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 <SkPath.h>
22
23#include "Debug.h"
24#include "Matrix.h"
25
26namespace android {
27namespace uirenderer {
28
29class VertexBuffer;
30
31// All SHADOW_* are used to define all the geometry property of shadows.
32// Use a simplified example to illustrate the geometry setup here.
33// Assuming we use 6 rays and only 1 layer, Then we will have 2 hexagons, which
34// are 0 to 5 and 6 to 11. The area between them will be the penumbra area, and
35// the area inside the 2nd hexagon is the umbra.
36// Ambient shadow is using only 1 layer for opaque caster, otherwise, spot
37// shadow and ambient shadow are using 2 layers.
38// Triange strip indices for penumbra area: (0, 6, 1, 7, 2, 8, 3, 9, 4, 10, 5, 11, 0, 6)
39//                 0
40//
41//      5          6         1
42//           11         7
43//
44//           10         8
45//      4          9         2
46//
47//                 3
48
49// The total number of rays starting from the centroid of shadow area, in order
50// to generate the shadow geometry.
51#define SHADOW_RAY_COUNT 128
52
53// The total number of all the vertices representing the shadow.
54// For the case we only have 1 layer, then we will just fill only 2/3 of it.
55#define SHADOW_VERTEX_COUNT (3 * SHADOW_RAY_COUNT)
56
57// The total number of indices used for drawing the shadow geometry as triangle strips.
58// Depending on the mode we are drawing, we can have 1 layer or 2 layers.
59// Therefore, we only build the longer index buffer.
60#define TWO_POLY_RING_SHADOW_INDEX_COUNT (4 * (SHADOW_RAY_COUNT + 1))
61#define ONE_POLY_RING_SHADOW_INDEX_COUNT (2 * (SHADOW_RAY_COUNT + 1))
62
63#define MAX_SHADOW_INDEX_COUNT TWO_POLY_RING_SHADOW_INDEX_COUNT
64
65#define SHADOW_MIN_CASTER_Z 0.001f
66
67#define MINIMAL_DELTA_THETA (M_PI / 180 / 1000)
68
69class ShadowTessellator {
70public:
71    static void tessellateAmbientShadow(bool isCasterOpaque,
72            const Vector3* casterPolygon, int casterVertexCount,
73            const Vector3& centroid3d,  const Rect& casterBounds,
74            const Rect& localClip, float maxZ, VertexBuffer& shadowVertexBuffer);
75
76    static void tessellateSpotShadow(bool isCasterOpaque,
77            const Vector3* casterPolygon, int casterVertexCount, const Vector3& casterCentroid,
78            const mat4& receiverTransform, const Vector3& lightCenter, int lightRadius,
79            const Rect& casterBounds, const Rect& localClip, VertexBuffer& shadowVertexBuffer);
80
81    static Vector2 centroid2d(const Vector2* poly, int polyLength);
82
83    static Vector2 calculateNormal(const Vector2& p1, const Vector2& p2);
84
85    static int getExtraVertexNumber(const Vector2& vector1, const Vector2& vector2,
86            float divisor);
87
88    static void checkOverflow(int used, int total, const char* bufferName);
89}; // ShadowTessellator
90
91}; // namespace uirenderer
92}; // namespace android
93
94#endif // ANDROID_HWUI_SHADOW_TESSELLATOR_H
95