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 <memory>
23 #include <SkCanvas.h>
24 #include <SkBitmap.h>
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[] = {
34 GL_TEXTURE0,
35 GL_TEXTURE1,
36 GL_TEXTURE2,
37 GL_TEXTURE3
38 };
39
TextureState()40 TextureState::TextureState()
41 : mTextureUnit(0) {
42 glActiveTexture(kTextureUnits[0]);
43 resetBoundTextures();
44
45 GLint maxTextureUnits;
46 glGetIntegerv(GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS, &maxTextureUnits);
47 LOG_ALWAYS_FATAL_IF(maxTextureUnits < kTextureUnitsCount,
48 "At least %d texture units are required!", kTextureUnitsCount);
49 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
50 }
51
~TextureState()52 TextureState::~TextureState() {
53 if (mShadowLutTexture != nullptr) {
54 mShadowLutTexture->deleteTexture();
55 }
56 }
57
58 /**
59 * Maps shadow geometry 'alpha' varying (1 for darkest, 0 for transparent) to
60 * darkness at that spot. Input values of 0->1 should be mapped within the same
61 * range, but can affect the curve for a different visual falloff.
62 *
63 * This is used to populate the shadow LUT texture for quick lookup in the
64 * shadow shader.
65 */
computeShadowOpacity(float ratio)66 static float computeShadowOpacity(float ratio) {
67 // exponential falloff function provided by UX
68 float val = 1 - ratio;
69 return exp(-val * val * 4.0) - 0.018;
70 }
71
constructTexture(Caches & caches)72 void TextureState::constructTexture(Caches& caches) {
73 if (mShadowLutTexture == nullptr) {
74 mShadowLutTexture.reset(new Texture(caches));
75
76 unsigned char bytes[SHADOW_LUT_SIZE];
77 for (int i = 0; i < SHADOW_LUT_SIZE; i++) {
78 float inputRatio = i / (SHADOW_LUT_SIZE - 1.0f);
79 bytes[i] = computeShadowOpacity(inputRatio) * 255;
80 }
81 mShadowLutTexture->upload(GL_ALPHA, SHADOW_LUT_SIZE, 1, GL_ALPHA, GL_UNSIGNED_BYTE, &bytes);
82 mShadowLutTexture->setFilter(GL_LINEAR);
83 mShadowLutTexture->setWrap(GL_CLAMP_TO_EDGE);
84 }
85 }
86
activateTexture(GLuint textureUnit)87 void TextureState::activateTexture(GLuint textureUnit) {
88 LOG_ALWAYS_FATAL_IF(textureUnit >= kTextureUnitsCount,
89 "Tried to use texture unit index %d, only %d exist",
90 textureUnit, kTextureUnitsCount);
91 if (mTextureUnit != textureUnit) {
92 glActiveTexture(kTextureUnits[textureUnit]);
93 mTextureUnit = textureUnit;
94 }
95 }
96
resetActiveTexture()97 void TextureState::resetActiveTexture() {
98 mTextureUnit = -1;
99 }
100
bindTexture(GLuint texture)101 void TextureState::bindTexture(GLuint texture) {
102 if (mBoundTextures[mTextureUnit] != texture) {
103 glBindTexture(GL_TEXTURE_2D, texture);
104 mBoundTextures[mTextureUnit] = texture;
105 }
106 }
107
bindTexture(GLenum target,GLuint texture)108 void TextureState::bindTexture(GLenum target, GLuint texture) {
109 if (target == GL_TEXTURE_2D) {
110 bindTexture(texture);
111 } else {
112 // GLConsumer directly calls glBindTexture() with
113 // target=GL_TEXTURE_EXTERNAL_OES, don't cache this target
114 // since the cached state could be stale
115 glBindTexture(target, texture);
116 }
117 }
118
deleteTexture(GLuint texture)119 void TextureState::deleteTexture(GLuint texture) {
120 // When glDeleteTextures() is called on a currently bound texture,
121 // OpenGL ES specifies that the texture is then considered unbound
122 // Consider the following series of calls:
123 //
124 // glGenTextures -> creates texture name 2
125 // glBindTexture(2)
126 // glDeleteTextures(2) -> 2 is now unbound
127 // glGenTextures -> can return 2 again
128 //
129 // If we don't call glBindTexture(2) after the second glGenTextures
130 // call, any texture operation will be performed on the default
131 // texture (name=0)
132
133 unbindTexture(texture);
134
135 glDeleteTextures(1, &texture);
136 }
137
resetBoundTextures()138 void TextureState::resetBoundTextures() {
139 for (int i = 0; i < kTextureUnitsCount; i++) {
140 mBoundTextures[i] = 0;
141 }
142 }
143
unbindTexture(GLuint texture)144 void TextureState::unbindTexture(GLuint texture) {
145 for (int i = 0; i < kTextureUnitsCount; i++) {
146 if (mBoundTextures[i] == texture) {
147 mBoundTextures[i] = 0;
148 }
149 }
150 }
151
152 } /* namespace uirenderer */
153 } /* namespace android */
154
155