Home | History | Annotate | Download | only in hwui 
      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