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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 "Debug.h"
     18 #include "Extensions.h"
     19 #include "Properties.h"
     20 #include "Stencil.h"
     21 
     22 #include <GLES2/gl2ext.h>
     23 
     24 namespace android {
     25 namespace uirenderer {
     26 
     27 #if DEBUG_STENCIL
     28 #define STENCIL_WRITE_VALUE 0xff
     29 #define STENCIL_MASK_VALUE 0xff
     30 #else
     31 #define STENCIL_WRITE_VALUE 0x1
     32 #define STENCIL_MASK_VALUE 0x1
     33 #endif
     34 
     35 Stencil::Stencil(): mState(kDisabled) {
     36 }
     37 
     38 uint32_t Stencil::getStencilSize() {
     39     return STENCIL_BUFFER_SIZE;
     40 }
     41 
     42 GLenum Stencil::getSmallestStencilFormat() {
     43 #if !DEBUG_STENCIL
     44     const Extensions& extensions = Extensions::getInstance();
     45     if (extensions.has1BitStencil()) {
     46         return GL_STENCIL_INDEX1_OES;
     47     } else if (extensions.has4BitStencil()) {
     48         return GL_STENCIL_INDEX4_OES;
     49     }
     50 #endif
     51     return GL_STENCIL_INDEX8;
     52 }
     53 
     54 void Stencil::clear() {
     55     glClearStencil(0);
     56     glClear(GL_STENCIL_BUFFER_BIT);
     57 }
     58 
     59 void Stencil::enableTest() {
     60     if (mState != kTest) {
     61         enable();
     62         glStencilFunc(GL_EQUAL, STENCIL_WRITE_VALUE, STENCIL_MASK_VALUE);
     63         // We only want to test, let's keep everything
     64         glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
     65         glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
     66         mState = kTest;
     67     }
     68 }
     69 
     70 void Stencil::enableWrite() {
     71     if (mState != kWrite) {
     72         enable();
     73         glStencilFunc(GL_ALWAYS, STENCIL_WRITE_VALUE, STENCIL_MASK_VALUE);
     74         // The test always passes so the first two values are meaningless
     75         glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
     76         glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
     77         mState = kWrite;
     78     }
     79 }
     80 
     81 void Stencil::enableDebugTest(GLint value, bool greater) {
     82     enable();
     83     glStencilFunc(greater ? GL_LESS : GL_EQUAL, value, 0xffffffff);
     84     // We only want to test, let's keep everything
     85     glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
     86     mState = kTest;
     87 }
     88 
     89 void Stencil::enableDebugWrite() {
     90     if (mState != kWrite) {
     91         enable();
     92         glStencilFunc(GL_ALWAYS, 0x1, 0xffffffff);
     93         // The test always passes so the first two values are meaningless
     94         glStencilOp(GL_KEEP, GL_KEEP, GL_INCR);
     95         glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
     96         mState = kWrite;
     97     }
     98 }
     99 
    100 void Stencil::enable() {
    101     if (mState == kDisabled) {
    102         glEnable(GL_STENCIL_TEST);
    103     }
    104 }
    105 
    106 void Stencil::disable() {
    107     if (mState != kDisabled) {
    108         glDisable(GL_STENCIL_TEST);
    109         mState = kDisabled;
    110     }
    111 }
    112 
    113 }; // namespace uirenderer
    114 }; // namespace android
    115