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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 #include <math.h>
18 #include <utils/Log.h>
19 #include <utils/Trace.h>
20 #include <utils/MathUtils.h>
21 
22 #include "AmbientShadow.h"
23 #include "Properties.h"
24 #include "ShadowTessellator.h"
25 #include "SpotShadow.h"
26 #include "Vector.h"
27 
28 namespace android {
29 namespace uirenderer {
30 
tessellateAmbientShadow(bool isCasterOpaque,const Vector3 * casterPolygon,int casterVertexCount,const Vector3 & centroid3d,const Rect & casterBounds,const Rect & localClip,float maxZ,VertexBuffer & shadowVertexBuffer)31 void ShadowTessellator::tessellateAmbientShadow(bool isCasterOpaque,
32         const Vector3* casterPolygon, int casterVertexCount,
33         const Vector3& centroid3d, const Rect& casterBounds,
34         const Rect& localClip, float maxZ, VertexBuffer& shadowVertexBuffer) {
35     ATRACE_CALL();
36 
37     // A bunch of parameters to tweak the shadow.
38     // TODO: Allow some of these changable by debug settings or APIs.
39     float heightFactor = 1.0f / 128;
40     const float geomFactor = 64;
41 
42     if (CC_UNLIKELY(Properties::overrideAmbientRatio > 0.0f)) {
43         heightFactor *= Properties::overrideAmbientRatio;
44     }
45 
46     Rect ambientShadowBounds(casterBounds);
47     ambientShadowBounds.outset(maxZ * geomFactor * heightFactor);
48 
49     if (!localClip.intersects(ambientShadowBounds)) {
50 #if DEBUG_SHADOW
51         ALOGD("Ambient shadow is out of clip rect!");
52 #endif
53         return;
54     }
55 
56     AmbientShadow::createAmbientShadow(isCasterOpaque, casterPolygon,
57             casterVertexCount, centroid3d, heightFactor, geomFactor,
58             shadowVertexBuffer);
59 }
60 
tessellateSpotShadow(bool isCasterOpaque,const Vector3 * casterPolygon,int casterVertexCount,const Vector3 & casterCentroid,const mat4 & receiverTransform,const Vector3 & lightCenter,int lightRadius,const Rect & casterBounds,const Rect & localClip,VertexBuffer & shadowVertexBuffer)61 void ShadowTessellator::tessellateSpotShadow(bool isCasterOpaque,
62         const Vector3* casterPolygon, int casterVertexCount, const Vector3& casterCentroid,
63         const mat4& receiverTransform, const Vector3& lightCenter, int lightRadius,
64         const Rect& casterBounds, const Rect& localClip, VertexBuffer& shadowVertexBuffer) {
65     ATRACE_CALL();
66 
67     Vector3 adjustedLightCenter(lightCenter);
68     if (CC_UNLIKELY(Properties::overrideLightPosY > 0)) {
69         adjustedLightCenter.y = - Properties::overrideLightPosY; // negated since this shifts up
70     }
71     if (CC_UNLIKELY(Properties::overrideLightPosZ > 0)) {
72         adjustedLightCenter.z = Properties::overrideLightPosZ;
73     }
74 
75 #if DEBUG_SHADOW
76     ALOGD("light center %f %f %f %d",
77             adjustedLightCenter.x, adjustedLightCenter.y, adjustedLightCenter.z, lightRadius);
78 #endif
79     if (isnan(adjustedLightCenter.x)
80             || isnan(adjustedLightCenter.y)
81             || isnan(adjustedLightCenter.z)) {
82         return;
83     }
84 
85     // light position (because it's in local space) needs to compensate for receiver transform
86     // TODO: should apply to light orientation, not just position
87     Matrix4 reverseReceiverTransform;
88     reverseReceiverTransform.loadInverse(receiverTransform);
89     reverseReceiverTransform.mapPoint3d(adjustedLightCenter);
90 
91     if (CC_UNLIKELY(Properties::overrideLightRadius > 0)) {
92         lightRadius = Properties::overrideLightRadius;
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 
117 /**
118  * Calculate the centroid of a 2d polygon.
119  *
120  * @param poly The polygon, which is represented in a Vector2 array.
121  * @param polyLength The length of the polygon in terms of number of vertices.
122  * @return the centroid of the polygon.
123  */
centroid2d(const Vector2 * poly,int polyLength)124 Vector2 ShadowTessellator::centroid2d(const Vector2* poly, int polyLength) {
125     double sumx = 0;
126     double sumy = 0;
127     int p1 = polyLength - 1;
128     double area = 0;
129     for (int p2 = 0; p2 < polyLength; p2++) {
130         double x1 = poly[p1].x;
131         double y1 = poly[p1].y;
132         double x2 = poly[p2].x;
133         double y2 = poly[p2].y;
134         double a = (x1 * y2 - x2 * y1);
135         sumx += (x1 + x2) * a;
136         sumy += (y1 + y2) * a;
137         area += a;
138         p1 = p2;
139     }
140 
141     Vector2 centroid = poly[0];
142     if (area != 0) {
143         centroid = (Vector2){static_cast<float>(sumx / (3 * area)),
144             static_cast<float>(sumy / (3 * area))};
145     } else {
146         ALOGW("Area is 0 while computing centroid!");
147     }
148     return centroid;
149 }
150 
151 // Make sure p1 -> p2 is going CW around the poly.
calculateNormal(const Vector2 & p1,const Vector2 & p2)152 Vector2 ShadowTessellator::calculateNormal(const Vector2& p1, const Vector2& p2) {
153     Vector2 result = p2 - p1;
154     if (result.x != 0 || result.y != 0) {
155         result.normalize();
156         // Calculate the normal , which is CCW 90 rotate to the delta.
157         float tempy = result.y;
158         result.y = result.x;
159         result.x = -tempy;
160     }
161     return result;
162 }
163 
getExtraVertexNumber(const Vector2 & vector1,const Vector2 & vector2,float divisor)164 int ShadowTessellator::getExtraVertexNumber(const Vector2& vector1,
165         const Vector2& vector2, float divisor) {
166     // When there is no distance difference, there is no need for extra vertices.
167     if (vector1.lengthSquared() == 0 || vector2.lengthSquared() == 0) {
168         return 0;
169     }
170     // The formula is :
171     // extraNumber = floor(acos(dot(n1, n2)) / (M_PI / EXTRA_VERTEX_PER_PI))
172     // The value ranges for each step are:
173     // dot( ) --- [-1, 1]
174     // acos( )     --- [0, M_PI]
175     // floor(...)  --- [0, EXTRA_VERTEX_PER_PI]
176     float dotProduct = vector1.dot(vector2);
177     // make sure that dotProduct value is in acsof input range [-1, 1]
178     dotProduct = MathUtils::clamp(dotProduct, -1.0f, 1.0f);
179     // TODO: Use look up table for the dotProduct to extraVerticesNumber
180     // computation, if needed.
181     float angle = acosf(dotProduct);
182     return (int) floor(angle / divisor);
183 }
184 
checkOverflow(int used,int total,const char * bufferName)185 void ShadowTessellator::checkOverflow(int used, int total, const char* bufferName) {
186     LOG_ALWAYS_FATAL_IF(used > total, "Error: %s overflow!!! used %d, total %d",
187             bufferName, used, total);
188 }
189 
190 }; // namespace uirenderer
191 }; // namespace android
192