1 /* 2 * Copyright (C) 2018 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 package android.view.shadow; 18 19 import android.view.math.Math3DHelper; 20 21 /** 22 * Generates vertices, colours, and indices required for ambient shadow. Ambient shadows are 23 * assumed to be raycasted from the centroid of the polygon, and reaches upto a ratio based on 24 * the polygon's z-height. 25 */ 26 class AmbientShadowVertexCalculator { 27 28 private final float[] mVertex; 29 private final float[] mColor; 30 private final int[] mIndex; 31 private final AmbientShadowConfig mConfig; 32 AmbientShadowVertexCalculator(AmbientShadowConfig config)33 public AmbientShadowVertexCalculator(AmbientShadowConfig config) { 34 mConfig = config; 35 36 int size = mConfig.getPolygon().length / 3; 37 38 mVertex = new float[size * 2 * 2]; 39 mColor = new float[size * 2 * 4]; 40 mIndex = new int[(size * 3 - 2) * 3]; 41 } 42 43 /** 44 * Generates ambient shadow triangulation using configuration provided 45 */ generateVertex()46 public void generateVertex() { 47 float[] polygon = mConfig.getPolygon(); 48 float cx = mConfig.getLightSourcePosition()[0]; 49 float cy = mConfig.getLightSourcePosition()[1]; 50 51 int polygonLength = polygon.length/3; 52 53 float opacity = .8f * (0.5f / (mConfig.getEdgeScale() / 10f)); 54 55 int trShift = 0; 56 for (int i = 0; i < polygonLength; ++i, trShift += 6) { 57 int shift = i * 4; 58 int colorShift = i * 8; 59 int idxShift = i * 2; 60 61 float px = polygon[3 * i + 0]; 62 float py = polygon[3 * i + 1]; 63 mVertex[shift + 0] = px; 64 mVertex[shift + 1] = py; 65 66 // TODO: I do not really understand this but this matches the previous behavior. 67 // The weird bit is that for outlines with low elevation the ambient shadow is 68 // entirely drawn underneath the shadow caster. This is most probably incorrect 69 float h = polygon[3 * i + 2] * mConfig.getShadowBoundRatio(); 70 71 mVertex[shift + 2] = cx + h * (px - cx); 72 mVertex[shift + 3] = cy + h * (py - cy); 73 74 mColor[colorShift + 3] = opacity; 75 76 mIndex[trShift + 0] = idxShift + 0; 77 mIndex[trShift + 1] = idxShift + 1; 78 mIndex[trShift + 2] = idxShift + 2; 79 80 mIndex[trShift + 3] = idxShift + 1; 81 mIndex[trShift + 4] = idxShift + 2; 82 mIndex[trShift + 5] = idxShift + 3; 83 } 84 // cycle back to the front 85 mIndex[trShift - 1] = 1; 86 mIndex[trShift - 2] = 0; 87 mIndex[trShift - 4] = 0; 88 89 // Filling the shadow right under the outline. Can we skip that? 90 for (int i = 1; i < polygonLength - 1; ++i, trShift += 3) { 91 mIndex[trShift + 0] = 0; 92 mIndex[trShift + 1] = 2 * i; 93 mIndex[trShift + 2] = 2 * (i+1); 94 } 95 } 96 getIndex()97 public int[] getIndex() { 98 return mIndex; 99 } 100 101 /** 102 * @return list of vertices in 2d in format : {x1, y1, x2, y2 ...} 103 */ getVertex()104 public float[] getVertex() { 105 return mVertex; 106 } 107 getColor()108 public float[] getColor() { 109 return mColor; 110 } 111 } 112