ShadowTessellator.cpp revision 05f3d6e5111fd08df5cd9aae2c3d28399dc0e7f5 
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
32template<typename T>
33static inline T max(T a, T b) {
34    return a > b ? a : b;
35}
36
37void ShadowTessellator::tessellateAmbientShadow(bool isCasterOpaque,
38        const Vector3* casterPolygon, int casterVertexCount,
39        const Vector3& centroid3d, const Rect& casterBounds,
40        const Rect& localClip, float maxZ, VertexBuffer& shadowVertexBuffer) {
41    ATRACE_CALL();
42
43    // A bunch of parameters to tweak the shadow.
44    // TODO: Allow some of these changable by debug settings or APIs.
45    float heightFactor = 1.0f / 128;
46    const float geomFactor = 64;
47
48    Caches& caches = Caches::getInstance();
49    if (CC_UNLIKELY(caches.propertyAmbientRatio > 0.0f)) {
50        heightFactor *= caches.propertyAmbientRatio;
51    }
52
53    Rect ambientShadowBounds(casterBounds);
54    ambientShadowBounds.outset(maxZ * geomFactor * heightFactor);
55
56    if (!localClip.intersects(ambientShadowBounds)) {
57#if DEBUG_SHADOW
58        ALOGD("Ambient shadow is out of clip rect!");
59#endif
60        return;
61    }
62
63    AmbientShadow::createAmbientShadow(isCasterOpaque, casterPolygon,
64            casterVertexCount, centroid3d, heightFactor, geomFactor,
65            shadowVertexBuffer);
66}
67
68void ShadowTessellator::tessellateSpotShadow(bool isCasterOpaque,
69        const Vector3* casterPolygon, int casterVertexCount,
70        const mat4& receiverTransform, const Vector3& lightCenter, int lightRadius,
71        const Rect& casterBounds, const Rect& localClip, VertexBuffer& shadowVertexBuffer) {
72    ATRACE_CALL();
73
74    Caches& caches = Caches::getInstance();
75
76    Vector3 adjustedLightCenter(lightCenter);
77    if (CC_UNLIKELY(caches.propertyLightPosY > 0)) {
78        adjustedLightCenter.y = - caches.propertyLightPosY; // negated since this shifts up
79    }
80    if (CC_UNLIKELY(caches.propertyLightPosZ > 0)) {
81        adjustedLightCenter.z = caches.propertyLightPosZ;
82    }
83
84#if DEBUG_SHADOW
85    ALOGD("light center %f %f %f",
86            adjustedLightCenter.x, adjustedLightCenter.y, adjustedLightCenter.z);
87#endif
88
89    // light position (because it's in local space) needs to compensate for receiver transform
90    // TODO: should apply to light orientation, not just position
91    Matrix4 reverseReceiverTransform;
92    reverseReceiverTransform.loadInverse(receiverTransform);
93    reverseReceiverTransform.mapPoint3d(adjustedLightCenter);
94
95    const int lightVertexCount = 8;
96    if (CC_UNLIKELY(caches.propertyLightDiameter > 0)) {
97        lightRadius = caches.propertyLightDiameter;
98    }
99
100    // Now light and caster are both in local space, we will check whether
101    // the shadow is within the clip area.
102    Rect lightRect = Rect(adjustedLightCenter.x - lightRadius, adjustedLightCenter.y - lightRadius,
103            adjustedLightCenter.x + lightRadius, adjustedLightCenter.y + lightRadius);
104    lightRect.unionWith(localClip);
105    if (!lightRect.intersects(casterBounds)) {
106#if DEBUG_SHADOW
107        ALOGD("Spot shadow is out of clip rect!");
108#endif
109        return;
110    }
111
112    SpotShadow::createSpotShadow(isCasterOpaque,
113            casterPolygon, casterVertexCount, adjustedLightCenter, lightRadius,
114            lightVertexCount, shadowVertexBuffer);
115#if DEBUG_SHADOW
116     if(shadowVertexBuffer.getVertexCount() <= 0) {
117        ALOGD("Spot shadow generation failed %d", shadowVertexBuffer.getVertexCount());
118     }
119#endif
120}
121
122void ShadowTessellator::generateShadowIndices(uint16_t* shadowIndices) {
123    int currentIndex = 0;
124    const int rays = SHADOW_RAY_COUNT;
125    // For the penumbra area.
126    for (int layer = 0; layer < 2; layer ++) {
127        int baseIndex = layer * rays;
128        for (int i = 0; i < rays; i++) {
129            shadowIndices[currentIndex++] = i + baseIndex;
130            shadowIndices[currentIndex++] = rays + i + baseIndex;
131        }
132        // To close the loop, back to the ray 0.
133        shadowIndices[currentIndex++] = 0 + baseIndex;
134         // Note this is the same as the first index of next layer loop.
135        shadowIndices[currentIndex++] = rays + baseIndex;
136    }
137
138#if DEBUG_SHADOW
139    if (currentIndex != MAX_SHADOW_INDEX_COUNT) {
140        ALOGW("vertex index count is wrong. current %d, expected %d",
141                currentIndex, MAX_SHADOW_INDEX_COUNT);
142    }
143    for (int i = 0; i < MAX_SHADOW_INDEX_COUNT; i++) {
144        ALOGD("vertex index is (%d, %d)", i, shadowIndices[i]);
145    }
146#endif
147}
148
149/**
150 * Calculate the centroid of a 2d polygon.
151 *
152 * @param poly The polygon, which is represented in a Vector2 array.
153 * @param polyLength The length of the polygon in terms of number of vertices.
154 * @return the centroid of the polygon.
155 */
156Vector2 ShadowTessellator::centroid2d(const Vector2* poly, int polyLength) {
157    double sumx = 0;
158    double sumy = 0;
159    int p1 = polyLength - 1;
160    double area = 0;
161    for (int p2 = 0; p2 < polyLength; p2++) {
162        double x1 = poly[p1].x;
163        double y1 = poly[p1].y;
164        double x2 = poly[p2].x;
165        double y2 = poly[p2].y;
166        double a = (x1 * y2 - x2 * y1);
167        sumx += (x1 + x2) * a;
168        sumy += (y1 + y2) * a;
169        area += a;
170        p1 = p2;
171    }
172
173    Vector2 centroid = poly[0];
174    if (area != 0) {
175        centroid = Vector2(sumx / (3 * area), sumy / (3 * area));
176    } else {
177        ALOGW("Area is 0 while computing centroid!");
178    }
179    return centroid;
180}
181
182/**
183 * Test whether the polygon is order in clockwise.
184 *
185 * @param polygon the polygon as a Vector2 array
186 * @param len the number of points of the polygon
187 */
188bool ShadowTessellator::isClockwise(const Vector2* polygon, int len) {
189    if (len < 2 || polygon == NULL) {
190        ALOGW("Invalid polygon %p, length is %d @ isClockwise()", polygon, len);
191        return true;
192    }
193    double sum = 0;
194    double p1x = polygon[len - 1].x;
195    double p1y = polygon[len - 1].y;
196    for (int i = 0; i < len; i++) {
197
198        double p2x = polygon[i].x;
199        double p2y = polygon[i].y;
200        sum += p1x * p2y - p2x * p1y;
201        p1x = p2x;
202        p1y = p2y;
203    }
204    return sum < 0;
205}
206
207bool ShadowTessellator::isClockwisePath(const SkPath& path) {
208    SkPath::Iter iter(path, false);
209    SkPoint pts[4];
210    SkPath::Verb v;
211
212    Vector<Vector2> arrayForDirection;
213    while (SkPath::kDone_Verb != (v = iter.next(pts))) {
214            switch (v) {
215            case SkPath::kMove_Verb:
216                arrayForDirection.add(Vector2(pts[0].x(), pts[0].y()));
217                break;
218            case SkPath::kLine_Verb:
219                arrayForDirection.add(Vector2(pts[1].x(), pts[1].y()));
220                break;
221            case SkPath::kQuad_Verb:
222                arrayForDirection.add(Vector2(pts[1].x(), pts[1].y()));
223                arrayForDirection.add(Vector2(pts[2].x(), pts[2].y()));
224                break;
225            case SkPath::kCubic_Verb:
226                arrayForDirection.add(Vector2(pts[1].x(), pts[1].y()));
227                arrayForDirection.add(Vector2(pts[2].x(), pts[2].y()));
228                arrayForDirection.add(Vector2(pts[3].x(), pts[3].y()));
229                break;
230            default:
231                break;
232            }
233    }
234
235    return isClockwise(arrayForDirection.array(), arrayForDirection.size());
236}
237
238void ShadowTessellator::reverseVertexArray(Vertex* polygon, int len) {
239    int n = len / 2;
240    for (int i = 0; i < n; i++) {
241        Vertex tmp = polygon[i];
242        int k = len - 1 - i;
243        polygon[i] = polygon[k];
244        polygon[k] = tmp;
245    }
246}
247
248}; // namespace uirenderer
249}; // namespace android
250