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 "Caches.h"
18 #include "Dither.h"
19
20 namespace android {
21 namespace uirenderer {
22
23 ///////////////////////////////////////////////////////////////////////////////
24 // Lifecycle
25 ///////////////////////////////////////////////////////////////////////////////
26
Dither(Caches & caches)27 Dither::Dither(Caches& caches)
28 : mCaches(caches)
29 , mInitialized(false)
30 , mDitherTexture(0) {
31 }
32
bindDitherTexture()33 void Dither::bindDitherTexture() {
34 if (!mInitialized) {
35 glGenTextures(1, &mDitherTexture);
36 mCaches.textureState().bindTexture(mDitherTexture);
37
38 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
39 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
40
41 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
42 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
43
44 if (mCaches.extensions().hasFloatTextures()) {
45 // We use a R16F texture, let's remap the alpha channel to the
46 // red channel to avoid changing the shader sampling code on GL ES 3.0+
47 glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_SWIZZLE_A, GL_RED);
48
49 float dither = 1.0f / (255.0f * DITHER_KERNEL_SIZE * DITHER_KERNEL_SIZE);
50 const GLfloat pattern[] = {
51 0 * dither, 8 * dither, 2 * dither, 10 * dither,
52 12 * dither, 4 * dither, 14 * dither, 6 * dither,
53 3 * dither, 11 * dither, 1 * dither, 9 * dither,
54 15 * dither, 7 * dither, 13 * dither, 5 * dither
55 };
56
57 glPixelStorei(GL_UNPACK_ALIGNMENT, sizeof(GLfloat));
58 glTexImage2D(GL_TEXTURE_2D, 0, GL_R16F, DITHER_KERNEL_SIZE, DITHER_KERNEL_SIZE, 0,
59 GL_RED, GL_FLOAT, &pattern);
60 } else {
61 const uint8_t pattern[] = {
62 0, 8, 2, 10,
63 12, 4, 14, 6,
64 3, 11, 1, 9,
65 15, 7, 13, 5
66 };
67
68 glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
69 glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, DITHER_KERNEL_SIZE, DITHER_KERNEL_SIZE, 0,
70 GL_ALPHA, GL_UNSIGNED_BYTE, &pattern);
71 }
72
73 mInitialized = true;
74 } else {
75 mCaches.textureState().bindTexture(mDitherTexture);
76 }
77 }
78
clear()79 void Dither::clear() {
80 if (mInitialized) {
81 mCaches.textureState().deleteTexture(mDitherTexture);
82 mInitialized = false;
83 }
84 }
85
86 ///////////////////////////////////////////////////////////////////////////////
87 // Program management
88 ///////////////////////////////////////////////////////////////////////////////
89
setupProgram(Program & program,GLuint * textureUnit)90 void Dither::setupProgram(Program& program, GLuint* textureUnit) {
91 GLuint textureSlot = (*textureUnit)++;
92 mCaches.textureState().activateTexture(textureSlot);
93
94 bindDitherTexture();
95
96 glUniform1i(program.getUniform("ditherSampler"), textureSlot);
97 }
98
99 }; // namespace uirenderer
100 }; // namespace android
101