1 2 /* 3 * Copyright (C) 2013 The Android Open Source Project 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 18 #ifndef ANDROID_HWUI_SHADOW_TESSELLATOR_H 19 #define ANDROID_HWUI_SHADOW_TESSELLATOR_H 20 21 #include "Debug.h" 22 #include "Matrix.h" 23 #include "OpenGLRenderer.h" 24 #include "VertexBuffer.h" 25 26 namespace android { 27 namespace uirenderer { 28 29 // All SHADOW_* are used to define all the geometry property of shadows. 30 // Use a simplified example to illustrate the geometry setup here. 31 // Assuming we use 6 rays and only 1 layer, Then we will have 2 hexagons, which 32 // are 0 to 5 and 6 to 11. The area between them will be the penumbra area, and 33 // the area inside the 2nd hexagon is the umbra. 34 // Ambient shadow is using only 1 layer for opaque caster, otherwise, spot 35 // shadow and ambient shadow are using 2 layers. 36 // Triange strip indices for penumbra area: (0, 6, 1, 7, 2, 8, 3, 9, 4, 10, 5, 11, 0, 6) 37 // 0 38 // 39 // 5 6 1 40 // 11 7 41 // 42 // 10 8 43 // 4 9 2 44 // 45 // 3 46 47 // The total number of rays starting from the centroid of shadow area, in order 48 // to generate the shadow geometry. 49 #define SHADOW_RAY_COUNT 128 50 51 // The total number of all the vertices representing the shadow. 52 // For the case we only have 1 layer, then we will just fill only 2/3 of it. 53 #define SHADOW_VERTEX_COUNT (3 * SHADOW_RAY_COUNT) 54 55 // The total number of indices used for drawing the shadow geometry as triangle strips. 56 // Depending on the mode we are drawing, we can have 1 layer or 2 layers. 57 // Therefore, we only build the longer index buffer. 58 #define TWO_POLY_RING_SHADOW_INDEX_COUNT (4 * (SHADOW_RAY_COUNT + 1)) 59 #define ONE_POLY_RING_SHADOW_INDEX_COUNT (2 * (SHADOW_RAY_COUNT + 1)) 60 61 #define MAX_SHADOW_INDEX_COUNT TWO_POLY_RING_SHADOW_INDEX_COUNT 62 63 #define SHADOW_MIN_CASTER_Z 0.001f 64 65 #define MINIMAL_DELTA_THETA (M_PI / 180 / 1000) 66 67 class ShadowTessellator { 68 public: 69 static void tessellateAmbientShadow(bool isCasterOpaque, 70 const Vector3* casterPolygon, int casterVertexCount, 71 const Vector3& centroid3d, const Rect& casterBounds, 72 const Rect& localClip, float maxZ, VertexBuffer& shadowVertexBuffer); 73 74 static void tessellateSpotShadow(bool isCasterOpaque, 75 const Vector3* casterPolygon, int casterVertexCount, const Vector3& casterCentroid, 76 const mat4& receiverTransform, const Vector3& lightCenter, int lightRadius, 77 const Rect& casterBounds, const Rect& localClip, VertexBuffer& shadowVertexBuffer); 78 79 static void generateShadowIndices(uint16_t* shadowIndices); 80 81 static Vector2 centroid2d(const Vector2* poly, int polyLength); 82 83 static bool isClockwise(const Vector2* polygon, int len); 84 85 static Vector2 calculateNormal(const Vector2& p1, const Vector2& p2); 86 /** 87 * Determine whether the path is clockwise, using the control points. 88 * 89 * TODO: Given the skia is using inverted Y coordinate, shadow system needs 90 * to convert to the same coordinate to avoid the extra reverse. 91 * 92 * @param path The path to be examined. 93 */ 94 static bool isClockwisePath(const SkPath &path); 95 96 /** 97 * Reverse the vertex array. 98 * 99 * @param polygon The vertex array to be reversed. 100 * @param len The length of the vertex array. 101 */ 102 static void reverseVertexArray(Vertex* polygon, int len); 103 104 static int getExtraVertexNumber(const Vector2& vector1, const Vector2& vector2, 105 float divisor); 106 107 static void checkOverflow(int used, int total, const char* bufferName); 108 }; // ShadowTessellator 109 110 }; // namespace uirenderer 111 }; // namespace android 112 113 #endif // ANDROID_HWUI_SHADOW_TESSELLATOR_H 114