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      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 
     26 namespace android {
     27 namespace 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 
     37 uint8_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  */
     48 GLenum 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 
     58 void 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 
     69 void 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 
     85 void 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 
    103 void 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 
    112 void 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 
    122 void Stencil::enable() {
    123     if (mState == StencilState::Disabled) {
    124         glEnable(GL_STENCIL_TEST);
    125     }
    126 }
    127 
    128 void Stencil::disable() {
    129     if (mState != StencilState::Disabled) {
    130         glDisable(GL_STENCIL_TEST);
    131         mState = StencilState::Disabled;
    132     }
    133 }
    134 
    135 void Stencil::dump() {
    136     ALOGD("Stencil: state %d", mState);
    137 }
    138 
    139 }; // namespace uirenderer
    140 }; // namespace android
    141