1/*
2 * Copyright (C) 2012 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#include "renderstate/Stencil.h"
18
19#include "Caches.h"
20#include "Debug.h"
21#include "Extensions.h"
22#include "Properties.h"
23
24#include <GLES2/gl2ext.h>
25
26namespace android {
27namespace uirenderer {
28
29#if DEBUG_STENCIL
30#define STENCIL_WRITE_VALUE 0xff
31#define STENCIL_MASK_VALUE 0xff
32#else
33#define STENCIL_WRITE_VALUE 0x1
34#define STENCIL_MASK_VALUE 0x1
35#endif
36
37uint8_t Stencil::getStencilSize() {
38    return STENCIL_BUFFER_SIZE;
39}
40
41/**
42 * This method will return either GL_STENCIL_INDEX4_OES if supported,
43 * GL_STENCIL_INDEX8 if not.
44 *
45 * Layers can't use a single bit stencil because multi-rect ClipArea needs a high enough
46 * stencil resolution to represent the summation of multiple intersecting rect geometries.
47 */
48GLenum Stencil::getLayerStencilFormat() {
49#if !DEBUG_STENCIL
50    const Extensions& extensions = Caches::getInstance().extensions();
51    if (extensions.has4BitStencil()) {
52        return GL_STENCIL_INDEX4_OES;
53    }
54#endif
55    return GL_STENCIL_INDEX8;
56}
57
58void Stencil::clear() {
59    glStencilMask(0xff);
60    glClearStencil(0);
61    glClear(GL_STENCIL_BUFFER_BIT);
62
63    if (mState == StencilState::Test) {
64        // reset to test state, with immutable stencil
65        glStencilMask(0);
66    }
67}
68
69void Stencil::enableTest(int incrementThreshold) {
70    if (mState != StencilState::Test) {
71        enable();
72        if (incrementThreshold > 0) {
73            glStencilFunc(GL_EQUAL, incrementThreshold, 0xff);
74        } else {
75            glStencilFunc(GL_EQUAL, STENCIL_WRITE_VALUE, STENCIL_MASK_VALUE);
76        }
77        // We only want to test, let's keep everything
78        glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
79        glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
80        glStencilMask(0);
81        mState = StencilState::Test;
82    }
83}
84
85void Stencil::enableWrite(int incrementThreshold) {
86    if (mState != StencilState::Write) {
87        enable();
88        if (incrementThreshold > 0) {
89            glStencilFunc(GL_ALWAYS, 1, 0xff);
90            // The test always passes so the first two values are meaningless
91            glStencilOp(GL_INCR, GL_INCR, GL_INCR);
92        } else {
93            glStencilFunc(GL_ALWAYS, STENCIL_WRITE_VALUE, STENCIL_MASK_VALUE);
94            // The test always passes so the first two values are meaningless
95            glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
96        }
97        glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
98        glStencilMask(0xff);
99        mState = StencilState::Write;
100    }
101}
102
103void Stencil::enableDebugTest(GLint value, bool greater) {
104    enable();
105    glStencilFunc(greater ? GL_LESS : GL_EQUAL, value, 0xffffffff);
106    // We only want to test, let's keep everything
107    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
108    mState = StencilState::Test;
109    glStencilMask(0);
110}
111
112void Stencil::enableDebugWrite() {
113    enable();
114    glStencilFunc(GL_ALWAYS, 0x1, 0xffffffff);
115    // The test always passes so the first two values are meaningless
116    glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);
117    glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
118    mState = StencilState::Write;
119    glStencilMask(0xff);
120}
121
122void Stencil::enable() {
123    if (mState == StencilState::Disabled) {
124        glEnable(GL_STENCIL_TEST);
125    }
126}
127
128void Stencil::disable() {
129    if (mState != StencilState::Disabled) {
130        glDisable(GL_STENCIL_TEST);
131        mState = StencilState::Disabled;
132    }
133}
134
135void Stencil::dump() {
136    ALOGD("Stencil: state %d", mState);
137}
138
139}; // namespace uirenderer
140}; // namespace android
141