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      1 /*
      2  * Copyright (C) 2015 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 #include "renderstate/TextureState.h"
     17 
     18 #include "Caches.h"
     19 #include "utils/TraceUtils.h"
     20 
     21 #include <GLES3/gl3.h>
     22 #include <SkBitmap.h>
     23 #include <SkCanvas.h>
     24 #include <memory>
     25 
     26 namespace android {
     27 namespace uirenderer {
     28 
     29 // Width of mShadowLutTexture, defines how accurate the shadow alpha lookup table is
     30 static const int SHADOW_LUT_SIZE = 128;
     31 
     32 // Must define as many texture units as specified by kTextureUnitsCount
     33 const GLenum kTextureUnits[] = {GL_TEXTURE0, GL_TEXTURE1, GL_TEXTURE2, GL_TEXTURE3};
     34 
     35 TextureState::TextureState() : mTextureUnit(0) {
     36     glActiveTexture(kTextureUnits[0]);
     37     resetBoundTextures();
     38 
     39     GLint maxTextureUnits;
     40     glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &maxTextureUnits);
     41     LOG_ALWAYS_FATAL_IF(maxTextureUnits < kTextureUnitsCount,
     42                         "At least %d texture units are required!", kTextureUnitsCount);
     43     glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
     44 }
     45 
     46 TextureState::~TextureState() {
     47     if (mShadowLutTexture != nullptr) {
     48         mShadowLutTexture->deleteTexture();
     49     }
     50 }
     51 
     52 /**
     53  * Maps shadow geometry 'alpha' varying (1 for darkest, 0 for transparent) to
     54  * darkness at that spot. Input values of 0->1 should be mapped within the same
     55  * range, but can affect the curve for a different visual falloff.
     56  *
     57  * This is used to populate the shadow LUT texture for quick lookup in the
     58  * shadow shader.
     59  */
     60 static float computeShadowOpacity(float ratio) {
     61     // exponential falloff function provided by UX
     62     float val = 1 - ratio;
     63     return exp(-val * val * 4.0) - 0.018;
     64 }
     65 
     66 void TextureState::constructTexture(Caches& caches) {
     67     if (mShadowLutTexture == nullptr) {
     68         mShadowLutTexture.reset(new Texture(caches));
     69 
     70         unsigned char bytes[SHADOW_LUT_SIZE];
     71         for (int i = 0; i < SHADOW_LUT_SIZE; i++) {
     72             float inputRatio = i / (SHADOW_LUT_SIZE - 1.0f);
     73             bytes[i] = computeShadowOpacity(inputRatio) * 255;
     74         }
     75         mShadowLutTexture->upload(GL_ALPHA, SHADOW_LUT_SIZE, 1, GL_ALPHA, GL_UNSIGNED_BYTE, &bytes);
     76         mShadowLutTexture->setFilter(GL_LINEAR);
     77         mShadowLutTexture->setWrap(GL_CLAMP_TO_EDGE);
     78     }
     79 }
     80 
     81 void TextureState::activateTexture(GLuint textureUnit) {
     82     LOG_ALWAYS_FATAL_IF(textureUnit >= kTextureUnitsCount,
     83                         "Tried to use texture unit index %d, only %d exist", textureUnit,
     84                         kTextureUnitsCount);
     85     if (mTextureUnit != textureUnit) {
     86         glActiveTexture(kTextureUnits[textureUnit]);
     87         mTextureUnit = textureUnit;
     88     }
     89 }
     90 
     91 void TextureState::resetActiveTexture() {
     92     mTextureUnit = -1;
     93 }
     94 
     95 void TextureState::bindTexture(GLuint texture) {
     96     if (mBoundTextures[mTextureUnit] != texture) {
     97         glBindTexture(GL_TEXTURE_2D, texture);
     98         mBoundTextures[mTextureUnit] = texture;
     99     }
    100 }
    101 
    102 void TextureState::bindTexture(GLenum target, GLuint texture) {
    103     if (target == GL_TEXTURE_2D) {
    104         bindTexture(texture);
    105     } else {
    106         // GLConsumer directly calls glBindTexture() with
    107         // target=GL_TEXTURE_EXTERNAL_OES, don't cache this target
    108         // since the cached state could be stale
    109         glBindTexture(target, texture);
    110     }
    111 }
    112 
    113 void TextureState::deleteTexture(GLuint texture) {
    114     // When glDeleteTextures() is called on a currently bound texture,
    115     // OpenGL ES specifies that the texture is then considered unbound
    116     // Consider the following series of calls:
    117     //
    118     // glGenTextures -> creates texture name 2
    119     // glBindTexture(2)
    120     // glDeleteTextures(2) -> 2 is now unbound
    121     // glGenTextures -> can return 2 again
    122     //
    123     // If we don't call glBindTexture(2) after the second glGenTextures
    124     // call, any texture operation will be performed on the default
    125     // texture (name=0)
    126 
    127     unbindTexture(texture);
    128 
    129     glDeleteTextures(1, &texture);
    130 }
    131 
    132 void TextureState::resetBoundTextures() {
    133     for (int i = 0; i < kTextureUnitsCount; i++) {
    134         mBoundTextures[i] = 0;
    135     }
    136 }
    137 
    138 void TextureState::unbindTexture(GLuint texture) {
    139     for (int i = 0; i < kTextureUnitsCount; i++) {
    140         if (mBoundTextures[i] == texture) {
    141             mBoundTextures[i] = 0;
    142         }
    143     }
    144 }
    145 
    146 } /* namespace uirenderer */
    147 } /* namespace android */
    148