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