SpotShadow::createSpotShadow(isCasterOpaque, adjustedLightCenter, lightRadius,
108            casterPolygon, casterVertexCount, casterCentroid, shadowVertexBuffer);
109
110#if DEBUG_SHADOW
111     if(shadowVertexBuffer.getVertexCount() <= 0) {
112        ALOGD("Spot shadow generation failed %d", shadowVertexBuffer.getVertexCount());
113     }
114#endif
115}
116
117void ShadowTessellator::generateShadowIndices(uint16_t* shadowIndices) {
118    int currentIndex = 0;
119    const int rays = SHADOW_RAY_COUNT;
120    // For the penumbra area.
121    for (int layer = 0; layer < 2; layer ++) {
122        int baseIndex = layer * rays;
123        for (int i = 0; i < rays; i++) {
124            shadowIndices[currentIndex++] = i + baseIndex;
125            shadowIndices[currentIndex++] = rays + i + baseIndex;
126        }
127        // To close the loop, back to the ray 0.
128        shadowIndices[currentIndex++] = 0 + baseIndex;
129         // Note this is the same as the first index of next layer loop.
130        shadowIndices[currentIndex++] = rays + baseIndex;
131    }
132
133#if DEBUG_SHADOW
134    if (currentIndex != MAX_SHADOW_INDEX_COUNT) {
135        ALOGW("vertex index count is wrong. current %d, expected %d",
136                currentIndex, MAX_SHADOW_INDEX_COUNT);
137    }
138    for (int i = 0; i < MAX_SHADOW_INDEX_COUNT; i++) {
139        ALOGD("vertex index is (%d, %d)", i, shadowIndices[i]);
140    }
141#endif
142}
143
144/**
145 * Calculate the centroid of a 2d polygon.
146 *
147 * @param poly The polygon, which is represented in a Vector2 array.
148 * @param polyLength The length of the polygon in terms of number of vertices.
149 * @return the centroid of the polygon.
150 */
151Vector2 ShadowTessellator::centroid2d(const Vector2* poly, int polyLength) {
152    double sumx = 0;
153    double sumy = 0;
154    int p1 = polyLength - 1;
155    double area = 0;
156    for (int p2 = 0; p2 < polyLength; p2++) {
157        double x1 = poly[p1].x;
158        double y1 = poly[p1].y;
159        double x2 = poly[p2].x;
160        double y2 = poly[p2].y;
161        double a = (x1 * y2 - x2 * y1);
162        sumx += (x1 + x2) * a;
163        sumy += (y1 + y2) * a;
164        area += a;
165        p1 = p2;
166    }
167
168    Vector2 centroid = poly[0];
169    if (area != 0) {
170        centroid = (Vector2){static_cast<float>(sumx / (3 * area)),
171            static_cast<float>(sumy / (3 * area))};
172    } else {
173        ALOGW("Area is 0 while computing centroid!");
174    }
175    return centroid;
176}
177
178// Make sure p1 -> p2 is going CW around the poly.
179Vector2 ShadowTessellator::calculateNormal(const Vector2& p1, const Vector2& p2) {
180    Vector2 result = p2 - p1;
181    if (result.x != 0 || result.y != 0) {
182        result.normalize();
183        // Calculate the normal , which is CCW 90 rotate to the delta.
184        float tempy = result.y;
185        result.y = result.x;
186        result.x = -tempy;
187    }
188    return result;
189}
190/**
191 * Test whether the polygon is order in clockwise.
192 *
193 * @param polygon the polygon as a Vector2 array
194 * @param len the number of points of the polygon
195 */
196bool ShadowTessellator::isClockwise(const Vector2* polygon, int len) {
197    if (len < 2 || polygon == NULL) {
198        return true;
199    }
200    double sum = 0;
201    double p1x = polygon[len - 1].x;
202    double p1y = polygon[len - 1].y;
203    for (int i = 0; i < len; i++) {
204
205        double p2x = polygon[i].x;
206        double p2y = polygon[i].y;
207        sum += p1x * p2y - p2x * p1y;
208        p1x = p2x;
209        p1y = p2y;
210    }
211    return sum < 0;
212}
213
214bool ShadowTessellator::isClockwisePath(const SkPath& path) {
215    SkPath::Iter iter(path, false);
216    SkPoint pts[4];
217    SkPath::Verb v;
218
219    Vector<Vector2> arrayForDirection;
220    while (SkPath::kDone_Verb != (v = iter.next(pts))) {
221            switch (v) {
222            case SkPath::kMove_Verb:
223                arrayForDirection.add((Vector2){pts[0].x(), pts[0].y()});
224                break;
225            case SkPath::kLine_Verb:
226                arrayForDirection.add((Vector2){pts[1].x(), pts[1].y()});
227                break;
228            case SkPath::kQuad_Verb:
229                arrayForDirection.add((Vector2){pts[1].x(), pts[1].y()});
230                arrayForDirection.add((Vector2){pts[2].x(), pts[2].y()});
231                break;
232            case SkPath::kCubic_Verb:
233                arrayForDirection.add((Vector2){pts[1].x(), pts[1].y()});
234                arrayForDirection.add((Vector2){pts[2].x(), pts[2].y()});
235                arrayForDirection.add((Vector2){pts[3].x(), pts[3].y()});
236                break;
237            default:
238                break;
239            }
240    }
241
242    return isClockwise(arrayForDirection.array(), arrayForDirection.size());
243}
244
245void ShadowTessellator::reverseVertexArray(Vertex* polygon, int len) {
246    int n = len / 2;
247    for (int i = 0; i < n; i++) {
248        Vertex tmp = polygon[i];
249        int k = len - 1 - i;
250        polygon[i] = polygon[k];
251        polygon[k] = tmp;
252    }
253}
254
255int ShadowTessellator::getExtraVertexNumber(const Vector2& vector1,
256        const Vector2& vector2, float divisor) {
257    // When there is no distance difference, there is no need for extra vertices.
258    if (vector1.lengthSquared() == 0 || vector2.lengthSquared() == 0) {
259        return 0;
260    }
261    // The formula is :
262    // extraNumber = floor(acos(dot(n1, n2)) / (M_PI / EXTRA_VERTEX_PER_PI))
263    // The value ranges for each step are:
264    // dot( ) --- [-1, 1]
265    // acos( )     --- [0, M_PI]
266    // floor(...)  --- [0, EXTRA_VERTEX_PER_PI]
267    float dotProduct = vector1.dot(vector2);
268    // TODO: Use look up table for the dotProduct to extraVerticesNumber
269    // computation, if needed.
270    float angle = acosf(dotProduct);
271    return (int) floor(angle / divisor);
272}
273
274void ShadowTessellator::checkOverflow(int used, int total, const char* bufferName) {
275    LOG_ALWAYS_FATAL_IF(used > total, "Error: %s overflow!!! used %d, total %d",
276            bufferName, used, total);
277}
278
279}; // namespace uirenderer
280}; // namespace android
281