ShadowTessellator.cpp revision 7b3dfa4d13ca79404f8b0be6e47002cf8daff0a2 
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
19#include <math.h>
20#include <utils/Log.h>
21
22#include "AmbientShadow.h"
23#include "ShadowTessellator.h"
24#include "SpotShadow.h"
25
26namespace android {
27namespace uirenderer {
28
29template<typename T>
30static inline T max(T a, T b) {
31    return a > b ? a : b;
32}
33
34// TODO: Support path as the input of the polygon instead of the rect's width
35// and height. And the z values need to be computed according to the
36// transformation for each vertex.
37/**
38 * Generate the polygon for the caster.
39 *
40 * @param width the width of the caster
41 * @param height the height of the caster
42 * @param casterTransform transformation info of the caster
43 * @param polygon return the caster's polygon
44 *
45 */
46void ShadowTessellator::generateCasterPolygon(float width, float height,
47        const mat4& casterTransform, int vertexCount, Vector3* polygon) {
48    Rect blockRect(0, 0, width, height);
49    polygon[0].x = blockRect.left;
50    polygon[0].y = blockRect.top;
51    polygon[0].z = 0;
52    polygon[1].x = blockRect.right;
53    polygon[1].y = blockRect.top;
54    polygon[1].z = 0;
55    polygon[2].x = blockRect.right;
56    polygon[2].y = blockRect.bottom;
57    polygon[2].z = 0;
58    polygon[3].x = blockRect.left;
59    polygon[3].y = blockRect.bottom;
60    polygon[3].z = 0;
61    casterTransform.mapPoint3d(polygon[0]);
62    casterTransform.mapPoint3d(polygon[1]);
63    casterTransform.mapPoint3d(polygon[2]);
64    casterTransform.mapPoint3d(polygon[3]);
65}
66
67void ShadowTessellator::tessellateAmbientShadow(float width, float height,
68        const mat4& casterTransform, VertexBuffer& shadowVertexBuffer) {
69
70    const int vertexCount = 4;
71    Vector3 polygon[vertexCount];
72    generateCasterPolygon(width, height, casterTransform, vertexCount, polygon);
73
74    // A bunch of parameters to tweak the shadow.
75    // TODO: Allow some of these changable by debug settings or APIs.
76    const int rays = 128;
77    const int layers = 2;
78    const float strength = 0.5;
79    const float heightFactor = 128;
80    const float geomFactor = 64;
81
82    AmbientShadow::createAmbientShadow(polygon, vertexCount, rays, layers, strength,
83            heightFactor, geomFactor, shadowVertexBuffer);
84
85}
86
87void ShadowTessellator::tessellateSpotShadow(float width, float height,
88        int screenWidth, int screenHeight,
89        const mat4& casterTransform, VertexBuffer& shadowVertexBuffer) {
90    const int vertexCount = 4;
91    Vector3 polygon[vertexCount];
92    generateCasterPolygon(width, height, casterTransform, vertexCount, polygon);
93
94    // A bunch of parameters to tweak the shadow.
95    // TODO: Allow some of these changable by debug settings or APIs.
96    const int rays = 256;
97    const int layers = 2;
98    const float strength = 0.5;
99    int maximal = max(screenWidth, screenHeight);
100    Vector3 lightCenter(screenWidth / 2, 0, maximal);
101#if DEBUG_SHADOW
102    ALOGD("light center %f %f %f", lightCenter.x, lightCenter.y, lightCenter.z);
103#endif
104    const float lightSize = maximal / 8;
105    const int lightVertexCount = 16;
106
107    SpotShadow::createSpotShadow(polygon, vertexCount, lightCenter, lightSize,
108            lightVertexCount, rays, layers, strength, shadowVertexBuffer);
109
110}
111}; // namespace uirenderer
112}; // namespace android
113