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#include <utils/Vector.h>
24#include <utils/MathUtils.h>
25
26#include "AmbientShadow.h"
27#include "Properties.h"
28#include "ShadowTessellator.h"
29#include "SpotShadow.h"
30#include "Vector.h"
31
32namespace android {
33namespace uirenderer {
34
35void ShadowTessellator::tessellateAmbientShadow(bool isCasterOpaque,
36        const Vector3* casterPolygon, int casterVertexCount,
37        const Vector3& centroid3d, const Rect& casterBounds,
38        const Rect& localClip, float maxZ, VertexBuffer& shadowVertexBuffer) {
39    ATRACE_CALL();
40
41    // A bunch of parameters to tweak the shadow.
42    // TODO: Allow some of these changable by debug settings or APIs.
43    float heightFactor = 1.0f / 128;
44    const float geomFactor = 64;
45
46    if (CC_UNLIKELY(Properties::overrideAmbientRatio > 0.0f)) {
47        heightFactor *= Properties::overrideAmbientRatio;
48    }
49
50    Rect ambientShadowBounds(casterBounds);
51    ambientShadowBounds.outset(maxZ * geomFactor * heightFactor);
52
53    if (!localClip.intersects(ambientShadowBounds)) {
54#if DEBUG_SHADOW
55        ALOGD("Ambient shadow is out of clip rect!");
56#endif
57        return;
58    }
59
60    AmbientShadow::createAmbientShadow(isCasterOpaque, casterPolygon,
61            casterVertexCount, centroid3d, heightFactor, geomFactor,
62            shadowVertexBuffer);
63}
64
65void ShadowTessellator::tessellateSpotShadow(bool isCasterOpaque,
66        const Vector3* casterPolygon, int casterVertexCount, const Vector3& casterCentroid,
67        const mat4& receiverTransform, const Vector3& lightCenter, int lightRadius,
68        const Rect& casterBounds, const Rect& localClip, VertexBuffer& shadowVertexBuffer) {
69    ATRACE_CALL();
70
71    Vector3 adjustedLightCenter(lightCenter);
72    if (CC_UNLIKELY(Properties::overrideLightPosY > 0)) {
73        adjustedLightCenter.y = - Properties::overrideLightPosY; // negated since this shifts up
74    }
75    if (CC_UNLIKELY(Properties::overrideLightPosZ > 0)) {
76        adjustedLightCenter.z = Properties::overrideLightPosZ;
77    }
78
79#if DEBUG_SHADOW
80    ALOGD("light center %f %f %f %d",
81            adjustedLightCenter.x, adjustedLightCenter.y, adjustedLightCenter.z, lightRadius);
82#endif
83    if (isnan(adjustedLightCenter.x)
84            || isnan(adjustedLightCenter.y)
85            || isnan(adjustedLightCenter.z)) {
86        return;
87    }
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    if (CC_UNLIKELY(Properties::overrideLightRadius > 0)) {
96        lightRadius = Properties::overrideLightRadius;
97    }
98
99    // Now light and caster are both in local space, we will check whether
100    // the shadow is within the clip area.
101    Rect lightRect = Rect(adjustedLightCenter.x - lightRadius, adjustedLightCenter.y - lightRadius,
102            adjustedLightCenter.x + lightRadius, adjustedLightCenter.y + lightRadius);
103    lightRect.unionWith(localClip);
104    if (!lightRect.intersects(casterBounds)) {
105#if DEBUG_SHADOW
106        ALOGD("Spot shadow is out of clip rect!");
107#endif
108        return;
109    }
110
111    SpotShadow::createSpotShadow(isCasterOpaque, adjustedLightCenter, lightRadius,
112            casterPolygon, casterVertexCount, casterCentroid, shadowVertexBuffer);
113
114#if DEBUG_SHADOW
115     if(shadowVertexBuffer.getVertexCount() <= 0) {
116        ALOGD("Spot shadow generation failed %d", shadowVertexBuffer.getVertexCount());
117     }
118#endif
119}
120
121/**
122 * Calculate the centroid of a 2d polygon.
123 *
124 * @param poly The polygon, which is represented in a Vector2 array.
125 * @param polyLength The length of the polygon in terms of number of vertices.
126 * @return the centroid of the polygon.
127 */
128Vector2 ShadowTessellator::centroid2d(const Vector2* poly, int polyLength) {
129    double sumx = 0;
130    double sumy = 0;
131    int p1 = polyLength - 1;
132    double area = 0;
133    for (int p2 = 0; p2 < polyLength; p2++) {
134        double x1 = poly[p1].x;
135        double y1 = poly[p1].y;
136        double x2 = poly[p2].x;
137        double y2 = poly[p2].y;
138        double a = (x1 * y2 - x2 * y1);
139        sumx += (x1 + x2) * a;
140        sumy += (y1 + y2) * a;
141        area += a;
142        p1 = p2;
143    }
144
145    Vector2 centroid = poly[0];
146    if (area != 0) {
147        centroid = (Vector2){static_cast<float>(sumx / (3 * area)),
148            static_cast<float>(sumy / (3 * area))};
149    } else {
150        ALOGW("Area is 0 while computing centroid!");
151    }
152    return centroid;
153}
154
155// Make sure p1 -> p2 is going CW around the poly.
156Vector2 ShadowTessellator::calculateNormal(const Vector2& p1, const Vector2& p2) {
157    Vector2 result = p2 - p1;
158    if (result.x != 0 || result.y != 0) {
159        result.normalize();
160        // Calculate the normal , which is CCW 90 rotate to the delta.
161        float tempy = result.y;
162        result.y = result.x;
163        result.x = -tempy;
164    }
165    return result;
166}
167
168int ShadowTessellator::getExtraVertexNumber(const Vector2& vector1,
169        const Vector2& vector2, float divisor) {
170    // When there is no distance difference, there is no need for extra vertices.
171    if (vector1.lengthSquared() == 0 || vector2.lengthSquared() == 0) {
172        return 0;
173    }
174    // The formula is :
175    // extraNumber = floor(acos(dot(n1, n2)) / (M_PI / EXTRA_VERTEX_PER_PI))
176    // The value ranges for each step are:
177    // dot( ) --- [-1, 1]
178    // acos( )     --- [0, M_PI]
179    // floor(...)  --- [0, EXTRA_VERTEX_PER_PI]
180    float dotProduct = vector1.dot(vector2);
181    // make sure that dotProduct value is in acsof input range [-1, 1]
182    dotProduct = MathUtils::clamp(dotProduct, -1.0f, 1.0f);
183    // TODO: Use look up table for the dotProduct to extraVerticesNumber
184    // computation, if needed.
185    float angle = acosf(dotProduct);
186    return (int) floor(angle / divisor);
187}
188
189void ShadowTessellator::checkOverflow(int used, int total, const char* bufferName) {
190    LOG_ALWAYS_FATAL_IF(used > total, "Error: %s overflow!!! used %d, total %d",
191            bufferName, used, total);
192}
193
194}; // namespace uirenderer
195}; // namespace android
196