032d47af73
This is a more elegant way to sample from a float alpha texture. Instead of sampling from the red channel in the fragment shader we can set the alpha channel swizzle to redirect it to the red channel. This lets us sample from the alpha channel in the fragment shader and get the correct value. Change-Id: I95bbf7a82964e1bf42c0fee1b782b6bdbbcef618
96 lines
3.3 KiB
C++
96 lines
3.3 KiB
C++
/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "Caches.h"
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#include "Dither.h"
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namespace android {
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namespace uirenderer {
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///////////////////////////////////////////////////////////////////////////////
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// Lifecycle
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///////////////////////////////////////////////////////////////////////////////
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void Dither::bindDitherTexture() {
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if (!mInitialized) {
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bool useFloatTexture = Extensions::getInstance().getMajorGlVersion() >= 3;
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glGenTextures(1, &mDitherTexture);
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glBindTexture(GL_TEXTURE_2D, mDitherTexture);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
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if (useFloatTexture) {
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// We use a R16F texture, let's remap the alpha channel to the
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// red channel to avoid changing the shader sampling code on GL ES 3.0+
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glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_SWIZZLE_A, GL_RED);
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float dither = 1.0f / (255.0f * DITHER_KERNEL_SIZE * DITHER_KERNEL_SIZE);
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const GLfloat pattern[] = {
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0 * dither, 8 * dither, 2 * dither, 10 * dither,
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12 * dither, 4 * dither, 14 * dither, 6 * dither,
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3 * dither, 11 * dither, 1 * dither, 9 * dither,
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15 * dither, 7 * dither, 13 * dither, 5 * dither
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};
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glPixelStorei(GL_UNPACK_ALIGNMENT, sizeof(GLfloat));
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glTexImage2D(GL_TEXTURE_2D, 0, GL_R16F, DITHER_KERNEL_SIZE, DITHER_KERNEL_SIZE, 0,
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GL_RED, GL_FLOAT, &pattern);
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} else {
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const uint8_t pattern[] = {
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0, 8, 2, 10,
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12, 4, 14, 6,
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3, 11, 1, 9,
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15, 7, 13, 5
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};
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glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
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glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, DITHER_KERNEL_SIZE, DITHER_KERNEL_SIZE, 0,
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GL_ALPHA, GL_UNSIGNED_BYTE, &pattern);
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}
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mInitialized = true;
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} else {
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glBindTexture(GL_TEXTURE_2D, mDitherTexture);
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}
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}
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void Dither::clear() {
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if (mInitialized) {
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glDeleteTextures(1, &mDitherTexture);
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}
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}
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///////////////////////////////////////////////////////////////////////////////
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// Program management
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///////////////////////////////////////////////////////////////////////////////
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void Dither::setupProgram(Program* program, GLuint* textureUnit) {
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GLuint textureSlot = (*textureUnit)++;
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Caches::getInstance().activeTexture(textureSlot);
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bindDitherTexture();
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glUniform1i(program->getUniform("ditherSampler"), textureSlot);
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}
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}; // namespace uirenderer
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}; // namespace android
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