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
TextureState()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
~TextureState()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 */
computeShadowOpacity(float ratio)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
constructTexture(Caches & caches)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
activateTexture(GLuint textureUnit)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
resetActiveTexture()91 void TextureState::resetActiveTexture() {
92 mTextureUnit = -1;
93 }
94
bindTexture(GLuint texture)95 void TextureState::bindTexture(GLuint texture) {
96 if (mBoundTextures[mTextureUnit] != texture) {
97 glBindTexture(GL_TEXTURE_2D, texture);
98 mBoundTextures[mTextureUnit] = texture;
99 }
100 }
101
bindTexture(GLenum target,GLuint texture)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
deleteTexture(GLuint texture)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
resetBoundTextures()132 void TextureState::resetBoundTextures() {
133 for (int i = 0; i < kTextureUnitsCount; i++) {
134 mBoundTextures[i] = 0;
135 }
136 }
137
unbindTexture(GLuint texture)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