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 glTexImage2D(GL_TEXTURE_2D, 0, GL_R16F, DITHER_KERNEL_SIZE, DITHER_KERNEL_SIZE, 0,
58 GL_RED, GL_FLOAT, &pattern);
59 } else {
60 const uint8_t pattern[] = {
61 0, 8, 2, 10,
62 12, 4, 14, 6,
63 3, 11, 1, 9,
64 15, 7, 13, 5
65 };
66
67 glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, DITHER_KERNEL_SIZE, DITHER_KERNEL_SIZE, 0,
68 GL_ALPHA, GL_UNSIGNED_BYTE, &pattern);
69 }
70
71 mInitialized = true;
72 } else {
73 mCaches.textureState().bindTexture(mDitherTexture);
74 }
75 }
76
clear()77 void Dither::clear() {
78 if (mInitialized) {
79 mCaches.textureState().deleteTexture(mDitherTexture);
80 mInitialized = false;
81 }
82 }
83
84 ///////////////////////////////////////////////////////////////////////////////
85 // Program management
86 ///////////////////////////////////////////////////////////////////////////////
87
setupProgram(Program & program,GLuint * textureUnit)88 void Dither::setupProgram(Program& program, GLuint* textureUnit) {
89 GLuint textureSlot = (*textureUnit)++;
90 mCaches.textureState().activateTexture(textureSlot);
91
92 bindDitherTexture();
93
94 glUniform1i(program.getUniform("ditherSampler"), textureSlot);
95 }
96
97 }; // namespace uirenderer
98 }; // namespace android
99