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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 "Extensions.h"
     18 #include "Properties.h"
     19 #include "Stencil.h"
     20 
     21 #include <GLES2/gl2ext.h>
     22 
     23 namespace android {
     24 namespace uirenderer {
     25 
     26 #if DEBUG_STENCIL
     27 #define STENCIL_WRITE_VALUE 0xff
     28 #define STENCIL_MASK_VALUE 0xff
     29 #else
     30 #define STENCIL_WRITE_VALUE 0x1
     31 #define STENCIL_MASK_VALUE 0x1
     32 #endif
     33 
     34 Stencil::Stencil(): mState(kDisabled) {
     35 }
     36 
     37 uint32_t Stencil::getStencilSize() {
     38     return STENCIL_BUFFER_SIZE;
     39 }
     40 
     41 GLenum Stencil::getSmallestStencilFormat() {
     42 #if !DEBUG_STENCIL
     43     const Extensions& extensions = Extensions::getInstance();
     44     if (extensions.has1BitStencil()) {
     45         return GL_STENCIL_INDEX1_OES;
     46     } else if (extensions.has4BitStencil()) {
     47         return GL_STENCIL_INDEX4_OES;
     48     }
     49 #endif
     50     return GL_STENCIL_INDEX8;
     51 }
     52 
     53 void Stencil::clear() {
     54     glClearStencil(0);
     55     glClear(GL_STENCIL_BUFFER_BIT);
     56 }
     57 
     58 void Stencil::enableTest() {
     59     if (mState != kTest) {
     60         enable();
     61         glStencilFunc(GL_EQUAL, STENCIL_WRITE_VALUE, STENCIL_MASK_VALUE);
     62         // We only want to test, let's keep everything
     63         glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
     64         glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
     65         mState = kTest;
     66     }
     67 }
     68 
     69 void Stencil::enableWrite() {
     70     if (mState != kWrite) {
     71         enable();
     72         glStencilFunc(GL_ALWAYS, STENCIL_WRITE_VALUE, STENCIL_MASK_VALUE);
     73         // The test always passes so the first two values are meaningless
     74         glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
     75         glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
     76         mState = kWrite;
     77     }
     78 }
     79 
     80 void Stencil::enableDebugTest(GLint value, bool greater) {
     81     enable();
     82     glStencilFunc(greater ? GL_LESS : GL_EQUAL, value, 0xffffffff);
     83     // We only want to test, let's keep everything
     84     glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
     85     mState = kTest;
     86 }
     87 
     88 void Stencil::enableDebugWrite() {
     89     if (mState != kWrite) {
     90         enable();
     91         glStencilFunc(GL_ALWAYS, 0x1, 0xffffffff);
     92         // The test always passes so the first two values are meaningless
     93         glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);
     94         glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
     95         mState = kWrite;
     96     }
     97 }
     98 
     99 void Stencil::enable() {
    100     if (mState == kDisabled) {
    101         glEnable(GL_STENCIL_TEST);
    102     }
    103 }
    104 
    105 void Stencil::disable() {
    106     if (mState != kDisabled) {
    107         glDisable(GL_STENCIL_TEST);
    108         mState = kDisabled;
    109     }
    110 }
    111 
    112 }; // namespace uirenderer
    113 }; // namespace android
    114