ShadowTessellator.cpp revision fca52b7583d1e5f5ff8ed06554875d2a30ef56fa
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 25#include "AmbientShadow.h" 26#include "Properties.h" 27#include "ShadowTessellator.h" 28#include "SpotShadow.h" 29#include "Vector.h" 30 31namespace android { 32namespace uirenderer { 33 34void ShadowTessellator::tessellateAmbientShadow(bool isCasterOpaque, 35 const Vector3* casterPolygon, int casterVertexCount, 36 const Vector3& centroid3d, const Rect& casterBounds, 37 const Rect& localClip, float maxZ, VertexBuffer& shadowVertexBuffer) { 38 ATRACE_CALL(); 39 40 // A bunch of parameters to tweak the shadow. 41 // TODO: Allow some of these changable by debug settings or APIs. 42 float heightFactor = 1.0f / 128; 43 const float geomFactor = 64; 44 45 if (CC_UNLIKELY(Properties::overrideAmbientRatio > 0.0f)) { 46 heightFactor *= Properties::overrideAmbientRatio; 47 } 48 49 Rect ambientShadowBounds(casterBounds); 50 ambientShadowBounds.outset(maxZ * geomFactor * heightFactor); 51 52 if (!localClip.intersects(ambientShadowBounds)) { 53#if DEBUG_SHADOW 54 ALOGD("Ambient shadow is out of clip rect!"); 55#endif 56 return; 57 } 58 59 AmbientShadow::createAmbientShadow(isCasterOpaque, casterPolygon, 60 casterVertexCount, centroid3d, heightFactor, geomFactor, 61 shadowVertexBuffer); 62} 63 64void ShadowTessellator::tessellateSpotShadow(bool isCasterOpaque, 65 const Vector3* casterPolygon, int casterVertexCount, const Vector3& casterCentroid, 66 const mat4& receiverTransform, const Vector3& lightCenter, int lightRadius, 67 const Rect& casterBounds, const Rect& localClip, VertexBuffer& shadowVertexBuffer) { 68 ATRACE_CALL(); 69 70 Vector3 adjustedLightCenter(lightCenter); 71 if (CC_UNLIKELY(Properties::overrideLightPosY > 0)) { 72 adjustedLightCenter.y = - Properties::overrideLightPosY; // negated since this shifts up 73 } 74 if (CC_UNLIKELY(Properties::overrideLightPosZ > 0)) { 75 adjustedLightCenter.z = Properties::overrideLightPosZ; 76 } 77 78#if DEBUG_SHADOW 79 ALOGD("light center %f %f %f", 80 adjustedLightCenter.x, adjustedLightCenter.y, adjustedLightCenter.z); 81#endif 82 83 // light position (because it's in local space) needs to compensate for receiver transform 84 // TODO: should apply to light orientation, not just position 85 Matrix4 reverseReceiverTransform; 86 reverseReceiverTransform.loadInverse(receiverTransform); 87 reverseReceiverTransform.mapPoint3d(adjustedLightCenter); 88 89 if (CC_UNLIKELY(Properties::overrideLightRadius > 0)) { 90 lightRadius = Properties::overrideLightRadius; 91 } 92 93 // Now light and caster are both in local space, we will check whether 94 // the shadow is within the clip area. 95 Rect lightRect = Rect(adjustedLightCenter.x - lightRadius, adjustedLightCenter.y - lightRadius, 96 adjustedLightCenter.x + lightRadius, adjustedLightCenter.y + lightRadius); 97 lightRect.unionWith(localClip); 98 if (!lightRect.intersects(casterBounds)) { 99#if DEBUG_SHADOW 100 ALOGD("Spot shadow is out of clip rect!"); 101#endif 102 return; 103 } 104 105 SpotShadow::createSpotShadow(isCasterOpaque, adjustedLightCenter, lightRadius, 106 casterPolygon, casterVertexCount, casterCentroid, shadowVertexBuffer); 107 108#if DEBUG_SHADOW 109 if(shadowVertexBuffer.getVertexCount() <= 0) { 110 ALOGD("Spot shadow generation failed %d", shadowVertexBuffer.getVertexCount()); 111 } 112#endif 113} 114 115/** 116 * Calculate the centroid of a 2d polygon. 117 * 118 * @param poly The polygon, which is represented in a Vector2 array. 119 * @param polyLength The length of the polygon in terms of number of vertices. 120 * @return the centroid of the polygon. 121 */ 122Vector2 ShadowTessellator::centroid2d(const Vector2* poly, int polyLength) { 123 double sumx = 0; 124 double sumy = 0; 125 int p1 = polyLength - 1; 126 double area = 0; 127 for (int p2 = 0; p2 < polyLength; p2++) { 128 double x1 = poly[p1].x; 129 double y1 = poly[p1].y; 130 double x2 = poly[p2].x; 131 double y2 = poly[p2].y; 132 double a = (x1 * y2 - x2 * y1); 133 sumx += (x1 + x2) * a; 134 sumy += (y1 + y2) * a; 135 area += a; 136 p1 = p2; 137 } 138 139 Vector2 centroid = poly[0]; 140 if (area != 0) { 141 centroid = (Vector2){static_cast<float>(sumx / (3 * area)), 142 static_cast<float>(sumy / (3 * area))}; 143 } else { 144 ALOGW("Area is 0 while computing centroid!"); 145 } 146 return centroid; 147} 148 149// Make sure p1 -> p2 is going CW around the poly. 150Vector2 ShadowTessellator::calculateNormal(const Vector2& p1, const Vector2& p2) { 151 Vector2 result = p2 - p1; 152 if (result.x != 0 || result.y != 0) { 153 result.normalize(); 154 // Calculate the normal , which is CCW 90 rotate to the delta. 155 float tempy = result.y; 156 result.y = result.x; 157 result.x = -tempy; 158 } 159 return result; 160} 161 162int ShadowTessellator::getExtraVertexNumber(const Vector2& vector1, 163 const Vector2& vector2, float divisor) { 164 // When there is no distance difference, there is no need for extra vertices. 165 if (vector1.lengthSquared() == 0 || vector2.lengthSquared() == 0) { 166 return 0; 167 } 168 // The formula is : 169 // extraNumber = floor(acos(dot(n1, n2)) / (M_PI / EXTRA_VERTEX_PER_PI)) 170 // The value ranges for each step are: 171 // dot( ) --- [-1, 1] 172 // acos( ) --- [0, M_PI] 173 // floor(...) --- [0, EXTRA_VERTEX_PER_PI] 174 float dotProduct = vector1.dot(vector2); 175 // TODO: Use look up table for the dotProduct to extraVerticesNumber 176 // computation, if needed. 177 float angle = acosf(dotProduct); 178 return (int) floor(angle / divisor); 179} 180 181void ShadowTessellator::checkOverflow(int used, int total, const char* bufferName) { 182 LOG_ALWAYS_FATAL_IF(used > total, "Error: %s overflow!!! used %d, total %d", 183 bufferName, used, total); 184} 185 186}; // namespace uirenderer 187}; // namespace android 188